/* vi: set sw=4 ts=4: */
/*
 * awk implementation for busybox
 *
 * Copyright (C) 2002 by Dmitry Zakharov <dmit@crp.bank.gov.ua>
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
//config:config AWK
//config:       bool "awk (23 kb)"
//config:       default y
//config:       help
//config:       Awk is used as a pattern scanning and processing language.
//config:
//config:config FEATURE_AWK_LIBM
//config:       bool "Enable math functions (requires libm)"
//config:       default y
//config:       depends on AWK
//config:       help
//config:       Enable math functions of the Awk programming language.
//config:       NOTE: This requires libm to be present for linking.
//config:
//config:config FEATURE_AWK_GNU_EXTENSIONS
//config:       bool "Enable a few GNU extensions"
//config:       default y
//config:       depends on AWK
//config:       help
//config:       Enable a few features from gawk:
//config:       * command line option -e AWK_PROGRAM
//config:       * simultaneous use of -f and -e on the command line.
//config:       This enables the use of awk library files.
//config:       Example: awk -f mylib.awk -e '{print myfunction($1);}' ...

//applet:IF_AWK(APPLET_NOEXEC(awk, awk, BB_DIR_USR_BIN, BB_SUID_DROP, awk))

//kbuild:lib-$(CONFIG_AWK) += awk.o

//usage:#define awk_trivial_usage
//usage:       "[OPTIONS] [AWK_PROGRAM] [FILE]..."
//usage:#define awk_full_usage "\n\n"
//usage:       "        -v VAR=VAL      Set variable"
//usage:     "\n        -F SEP          Use SEP as field separator"
//usage:     "\n        -f FILE         Read program from FILE"
//usage:        IF_FEATURE_AWK_GNU_EXTENSIONS(
//usage:     "\n        -e AWK_PROGRAM"
//usage:        )

#include "libbb.h"
#include "xregex.h"
#include <math.h>

/* This is a NOEXEC applet. Be very careful! */


/* If you comment out one of these below, it will be #defined later
 * to perform debug printfs to stderr: */
#define debug_printf_walker(...)  do {} while (0)
#define debug_printf_eval(...)  do {} while (0)
#define debug_printf_parse(...)  do {} while (0)

#ifndef debug_printf_walker
# define debug_printf_walker(...) (fprintf(stderr, __VA_ARGS__))
#endif
#ifndef debug_printf_eval
# define debug_printf_eval(...) (fprintf(stderr, __VA_ARGS__))
#endif
#ifndef debug_printf_parse
# define debug_printf_parse(...) (fprintf(stderr, __VA_ARGS__))
#endif


/* "+": stop on first non-option:
 * $ awk 'BEGIN { for(i=1; i<ARGC; ++i) { print i ": " ARGV[i] }}' -argz
 * 1: -argz
 */
#define OPTSTR_AWK "+" \
        "F:v:*f:*" \
        IF_FEATURE_AWK_GNU_EXTENSIONS("e:*") \
        "W:"
enum {
        OPTBIT_F,       /* define field separator */
        OPTBIT_v,       /* define variable */
        OPTBIT_f,       /* pull in awk program from file */
        IF_FEATURE_AWK_GNU_EXTENSIONS(OPTBIT_e,) /* -e AWK_PROGRAM */
        OPTBIT_W,       /* -W ignored */
        OPT_F = 1 << OPTBIT_F,
        OPT_v = 1 << OPTBIT_v,
        OPT_f = 1 << OPTBIT_f,
        OPT_e = IF_FEATURE_AWK_GNU_EXTENSIONS((1 << OPTBIT_e)) + 0,
        OPT_W = 1 << OPTBIT_W
};

#define MAXVARFMT       240
#define MINNVBLOCK      64

/* variable flags */
#define VF_NUMBER       0x0001  /* 1 = primary type is number */
#define VF_ARRAY        0x0002  /* 1 = it's an array */

#define VF_CACHED       0x0100  /* 1 = num/str value has cached str/num eq */
#define VF_USER         0x0200  /* 1 = user input (may be numeric string) */
#define VF_SPECIAL      0x0400  /* 1 = requires extra handling when changed */
#define VF_WALK         0x0800  /* 1 = variable has alloc'd x.walker list */
#define VF_FSTR         0x1000  /* 1 = var::string points to fstring buffer */
#define VF_CHILD        0x2000  /* 1 = function arg; x.parent points to source */
#define VF_DIRTY        0x4000  /* 1 = variable was set explicitly */

/* these flags are static, don't change them when value is changed */
#define VF_DONTTOUCH    (VF_ARRAY | VF_SPECIAL | VF_WALK | VF_CHILD | VF_DIRTY)

typedef struct walker_list {
        char *end;
        char *cur;
        struct walker_list *prev;
        char wbuf[1];
} walker_list;

/* Variable */
typedef struct var_s {
        unsigned type;            /* flags */
        double number;
        char *string;
        union {
                int aidx;               /* func arg idx (for compilation stage) */
                struct xhash_s *array;  /* array ptr */
                struct var_s *parent;   /* for func args, ptr to actual parameter */
                walker_list *walker;    /* list of array elements (for..in) */
        } x;
} var;

/* Node chain (pattern-action chain, BEGIN, END, function bodies) */
typedef struct chain_s {
        struct node_s *first;
        struct node_s *last;
        const char *programname;
} chain;

/* Function */
typedef struct func_s {
        unsigned nargs;
        struct chain_s body;
} func;

/* I/O stream */
typedef struct rstream_s {
        FILE *F;
        char *buffer;
        int adv;
        int size;
        int pos;
        smallint is_pipe;
} rstream;

typedef struct hash_item_s {
        union {
                struct var_s v;         /* variable/array hash */
                struct rstream_s rs;    /* redirect streams hash */
                struct func_s f;        /* functions hash */
        } data;
        struct hash_item_s *next;       /* next in chain */
        char name[1];                   /* really it's longer */
} hash_item;

typedef struct xhash_s {
        unsigned nel;           /* num of elements */
        unsigned csize;         /* current hash size */
        unsigned nprime;        /* next hash size in PRIMES[] */
        unsigned glen;          /* summary length of item names */
        struct hash_item_s **items;
} xhash;

/* Tree node */
typedef struct node_s {
        uint32_t info;
        unsigned lineno;
        union {
                struct node_s *n;
                var *v;
                int aidx;
                char *new_progname;
                regex_t *re;
        } l;
        union {
                struct node_s *n;
                regex_t *ire;
                func *f;
        } r;
        union {
                struct node_s *n;
        } a;
} node;

/* Block of temporary variables */
typedef struct nvblock_s {
        int size;
        var *pos;
        struct nvblock_s *prev;
        struct nvblock_s *next;
        var nv[];
} nvblock;

typedef struct tsplitter_s {
        node n;
        regex_t re[2];
} tsplitter;

/* simple token classes */
/* Order and hex values are very important!!!  See next_token() */
#define TC_SEQSTART     (1 << 0)                /* ( */
#define TC_SEQTERM      (1 << 1)                /* ) */
#define TC_REGEXP       (1 << 2)                /* /.../ */
#define TC_OUTRDR       (1 << 3)                /* | > >> */
#define TC_UOPPOST      (1 << 4)                /* unary postfix operator */
#define TC_UOPPRE1      (1 << 5)                /* unary prefix operator */
#define TC_BINOPX       (1 << 6)                /* two-opnd operator */
#define TC_IN           (1 << 7)
#define TC_COMMA        (1 << 8)
#define TC_PIPE         (1 << 9)                /* input redirection pipe */
#define TC_UOPPRE2      (1 << 10)               /* unary prefix operator */
#define TC_ARRTERM      (1 << 11)               /* ] */
#define TC_GRPSTART     (1 << 12)               /* { */
#define TC_GRPTERM      (1 << 13)               /* } */
#define TC_SEMICOL      (1 << 14)
#define TC_NEWLINE      (1 << 15)
#define TC_STATX        (1 << 16)               /* ctl statement (for, next...) */
#define TC_WHILE        (1 << 17)
#define TC_ELSE         (1 << 18)
#define TC_BUILTIN      (1 << 19)
/* This costs ~50 bytes of code.
 * A separate class to support deprecated "length" form. If we don't need that
 * (i.e. if we demand that only "length()" with () is valid), then TC_LENGTH
 * can be merged with TC_BUILTIN:
 */
#define TC_LENGTH       (1 << 20)
#define TC_GETLINE      (1 << 21)
#define TC_FUNCDECL     (1 << 22)               /* 'function' 'func' */
#define TC_BEGIN        (1 << 23)
#define TC_END          (1 << 24)
#define TC_EOF          (1 << 25)
#define TC_VARIABLE     (1 << 26)
#define TC_ARRAY        (1 << 27)
#define TC_FUNCTION     (1 << 28)
#define TC_STRING       (1 << 29)
#define TC_NUMBER       (1 << 30)

#define TC_UOPPRE  (TC_UOPPRE1 | TC_UOPPRE2)

/* combined token classes */
#define TC_BINOP   (TC_BINOPX | TC_COMMA | TC_PIPE | TC_IN)
//#define       TC_UNARYOP (TC_UOPPRE | TC_UOPPOST)
#define TC_OPERAND (TC_VARIABLE | TC_ARRAY | TC_FUNCTION \
                   | TC_BUILTIN | TC_LENGTH | TC_GETLINE \
                   | TC_SEQSTART | TC_STRING | TC_NUMBER)

#define TC_STATEMNT (TC_STATX | TC_WHILE)
#define TC_OPTERM  (TC_SEMICOL | TC_NEWLINE)

/* word tokens, cannot mean something else if not expected */
#define TC_WORD    (TC_IN | TC_STATEMNT | TC_ELSE \
                   | TC_BUILTIN | TC_LENGTH | TC_GETLINE \
                   | TC_FUNCDECL | TC_BEGIN | TC_END)

/* discard newlines after these */
#define TC_NOTERM  (TC_COMMA | TC_GRPSTART | TC_GRPTERM \
                   | TC_BINOP | TC_OPTERM)

/* what can expression begin with */
#define TC_OPSEQ   (TC_OPERAND | TC_UOPPRE | TC_REGEXP)
/* what can group begin with */
#define TC_GRPSEQ  (TC_OPSEQ | TC_OPTERM | TC_STATEMNT | TC_GRPSTART)

/* if previous token class is CONCAT1 and next is CONCAT2, concatenation */
/* operator is inserted between them */
#define TC_CONCAT1 (TC_VARIABLE | TC_ARRTERM | TC_SEQTERM \
                   | TC_STRING | TC_NUMBER | TC_UOPPOST \
                   | TC_LENGTH)
#define TC_CONCAT2 (TC_OPERAND | TC_UOPPRE)

#define OF_RES1     0x010000
#define OF_RES2     0x020000
#define OF_STR1     0x040000
#define OF_STR2     0x080000
#define OF_NUM1     0x100000
#define OF_CHECKED  0x200000
#define OF_REQUIRED 0x400000


/* combined operator flags */
#define xx      0
#define xV      OF_RES2
#define xS      (OF_RES2 | OF_STR2)
#define Vx      OF_RES1
#define Rx      (OF_RES1 | OF_NUM1 | OF_REQUIRED)
#define VV      (OF_RES1 | OF_RES2)
#define Nx      (OF_RES1 | OF_NUM1)
#define NV      (OF_RES1 | OF_NUM1 | OF_RES2)
#define Sx      (OF_RES1 | OF_STR1)
#define SV      (OF_RES1 | OF_STR1 | OF_RES2)
#define SS      (OF_RES1 | OF_STR1 | OF_RES2 | OF_STR2)

#define OPCLSMASK 0xFF00
#define OPNMASK   0x007F

/* operator priority is a highest byte (even: r->l, odd: l->r grouping)
 * For builtins it has different meaning: n n s3 s2 s1 v3 v2 v1,
 * n - min. number of args, vN - resolve Nth arg to var, sN - resolve to string
 */
#undef P
#undef PRIMASK
#undef PRIMASK2
#define P(x)      (x << 24)
#define PRIMASK   0x7F000000
#define PRIMASK2  0x7E000000

/* Operation classes */

#define SHIFT_TIL_THIS  0x0600
#define RECUR_FROM_THIS 0x1000

enum {
        OC_DELETE = 0x0100,     OC_EXEC = 0x0200,       OC_NEWSOURCE = 0x0300,
        OC_PRINT = 0x0400,      OC_PRINTF = 0x0500,     OC_WALKINIT = 0x0600,

        OC_BR = 0x0700,         OC_BREAK = 0x0800,      OC_CONTINUE = 0x0900,
        OC_EXIT = 0x0a00,       OC_NEXT = 0x0b00,       OC_NEXTFILE = 0x0c00,
        OC_TEST = 0x0d00,       OC_WALKNEXT = 0x0e00,

        OC_BINARY = 0x1000,     OC_BUILTIN = 0x1100,    OC_COLON = 0x1200,
        OC_COMMA = 0x1300,      OC_COMPARE = 0x1400,    OC_CONCAT = 0x1500,
        OC_FBLTIN = 0x1600,     OC_FIELD = 0x1700,      OC_FNARG = 0x1800,
        OC_FUNC = 0x1900,       OC_GETLINE = 0x1a00,    OC_IN = 0x1b00,
        OC_LAND = 0x1c00,       OC_LOR = 0x1d00,        OC_MATCH = 0x1e00,
        OC_MOVE = 0x1f00,       OC_PGETLINE = 0x2000,   OC_REGEXP = 0x2100,
        OC_REPLACE = 0x2200,    OC_RETURN = 0x2300,     OC_SPRINTF = 0x2400,
        OC_TERNARY = 0x2500,    OC_UNARY = 0x2600,      OC_VAR = 0x2700,
        OC_DONE = 0x2800,

        ST_IF = 0x3000,         ST_DO = 0x3100,         ST_FOR = 0x3200,
        ST_WHILE = 0x3300
};

/* simple builtins */
enum {
        F_in,   F_rn,   F_co,   F_ex,   F_lg,   F_si,   F_sq,   F_sr,
        F_ti,   F_le,   F_sy,   F_ff,   F_cl
};

/* builtins */
enum {
        B_a2,   B_ix,   B_ma,   B_sp,   B_ss,   B_ti,   B_mt,   B_lo,   B_up,
        B_ge,   B_gs,   B_su,
        B_an,   B_co,   B_ls,   B_or,   B_rs,   B_xo,
};

/* tokens and their corresponding info values */

#define NTC     "\377"  /* switch to next token class (tc<<1) */
#define NTCC    '\377'

static const char tokenlist[] ALIGN1 =
        "\1("         NTC                                   /* TC_SEQSTART */
        "\1)"         NTC                                   /* TC_SEQTERM */
        "\1/"         NTC                                   /* TC_REGEXP */
        "\2>>"        "\1>"         "\1|"       NTC         /* TC_OUTRDR */
        "\2++"        "\2--"        NTC                     /* TC_UOPPOST */
        "\2++"        "\2--"        "\1$"       NTC         /* TC_UOPPRE1 */
        "\2=="        "\1="         "\2+="      "\2-="      /* TC_BINOPX */
        "\2*="        "\2/="        "\2%="      "\2^="
        "\1+"         "\1-"         "\3**="     "\2**"
        "\1/"         "\1%"         "\1^"       "\1*"
        "\2!="        "\2>="        "\2<="      "\1>"
        "\1<"         "\2!~"        "\1~"       "\2&&"
        "\2||"        "\1?"         "\1:"       NTC
        "\2in"        NTC                                   /* TC_IN */
        "\1,"         NTC                                   /* TC_COMMA */
        "\1|"         NTC                                   /* TC_PIPE */
        "\1+"         "\1-"         "\1!"       NTC         /* TC_UOPPRE2 */
        "\1]"         NTC                                   /* TC_ARRTERM */
        "\1{"         NTC                                   /* TC_GRPSTART */
        "\1}"         NTC                                   /* TC_GRPTERM */
        "\1;"         NTC                                   /* TC_SEMICOL */
        "\1\n"        NTC                                   /* TC_NEWLINE */
        "\2if"        "\2do"        "\3for"     "\5break"   /* TC_STATX */
        "\10continue" "\6delete"    "\5print"
        "\6printf"    "\4next"      "\10nextfile"
        "\6return"    "\4exit"      NTC
        "\5while"     NTC                                   /* TC_WHILE */
        "\4else"      NTC                                   /* TC_ELSE */
        "\3and"       "\5compl"     "\6lshift"  "\2or"      /* TC_BUILTIN */
        "\6rshift"    "\3xor"
        "\5close"     "\6system"    "\6fflush"  "\5atan2"
        "\3cos"       "\3exp"       "\3int"     "\3log"
        "\4rand"      "\3sin"       "\4sqrt"    "\5srand"
        "\6gensub"    "\4gsub"      "\5index"   /* "\6length" was here */
        "\5match"     "\5split"     "\7sprintf" "\3sub"
        "\6substr"    "\7systime"   "\10strftime" "\6mktime"
        "\7tolower"   "\7toupper"   NTC
        "\6length"    NTC                                   /* TC_LENGTH */
        "\7getline"   NTC                                   /* TC_GETLINE */
        "\4func"      "\10function" NTC                     /* TC_FUNCDECL */
        "\5BEGIN"     NTC                                   /* TC_BEGIN */
        "\3END"                                             /* TC_END */
        /* compiler adds trailing "\0" */
        ;

#define OC_B  OC_BUILTIN

static const uint32_t tokeninfo[] ALIGN4 = {
        0,
        0,
        OC_REGEXP,
        xS|'a',                  xS|'w',                  xS|'|',
        OC_UNARY|xV|P(9)|'p',    OC_UNARY|xV|P(9)|'m',
        OC_UNARY|xV|P(9)|'P',    OC_UNARY|xV|P(9)|'M',    OC_FIELD|xV|P(5),
        OC_COMPARE|VV|P(39)|5,   OC_MOVE|VV|P(74),        OC_REPLACE|NV|P(74)|'+', OC_REPLACE|NV|P(74)|'-',
        OC_REPLACE|NV|P(74)|'*', OC_REPLACE|NV|P(74)|'/', OC_REPLACE|NV|P(74)|'%', OC_REPLACE|NV|P(74)|'&',
        OC_BINARY|NV|P(29)|'+',  OC_BINARY|NV|P(29)|'-',  OC_REPLACE|NV|P(74)|'&', OC_BINARY|NV|P(15)|'&',
        OC_BINARY|NV|P(25)|'/',  OC_BINARY|NV|P(25)|'%',  OC_BINARY|NV|P(15)|'&',  OC_BINARY|NV|P(25)|'*',
        OC_COMPARE|VV|P(39)|4,   OC_COMPARE|VV|P(39)|3,   OC_COMPARE|VV|P(39)|0,   OC_COMPARE|VV|P(39)|1,
        OC_COMPARE|VV|P(39)|2,   OC_MATCH|Sx|P(45)|'!',   OC_MATCH|Sx|P(45)|'~',   OC_LAND|Vx|P(55),
        OC_LOR|Vx|P(59),         OC_TERNARY|Vx|P(64)|'?', OC_COLON|xx|P(67)|':',
        OC_IN|SV|P(49), /* TC_IN */
        OC_COMMA|SS|P(80),
        OC_PGETLINE|SV|P(37),
        OC_UNARY|xV|P(19)|'+',   OC_UNARY|xV|P(19)|'-',   OC_UNARY|xV|P(19)|'!',
        0, /* ] */
        0,
        0,
        0,
        0, /* \n */
        ST_IF,        ST_DO,        ST_FOR,      OC_BREAK,
        OC_CONTINUE,  OC_DELETE|Rx, OC_PRINT,
        OC_PRINTF,    OC_NEXT,      OC_NEXTFILE,
        OC_RETURN|Vx, OC_EXIT|Nx,
        ST_WHILE,
        0, /* else */
        OC_B|B_an|P(0x83), OC_B|B_co|P(0x41), OC_B|B_ls|P(0x83), OC_B|B_or|P(0x83),
        OC_B|B_rs|P(0x83), OC_B|B_xo|P(0x83),
        OC_FBLTIN|Sx|F_cl, OC_FBLTIN|Sx|F_sy, OC_FBLTIN|Sx|F_ff, OC_B|B_a2|P(0x83),
        OC_FBLTIN|Nx|F_co, OC_FBLTIN|Nx|F_ex, OC_FBLTIN|Nx|F_in, OC_FBLTIN|Nx|F_lg,
        OC_FBLTIN|F_rn,    OC_FBLTIN|Nx|F_si, OC_FBLTIN|Nx|F_sq, OC_FBLTIN|Nx|F_sr,
        OC_B|B_ge|P(0xd6), OC_B|B_gs|P(0xb6), OC_B|B_ix|P(0x9b), /* OC_FBLTIN|Sx|F_le, was here */
        OC_B|B_ma|P(0x89), OC_B|B_sp|P(0x8b), OC_SPRINTF,        OC_B|B_su|P(0xb6),
        OC_B|B_ss|P(0x8f), OC_FBLTIN|F_ti,    OC_B|B_ti|P(0x0b), OC_B|B_mt|P(0x0b),
        OC_B|B_lo|P(0x49), OC_B|B_up|P(0x49),
        OC_FBLTIN|Sx|F_le, /* TC_LENGTH */
        OC_GETLINE|SV|P(0),
        0,                 0,
        0,
        0 /* TC_END */
};

/* internal variable names and their initial values       */
/* asterisk marks SPECIAL vars; $ is just no-named Field0 */
enum {
        CONVFMT,    OFMT,       FS,         OFS,
        ORS,        RS,         RT,         FILENAME,
        SUBSEP,     F0,         ARGIND,     ARGC,
        ARGV,       ERRNO,      FNR,        NR,
        NF,         IGNORECASE, ENVIRON,    NUM_INTERNAL_VARS
};

static const char vNames[] ALIGN1 =
        "CONVFMT\0" "OFMT\0"    "FS\0*"     "OFS\0"
        "ORS\0"     "RS\0*"     "RT\0"      "FILENAME\0"
        "SUBSEP\0"  "$\0*"      "ARGIND\0"  "ARGC\0"
        "ARGV\0"    "ERRNO\0"   "FNR\0"     "NR\0"
        "NF\0*"     "IGNORECASE\0*" "ENVIRON\0" "\0";

static const char vValues[] ALIGN1 =
        "%.6g\0"    "%.6g\0"    " \0"       " \0"
        "\n\0"      "\n\0"      "\0"        "\0"
        "\034\0"    "\0"        "\377";

/* hash size may grow to these values */
#define FIRST_PRIME 61
static const uint16_t PRIMES[] ALIGN2 = { 251, 1021, 4093, 16381, 65521 };


/* Globals. Split in two parts so that first one is addressed
 * with (mostly short) negative offsets.
 * NB: it's unsafe to put members of type "double"
 * into globals2 (gcc may fail to align them).
 */
struct globals {
        double t_double;
        chain beginseq, mainseq, endseq;
        chain *seq;
        node *break_ptr, *continue_ptr;
        rstream *iF;
        xhash *vhash, *ahash, *fdhash, *fnhash;
        const char *g_progname;
        int g_lineno;
        int nfields;
        int maxfields; /* used in fsrealloc() only */
        var *Fields;
        nvblock *g_cb;
        char *g_pos;
        char *g_buf;
        smallint icase;
        smallint exiting;
        smallint nextrec;
        smallint nextfile;
        smallint is_f0_split;
        smallint t_rollback;
};
struct globals2 {
        uint32_t t_info; /* often used */
        uint32_t t_tclass;
        char *t_string;
        int t_lineno;

        var *intvar[NUM_INTERNAL_VARS]; /* often used */

        /* former statics from various functions */
        char *split_f0__fstrings;

        uint32_t next_token__save_tclass;
        uint32_t next_token__save_info;
        uint32_t next_token__ltclass;
        smallint next_token__concat_inserted;

        smallint next_input_file__files_happen;
        rstream next_input_file__rsm;

        var *evaluate__fnargs;
        unsigned evaluate__seed;
        regex_t evaluate__sreg;

        var ptest__v;

        tsplitter exec_builtin__tspl;

        /* biggest and least used members go last */
        tsplitter fsplitter, rsplitter;
};
#define G1 (ptr_to_globals[-1])
#define G (*(struct globals2 *)ptr_to_globals)
/* For debug. nm --size-sort awk.o | grep -vi ' [tr] ' */
/*char G1size[sizeof(G1)]; - 0x74 */
/*char Gsize[sizeof(G)]; - 0x1c4 */
/* Trying to keep most of members accessible with short offsets: */
/*char Gofs_seed[offsetof(struct globals2, evaluate__seed)]; - 0x90 */
#define t_double     (G1.t_double    )
#define beginseq     (G1.beginseq    )
#define mainseq      (G1.mainseq     )
#define endseq       (G1.endseq      )
#define seq          (G1.seq         )
#define break_ptr    (G1.break_ptr   )
#define continue_ptr (G1.continue_ptr)
#define iF           (G1.iF          )
#define vhash        (G1.vhash       )
#define ahash        (G1.ahash       )
#define fdhash       (G1.fdhash      )
#define fnhash       (G1.fnhash      )
#define g_progname   (G1.g_progname  )
#define g_lineno     (G1.g_lineno    )
#define nfields      (G1.nfields     )
#define maxfields    (G1.maxfields   )
#define Fields       (G1.Fields      )
#define g_cb         (G1.g_cb        )
#define g_pos        (G1.g_pos       )
#define g_buf        (G1.g_buf       )
#define icase        (G1.icase       )
#define exiting      (G1.exiting     )
#define nextrec      (G1.nextrec     )
#define nextfile     (G1.nextfile    )
#define is_f0_split  (G1.is_f0_split )
#define t_rollback   (G1.t_rollback  )
#define t_info       (G.t_info      )
#define t_tclass     (G.t_tclass    )
#define t_string     (G.t_string    )
#define t_lineno     (G.t_lineno    )
#define intvar       (G.intvar      )
#define fsplitter    (G.fsplitter   )
#define rsplitter    (G.rsplitter   )
#define INIT_G() do { \
        SET_PTR_TO_GLOBALS((char*)xzalloc(sizeof(G1)+sizeof(G)) + sizeof(G1)); \
        G.next_token__ltclass = TC_OPTERM; \
        G.evaluate__seed = 1; \
} while (0)


/* function prototypes */
static void handle_special(var *);
static node *parse_expr(uint32_t);
static void chain_group(void);
static var *evaluate(node *, var *);
static rstream *next_input_file(void);
static int fmt_num(char *, int, const char *, double, int);
static int awk_exit(int) NORETURN;

/* ---- error handling ---- */

static const char EMSG_INTERNAL_ERROR[] ALIGN1 = "Internal error";
static const char EMSG_UNEXP_EOS[] ALIGN1 = "Unexpected end of string";
static const char EMSG_UNEXP_TOKEN[] ALIGN1 = "Unexpected token";
static const char EMSG_DIV_BY_ZERO[] ALIGN1 = "Division by zero";
static const char EMSG_INV_FMT[] ALIGN1 = "Invalid format specifier";
static const char EMSG_TOO_FEW_ARGS[] ALIGN1 = "Too few arguments";
static const char EMSG_NOT_ARRAY[] ALIGN1 = "Not an array";
static const char EMSG_POSSIBLE_ERROR[] ALIGN1 = "Possible syntax error";
static const char EMSG_UNDEF_FUNC[] ALIGN1 = "Call to undefined function";
static const char EMSG_NO_MATH[] ALIGN1 = "Math support is not compiled in";
static const char EMSG_NEGATIVE_FIELD[] ALIGN1 = "Access to negative field";

static void zero_out_var(var *vp)
{
        memset(vp, 0, sizeof(*vp));
}

static void syntax_error(const char *message) NORETURN;
static void syntax_error(const char *message)
{
        bb_error_msg_and_die("%s:%i: %s", g_progname, g_lineno, message);
}

/* ---- hash stuff ---- */

static unsigned hashidx(const char *name)
{
        unsigned idx = 0;

        while (*name)
                idx = *name++ + (idx << 6) - idx;
        return idx;
}

/* create new hash */
static xhash *hash_init(void)
{
        xhash *newhash;

        newhash = xzalloc(sizeof(*newhash));
        newhash->csize = FIRST_PRIME;
        newhash->items = xzalloc(FIRST_PRIME * sizeof(newhash->items[0]));

        return newhash;
}

/* find item in hash, return ptr to data, NULL if not found */
static void *hash_search(xhash *hash, const char *name)
{
        hash_item *hi;

        hi = hash->items[hashidx(name) % hash->csize];
        while (hi) {
                if (strcmp(hi->name, name) == 0)
                        return &hi->data;
                hi = hi->next;
        }
        return NULL;
}

/* grow hash if it becomes too big */
static void hash_rebuild(xhash *hash)
{
        unsigned newsize, i, idx;
        hash_item **newitems, *hi, *thi;

        if (hash->nprime == ARRAY_SIZE(PRIMES))
                return;

        newsize = PRIMES[hash->nprime++];
        newitems = xzalloc(newsize * sizeof(newitems[0]));

        for (i = 0; i < hash->csize; i++) {
                hi = hash->items[i];
                while (hi) {
                        thi = hi;
                        hi = thi->next;
                        idx = hashidx(thi->name) % newsize;
                        thi->next = newitems[idx];
                        newitems[idx] = thi;
                }
        }

        free(hash->items);
        hash->csize = newsize;
        hash->items = newitems;
}

/* find item in hash, add it if necessary. Return ptr to data */
static void *hash_find(xhash *hash, const char *name)
{
        hash_item *hi;
        unsigned idx;
        int l;

        hi = hash_search(hash, name);
        if (!hi) {
                if (++hash->nel / hash->csize > 10)
                        hash_rebuild(hash);

                l = strlen(name) + 1;
                hi = xzalloc(sizeof(*hi) + l);
                strcpy(hi->name, name);

                idx = hashidx(name) % hash->csize;
                hi->next = hash->items[idx];
                hash->items[idx] = hi;
                hash->glen += l;
        }
        return &hi->data;
}

#define findvar(hash, name) ((var*)    hash_find((hash), (name)))
#define newvar(name)        ((var*)    hash_find(vhash, (name)))
#define newfile(name)       ((rstream*)hash_find(fdhash, (name)))
#define newfunc(name)       ((func*)   hash_find(fnhash, (name)))

static void hash_remove(xhash *hash, const char *name)
{
        hash_item *hi, **phi;

        phi = &hash->items[hashidx(name) % hash->csize];
        while (*phi) {
                hi = *phi;
                if (strcmp(hi->name, name) == 0) {
                        hash->glen -= (strlen(name) + 1);
                        hash->nel--;
                        *phi = hi->next;
                        free(hi);
                        break;
                }
                phi = &hi->next;
        }
}

/* ------ some useful functions ------ */

static char *skip_spaces(char *p)
{
        while (1) {
                if (*p == '\\' && p[1] == '\n') {
                        p++;
                        t_lineno++;
                } else if (*p != ' ' && *p != '\t') {
                        break;
                }
                p++;
        }
        return p;
}

/* returns old *s, advances *s past word and terminating NUL */
static char *nextword(char **s)
{
        char *p = *s;
        while (*(*s)++ != '\0')
                continue;
        return p;
}

static char nextchar(char **s)
{
        char c, *pps;

        c = *(*s)++;
        pps = *s;
        if (c == '\\')
                c = bb_process_escape_sequence((const char**)s);
        /* Example awk statement:
         * s = "abc\"def"
         * we must treat \" as "
         */
        if (c == '\\' && *s == pps) { /* unrecognized \z? */
                c = *(*s); /* yes, fetch z */
                if (c)
                        (*s)++; /* advance unless z = NUL */
        }
        return c;
}

/* TODO: merge with strcpy_and_process_escape_sequences()?
 */
static void unescape_string_in_place(char *s1)
{
        char *s = s1;
        while ((*s1 = nextchar(&s)) != '\0')
                s1++;
}

static ALWAYS_INLINE int isalnum_(int c)
{
        return (isalnum(c) || c == '_');
}

static double my_strtod(char **pp)
{
        char *cp = *pp;
        if (ENABLE_DESKTOP && cp[0] == '0') {
                /* Might be hex or octal integer: 0x123abc or 07777 */
                char c = (cp[1] | 0x20);
                if (c == 'x' || isdigit(cp[1])) {
                        unsigned long long ull = strtoull(cp, pp, 0);
                        if (c == 'x')
                                return ull;
                        c = **pp;
                        if (!isdigit(c) && c != '.')
                                return ull;
                        /* else: it may be a floating number. Examples:
                         * 009.123 (*pp points to '9')
                         * 000.123 (*pp points to '.')
                         * fall through to strtod.
                         */
                }
        }
        return strtod(cp, pp);
}

/* -------- working with variables (set/get/copy/etc) -------- */

static xhash *iamarray(var *v)
{
        var *a = v;

        while (a->type & VF_CHILD)
                a = a->x.parent;

        if (!(a->type & VF_ARRAY)) {
                a->type |= VF_ARRAY;
                a->x.array = hash_init();
        }
        return a->x.array;
}

static void clear_array(xhash *array)
{
        unsigned i;
        hash_item *hi, *thi;

        for (i = 0; i < array->csize; i++) {
                hi = array->items[i];
                while (hi) {
                        thi = hi;
                        hi = hi->next;
                        free(thi->data.v.string);
                        free(thi);
                }
                array->items[i] = NULL;
        }
        array->glen = array->nel = 0;
}

/* clear a variable */
static var *clrvar(var *v)
{
        if (!(v->type & VF_FSTR))
                free(v->string);

        v->type &= VF_DONTTOUCH;
        v->type |= VF_DIRTY;
        v->string = NULL;
        return v;
}

/* assign string value to variable */
static var *setvar_p(var *v, char *value)
{
        clrvar(v);
        v->string = value;
        handle_special(v);
        return v;
}

/* same as setvar_p but make a copy of string */
static var *setvar_s(var *v, const char *value)
{
        return setvar_p(v, (value && *value) ? xstrdup(value) : NULL);
}

/* same as setvar_s but sets USER flag */
static var *setvar_u(var *v, const char *value)
{
        v = setvar_s(v, value);
        v->type |= VF_USER;
        return v;
}

/* set array element to user string */
static void setari_u(var *a, int idx, const char *s)
{
        var *v;

        v = findvar(iamarray(a), itoa(idx));
        setvar_u(v, s);
}

/* assign numeric value to variable */
static var *setvar_i(var *v, double value)
{
        clrvar(v);
        v->type |= VF_NUMBER;
        v->number = value;
        handle_special(v);
        return v;
}

static const char *getvar_s(var *v)
{
        /* if v is numeric and has no cached string, convert it to string */
        if ((v->type & (VF_NUMBER | VF_CACHED)) == VF_NUMBER) {
                fmt_num(g_buf, MAXVARFMT, getvar_s(intvar[CONVFMT]), v->number, TRUE);
                v->string = xstrdup(g_buf);
                v->type |= VF_CACHED;
        }
        return (v->string == NULL) ? "" : v->string;
}

static double getvar_i(var *v)
{
        char *s;

        if ((v->type & (VF_NUMBER | VF_CACHED)) == 0) {
                v->number = 0;
                s = v->string;
                if (s && *s) {
                        debug_printf_eval("getvar_i: '%s'->", s);
                        v->number = my_strtod(&s);
                        debug_printf_eval("%f (s:'%s')\n", v->number, s);
                        if (v->type & VF_USER) {
                                s = skip_spaces(s);
                                if (*s != '\0')
                                        v->type &= ~VF_USER;
                        }
                } else {
                        debug_printf_eval("getvar_i: '%s'->zero\n", s);
                        v->type &= ~VF_USER;
                }
                v->type |= VF_CACHED;
        }
        debug_printf_eval("getvar_i: %f\n", v->number);
        return v->number;
}

/* Used for operands of bitwise ops */
static unsigned long getvar_i_int(var *v)
{
        double d = getvar_i(v);

        /* Casting doubles to longs is undefined for values outside
         * of target type range. Try to widen it as much as possible */
        if (d >= 0)
                return (unsigned long)d;
        /* Why? Think about d == -4294967295.0 (assuming 32bit longs) */
        return - (long) (unsigned long) (-d);
}

static var *copyvar(var *dest, const var *src)
{
        if (dest != src) {
                clrvar(dest);
                dest->type |= (src->type & ~(VF_DONTTOUCH | VF_FSTR));
                debug_printf_eval("copyvar: number:%f string:'%s'\n", src->number, src->string);
                dest->number = src->number;
                if (src->string)
                        dest->string = xstrdup(src->string);
        }
        handle_special(dest);
        return dest;
}

static var *incvar(var *v)
{
        return setvar_i(v, getvar_i(v) + 1.0);
}

/* return true if v is number or numeric string */
static int is_numeric(var *v)
{
        getvar_i(v);
        return ((v->type ^ VF_DIRTY) & (VF_NUMBER | VF_USER | VF_DIRTY));
}

/* return 1 when value of v corresponds to true, 0 otherwise */
static int istrue(var *v)
{
        if (is_numeric(v))
                return (v->number != 0);
        return (v->string && v->string[0]);
}

/* temporary variables allocator. Last allocated should be first freed */
static var *nvalloc(int n)
{
        nvblock *pb = NULL;
        var *v, *r;
        int size;

        while (g_cb) {
                pb = g_cb;
                if ((g_cb->pos - g_cb->nv) + n <= g_cb->size)
                        break;
                g_cb = g_cb->next;
        }

        if (!g_cb) {
                size = (n <= MINNVBLOCK) ? MINNVBLOCK : n;
                g_cb = xzalloc(sizeof(nvblock) + size * sizeof(var));

                g_cb->size = size;
                g_cb->pos = g_cb->nv;
                g_cb->prev = pb;
                /*g_cb->next = NULL; - xzalloc did it */
                if (pb)
                        pb->next = g_cb;
        }

        v = r = g_cb->pos;
        g_cb->pos += n;

        while (v < g_cb->pos) {
                v->type = 0;
                v->string = NULL;
                v++;
        }

        return r;
}

static void nvfree(var *v)
{
        var *p;

        if (v < g_cb->nv || v >= g_cb->pos)
                syntax_error(EMSG_INTERNAL_ERROR);

        for (p = v; p < g_cb->pos; p++) {
                if ((p->type & (VF_ARRAY | VF_CHILD)) == VF_ARRAY) {
                        clear_array(iamarray(p));
                        free(p->x.array->items);
                        free(p->x.array);
                }
                if (p->type & VF_WALK) {
                        walker_list *n;
                        walker_list *w = p->x.walker;
                        debug_printf_walker("nvfree: freeing walker @%p\n", &p->x.walker);
                        p->x.walker = NULL;
                        while (w) {
                                n = w->prev;
                                debug_printf_walker(" free(%p)\n", w);
                                free(w);
                                w = n;
                        }
                }
                clrvar(p);
        }

        g_cb->pos = v;
        while (g_cb->prev && g_cb->pos == g_cb->nv) {
                g_cb = g_cb->prev;
        }
}

/* ------- awk program text parsing ------- */

/* Parse next token pointed by global pos, place results into global ttt.
 * If token isn't expected, give away. Return token class
 */
static uint32_t next_token(uint32_t expected)
{
#define concat_inserted (G.next_token__concat_inserted)
#define save_tclass     (G.next_token__save_tclass)
#define save_info       (G.next_token__save_info)
/* Initialized to TC_OPTERM: */
#define ltclass         (G.next_token__ltclass)

        char *p, *s;
        const char *tl;
        uint32_t tc;
        const uint32_t *ti;

        if (t_rollback) {
                debug_printf_parse("%s: using rolled-back token\n", __func__);
                t_rollback = FALSE;
        } else if (concat_inserted) {
                debug_printf_parse("%s: using concat-inserted token\n", __func__);
                concat_inserted = FALSE;
                t_tclass = save_tclass;
                t_info = save_info;
        } else {
                p = g_pos;
 readnext:
                p = skip_spaces(p);
                g_lineno = t_lineno;
                if (*p == '#')
                        while (*p != '\n' && *p != '\0')
                                p++;

                if (*p == '\n')
                        t_lineno++;

                if (*p == '\0') {
                        tc = TC_EOF;
                        debug_printf_parse("%s: token found: TC_EOF\n", __func__);
                } else if (*p == '\"') {
                        /* it's a string */
                        t_string = s = ++p;
                        while (*p != '\"') {
                                char *pp;
                                if (*p == '\0' || *p == '\n')
                                        syntax_error(EMSG_UNEXP_EOS);
                                pp = p;
                                *s++ = nextchar(&pp);
                                p = pp;
                        }
                        p++;
                        *s = '\0';
                        tc = TC_STRING;
                        debug_printf_parse("%s: token found:'%s' TC_STRING\n", __func__, t_string);
                } else if ((expected & TC_REGEXP) && *p == '/') {
                        /* it's regexp */
                        t_string = s = ++p;
                        while (*p != '/') {
                                if (*p == '\0' || *p == '\n')
                                        syntax_error(EMSG_UNEXP_EOS);
                                *s = *p++;
                                if (*s++ == '\\') {
                                        char *pp = p;
                                        s[-1] = bb_process_escape_sequence((const char **)&pp);
                                        if (*p == '\\')
                                                *s++ = '\\';
                                        if (pp == p)
                                                *s++ = *p++;
                                        else
                                                p = pp;
                                }
                        }
                        p++;
                        *s = '\0';
                        tc = TC_REGEXP;
                        debug_printf_parse("%s: token found:'%s' TC_REGEXP\n", __func__, t_string);

                } else if (*p == '.' || isdigit(*p)) {
                        /* it's a number */
                        char *pp = p;
                        t_double = my_strtod(&pp);
                        p = pp;
                        if (*p == '.')
                                syntax_error(EMSG_UNEXP_TOKEN);
                        tc = TC_NUMBER;
                        debug_printf_parse("%s: token found:%f TC_NUMBER\n", __func__, t_double);
                } else {
                        /* search for something known */
                        tl = tokenlist;
                        tc = 0x00000001;
                        ti = tokeninfo;
                        while (*tl) {
                                int l = (unsigned char) *tl++;
                                if (l == (unsigned char) NTCC) {
                                        tc <<= 1;
                                        continue;
                                }
                                /* if token class is expected,
                                 * token matches,
                                 * and it's not a longer word,
                                 */
                                if ((tc & (expected | TC_WORD | TC_NEWLINE))
                                 && strncmp(p, tl, l) == 0
                                 && !((tc & TC_WORD) && isalnum_(p[l]))
                                ) {
                                        /* then this is what we are looking for */
                                        t_info = *ti;
                                        debug_printf_parse("%s: token found:'%.*s' t_info:%x\n", __func__, l, p, t_info);
                                        p += l;
                                        goto token_found;
                                }
                                ti++;
                                tl += l;
                        }
                        /* not a known token */

                        /* is it a name? (var/array/function) */
                        if (!isalnum_(*p))
                                syntax_error(EMSG_UNEXP_TOKEN); /* no */
                        /* yes */
                        t_string = --p;
                        while (isalnum_(*++p)) {
                                p[-1] = *p;
                        }
                        p[-1] = '\0';
                        tc = TC_VARIABLE;
                        /* also consume whitespace between functionname and bracket */
                        if (!(expected & TC_VARIABLE) || (expected & TC_ARRAY))
                                p = skip_spaces(p);
                        if (*p == '(') {
                                tc = TC_FUNCTION;
                                debug_printf_parse("%s: token found:'%s' TC_FUNCTION\n", __func__, t_string);
                        } else {
                                if (*p == '[') {
                                        p++;
                                        tc = TC_ARRAY;
                                        debug_printf_parse("%s: token found:'%s' TC_ARRAY\n", __func__, t_string);
                                } else
                                        debug_printf_parse("%s: token found:'%s' TC_VARIABLE\n", __func__, t_string);
                        }
                }
 token_found:
                g_pos = p;

                /* skipping newlines in some cases */
                if ((ltclass & TC_NOTERM) && (tc & TC_NEWLINE))
                        goto readnext;

                /* insert concatenation operator when needed */
                debug_printf_parse("%s: %x %x %x concat_inserted?\n", __func__,
                        (ltclass & TC_CONCAT1), (tc & TC_CONCAT2), (expected & TC_BINOP));
                if ((ltclass & TC_CONCAT1) && (tc & TC_CONCAT2) && (expected & TC_BINOP)
                 && !(ltclass == TC_LENGTH && tc == TC_SEQSTART) /* but not for "length(..." */
                ) {
                        concat_inserted = TRUE;
                        save_tclass = tc;
                        save_info = t_info;
                        tc = TC_BINOP;
                        t_info = OC_CONCAT | SS | P(35);
                }

                debug_printf_parse("%s: t_tclass=tc=%x\n", __func__, t_tclass);
                t_tclass = tc;
        }
        ltclass = t_tclass;

        /* Are we ready for this? */
        if (!(ltclass & expected)) {
                syntax_error((ltclass & (TC_NEWLINE | TC_EOF)) ?
                                EMSG_UNEXP_EOS : EMSG_UNEXP_TOKEN);
        }

        debug_printf_parse("%s: returning, ltclass:%x t_double:%f\n", __func__, ltclass, t_double);
        return ltclass;
#undef concat_inserted
#undef save_tclass
#undef save_info
#undef ltclass
}

static void rollback_token(void)
{
        t_rollback = TRUE;
}

static node *new_node(uint32_t info)
{
        node *n;

        n = xzalloc(sizeof(node));
        n->info = info;
        n->lineno = g_lineno;
        return n;
}

static void mk_re_node(const char *s, node *n, regex_t *re)
{
        n->info = OC_REGEXP;
        n->l.re = re;
        n->r.ire = re + 1;
        xregcomp(re, s, REG_EXTENDED);
        xregcomp(re + 1, s, REG_EXTENDED | REG_ICASE);
}

static node *condition(void)
{
        next_token(TC_SEQSTART);
        return parse_expr(TC_SEQTERM);
}

/* parse expression terminated by given argument, return ptr
 * to built subtree. Terminator is eaten by parse_expr */
static node *parse_expr(uint32_t iexp)
{
        node sn;
        node *cn = &sn;
        node *vn, *glptr;
        uint32_t tc, xtc;
        var *v;

        debug_printf_parse("%s(%x)\n", __func__, iexp);

        sn.info = PRIMASK;
        sn.r.n = sn.a.n = glptr = NULL;
        xtc = TC_OPERAND | TC_UOPPRE | TC_REGEXP | iexp;

        while (!((tc = next_token(xtc)) & iexp)) {

                if (glptr && (t_info == (OC_COMPARE | VV | P(39) | 2))) {
                        /* input redirection (<) attached to glptr node */
                        debug_printf_parse("%s: input redir\n", __func__);
                        cn = glptr->l.n = new_node(OC_CONCAT | SS | P(37));
                        cn->a.n = glptr;
                        xtc = TC_OPERAND | TC_UOPPRE;
                        glptr = NULL;

                } else if (tc & (TC_BINOP | TC_UOPPOST)) {
                        debug_printf_parse("%s: TC_BINOP | TC_UOPPOST tc:%x\n", __func__, tc);
                        /* for binary and postfix-unary operators, jump back over
                         * previous operators with higher priority */
                        vn = cn;
                        while (((t_info & PRIMASK) > (vn->a.n->info & PRIMASK2))
                            || ((t_info == vn->info) && ((t_info & OPCLSMASK) == OC_COLON))
                        ) {
                                vn = vn->a.n;
                                if (!vn->a.n) syntax_error(EMSG_UNEXP_TOKEN);
                        }
                        if ((t_info & OPCLSMASK) == OC_TERNARY)
                                t_info += P(6);
                        cn = vn->a.n->r.n = new_node(t_info);
                        cn->a.n = vn->a.n;
                        if (tc & TC_BINOP) {
                                cn->l.n = vn;
                                xtc = TC_OPERAND | TC_UOPPRE | TC_REGEXP;
                                if ((t_info & OPCLSMASK) == OC_PGETLINE) {
                                        /* it's a pipe */
                                        next_token(TC_GETLINE);
                                        /* give maximum priority to this pipe */
                                        cn->info &= ~PRIMASK;
                                        xtc = TC_OPERAND | TC_UOPPRE | TC_BINOP | iexp;
                                }
                        } else {
                                cn->r.n = vn;
                                xtc = TC_OPERAND | TC_UOPPRE | TC_BINOP | iexp;
                        }
                        vn->a.n = cn;

                } else {
                        debug_printf_parse("%s: other\n", __func__);
                        /* for operands and prefix-unary operators, attach them
                         * to last node */
                        vn = cn;
                        cn = vn->r.n = new_node(t_info);
                        cn->a.n = vn;
                        xtc = TC_OPERAND | TC_UOPPRE | TC_REGEXP;
                        if (tc & (TC_OPERAND | TC_REGEXP)) {
                                debug_printf_parse("%s: TC_OPERAND | TC_REGEXP\n", __func__);
                                xtc = TC_UOPPRE | TC_UOPPOST | TC_BINOP | TC_OPERAND | iexp;
                                /* one should be very careful with switch on tclass -
                                 * only simple tclasses should be used! */
                                switch (tc) {
                                case TC_VARIABLE:
                                case TC_ARRAY:
                                        debug_printf_parse("%s: TC_VARIABLE | TC_ARRAY\n", __func__);
                                        cn->info = OC_VAR;
                                        v = hash_search(ahash, t_string);
                                        if (v != NULL) {
                                                cn->info = OC_FNARG;
                                                cn->l.aidx = v->x.aidx;
                                        } else {
                                                cn->l.v = newvar(t_string);
                                        }
                                        if (tc & TC_ARRAY) {
                                                cn->info |= xS;
                                                cn->r.n = parse_expr(TC_ARRTERM);
                                        }
                                        break;

                                case TC_NUMBER:
                                case TC_STRING:
                                        debug_printf_parse("%s: TC_NUMBER | TC_STRING\n", __func__);
                                        cn->info = OC_VAR;
                                        v = cn->l.v = xzalloc(sizeof(var));
                                        if (tc & TC_NUMBER)
                                                setvar_i(v, t_double);
                                        else {
                                                setvar_s(v, t_string);
                                                xtc &= ~TC_UOPPOST; /* "str"++ is not allowed */
                                        }
                                        break;

                                case TC_REGEXP:
                                        debug_printf_parse("%s: TC_REGEXP\n", __func__);
                                        mk_re_node(t_string, cn, xzalloc(sizeof(regex_t)*2));
                                        break;

                                case TC_FUNCTION:
                                        debug_printf_parse("%s: TC_FUNCTION\n", __func__);
                                        cn->info = OC_FUNC;
                                        cn->r.f = newfunc(t_string);
                                        cn->l.n = condition();
                                        break;

                                case TC_SEQSTART:
                                        debug_printf_parse("%s: TC_SEQSTART\n", __func__);
                                        cn = vn->r.n = parse_expr(TC_SEQTERM);
                                        if (!cn)
                                                syntax_error("Empty sequence");
                                        cn->a.n = vn;
                                        break;

                                case TC_GETLINE:
                                        debug_printf_parse("%s: TC_GETLINE\n", __func__);
                                        glptr = cn;
                                        xtc = TC_OPERAND | TC_UOPPRE | TC_BINOP | iexp;
                                        break;

                                case TC_BUILTIN:
                                        debug_printf_parse("%s: TC_BUILTIN\n", __func__);
                                        cn->l.n = condition();
                                        break;

                                case TC_LENGTH:
                                        debug_printf_parse("%s: TC_LENGTH\n", __func__);
                                        next_token(TC_SEQSTART /* length(...) */
                                                | TC_OPTERM    /* length; (or newline)*/
                                                | TC_GRPTERM   /* length } */
                                                | TC_BINOPX    /* length <op> NUM */
                                                | TC_COMMA     /* print length, 1 */
                                        );
                                        rollback_token();
                                        if (t_tclass & TC_SEQSTART) {
                                                /* It was a "(" token. Handle just like TC_BUILTIN */
                                                cn->l.n = condition();
                                        }
                                        break;
                                }
                        }
                }
        }

        debug_printf_parse("%s() returns %p\n", __func__, sn.r.n);
        return sn.r.n;
}

/* add node to chain. Return ptr to alloc'd node */
static node *chain_node(uint32_t info)
{
        node *n;

        if (!seq->first)
                seq->first = seq->last = new_node(0);

        if (seq->programname != g_progname) {
                seq->programname = g_progname;
                n = chain_node(OC_NEWSOURCE);
                n->l.new_progname = xstrdup(g_progname);
        }

        n = seq->last;
        n->info = info;
        seq->last = n->a.n = new_node(OC_DONE);

        return n;
}

static void chain_expr(uint32_t info)
{
        node *n;

        n = chain_node(info);

        n->l.n = parse_expr(TC_OPTERM | TC_GRPTERM);
        if ((info & OF_REQUIRED) && !n->l.n)
                syntax_error(EMSG_TOO_FEW_ARGS);

        if (t_tclass & TC_GRPTERM)
                rollback_token();
}

static node *chain_loop(node *nn)
{
        node *n, *n2, *save_brk, *save_cont;

        save_brk = break_ptr;
        save_cont = continue_ptr;

        n = chain_node(OC_BR | Vx);
        continue_ptr = new_node(OC_EXEC);
        break_ptr = new_node(OC_EXEC);
        chain_group();
        n2 = chain_node(OC_EXEC | Vx);
        n2->l.n = nn;
        n2->a.n = n;
        continue_ptr->a.n = n2;
        break_ptr->a.n = n->r.n = seq->last;

        continue_ptr = save_cont;
        break_ptr = save_brk;

        return n;
}

/* parse group and attach it to chain */
static void chain_group(void)
{
        uint32_t c;
        node *n, *n2, *n3;

        do {
                c = next_token(TC_GRPSEQ);
        } while (c & TC_NEWLINE);

        if (c & TC_GRPSTART) {
                debug_printf_parse("%s: TC_GRPSTART\n", __func__);
                while (next_token(TC_GRPSEQ | TC_GRPTERM) != TC_GRPTERM) {
                        debug_printf_parse("%s: !TC_GRPTERM\n", __func__);
                        if (t_tclass & TC_NEWLINE)
                                continue;
                        rollback_token();
                        chain_group();
                }
                debug_printf_parse("%s: TC_GRPTERM\n", __func__);
        } else if (c & (TC_OPSEQ | TC_OPTERM)) {
                debug_printf_parse("%s: TC_OPSEQ | TC_OPTERM\n", __func__);
                rollback_token();
                chain_expr(OC_EXEC | Vx);
        } else {
                /* TC_STATEMNT */
                debug_printf_parse("%s: TC_STATEMNT(?)\n", __func__);
                switch (t_info & OPCLSMASK) {
                case ST_IF:
                        debug_printf_parse("%s: ST_IF\n", __func__);
                        n = chain_node(OC_BR | Vx);
                        n->l.n = condition();
                        chain_group();
                        n2 = chain_node(OC_EXEC);
                        n->r.n = seq->last;
                        if (next_token(TC_GRPSEQ | TC_GRPTERM | TC_ELSE) == TC_ELSE) {
                                chain_group();
                                n2->a.n = seq->last;
                        } else {
                                rollback_token();
                        }
                        break;

                case ST_WHILE:
                        debug_printf_parse("%s: ST_WHILE\n", __func__);
                        n2 = condition();
                        n = chain_loop(NULL);
                        n->l.n = n2;
                        break;

                case ST_DO:
                        debug_printf_parse("%s: ST_DO\n", __func__);
                        n2 = chain_node(OC_EXEC);
                        n = chain_loop(NULL);
                        n2->a.n = n->a.n;
                        next_token(TC_WHILE);
                        n->l.n = condition();
                        break;

                case ST_FOR:
                        debug_printf_parse("%s: ST_FOR\n", __func__);
                        next_token(TC_SEQSTART);
                        n2 = parse_expr(TC_SEMICOL | TC_SEQTERM);
                        if (t_tclass & TC_SEQTERM) {    /* for-in */
                                if (!n2 || (n2->info & OPCLSMASK) != OC_IN)
                                        syntax_error(EMSG_UNEXP_TOKEN);
                                n = chain_node(OC_WALKINIT | VV);
                                n->l.n = n2->l.n;
                                n->r.n = n2->r.n;
                                n = chain_loop(NULL);
                                n->info = OC_WALKNEXT | Vx;
                                n->l.n = n2->l.n;
                        } else {                        /* for (;;) */
                                n = chain_node(OC_EXEC | Vx);
                                n->l.n = n2;
                                n2 = parse_expr(TC_SEMICOL);
                                n3 = parse_expr(TC_SEQTERM);
                                n = chain_loop(n3);
                                n->l.n = n2;
                                if (!n2)
                                        n->info = OC_EXEC;
                        }
                        break;

                case OC_PRINT:
                case OC_PRINTF:
                        debug_printf_parse("%s: OC_PRINT[F]\n", __func__);
                        n = chain_node(t_info);
                        n->l.n = parse_expr(TC_OPTERM | TC_OUTRDR | TC_GRPTERM);
                        if (t_tclass & TC_OUTRDR) {
                                n->info |= t_info;
                                n->r.n = parse_expr(TC_OPTERM | TC_GRPTERM);
                        }
                        if (t_tclass & TC_GRPTERM)
                                rollback_token();
                        break;

                case OC_BREAK:
                        debug_printf_parse("%s: OC_BREAK\n", __func__);
                        n = chain_node(OC_EXEC);
                        n->a.n = break_ptr;
                        chain_expr(t_info);
                        break;

                case OC_CONTINUE:
                        debug_printf_parse("%s: OC_CONTINUE\n", __func__);
                        n = chain_node(OC_EXEC);
                        n->a.n = continue_ptr;
                        chain_expr(t_info);
                        break;

                /* delete, next, nextfile, return, exit */
                default:
                        debug_printf_parse("%s: default\n", __func__);
                        chain_expr(t_info);
                }
        }
}

static void parse_program(char *p)
{
        uint32_t tclass;
        node *cn;
        func *f;
        var *v;

        g_pos = p;
        t_lineno = 1;
        while ((tclass = next_token(TC_EOF | TC_OPSEQ | TC_GRPSTART |
                        TC_OPTERM | TC_BEGIN | TC_END | TC_FUNCDECL)) != TC_EOF) {

                if (tclass & TC_OPTERM) {
                        debug_printf_parse("%s: TC_OPTERM\n", __func__);
                        continue;
                }

                seq = &mainseq;
                if (tclass & TC_BEGIN) {
                        debug_printf_parse("%s: TC_BEGIN\n", __func__);
                        seq = &beginseq;
                        chain_group();
                } else if (tclass & TC_END) {
                        debug_printf_parse("%s: TC_END\n", __func__);
                        seq = &endseq;
                        chain_group();
                } else if (tclass & TC_FUNCDECL) {
                        debug_printf_parse("%s: TC_FUNCDECL\n", __func__);
                        next_token(TC_FUNCTION);
                        g_pos++;
                        f = newfunc(t_string);
                        f->body.first = NULL;
                        f->nargs = 0;
                        /* Match func arg list: a comma sep list of >= 0 args, and a close paren */
                        while (next_token(TC_VARIABLE | TC_SEQTERM | TC_COMMA)) {
                                /* Either an empty arg list, or trailing comma from prev iter
                                 * must be followed by an arg */
                                if (f->nargs == 0 && t_tclass == TC_SEQTERM)
                                        break;

                                /* TC_SEQSTART/TC_COMMA must be followed by TC_VARIABLE */
                                if (t_tclass != TC_VARIABLE)
                                        syntax_error(EMSG_UNEXP_TOKEN);

                                v = findvar(ahash, t_string);
                                v->x.aidx = f->nargs++;

                                /* Arg followed either by end of arg list or 1 comma */
                                if (next_token(TC_COMMA | TC_SEQTERM) & TC_SEQTERM)
                                        break;
                                if (t_tclass != TC_COMMA)
                                        syntax_error(EMSG_UNEXP_TOKEN);
                        }
                        seq = &f->body;
                        chain_group();
                        clear_array(ahash);
                } else if (tclass & TC_OPSEQ) {
                        debug_printf_parse("%s: TC_OPSEQ\n", __func__);
                        rollback_token();
                        cn = chain_node(OC_TEST);
                        cn->l.n = parse_expr(TC_OPTERM | TC_EOF | TC_GRPSTART);
                        if (t_tclass & TC_GRPSTART) {
                                debug_printf_parse("%s: TC_GRPSTART\n", __func__);
                                rollback_token();
                                chain_group();
                        } else {
                                debug_printf_parse("%s: !TC_GRPSTART\n", __func__);
                                chain_node(OC_PRINT);
                        }
                        cn->r.n = mainseq.last;
                } else /* if (tclass & TC_GRPSTART) */ {
                        debug_printf_parse("%s: TC_GRPSTART(?)\n", __func__);
                        rollback_token();
                        chain_group();
                }
        }
        debug_printf_parse("%s: TC_EOF\n", __func__);
}


/* -------- program execution part -------- */

static node *mk_splitter(const char *s, tsplitter *spl)
{
        regex_t *re, *ire;
        node *n;

        re = &spl->re[0];
        ire = &spl->re[1];
        n = &spl->n;
        if ((n->info & OPCLSMASK) == OC_REGEXP) {
                regfree(re);
                regfree(ire); // TODO: nuke ire, use re+1?
        }
        if (s[0] && s[1]) { /* strlen(s) > 1 */
                mk_re_node(s, n, re);
        } else {
                n->info = (uint32_t) s[0];
        }

        return n;
}

/* use node as a regular expression. Supplied with node ptr and regex_t
 * storage space. Return ptr to regex (if result points to preg, it should
 * be later regfree'd manually
 */
static regex_t *as_regex(node *op, regex_t *preg)
{
        int cflags;
        var *v;
        const char *s;

        if ((op->info & OPCLSMASK) == OC_REGEXP) {
                return icase ? op->r.ire : op->l.re;
        }
        v = nvalloc(1);
        s = getvar_s(evaluate(op, v));

        cflags = icase ? REG_EXTENDED | REG_ICASE : REG_EXTENDED;
        /* Testcase where REG_EXTENDED fails (unpaired '{'):
         * echo Hi | awk 'gsub("@(samp|code|file)\{","");'
         * gawk 3.1.5 eats this. We revert to ~REG_EXTENDED
         * (maybe gsub is not supposed to use REG_EXTENDED?).
         */
        if (regcomp(preg, s, cflags)) {
                cflags &= ~REG_EXTENDED;
                xregcomp(preg, s, cflags);
        }
        nvfree(v);
        return preg;
}

/* gradually increasing buffer.
 * note that we reallocate even if n == old_size,
 * and thus there is at least one extra allocated byte.
 */
static char* qrealloc(char *b, int n, int *size)
{
        if (!b || n >= *size) {
                *size = n + (n>>1) + 80;
                b = xrealloc(b, *size);
        }
        return b;
}

/* resize field storage space */
static void fsrealloc(int size)
{
        int i;

        if (size >= maxfields) {
                i = maxfields;
                maxfields = size + 16;
                Fields = xrealloc(Fields, maxfields * sizeof(Fields[0]));
                for (; i < maxfields; i++) {
                        Fields[i].type = VF_SPECIAL;
                        Fields[i].string = NULL;
                }
        }
        /* if size < nfields, clear extra field variables */
        for (i = size; i < nfields; i++) {
                clrvar(Fields + i);
        }
        nfields = size;
}

static int regexec1_nonempty(const regex_t *preg, const char *s, regmatch_t pmatch[])
{
        int r = regexec(preg, s, 1, pmatch, 0);
        if (r == 0 && pmatch[0].rm_eo == 0) {
                /* For example, happens when FS can match
                 * an empty string (awk -F ' *'). Logically,
                 * this should split into one-char fields.
                 * However, gawk 5.0.1 searches for first
                 * _non-empty_ separator string match:
                 */
                size_t ofs = 0;
                do {
                        ofs++;
                        if (!s[ofs])
                                return REG_NOMATCH;
                        regexec(preg, s + ofs, 1, pmatch, 0);
                } while (pmatch[0].rm_eo == 0);
                pmatch[0].rm_so += ofs;
                pmatch[0].rm_eo += ofs;
        }
        return r;
}

static int awk_split(const char *s, node *spl, char **slist)
{
        int n;
        char c[4];
        char *s1;

        /* in worst case, each char would be a separate field */
        *slist = s1 = xzalloc(strlen(s) * 2 + 3);
        strcpy(s1, s);

        c[0] = c[1] = (char)spl->info;
        c[2] = c[3] = '\0';
        if (*getvar_s(intvar[RS]) == '\0')
                c[2] = '\n';

        n = 0;
        if ((spl->info & OPCLSMASK) == OC_REGEXP) {  /* regex split */
                if (!*s)
                        return n; /* "": zero fields */
                n++; /* at least one field will be there */
                do {
                        int l;
                        regmatch_t pmatch[2]; // TODO: why [2]? [1] is enough...

                        l = strcspn(s, c+2); /* len till next NUL or \n */
                        if (regexec1_nonempty(icase ? spl->r.ire : spl->l.re, s, pmatch) == 0
                         && pmatch[0].rm_so <= l
                        ) {
                                /* if (pmatch[0].rm_eo == 0) ... - impossible */
                                l = pmatch[0].rm_so;
                                n++; /* we saw yet another delimiter */
                        } else {
                                pmatch[0].rm_eo = l;
                                if (s[l])
                                        pmatch[0].rm_eo++;
                        }
                        s1 = mempcpy(s1, s, l);
                        *s1++ = '\0';
                        s += pmatch[0].rm_eo;
                } while (*s);

                /* echo a-- | awk -F-- '{ print NF, length($NF), $NF }'
                 * should print "2 0 ":
                 */
                *s1 = '\0';

                return n;
        }
        if (c[0] == '\0') {  /* null split */
                while (*s) {
                        *s1++ = *s++;
                        *s1++ = '\0';
                        n++;
                }
                return n;
        }
        if (c[0] != ' ') {  /* single-character split */
                if (icase) {
                        c[0] = toupper(c[0]);
                        c[1] = tolower(c[1]);
                }
                if (*s1)
                        n++;
                while ((s1 = strpbrk(s1, c)) != NULL) {
                        *s1++ = '\0';
                        n++;
                }
                return n;
        }
        /* space split */
        while (*s) {
                s = skip_whitespace(s);
                if (!*s)
                        break;
                n++;
                while (*s && !isspace(*s))
                        *s1++ = *s++;
                *s1++ = '\0';
        }
        return n;
}

static void split_f0(void)
{
/* static char *fstrings; */
#define fstrings (G.split_f0__fstrings)

        int i, n;
        char *s;

        if (is_f0_split)
                return;

        is_f0_split = TRUE;
        free(fstrings);
        fsrealloc(0);
        n = awk_split(getvar_s(intvar[F0]), &fsplitter.n, &fstrings);
        fsrealloc(n);
        s = fstrings;
        for (i = 0; i < n; i++) {
                Fields[i].string = nextword(&s);
                Fields[i].type |= (VF_FSTR | VF_USER | VF_DIRTY);
        }

        /* set NF manually to avoid side effects */
        clrvar(intvar[NF]);
        intvar[NF]->type = VF_NUMBER | VF_SPECIAL;
        intvar[NF]->number = nfields;
#undef fstrings
}

/* perform additional actions when some internal variables changed */
static void handle_special(var *v)
{
        int n;
        char *b;
        const char *sep, *s;
        int sl, l, len, i, bsize;

        if (!(v->type & VF_SPECIAL))
                return;

        if (v == intvar[NF]) {
                n = (int)getvar_i(v);
                if (n < 0)
                        syntax_error("NF set to negative value");
                fsrealloc(n);

                /* recalculate $0 */
                sep = getvar_s(intvar[OFS]);
                sl = strlen(sep);
                b = NULL;
                len = 0;
                for (i = 0; i < n; i++) {
                        s = getvar_s(&Fields[i]);
                        l = strlen(s);
                        if (b) {
                                memcpy(b+len, sep, sl);
                                len += sl;
                        }
                        b = qrealloc(b, len+l+sl, &bsize);
                        memcpy(b+len, s, l);
                        len += l;
                }
                if (b)
                        b[len] = '\0';
                setvar_p(intvar[F0], b);
                is_f0_split = TRUE;

        } else if (v == intvar[F0]) {
                is_f0_split = FALSE;

        } else if (v == intvar[FS]) {
                /*
                 * The POSIX-2008 standard says that changing FS should have no effect on the
                 * current input line, but only on the next one. The language is:
                 *
                 * > Before the first reference to a field in the record is evaluated, the record
                 * > shall be split into fields, according to the rules in Regular Expressions,
                 * > using the value of FS that was current at the time the record was read.
                 *
                 * So, split up current line before assignment to FS:
                 */
                split_f0();

                mk_splitter(getvar_s(v), &fsplitter);
        } else if (v == intvar[RS]) {
                mk_splitter(getvar_s(v), &rsplitter);
        } else if (v == intvar[IGNORECASE]) {
                icase = istrue(v);
        } else {                                /* $n */
                n = getvar_i(intvar[NF]);
                setvar_i(intvar[NF], n > v-Fields ? n : v-Fields+1);
                /* right here v is invalid. Just to note... */
        }
}

/* step through func/builtin/etc arguments */
static node *nextarg(node **pn)
{
        node *n;

        n = *pn;
        if (n && (n->info & OPCLSMASK) == OC_COMMA) {
                *pn = n->r.n;
                n = n->l.n;
        } else {
                *pn = NULL;
        }
        return n;
}

static void hashwalk_init(var *v, xhash *array)
{
        hash_item *hi;
        unsigned i;
        walker_list *w;
        walker_list *prev_walker;

        if (v->type & VF_WALK) {
                prev_walker = v->x.walker;
        } else {
                v->type |= VF_WALK;
                prev_walker = NULL;
        }
        debug_printf_walker("hashwalk_init: prev_walker:%p\n", prev_walker);

        w = v->x.walker = xzalloc(sizeof(*w) + array->glen + 1); /* why + 1? */
        debug_printf_walker(" walker@%p=%p\n", &v->x.walker, w);
        w->cur = w->end = w->wbuf;
        w->prev = prev_walker;
        for (i = 0; i < array->csize; i++) {

                hi = array->items[i];
                while (hi) {
                        strcpy(w->end, hi->name);
                        nextword(&w->end);
                        hi = hi->next;
                }
        }
}

static int hashwalk_next(var *v)
{
        walker_list *w = v->x.walker;

        if (w->cur >= w->end) {
                walker_list *prev_walker = w->prev;

                debug_printf_walker("end of iteration, free(walker@%p:%p), prev_walker:%p\n", &v->x.walker, w, prev_walker);
                free(w);
                v->x.walker = prev_walker;
                return FALSE;
        }

        setvar_s(v, nextword(&w->cur));
        return TRUE;
}

/* evaluate node, return 1 when result is true, 0 otherwise */
static int ptest(node *pattern)
{
        /* ptest__v is "static": to save stack space? */
        return istrue(evaluate(pattern, &G.ptest__v));
}

/* read next record from stream rsm into a variable v */
static int awk_getline(rstream *rsm, var *v)
{
        char *b;
        regmatch_t pmatch[2]; // TODO: why [2]? [1] is enough...
        int size, a, p, pp = 0;
        int fd, so, eo, r, rp;
        char c, *m, *s;

        debug_printf_eval("entered %s()\n", __func__);

        /* we're using our own buffer since we need access to accumulating
         * characters
         */
        fd = fileno(rsm->F);
        m = rsm->buffer;
        a = rsm->adv;
        p = rsm->pos;
        size = rsm->size;
        c = (char) rsplitter.n.info;
        rp = 0;

        if (!m)
                m = qrealloc(m, 256, &size);

        do {
                b = m + a;
                so = eo = p;
                r = 1;
                if (p > 0) {
                        if ((rsplitter.n.info & OPCLSMASK) == OC_REGEXP) {
                                if (regexec(icase ? rsplitter.n.r.ire : rsplitter.n.l.re,
                                                        b, 1, pmatch, 0) == 0) {
                                        so = pmatch[0].rm_so;
                                        eo = pmatch[0].rm_eo;
                                        if (b[eo] != '\0')
                                                break;
                                }
                        } else if (c != '\0') {
                                s = strchr(b+pp, c);
                                if (!s)
                                        s = memchr(b+pp, '\0', p - pp);
                                if (s) {
                                        so = eo = s-b;
                                        eo++;
                                        break;
                                }
                        } else {
                                while (b[rp] == '\n')
                                        rp++;
                                s = strstr(b+rp, "\n\n");
                                if (s) {
                                        so = eo = s-b;
                                        while (b[eo] == '\n')
                                                eo++;
                                        if (b[eo] != '\0')
                                                break;
                                }
                        }
                }

                if (a > 0) {
                        memmove(m, m+a, p+1);
                        b = m;
                        a = 0;
                }

                m = qrealloc(m, a+p+128, &size);
                b = m + a;
                pp = p;
                p += safe_read(fd, b+p, size-p-1);
                if (p < pp) {
                        p = 0;
                        r = 0;
                        setvar_i(intvar[ERRNO], errno);
                }
                b[p] = '\0';

        } while (p > pp);

        if (p == 0) {
                r--;
        } else {
                c = b[so]; b[so] = '\0';
                setvar_s(v, b+rp);
                v->type |= VF_USER;
                b[so] = c;
                c = b[eo]; b[eo] = '\0';
                setvar_s(intvar[RT], b+so);
                b[eo] = c;
        }

        rsm->buffer = m;
        rsm->adv = a + eo;
        rsm->pos = p - eo;
        rsm->size = size;

        debug_printf_eval("returning from %s(): %d\n", __func__, r);

        return r;
}

static int fmt_num(char *b, int size, const char *format, double n, int int_as_int)
{
        int r = 0;
        char c;
        const char *s = format;

        if (int_as_int && n == (long long)n) {
                r = snprintf(b, size, "%lld", (long long)n);
        } else {
                do { c = *s; } while (c && *++s);
                if (strchr("diouxX", c)) {
                        r = snprintf(b, size, format, (int)n);
                } else if (strchr("eEfgG", c)) {
                        r = snprintf(b, size, format, n);
                } else {
                        syntax_error(EMSG_INV_FMT);
                }
        }
        return r;
}

/* formatted output into an allocated buffer, return ptr to buffer */
static char *awk_printf(node *n)
{
        char *b = NULL;
        char *fmt, *s, *f;
        const char *s1;
        int i, j, incr, bsize;
        char c, c1;
        var *v, *arg;

        v = nvalloc(1);
        fmt = f = xstrdup(getvar_s(evaluate(nextarg(&n), v)));

        i = 0;
        while (*f) {
                s = f;
                while (*f && (*f != '%' || *++f == '%'))
                        f++;
                while (*f && !isalpha(*f)) {
                        if (*f == '*')
                                syntax_error("%*x formats are not supported");
                        f++;
                }

                incr = (f - s) + MAXVARFMT;
                b = qrealloc(b, incr + i, &bsize);
                c = *f;
                if (c != '\0')
                        f++;
                c1 = *f;
                *f = '\0';
                arg = evaluate(nextarg(&n), v);

                j = i;
                if (c == 'c' || !c) {
                        i += sprintf(b+i, s, is_numeric(arg) ?
                                        (char)getvar_i(arg) : *getvar_s(arg));
                } else if (c == 's') {
                        s1 = getvar_s(arg);
                        b = qrealloc(b, incr+i+strlen(s1), &bsize);
                        i += sprintf(b+i, s, s1);
                } else {
                        i += fmt_num(b+i, incr, s, getvar_i(arg), FALSE);
                }
                *f = c1;

                /* if there was an error while sprintf, return value is negative */
                if (i < j)
                        i = j;
        }

        free(fmt);
        nvfree(v);
        b = xrealloc(b, i + 1);
        b[i] = '\0';
        return b;
}

/* Common substitution routine.
 * Replace (nm)'th substring of (src) that matches (rn) with (repl),
 * store result into (dest), return number of substitutions.
 * If nm = 0, replace all matches.
 * If src or dst is NULL, use $0.
 * If subexp != 0, enable subexpression matching (\1-\9).
 */
static int awk_sub(node *rn, const char *repl, int nm, var *src, var *dest, int subexp)
{
        char *resbuf;
        const char *sp;
        int match_no, residx, replen, resbufsize;
        int regexec_flags;
        regmatch_t pmatch[10];
        regex_t sreg, *regex;

        resbuf = NULL;
        residx = 0;
        match_no = 0;
        regexec_flags = 0;
        regex = as_regex(rn, &sreg);
        sp = getvar_s(src ? src : intvar[F0]);
        replen = strlen(repl);
        while (regexec(regex, sp, 10, pmatch, regexec_flags) == 0) {
                int so = pmatch[0].rm_so;
                int eo = pmatch[0].rm_eo;

                //bb_error_msg("match %u: [%u,%u] '%s'%p", match_no+1, so, eo, sp,sp);
                resbuf = qrealloc(resbuf, residx + eo + replen, &resbufsize);
                memcpy(resbuf + residx, sp, eo);
                residx += eo;
                if (++match_no >= nm) {
                        const char *s;
                        int nbs;

                        /* replace */
                        residx -= (eo - so);
                        nbs = 0;
                        for (s = repl; *s; s++) {
                                char c = resbuf[residx++] = *s;
                                if (c == '\\') {
                                        nbs++;
                                        continue;
                                }
                                if (c == '&' || (subexp && c >= '0' && c <= '9')) {
                                        int j;
                                        residx -= ((nbs + 3) >> 1);
                                        j = 0;
                                        if (c != '&') {
                                                j = c - '0';
                                                nbs++;
                                        }
                                        if (nbs % 2) {
                                                resbuf[residx++] = c;
                                        } else {
                                                int n = pmatch[j].rm_eo - pmatch[j].rm_so;
                                                resbuf = qrealloc(resbuf, residx + replen + n, &resbufsize);
                                                memcpy(resbuf + residx, sp + pmatch[j].rm_so, n);
                                                residx += n;
                                        }
                                }
                                nbs = 0;
                        }
                }

                regexec_flags = REG_NOTBOL;
                sp += eo;
                if (match_no == nm)
                        break;
                if (eo == so) {
                        /* Empty match (e.g. "b*" will match anywhere).
                         * Advance by one char. */
//BUG (bug 1333):
//gsub(/\<b*/,"") on "abc" will reach this point, advance to "bc"
//... and will erroneously match "b" even though it is NOT at the word start.
//we need REG_NOTBOW but it does not exist...
//TODO: if EXTRA_COMPAT=y, use GNU matching and re_search,
//it should be able to do it correctly.
                        /* Subtle: this is safe only because
                         * qrealloc allocated at least one extra byte */
                        resbuf[residx] = *sp;
                        if (*sp == '\0')
                                goto ret;
                        sp++;
                        residx++;
                }
        }

        resbuf = qrealloc(resbuf, residx + strlen(sp), &resbufsize);
        strcpy(resbuf + residx, sp);
 ret:
        //bb_error_msg("end sp:'%s'%p", sp,sp);
        setvar_p(dest ? dest : intvar[F0], resbuf);
        if (regex == &sreg)
                regfree(regex);
        return match_no;
}

static NOINLINE int do_mktime(const char *ds)
{
        struct tm then;
        int count;

        /*memset(&then, 0, sizeof(then)); - not needed */
        then.tm_isdst = -1; /* default is unknown */

        /* manpage of mktime says these fields are ints,
         * so we can sscanf stuff directly into them */
        count = sscanf(ds, "%u %u %u %u %u %u %d",
                &then.tm_year, &then.tm_mon, &then.tm_mday,
                &then.tm_hour, &then.tm_min, &then.tm_sec,
                &then.tm_isdst);

        if (count < 6
         || (unsigned)then.tm_mon < 1
         || (unsigned)then.tm_year < 1900
        ) {
                return -1;
        }

        then.tm_mon -= 1;
        then.tm_year -= 1900;

        return mktime(&then);
}

static NOINLINE var *exec_builtin(node *op, var *res)
{
#define tspl (G.exec_builtin__tspl)

        var *tv;
        node *an[4];
        var *av[4];
        const char *as[4];
        regmatch_t pmatch[2];
        regex_t sreg, *re;
        node *spl;
        uint32_t isr, info;
        int nargs;
        time_t tt;
        int i, l, ll, n;

        tv = nvalloc(4);
        isr = info = op->info;
        op = op->l.n;

        av[2] = av[3] = NULL;
        for (i = 0; i < 4 && op; i++) {
                an[i] = nextarg(&op);
                if (isr & 0x09000000)
                        av[i] = evaluate(an[i], &tv[i]);
                if (isr & 0x08000000)
                        as[i] = getvar_s(av[i]);
                isr >>= 1;
        }

        nargs = i;
        if ((uint32_t)nargs < (info >> 30))
                syntax_error(EMSG_TOO_FEW_ARGS);

        info &= OPNMASK;
        switch (info) {

        case B_a2:
                if (ENABLE_FEATURE_AWK_LIBM)
                        setvar_i(res, atan2(getvar_i(av[0]), getvar_i(av[1])));
                else
                        syntax_error(EMSG_NO_MATH);
                break;

        case B_sp: {
                char *s, *s1;

                if (nargs > 2) {
                        spl = (an[2]->info & OPCLSMASK) == OC_REGEXP ?
                                an[2] : mk_splitter(getvar_s(evaluate(an[2], &tv[2])), &tspl);
                } else {
                        spl = &fsplitter.n;
                }

                n = awk_split(as[0], spl, &s);
                s1 = s;
                clear_array(iamarray(av[1]));
                for (i = 1; i <= n; i++)
                        setari_u(av[1], i, nextword(&s));
                free(s1);
                setvar_i(res, n);
                break;
        }

        case B_ss: {
                char *s;

                l = strlen(as[0]);
                i = getvar_i(av[1]) - 1;
                if (i > l)
                        i = l;
                if (i < 0)
                        i = 0;
                n = (nargs > 2) ? getvar_i(av[2]) : l-i;
                if (n < 0)
                        n = 0;
                s = xstrndup(as[0]+i, n);
                setvar_p(res, s);
                break;
        }

        /* Bitwise ops must assume that operands are unsigned. GNU Awk 3.1.5:
         * awk '{ print or(-1,1) }' gives "4.29497e+09", not "-2.xxxe+09" */
        case B_an:
                setvar_i(res, getvar_i_int(av[0]) & getvar_i_int(av[1]));
                break;

        case B_co:
                setvar_i(res, ~getvar_i_int(av[0]));
                break;

        case B_ls:
                setvar_i(res, getvar_i_int(av[0]) << getvar_i_int(av[1]));
                break;

        case B_or:
                setvar_i(res, getvar_i_int(av[0]) | getvar_i_int(av[1]));
                break;

        case B_rs:
                setvar_i(res, getvar_i_int(av[0]) >> getvar_i_int(av[1]));
                break;

        case B_xo:
                setvar_i(res, getvar_i_int(av[0]) ^ getvar_i_int(av[1]));
                break;

        case B_lo:
        case B_up: {
                char *s, *s1;
                s1 = s = xstrdup(as[0]);
                while (*s1) {
                        //*s1 = (info == B_up) ? toupper(*s1) : tolower(*s1);
                        if ((unsigned char)((*s1 | 0x20) - 'a') <= ('z' - 'a'))
                                *s1 = (info == B_up) ? (*s1 & 0xdf) : (*s1 | 0x20);
                        s1++;
                }
                setvar_p(res, s);
                break;
        }

        case B_ix:
                n = 0;
                ll = strlen(as[1]);
                l = strlen(as[0]) - ll;
                if (ll > 0 && l >= 0) {
                        if (!icase) {
                                char *s = strstr(as[0], as[1]);
                                if (s)
                                        n = (s - as[0]) + 1;
                        } else {
                                /* this piece of code is terribly slow and
                                 * really should be rewritten
                                 */
                                for (i = 0; i <= l; i++) {
                                        if (strncasecmp(as[0]+i, as[1], ll) == 0) {
                                                n = i+1;
                                                break;
                                        }
                                }
                        }
                }
                setvar_i(res, n);
                break;

        case B_ti:
                if (nargs > 1)
                        tt = getvar_i(av[1]);
                else
                        time(&tt);
                //s = (nargs > 0) ? as[0] : "%a %b %d %H:%M:%S %Z %Y";
                i = strftime(g_buf, MAXVARFMT,
                        ((nargs > 0) ? as[0] : "%a %b %d %H:%M:%S %Z %Y"),
                        localtime(&tt));
                g_buf[i] = '\0';
                setvar_s(res, g_buf);
                break;

        case B_mt:
                setvar_i(res, do_mktime(as[0]));
                break;

        case B_ma:
                re = as_regex(an[1], &sreg);
                n = regexec(re, as[0], 1, pmatch, 0);
                if (n == 0) {
                        pmatch[0].rm_so++;
                        pmatch[0].rm_eo++;
                } else {
                        pmatch[0].rm_so = 0;
                        pmatch[0].rm_eo = -1;
                }
                setvar_i(newvar("RSTART"), pmatch[0].rm_so);
                setvar_i(newvar("RLENGTH"), pmatch[0].rm_eo - pmatch[0].rm_so);
                setvar_i(res, pmatch[0].rm_so);
                if (re == &sreg)
                        regfree(re);
                break;

        case B_ge:
                awk_sub(an[0], as[1], getvar_i(av[2]), av[3], res, TRUE);
                break;

        case B_gs:
                setvar_i(res, awk_sub(an[0], as[1], 0, av[2], av[2], FALSE));
                break;

        case B_su:
                setvar_i(res, awk_sub(an[0], as[1], 1, av[2], av[2], FALSE));
                break;
        }

        nvfree(tv);
        return res;
#undef tspl
}

/*
 * Evaluate node - the heart of the program. Supplied with subtree
 * and place where to store result. returns ptr to result.
 */
#define XC(n) ((n) >> 8)

static var *evaluate(node *op, var *res)
{
/* This procedure is recursive so we should count every byte */
#define fnargs (G.evaluate__fnargs)
/* seed is initialized to 1 */
#define seed   (G.evaluate__seed)
#define sreg   (G.evaluate__sreg)

        var *v1;

        if (!op)
                return setvar_s(res, NULL);

        debug_printf_eval("entered %s()\n", __func__);

        v1 = nvalloc(2);

        while (op) {
                struct {
                        var *v;
                        const char *s;
                } L = L; /* for compiler */
                struct {
                        var *v;
                        const char *s;
                } R = R;
                double L_d = L_d;
                uint32_t opinfo;
                int opn;
                node *op1;

                opinfo = op->info;
                opn = (opinfo & OPNMASK);
                g_lineno = op->lineno;
                op1 = op->l.n;
                debug_printf_eval("opinfo:%08x opn:%08x\n", opinfo, opn);

                /* "delete" is special:
                 * "delete array[var--]" must evaluate index expr only once,
                 * must not evaluate it in "execute inevitable things" part.
                 */
                if (XC(opinfo & OPCLSMASK) == XC(OC_DELETE)) {
                        uint32_t info = op1->info & OPCLSMASK;
                        var *v;

                        debug_printf_eval("DELETE\n");
                        if (info == OC_VAR) {
                                v = op1->l.v;
                        } else if (info == OC_FNARG) {
                                v = &fnargs[op1->l.aidx];
                        } else {
                                syntax_error(EMSG_NOT_ARRAY);
                        }
                        if (op1->r.n) { /* array ref? */
                                const char *s;
                                s = getvar_s(evaluate(op1->r.n, v1));
                                hash_remove(iamarray(v), s);
                        } else {
                                clear_array(iamarray(v));
                        }
                        goto next;
                }

                /* execute inevitable things */
                if (opinfo & OF_RES1)
                        L.v = evaluate(op1, v1);
                if (opinfo & OF_RES2)
                        R.v = evaluate(op->r.n, v1+1);
                if (opinfo & OF_STR1) {
                        L.s = getvar_s(L.v);
                        debug_printf_eval("L.s:'%s'\n", L.s);
                }
                if (opinfo & OF_STR2) {
                        R.s = getvar_s(R.v);
                        debug_printf_eval("R.s:'%s'\n", R.s);
                }
                if (opinfo & OF_NUM1) {
                        L_d = getvar_i(L.v);
                        debug_printf_eval("L_d:%f\n", L_d);
                }

                debug_printf_eval("switch(0x%x)\n", XC(opinfo & OPCLSMASK));
                switch (XC(opinfo & OPCLSMASK)) {

                /* -- iterative node type -- */

                /* test pattern */
                case XC( OC_TEST ):
                        if ((op1->info & OPCLSMASK) == OC_COMMA) {
                                /* it's range pattern */
                                if ((opinfo & OF_CHECKED) || ptest(op1->l.n)) {
                                        op->info |= OF_CHECKED;
                                        if (ptest(op1->r.n))
                                                op->info &= ~OF_CHECKED;
                                        op = op->a.n;
                                } else {
                                        op = op->r.n;
                                }
                        } else {
                                op = ptest(op1) ? op->a.n : op->r.n;
                        }
                        break;

                /* just evaluate an expression, also used as unconditional jump */
                case XC( OC_EXEC ):
                        break;

                /* branch, used in if-else and various loops */
                case XC( OC_BR ):
                        op = istrue(L.v) ? op->a.n : op->r.n;
                        break;

                /* initialize for-in loop */
                case XC( OC_WALKINIT ):
                        hashwalk_init(L.v, iamarray(R.v));
                        break;

                /* get next array item */
                case XC( OC_WALKNEXT ):
                        op = hashwalk_next(L.v) ? op->a.n : op->r.n;
                        break;

                case XC( OC_PRINT ):
                case XC( OC_PRINTF ): {
                        FILE *F = stdout;

                        if (op->r.n) {
                                rstream *rsm = newfile(R.s);
                                if (!rsm->F) {
                                        if (opn == '|') {
                                                rsm->F = popen(R.s, "w");
                                                if (rsm->F == NULL)
                                                        bb_simple_perror_msg_and_die("popen");
                                                rsm->is_pipe = 1;
                                        } else {
                                                rsm->F = xfopen(R.s, opn=='w' ? "w" : "a");
                                        }
                                }
                                F = rsm->F;
                        }

                        if ((opinfo & OPCLSMASK) == OC_PRINT) {
                                if (!op1) {
                                        fputs(getvar_s(intvar[F0]), F);
                                } else {
                                        while (op1) {
                                                var *v = evaluate(nextarg(&op1), v1);
                                                if (v->type & VF_NUMBER) {
                                                        fmt_num(g_buf, MAXVARFMT, getvar_s(intvar[OFMT]),
                                                                        getvar_i(v), TRUE);
                                                        fputs(g_buf, F);
                                                } else {
                                                        fputs(getvar_s(v), F);
                                                }

                                                if (op1)
                                                        fputs(getvar_s(intvar[OFS]), F);
                                        }
                                }
                                fputs(getvar_s(intvar[ORS]), F);

                        } else {        /* OC_PRINTF */
                                char *s = awk_printf(op1);
                                fputs(s, F);
                                free(s);
                        }
                        fflush(F);
                        break;
                }

                /* case XC( OC_DELETE ): - moved to happen before arg evaluation */

                case XC( OC_NEWSOURCE ):
                        g_progname = op->l.new_progname;
                        break;

                case XC( OC_RETURN ):
                        copyvar(res, L.v);
                        break;

                case XC( OC_NEXTFILE ):
                        nextfile = TRUE;
                case XC( OC_NEXT ):
                        nextrec = TRUE;
                case XC( OC_DONE ):
                        clrvar(res);
                        break;

                case XC( OC_EXIT ):
                        awk_exit(L_d);

                /* -- recursive node type -- */

                case XC( OC_VAR ):
                        debug_printf_eval("VAR\n");
                        L.v = op->l.v;
                        if (L.v == intvar[NF])
                                split_f0();
                        goto v_cont;

                case XC( OC_FNARG ):
                        debug_printf_eval("FNARG[%d]\n", op->l.aidx);
                        L.v = &fnargs[op->l.aidx];
 v_cont:
                        res = op->r.n ? findvar(iamarray(L.v), R.s) : L.v;
                        break;

                case XC( OC_IN ):
                        setvar_i(res, hash_search(iamarray(R.v), L.s) ? 1 : 0);
                        break;

                case XC( OC_REGEXP ):
                        op1 = op;
                        L.s = getvar_s(intvar[F0]);
                        goto re_cont;

                case XC( OC_MATCH ):
                        op1 = op->r.n;
 re_cont:
                        {
                                regex_t *re = as_regex(op1, &sreg);
                                int i = regexec(re, L.s, 0, NULL, 0);
                                if (re == &sreg)
                                        regfree(re);
                                setvar_i(res, (i == 0) ^ (opn == '!'));
                        }
                        break;

                case XC( OC_MOVE ):
                        debug_printf_eval("MOVE\n");
                        /* if source is a temporary string, jusk relink it to dest */
//Disabled: if R.v is numeric but happens to have cached R.v->string,
//then L.v ends up being a string, which is wrong
//                      if (R.v == v1+1 && R.v->string) {
//                              res = setvar_p(L.v, R.v->string);
//                              R.v->string = NULL;
//                      } else {
                                res = copyvar(L.v, R.v);
//                      }
                        break;

                case XC( OC_TERNARY ):
                        if ((op->r.n->info & OPCLSMASK) != OC_COLON)
                                syntax_error(EMSG_POSSIBLE_ERROR);
                        res = evaluate(istrue(L.v) ? op->r.n->l.n : op->r.n->r.n, res);
                        break;

                case XC( OC_FUNC ): {
                        var *vbeg, *v;
                        const char *sv_progname;

                        /* The body might be empty, still has to eval the args */
                        if (!op->r.n->info && !op->r.f->body.first)
                                syntax_error(EMSG_UNDEF_FUNC);

                        vbeg = v = nvalloc(op->r.f->nargs + 1);
                        while (op1) {
                                var *arg = evaluate(nextarg(&op1), v1);
                                copyvar(v, arg);
                                v->type |= VF_CHILD;
                                v->x.parent = arg;
                                if (++v - vbeg >= op->r.f->nargs)
                                        break;
                        }

                        v = fnargs;
                        fnargs = vbeg;
                        sv_progname = g_progname;

                        res = evaluate(op->r.f->body.first, res);

                        g_progname = sv_progname;
                        nvfree(fnargs);
                        fnargs = v;

                        break;
                }

                case XC( OC_GETLINE ):
                case XC( OC_PGETLINE ): {
                        rstream *rsm;
                        int i;

                        if (op1) {
                                rsm = newfile(L.s);
                                if (!rsm->F) {
                                        if ((opinfo & OPCLSMASK) == OC_PGETLINE) {
                                                rsm->F = popen(L.s, "r");
                                                rsm->is_pipe = TRUE;
                                        } else {
                                                rsm->F = fopen_for_read(L.s);  /* not xfopen! */
                                        }
                                }
                        } else {
                                if (!iF)
                                        iF = next_input_file();
                                rsm = iF;
                        }

                        if (!rsm || !rsm->F) {
                                setvar_i(intvar[ERRNO], errno);
                                setvar_i(res, -1);
                                break;
                        }

                        if (!op->r.n)
                                R.v = intvar[F0];

                        i = awk_getline(rsm, R.v);
                        if (i > 0 && !op1) {
                                incvar(intvar[FNR]);
                                incvar(intvar[NR]);
                        }
                        setvar_i(res, i);
                        break;
                }

                /* simple builtins */
                case XC( OC_FBLTIN ): {
                        double R_d = R_d; /* for compiler */

                        switch (opn) {
                        case F_in:
                                R_d = (long long)L_d;
                                break;

                        case F_rn:
                                R_d = (double)rand() / (double)RAND_MAX;
                                break;

                        case F_co:
                                if (ENABLE_FEATURE_AWK_LIBM) {
                                        R_d = cos(L_d);
                                        break;
                                }

                        case F_ex:
                                if (ENABLE_FEATURE_AWK_LIBM) {
                                        R_d = exp(L_d);
                                        break;
                                }

                        case F_lg:
                                if (ENABLE_FEATURE_AWK_LIBM) {
                                        R_d = log(L_d);
                                        break;
                                }

                        case F_si:
                                if (ENABLE_FEATURE_AWK_LIBM) {
                                        R_d = sin(L_d);
                                        break;
                                }

                        case F_sq:
                                if (ENABLE_FEATURE_AWK_LIBM) {
                                        R_d = sqrt(L_d);
                                        break;
                                }

                                syntax_error(EMSG_NO_MATH);
                                break;

                        case F_sr:
                                R_d = (double)seed;
                                seed = op1 ? (unsigned)L_d : (unsigned)time(NULL);
                                srand(seed);
                                break;

                        case F_ti:
                                R_d = time(NULL);
                                break;

                        case F_le:
                                debug_printf_eval("length: L.s:'%s'\n", L.s);
                                if (!op1) {
                                        L.s = getvar_s(intvar[F0]);
                                        debug_printf_eval("length: L.s='%s'\n", L.s);
                                }
                                else if (L.v->type & VF_ARRAY) {
                                        R_d = L.v->x.array->nel;
                                        debug_printf_eval("length: array_len:%d\n", L.v->x.array->nel);
                                        break;
                                }
                                R_d = strlen(L.s);
                                break;

                        case F_sy:
                                fflush_all();
                                R_d = (ENABLE_FEATURE_ALLOW_EXEC && L.s && *L.s)
                                                ? (system(L.s) >> 8) : 0;
                                break;

                        case F_ff:
                                if (!op1) {
                                        fflush(stdout);
                                } else if (L.s && *L.s) {
                                        rstream *rsm = newfile(L.s);
                                        fflush(rsm->F);
                                } else {
                                        fflush_all();
                                }
                                break;

                        case F_cl: {
                                rstream *rsm;
                                int err = 0;
                                rsm = (rstream *)hash_search(fdhash, L.s);
                                debug_printf_eval("OC_FBLTIN F_cl rsm:%p\n", rsm);
                                if (rsm) {
                                        debug_printf_eval("OC_FBLTIN F_cl "
                                                "rsm->is_pipe:%d, ->F:%p\n",
                                                rsm->is_pipe, rsm->F);
                                        /* Can be NULL if open failed. Example:
                                         * getline line <"doesnt_exist";
                                         * close("doesnt_exist"); <--- here rsm->F is NULL
                                         */
                                        if (rsm->F)
                                                err = rsm->is_pipe ? pclose(rsm->F) : fclose(rsm->F);
                                        free(rsm->buffer);
                                        hash_remove(fdhash, L.s);
                                }
                                if (err)
                                        setvar_i(intvar[ERRNO], errno);
                                R_d = (double)err;
                                break;
                        }
                        } /* switch */
                        setvar_i(res, R_d);
                        break;
                }

                case XC( OC_BUILTIN ):
                        res = exec_builtin(op, res);
                        break;

                case XC( OC_SPRINTF ):
                        setvar_p(res, awk_printf(op1));
                        break;

                case XC( OC_UNARY ): {
                        double Ld, R_d;

                        Ld = R_d = getvar_i(R.v);
                        switch (opn) {
                        case 'P':
                                Ld = ++R_d;
                                goto r_op_change;
                        case 'p':
                                R_d++;
                                goto r_op_change;
                        case 'M':
                                Ld = --R_d;
                                goto r_op_change;
                        case 'm':
                                R_d--;
 r_op_change: