// SPDX-License-Identifier: GPL-2.0-or-later

/* P9 gunzip sample code for demonstrating the P9 NX hardware
 * interface.  Not intended for productive uses or for performance or
 * compression ratio measurements.  Note also that /dev/crypto/gzip,
 * VAS and skiboot support are required
 *
 * Copyright 2020 IBM Corp.
 *
 * Author: Bulent Abali <abali@us.ibm.com>
 *
 * https://github.com/libnxz/power-gzip for zlib api and other utils
 * Definitions of acronyms used here.  See
 * P9 NX Gzip Accelerator User's Manual for details:
 * https://github.com/libnxz/power-gzip/blob/develop/doc/power_nx_gzip_um.pdf
 *
 * adler/crc: 32 bit checksums appended to stream tail
 * ce:       completion extension
 * cpb:      coprocessor parameter block (metadata)
 * crb:      coprocessor request block (command)
 * csb:      coprocessor status block (status)
 * dht:      dynamic huffman table
 * dde:      data descriptor element (address, length)
 * ddl:      list of ddes
 * dh/fh:    dynamic and fixed huffman types
 * fc:       coprocessor function code
 * histlen:  history/dictionary length
 * history:  sliding window of up to 32KB of data
 * lzcount:  Deflate LZ symbol counts
 * rembytecnt: remaining byte count
 * sfbt:     source final block type; last block's type during decomp
 * spbc:     source processed byte count
 * subc:     source unprocessed bit count
 * tebc:     target ending bit count; valid bits in the last byte
 * tpbc:     target processed byte count
 * vas:      virtual accelerator switch; the user mode interface
 */

#define _ISOC11_SOURCE  // For aligned_alloc()
#define _DEFAULT_SOURCE // For endian.h

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/fcntl.h>
#include <sys/mman.h>
#include <endian.h>
#include <bits/endian.h>
#include <sys/ioctl.h>
#include <assert.h>
#include <errno.h>
#include <signal.h>
#include "nxu.h"
#include "nx.h"
#include "crb.h"

int nx_dbg;
FILE *nx_gzip_log;

#define NX_MIN(X, Y) (((X) < (Y))?(X):(Y))
#define NX_MAX(X, Y) (((X) > (Y))?(X):(Y))

#define GETINPC(X) fgetc(X)
#define FNAME_MAX 1024

/* fifo queue management */
#define fifo_used_bytes(used) (used)
#define fifo_free_bytes(used, len) ((len)-(used))
/* amount of free bytes in the first and last parts */
#define fifo_free_first_bytes(cur, used, len)  ((((cur)+(used)) <= (len)) \
                                                  ? (len)-((cur)+(used)) : 0)
#define fifo_free_last_bytes(cur, used, len)   ((((cur)+(used)) <= (len)) \
                                                  ? (cur) : (len)-(used))
/* amount of used bytes in the first and last parts */
#define fifo_used_first_bytes(cur, used, len)  ((((cur)+(used)) <= (len)) \
                                                  ? (used) : (len)-(cur))
#define fifo_used_last_bytes(cur, used, len)   ((((cur)+(used)) <= (len)) \
                                                  ? 0 : ((used)+(cur))-(len))
/* first and last free parts start here */
#define fifo_free_first_offset(cur, used)      ((cur)+(used))
#define fifo_free_last_offset(cur, used, len)  \
                                           fifo_used_last_bytes(cur, used, len)
/* first and last used parts start here */
#define fifo_used_first_offset(cur)            (cur)
#define fifo_used_last_offset(cur)             (0)

const int fifo_in_len = 1<<24;
const int fifo_out_len = 1<<24;
const int page_sz = 1<<16;
const int line_sz = 1<<7;
const int window_max = 1<<15;

/*
 * Adds an (address, len) pair to the list of ddes (ddl) and updates
 * the base dde.  ddl[0] is the only dde in a direct dde which
 * contains a single (addr,len) pair.  For more pairs, ddl[0] becomes
 * the indirect (base) dde that points to a list of direct ddes.
 * See Section 6.4 of the NX-gzip user manual for DDE description.
 * Addr=NULL, len=0 clears the ddl[0].  Returns the total number of
 * bytes in ddl.  Caller is responsible for allocting the array of
 * nx_dde_t *ddl.  If N addresses are required in the scatter-gather
 * list, the ddl array must have N+1 entries minimum.
 */
static inline uint32_t nx_append_dde(struct nx_dde_t *ddl, void *addr,
                                        uint32_t len)
{
        uint32_t ddecnt;
        uint32_t bytes;

        if (addr == NULL && len == 0) {
                clearp_dde(ddl);
                return 0;
        }

        NXPRT(fprintf(stderr, "%d: %s addr %p len %x\n", __LINE__, addr,
                        __func__, len));

        /* Number of ddes in the dde list ; == 0 when it is a direct dde */
        ddecnt = getpnn(ddl, dde_count);
        bytes = getp32(ddl, ddebc);

        if (ddecnt == 0 && bytes == 0) {
                /* First dde is unused; make it a direct dde */
                bytes = len;
                putp32(ddl, ddebc, bytes);
                putp64(ddl, ddead, (uint64_t) addr);
        } else if (ddecnt == 0) {
                /* Converting direct to indirect dde
                 * ddl[0] becomes head dde of ddl
                 * copy direct to indirect first.
                 */
                ddl[1] = ddl[0];

                /* Add the new dde next */
                clear_dde(ddl[2]);
                put32(ddl[2], ddebc, len);
                put64(ddl[2], ddead, (uint64_t) addr);

                /* Ddl head points to 2 direct ddes */
                ddecnt = 2;
                putpnn(ddl, dde_count, ddecnt);
                bytes = bytes + len;
                putp32(ddl, ddebc, bytes);
                /* Pointer to the first direct dde */
                putp64(ddl, ddead, (uint64_t) &ddl[1]);
        } else {
                /* Append a dde to an existing indirect ddl */
                ++ddecnt;
                clear_dde(ddl[ddecnt]);
                put64(ddl[ddecnt], ddead, (uint64_t) addr);
                put32(ddl[ddecnt], ddebc, len);

                putpnn(ddl, dde_count, ddecnt);
                bytes = bytes + len;
                putp32(ddl, ddebc, bytes); /* byte sum of all dde */
        }
        return bytes;
}

/*
 * Touch specified number of pages represented in number bytes
 * beginning from the first buffer in a dde list.
 * Do not touch the pages past buf_sz-th byte's page.
 *
 * Set buf_sz = 0 to touch all pages described by the ddep.
 */
static int nx_touch_pages_dde(struct nx_dde_t *ddep, long buf_sz, long page_sz,
                                int wr)
{
        uint32_t indirect_count;
        uint32_t buf_len;
        long total;
        uint64_t buf_addr;
        struct nx_dde_t *dde_list;
        int i;

        assert(!!ddep);

        indirect_count = getpnn(ddep, dde_count);

        NXPRT(fprintf(stderr, "%s dde_count %d request len ", __func__,
                        indirect_count));
        NXPRT(fprintf(stderr, "0x%lx\n", buf_sz));

        if (indirect_count == 0) {
                /* Direct dde */
                buf_len = getp32(ddep, ddebc);
                buf_addr = getp64(ddep, ddead);

                NXPRT(fprintf(stderr, "touch direct ddebc 0x%x ddead %p\n",
                                buf_len, (void *)buf_addr));

                if (buf_sz == 0)
                        nxu_touch_pages((void *)buf_addr, buf_len, page_sz, wr);
                else
                        nxu_touch_pages((void *)buf_addr, NX_MIN(buf_len,
                                        buf_sz), page_sz, wr);

                return ERR_NX_OK;
        }

        /* Indirect dde */
        if (indirect_count > MAX_DDE_COUNT)
                return ERR_NX_EXCESSIVE_DDE;

        /* First address of the list */
        dde_list = (struct nx_dde_t *) getp64(ddep, ddead);

        if (buf_sz == 0)
                buf_sz = getp32(ddep, ddebc);

        total = 0;
        for (i = 0; i < indirect_count; i++) {
                buf_len = get32(dde_list[i], ddebc);
                buf_addr = get64(dde_list[i], ddead);
                total += buf_len;

                NXPRT(fprintf(stderr, "touch loop len 0x%x ddead %p total ",
                                buf_len, (void *)buf_addr));
                NXPRT(fprintf(stderr, "0x%lx\n", total));

                /* Touching fewer pages than encoded in the ddebc */
                if (total > buf_sz) {
                        buf_len = NX_MIN(buf_len, total - buf_sz);
                        nxu_touch_pages((void *)buf_addr, buf_len, page_sz, wr);
                        NXPRT(fprintf(stderr, "touch loop break len 0x%x ",
                                      buf_len));
                        NXPRT(fprintf(stderr, "ddead %p\n", (void *)buf_addr));
                        break;
                }
                nxu_touch_pages((void *)buf_addr, buf_len, page_sz, wr);
        }
        return ERR_NX_OK;
}

/*
 * Src and dst buffers are supplied in scatter gather lists.
 * NX function code and other parameters supplied in cmdp.
 */
static int nx_submit_job(struct nx_dde_t *src, struct nx_dde_t *dst,
                         struct nx_gzip_crb_cpb_t *cmdp, void *handle)
{
        uint64_t csbaddr;

        memset((void *)&cmdp->crb.csb, 0, sizeof(cmdp->crb.csb));

        cmdp->crb.source_dde = *src;
        cmdp->crb.target_dde = *dst;

        /* Status, output byte count in tpbc */
        csbaddr = ((uint64_t) &cmdp->crb.csb) & csb_address_mask;
        put64(cmdp->crb, csb_address, csbaddr);

        /* NX reports input bytes in spbc; cleared */
        cmdp->cpb.out_spbc_comp_wrap = 0;
        cmdp->cpb.out_spbc_comp_with_count = 0;
        cmdp->cpb.out_spbc_decomp = 0;

        /* Clear output */
        put32(cmdp->cpb, out_crc, INIT_CRC);
        put32(cmdp->cpb, out_adler, INIT_ADLER);

        /* Submit the crb, the job descriptor, to the accelerator. */
        return nxu_submit_job(cmdp, handle);
}

int decompress_file(int argc, char **argv, void *devhandle)
{
        FILE *inpf = NULL;
        FILE *outf = NULL;

        int c, expect, i, cc, rc = 0;
        char gzfname[FNAME_MAX];

        /* Queuing, file ops, byte counting */
        char *fifo_in, *fifo_out;
        int used_in, cur_in, used_out, cur_out, read_sz, n;
        int first_free, last_free, first_used, last_used;
        int first_offset, last_offset;
        int write_sz, free_space, source_sz;
        int source_sz_estimate, target_sz_estimate;
        uint64_t last_comp_ratio = 0; /* 1000 max */
        uint64_t total_out = 0;
        int is_final, is_eof;

        /* nx hardware */
        int sfbt, subc, spbc, tpbc, nx_ce, fc, resuming = 0;
        int history_len = 0;
        struct nx_gzip_crb_cpb_t cmd, *cmdp;
        struct nx_dde_t *ddl_in;
        struct nx_dde_t dde_in[6] __aligned(128);
        struct nx_dde_t *ddl_out;
        struct nx_dde_t dde_out[6] __aligned(128);
        int pgfault_retries;

        /* when using mmap'ed files */
        off_t input_file_offset;

        if (argc > 2) {
                fprintf(stderr, "usage: %s <fname> or stdin\n", argv[0]);
                fprintf(stderr, "    writes to stdout or <fname>.nx.gunzip\n");
                return -1;
        }

        if (argc == 1) {
                inpf = stdin;
                outf = stdout;
        } else if (argc == 2) {
                char w[1024];
                char *wp;

                inpf = fopen(argv[1], "r");
                if (inpf == NULL) {
                        perror(argv[1]);
                        return -1;
                }

                /* Make a new file name to write to.  Ignoring '.gz' */
                wp = (NULL != (wp = strrchr(argv[1], '/'))) ? (wp+1) : argv[1];
                strcpy(w, wp);
                strcat(w, ".nx.gunzip");

                outf = fopen(w, "w");
                if (outf == NULL) {
                        perror(w);
                        return -1;
                }
        }

        /* Decode the gzip header */
        c = GETINPC(inpf); expect = 0x1f; /* ID1 */
        if (c != expect)
                goto err1;

        c = GETINPC(inpf); expect = 0x8b; /* ID2 */
        if (c != expect)
                goto err1;

        c = GETINPC(inpf); expect = 0x08; /* CM */
        if (c != expect)
                goto err1;

        int flg = GETINPC(inpf); /* FLG */

        if (flg & 0xE0 || flg & 0x4 || flg == EOF)
                goto err2;

        fprintf(stderr, "gzHeader FLG %x\n", flg);

        /* Read 6 bytes; ignoring the MTIME, XFL, OS fields in this
         * sample code.
         */
        for (i = 0; i < 6; i++) {
                char tmp[10];

                tmp[i] = GETINPC(inpf);
                if (tmp[i] == EOF)
                        goto err3;
                fprintf(stderr, "%02x ", tmp[i]);
                if (i == 5)
                        fprintf(stderr, "\n");
        }
        fprintf(stderr, "gzHeader MTIME, XFL, OS ignored\n");

        /* FNAME */
        if (flg & 0x8) {
                int k = 0;

                do {
                        c = GETINPC(inpf);
                        if (c == EOF || k >= FNAME_MAX)
                                goto err3;
                        gzfname[k++] = c;
                } while (c);
                fprintf(stderr, "gzHeader FNAME: %s\n", gzfname);
        }

        /* FHCRC */
        if (flg & 0x2) {
                c = GETINPC(inpf);
                if (c == EOF)
                        goto err3;
                c = GETINPC(inpf);
                if (c == EOF)
                        goto err3;
                fprintf(stderr, "gzHeader FHCRC: ignored\n");
        }

        used_in = cur_in = used_out = cur_out = 0;
        is_final = is_eof = 0;

        /* Allocate one page larger to prevent page faults due to NX
         * overfetching.
         * Either do this (char*)(uintptr_t)aligned_alloc or use
         * -std=c11 flag to make the int-to-pointer warning go away.
         */
        assert((fifo_in  = (char *)(uintptr_t)aligned_alloc(line_sz,
                                   fifo_in_len + page_sz)) != NULL);
        assert((fifo_out = (char *)(uintptr_t)aligned_alloc(line_sz,
                                   fifo_out_len + page_sz + line_sz)) != NULL);
        /* Leave unused space due to history rounding rules */
        fifo_out = fifo_out + line_sz;
        nxu_touch_pages(fifo_out, fifo_out_len, page_sz, 1);

        ddl_in  = &dde_in[0];
        ddl_out = &dde_out[0];
        cmdp = &cmd;
        memset(&cmdp->crb, 0, sizeof(cmdp->crb));

read_state:

        /* Read from .gz file */

        NXPRT(fprintf(stderr, "read_state:\n"));

        if (is_eof != 0)
                goto write_state;

        /* We read in to fifo_in in two steps: first: read in to from
         * cur_in to the end of the buffer.  last: if free space wrapped
         * around, read from fifo_in offset 0 to offset cur_in.
         */

        /* Reset fifo head to reduce unnecessary wrap arounds */
        cur_in = (used_in == 0) ? 0 : cur_in;

        /* Free space total is reduced by a gap */
        free_space = NX_MAX(0, fifo_free_bytes(used_in, fifo_in_len)
                            - line_sz);

        /* Free space may wrap around as first and last */
        first_free = fifo_free_first_bytes(cur_in, used_in, fifo_in_len);
        last_free  = fifo_free_last_bytes(cur_in, used_in, fifo_in_len);

        /* Start offsets of the free memory */
        first_offset = fifo_free_first_offset(cur_in, used_in);
        last_offset  = fifo_free_last_offset(cur_in, used_in, fifo_in_len);

        /* Reduce read_sz because of the line_sz gap */
        read_sz = NX_MIN(free_space, first_free);
        n = 0;
        if (read_sz > 0) {
                /* Read in to offset cur_in + used_in */
                n = fread(fifo_in + first_offset, 1, read_sz, inpf);
                used_in = used_in + n;
                free_space = free_space - n;
                assert(n <= read_sz);
                if (n != read_sz) {
                        /* Either EOF or error; exit the read loop */
                        is_eof = 1;
                        goto write_state;
                }
        }

        /* If free space wrapped around */
        if (last_free > 0) {
                /* Reduce read_sz because of the line_sz gap */
                read_sz = NX_MIN(free_space, last_free);
                n = 0;
                if (read_sz > 0) {
                        n = fread(fifo_in + last_offset, 1, read_sz, inpf);
                        used_in = used_in + n;       /* Increase used space */
                        free_space = free_space - n; /* Decrease free space */
                        assert(n <= read_sz);
                        if (n != read_sz) {
                                /* Either EOF or error; exit the read loop */
                                is_eof = 1;
                                goto write_state;
                        }
                }
        }

        /* At this point we have used_in bytes in fifo_in with the
         * data head starting at cur_in and possibly wrapping around.
         */

write_state:

        /* Write decompressed data to output file */

        NXPRT(fprintf(stderr, "write_state:\n"));

        if (used_out == 0)
                goto decomp_state;

        /* If fifo_out has data waiting, write it out to the file to
         * make free target space for the accelerator used bytes in
         * the first and last parts of fifo_out.
         */

        first_used = fifo_used_first_bytes(cur_out, used_out, fifo_out_len);
        last_used  = fifo_used_last_bytes(cur_out, used_out, fifo_out_len);

        write_sz = first_used;

        n = 0;
        if (write_sz > 0) {
                n = fwrite(fifo_out + cur_out, 1, write_sz, outf);
                used_out = used_out - n;
                /* Move head of the fifo */
                cur_out = (cur_out + n) % fifo_out_len;
                assert(n <= write_sz);
                if (n != write_sz) {
                        fprintf(stderr, "error: write\n");
                        rc = -1;
                        goto err5;
                }
        }

        if (last_used > 0) { /* If more data available in the last part */
                write_sz = last_used; /* Keep it here for later */
                n = 0;
                if (write_sz > 0) {
                        n = fwrite(fifo_out, 1, write_sz, outf);
                        used_out = used_out - n;
                        cur_out = (cur_out + n) % fifo_out_len;
                        assert(n <= write_sz);
                        if (n != write_sz) {
                                fprintf(stderr, "error: write\n");
                                rc = -1;
                                goto err5;
                        }
                }
        }

decomp_state:

        /* NX decompresses input data */

        NXPRT(fprintf(stderr, "decomp_state:\n"));

        if (is_final)
                goto finish_state;

        /* Address/len lists */
        clearp_dde(ddl_in);
        clearp_dde(ddl_out);

        /* FC, CRC, HistLen, Table 6-6 */
        if (resuming) {
                /* Resuming a partially decompressed input.
                 * The key to resume is supplying the 32KB
                 * dictionary (history) to NX, which is basically
                 * the last 32KB of output produced.
                 */
                fc = GZIP_FC_DECOMPRESS_RESUME;

                cmdp->cpb.in_crc   = cmdp->cpb.out_crc;
                cmdp->cpb.in_adler = cmdp->cpb.out_adler;

                /* Round up the history size to quadword.  Section 2.10 */
                history_len = (history_len + 15) / 16;
                putnn(cmdp->cpb, in_histlen, history_len);
                history_len = history_len * 16; /* bytes */

                if (history_len > 0) {
                        /* Chain in the history buffer to the DDE list */
                        if (cur_out >= history_len) {
                                nx_append_dde(ddl_in, fifo_out
                                              + (cur_out - history_len),
                                              history_len);
                        } else {
                                nx_append_dde(ddl_in, fifo_out
                                              + ((fifo_out_len + cur_out)
                                              - history_len),
                                              history_len - cur_out);
                                /* Up to 32KB history wraps around fifo_out */
                                nx_append_dde(ddl_in, fifo_out, cur_out);
                        }

                }
        } else {
                /* First decompress job */
                fc = GZIP_FC_DECOMPRESS;

                history_len = 0;
                /* Writing 0 clears out subc as well */
                cmdp->cpb.in_histlen = 0;
                total_out = 0;

                put32(cmdp->cpb, in_crc, INIT_CRC);
                put32(cmdp->cpb, in_adler, INIT_ADLER);
                put32(cmdp->cpb, out_crc, INIT_CRC);
                put32(cmdp->cpb, out_adler, INIT_ADLER);

                /* Assuming 10% compression ratio initially; use the
                 * most recently measured compression ratio as a
                 * heuristic to estimate the input and output
                 * sizes.  If we give too much input, the target buffer
                 * overflows and NX cycles are wasted, and then we
                 * must retry with smaller input size.  1000 is 100%.
                 */
                last_comp_ratio = 100UL;
        }
        cmdp->crb.gzip_fc = 0;
        putnn(cmdp->crb, gzip_fc, fc);

        /*
         * NX source buffers
         */
        first_used = fifo_used_first_bytes(cur_in, used_in, fifo_in_len);
        last_used = fifo_used_last_bytes(cur_in, used_in, fifo_in_len);

        if (first_used > 0)
                nx_append_dde(ddl_in, fifo_in + cur_in, first_used);

        if (last_used > 0)
                nx_append_dde(ddl_in, fifo_in, last_used);

        /*
         * NX target buffers
         */
        first_free = fifo_free_first_bytes(cur_out, used_out, fifo_out_len);
        last_free = fifo_free_last_bytes(cur_out, used_out, fifo_out_len);

        /* Reduce output free space amount not to overwrite the history */
        int target_max = NX_MAX(0, fifo_free_bytes(used_out, fifo_out_len)
                                - (1<<16));

        NXPRT(fprintf(stderr, "target_max %d (0x%x)\n", target_max,
                      target_max));

        first_free = NX_MIN(target_max, first_free);
        if (first_free > 0) {
                first_offset = fifo_free_first_offset(cur_out, used_out);
                nx_append_dde(ddl_out, fifo_out + first_offset, first_free);
        }

        if (last_free > 0) {
                last_free = NX_MIN(target_max - first_free, last_free);
                if (last_free > 0) {
                        last_offset = fifo_free_last_offset(cur_out, used_out,
                                                            fifo_out_len);
                        nx_append_dde(ddl_out, fifo_out + last_offset,
                                      last_free);
                }
        }

        /* Target buffer size is used to limit the source data size
         * based on previous measurements of compression ratio.
         */

        /* source_sz includes history */
        source_sz = getp32(ddl_in, ddebc);
        assert(source_sz > history_len);
        source_sz = source_sz - history_len;

        /* Estimating how much source is needed to 3/4 fill a
         * target_max size target buffer.  If we overshoot, then NX
         * must repeat the job with smaller input and we waste
         * bandwidth.  If we undershoot then we use more NX calls than
         * necessary.
         */

        source_sz_estimate = ((uint64_t)target_max * last_comp_ratio * 3UL)
                                / 4000;

        if (source_sz_estimate < source_sz) {
                /* Target might be small, therefore limiting the
                 * source data.
                 */
                source_sz = source_sz_estimate;
                target_sz_estimate = target_max;
        } else {
                /* Source file might be small, therefore limiting target
                 * touch pages to a smaller value to save processor cycles.
                 */
                target_sz_estimate = ((uint64_t)source_sz * 1000UL)
                                        / (last_comp_ratio + 1);
                target_sz_estimate = NX_MIN(2 * target_sz_estimate,
                                            target_max);
        }

        source_sz = source_sz + history_len;

        /* Some NX condition codes require submitting the NX job again.
         * Kernel doesn't handle NX page faults. Expects user code to
         * touch pages.
         */
        pgfault_retries = NX_MAX_FAULTS;

restart_nx:

        putp32(ddl_in, ddebc, source_sz);

        /* Fault in pages */
        nxu_touch_pages(cmdp, sizeof(struct nx_gzip_crb_cpb_t), page_sz, 1);
        nx_touch_pages_dde(ddl_in, 0, page_sz, 0);
        nx_touch_pages_dde(ddl_out, target_sz_estimate, page_sz, 1);

        /* Send job to NX */
        cc = nx_submit_job(ddl_in, ddl_out, cmdp, devhandle);

        switch (cc) {

        case ERR_NX_AT_FAULT:

                /* We touched the pages ahead of time.  In the most common case
                 * we shouldn't be here.  But may be some pages were paged out.
                 * Kernel should have placed the faulting address to fsaddr.
                 */
                NXPRT(fprintf(stderr, "ERR_NX_AT_FAULT %p\n",
                              (void *)cmdp->crb.csb.fsaddr));

                if (pgfault_retries == NX_MAX_FAULTS) {
                        /* Try once with exact number of pages */
                        --pgfault_retries;
                        goto restart_nx;
                } else if (pgfault_retries > 0) {
                        /* If still faulting try fewer input pages
                         * assuming memory outage
                         */
                        if (source_sz > page_sz)
                                source_sz = NX_MAX(source_sz / 2, page_sz);
                        --pgfault_retries;
                        goto restart_nx;
                } else {
                        fprintf(stderr, "cannot make progress; too many ");
                        fprintf(stderr, "page fault retries cc= %d\n", cc);
                        rc = -1;
                        goto err5;
                }

        case ERR_NX_DATA_LENGTH:

                NXPRT(fprintf(stderr, "ERR_NX_DATA_LENGTH; "));
                NXPRT(fprintf(stderr, "stream may have trailing data\n"));

                /* Not an error in the most common case; it just says
                 * there is trailing data that we must examine.
                 *
                 * CC=3 CE(1)=0 CE(0)=1 indicates partial completion
                 * Fig.6-7 and Table 6-8.
                 */
                nx_ce = get_csb_ce_ms3b(cmdp->crb.csb);

                if (!csb_ce_termination(nx_ce) &&
                    csb_ce_partial_completion(nx_ce)) {
                        /* Check CPB for more information
                         * spbc and tpbc are valid
                         */
                        sfbt = getnn(cmdp->cpb, out_sfbt); /* Table 6-4 */
                        subc = getnn(cmdp->cpb, out_subc); /* Table 6-4 */
                        spbc = get32(cmdp->cpb, out_spbc_decomp);
                        tpbc = get32(cmdp->crb.csb, tpbc);
                        assert(target_max >= tpbc);

                        goto ok_cc3; /* not an error */
                } else {
                        /* History length error when CE(1)=1 CE(0)=0. */
                        rc = -1;
                        fprintf(stderr, "history length error cc= %d\n", cc);
                        goto err5;
                }

        case ERR_NX_TARGET_SPACE:

                /* Target buffer not large enough; retry smaller input
                 * data; give at least 1 byte.  SPBC/TPBC are not valid.
                 */
                assert(source_sz > history_len);
                source_sz = ((source_sz - history_len + 2) / 2) + history_len;
                NXPRT(fprintf(stderr, "ERR_NX_TARGET_SPACE; retry with "));
                NXPRT(fprintf(stderr, "smaller input data src %d hist %d\n",
                              source_sz, history_len));
                goto restart_nx;

        case ERR_NX_OK:

                /* This should not happen for gzip formatted data;
                 * we need trailing crc and isize
                 */
                fprintf(stderr, "ERR_NX_OK\n");
                spbc = get32(cmdp->cpb, out_spbc_decomp);
                tpbc = get32(cmdp->crb.csb, tpbc);
                assert(target_max >= tpbc);
                assert(spbc >= history_len);
                source_sz = spbc - history_len;
                goto offsets_state;

        default:
                fprintf(stderr, "error: cc= %d\n", cc);
                rc = -1;
                goto err5;
        }

ok_cc3:

        NXPRT(fprintf(stderr, "cc3: sfbt: %x\n", sfbt));

        assert(spbc > history_len);
        source_sz = spbc - history_len;

        /* Table 6-4: Source Final Block Type (SFBT) describes the
         * last processed deflate block and clues the software how to
         * resume the next job.  SUBC indicates how many input bits NX
         * consumed but did not process.  SPBC indicates how many
         * bytes of source were given to the accelerator including
         * history bytes.
         */

        switch (sfbt) {
                int dhtlen;

        case 0x0: /* Deflate final EOB received */

                /* Calculating the checksum start position. */

                source_sz = source_sz - subc / 8;
                is_final = 1;
                break;

                /* Resume decompression cases are below. Basically
                 * indicates where NX has suspended and how to resume
                 * the input stream.
                 */

        case 0x8: /* Within a literal block; use rembytecount */
        case 0x9: /* Within a literal block; use rembytecount; bfinal=1 */

                /* Supply the partially processed source byte again */
                source_sz = source_sz - ((subc + 7) / 8);

                /* SUBC LS 3bits: number of bits in the first source byte need
                 * to be processed.
                 * 000 means all 8 bits;  Table 6-3
                 * Clear subc, histlen, sfbt, rembytecnt, dhtlen
                 */
                cmdp->cpb.in_subc = 0;
                cmdp->cpb.in_sfbt = 0;
                putnn(cmdp->cpb, in_subc, subc % 8);
                putnn(cmdp->cpb, in_sfbt, sfbt);
                putnn(cmdp->cpb, in_rembytecnt, getnn(cmdp->cpb,
                                                      out_rembytecnt));
                break;

        case 0xA: /* Within a FH block; */
        case 0xB: /* Within a FH block; bfinal=1 */

                source_sz = source_sz - ((subc + 7) / 8);

                /* Clear subc, histlen, sfbt, rembytecnt, dhtlen */
                cmdp->cpb.in_subc = 0;
                cmdp->cpb.in_sfbt = 0;
                putnn(cmdp->cpb, in_subc, subc % 8);
                putnn(cmdp->cpb, in_sfbt, sfbt);
                break;

        case 0xC: /* Within a DH block; */
        case 0xD: /* Within a DH block; bfinal=1 */

                source_sz = source_sz - ((subc + 7) / 8);

                /* Clear subc, histlen, sfbt, rembytecnt, dhtlen */
                cmdp->cpb.in_subc = 0;
                cmdp->cpb.in_sfbt = 0;
                putnn(cmdp->cpb, in_subc, subc % 8);
                putnn(cmdp->cpb, in_sfbt, sfbt);

                dhtlen = getnn(cmdp->cpb, out_dhtlen);
                putnn(cmdp->cpb, in_dhtlen, dhtlen);
                assert(dhtlen >= 42);

                /* Round up to a qword */
                dhtlen = (dhtlen + 127) / 128;

                while (dhtlen > 0) { /* Copy dht from cpb.out to cpb.in */
                        --dhtlen;
                        cmdp->cpb.in_dht[dhtlen] = cmdp->cpb.out_dht[dhtlen];
                }
                break;

        case 0xE: /* Within a block header; bfinal=0; */
                     /* Also given if source data exactly ends (SUBC=0) with
                      * EOB code with BFINAL=0.  Means the next byte will
                      * contain a block header.
                      */
        case 0xF: /* within a block header with BFINAL=1. */

                source_sz = source_sz - ((subc + 7) / 8);

                /* Clear subc, histlen, sfbt, rembytecnt, dhtlen */
                cmdp->cpb.in_subc = 0;
                cmdp->cpb.in_sfbt = 0;
                putnn(cmdp->cpb, in_subc, subc % 8);
                putnn(cmdp->cpb, in_sfbt, sfbt);

                /* Engine did not process any data */
                if (is_eof && (source_sz == 0))
                        is_final = 1;
        }

offsets_state:

        /* Adjust the source and target buffer offsets and lengths  */

        NXPRT(fprintf(stderr, "offsets_state:\n"));

        /* Delete input data from fifo_in */
        used_in = used_in - source_sz;
        cur_in = (cur_in + source_sz) % fifo_in_len;
        input_file_offset = input_file_offset + source_sz;

        /* Add output data to fifo_out */
        used_out = used_out + tpbc;

        assert(used_out <= fifo_out_len);

        total_out = total_out + tpbc;

        /* Deflate history is 32KB max.  No need to supply more
         * than 32KB on a resume.
         */
        history_len = (total_out > window_max) ? window_max : total_out;

        /* To estimate expected expansion in the next NX job; 500 means 50%.
         * Deflate best case is around 1 to 1000.
         */
        last_comp_ratio = (1000UL * ((uint64_t)source_sz + 1))
                          / ((uint64_t)tpbc + 1);
        last_comp_ratio = NX_MAX(NX_MIN(1000UL, last_comp_ratio), 1);
        NXPRT(fprintf(stderr, "comp_ratio %ld source_sz %d spbc %d tpbc %d\n",
                      last_comp_ratio, source_sz, spbc, tpbc));

        resuming = 1;

finish_state:

        NXPRT(fprintf(stderr, "finish_state:\n"));

        if (is_final) {
                if (used_out)
                        goto write_state; /* More data to write out */
                else if (used_in < 8) {
                        /* Need at least 8 more bytes containing gzip crc
                         * and isize.
                         */
                        rc = -1;
                        goto err4;
                } else {
                        /* Compare checksums and exit */
                        int i;
                        unsigned char tail[8];
                        uint32_t cksum, isize;

                        for (i = 0; i < 8; i++)
                                tail[i] = fifo_in[(cur_in + i) % fifo_in_len];
                        fprintf(stderr, "computed checksum %08x isize %08x\n",
                                cmdp->cpb.out_crc, (uint32_t) (total_out
                                % (1ULL<<32)));
                        cksum = ((uint32_t) tail[0] | (uint32_t) tail[1]<<8
                                 | (uint32_t) tail[2]<<16
                                 | (uint32_t) tail[3]<<24);
                        isize = ((uint32_t) tail[4] | (uint32_t) tail[5]<<8
                                 | (uint32_t) tail[6]<<16
                                 | (uint32_t) tail[7]<<24);
                        fprintf(stderr, "stored   checksum %08x isize %08x\n",
                                cksum, isize);

                        if (cksum == cmdp->cpb.out_crc && isize == (uint32_t)
                            (total_out % (1ULL<<32))) {
                                rc = 0; goto ok1;
                        } else {
                                rc = -1; goto err4;
                        }
                }
        } else
                goto read_state;

        return -1;

err1:
        fprintf(stderr, "error: not a gzip file, expect %x, read %x\n",
                expect, c);
        return -1;

err2:
        fprintf(stderr, "error: the FLG byte is wrong or not being handled\n");
        return -1;

err3:
        fprintf(stderr, "error: gzip header\n");
        return -1;

err4:
        fprintf(stderr, "error: checksum missing or mismatch\n");

err5:
ok1:
        fprintf(stderr, "decomp is complete: fclose\n");
        fclose(outf);

        return rc;
}

int main(int argc, char **argv)
{
        int rc;
        struct sigaction act;
        void *handle;

        nx_dbg = 0;
        nx_gzip_log = NULL;
        act.sa_handler = 0;
        act.sa_sigaction = nxu_sigsegv_handler;
        act.sa_flags = SA_SIGINFO;
        act.sa_restorer = 0;
        sigemptyset(&act.sa_mask);
        sigaction(SIGSEGV, &act, NULL);

        handle = nx_function_begin(NX_FUNC_COMP_GZIP, 0);
        if (!handle) {
                fprintf(stderr, "Unable to init NX, errno %d\n", errno);
                exit(-1);
        }

        rc = decompress_file(argc, argv, handle);

        nx_function_end(handle);

        return rc;
}