LXR linux/arch/x86/math-emu/poly.h

   1/*---------------------------------------------------------------------------+
   2 |  poly.h                                                                   |
   3 |                                                                           |
   4 |  Header file for the FPU-emu poly*.c source files.                        |
   5 |                                                                           |
   6 | Copyright (C) 1994,1999                                                   |
   7 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
   8 |                       Australia.  E-mail   billm@melbpc.org.au            |
   9 |                                                                           |
  10 | Declarations and definitions for functions operating on Xsig (12-byte     |
  11 | extended-significand) quantities.                                         |
  12 |                                                                           |
  13 +---------------------------------------------------------------------------*/
  14
  15#ifndef _POLY_H
  16#define _POLY_H
  17
  18/* This 12-byte structure is used to improve the accuracy of computation
  19   of transcendental functions.
  20   Intended to be used to get results better than 8-byte computation
  21   allows. 9-byte would probably be sufficient.
  22   */
  23typedef struct {
  24  unsigned long lsw;
  25  unsigned long midw;
  26  unsigned long msw;
  27} Xsig;
  28
  29asmlinkage void mul64(unsigned long long const *a, unsigned long long const *b,
  30                      unsigned long long *result);
  31asmlinkage void polynomial_Xsig(Xsig *, const unsigned long long *x,
  32                                const unsigned long long terms[], const int n);
  33
  34asmlinkage void mul32_Xsig(Xsig *, const unsigned long mult);
  35asmlinkage void mul64_Xsig(Xsig *, const unsigned long long *mult);
  36asmlinkage void mul_Xsig_Xsig(Xsig *dest, const Xsig *mult);
  37
  38asmlinkage void shr_Xsig(Xsig *, const int n);
  39asmlinkage int round_Xsig(Xsig *);
  40asmlinkage int norm_Xsig(Xsig *);
  41asmlinkage void div_Xsig(Xsig *x1, const Xsig *x2, const Xsig *dest);
  42
  43/* Macro to extract the most significant 32 bits from a long long */
  44#define LL_MSW(x)     (((unsigned long *)&x)[1])
  45
  46/* Macro to initialize an Xsig struct */
  47#define MK_XSIG(a,b,c)     { c, b, a }
  48
  49/* Macro to access the 8 ms bytes of an Xsig as a long long */
  50#define XSIG_LL(x)         (*(unsigned long long *)&x.midw)
  51
  52
  53/*
  54   Need to run gcc with optimizations on to get these to
  55   actually be in-line.
  56   */
  57
  58/* Multiply two fixed-point 32 bit numbers, producing a 32 bit result.
  59   The answer is the ms word of the product. */
  60/* Some versions of gcc make it difficult to stop eax from being clobbered.
  61   Merely specifying that it is used doesn't work...
  62 */
  63static inline unsigned long mul_32_32(const unsigned long arg1,
  64                                      const unsigned long arg2)
  65{
  66  int retval;
  67  asm volatile ("mull %2; movl %%edx,%%eax" \
  68                :"=a" (retval) \
  69                :"0" (arg1), "g" (arg2) \
  70                :"dx");
  71  return retval;
  72}
  73
  74
  75/* Add the 12 byte Xsig x2 to Xsig dest, with no checks for overflow. */
  76static inline void add_Xsig_Xsig(Xsig *dest, const Xsig *x2)
  77{
  78  asm volatile ("movl %1,%%edi; movl %2,%%esi;\n"
  79                "movl (%%esi),%%eax; addl %%eax,(%%edi);\n"
  80                "movl 4(%%esi),%%eax; adcl %%eax,4(%%edi);\n"
  81                "movl 8(%%esi),%%eax; adcl %%eax,8(%%edi);\n"
  82                 :"=g" (*dest):"g" (dest), "g" (x2)
  83                 :"ax","si","di");
  84}
  85
  86
  87/* Add the 12 byte Xsig x2 to Xsig dest, adjust exp if overflow occurs. */
  88/* Note: the constraints in the asm statement didn't always work properly
  89   with gcc 2.5.8.  Changing from using edi to using ecx got around the
  90   problem, but keep fingers crossed! */
  91static inline void add_two_Xsig(Xsig *dest, const Xsig *x2, long int *exp)
  92{
  93  asm volatile ("movl %2,%%ecx; movl %3,%%esi;\n"
  94                "movl (%%esi),%%eax; addl %%eax,(%%ecx);\n"
  95                "movl 4(%%esi),%%eax; adcl %%eax,4(%%ecx);\n"
  96                "movl 8(%%esi),%%eax; adcl %%eax,8(%%ecx);\n"
  97                "jnc 0f;\n"
  98                "rcrl 8(%%ecx); rcrl 4(%%ecx); rcrl (%%ecx)\n"
  99                "movl %4,%%ecx; incl (%%ecx)\n"
 100                "movl $1,%%eax; jmp 1f;\n"
 101                "0: xorl %%eax,%%eax;\n"
 102                "1:\n"
 103                :"=g" (*exp), "=g" (*dest)
 104                :"g" (dest), "g" (x2), "g" (exp)
 105                :"cx","si","ax");
 106}
 107
 108
 109/* Negate (subtract from 1.0) the 12 byte Xsig */
 110/* This is faster in a loop on my 386 than using the "neg" instruction. */
 111static inline void negate_Xsig(Xsig *x)
 112{
 113  asm volatile("movl %1,%%esi;\n"
 114               "xorl %%ecx,%%ecx;\n"
 115               "movl %%ecx,%%eax; subl (%%esi),%%eax; movl %%eax,(%%esi);\n"
 116               "movl %%ecx,%%eax; sbbl 4(%%esi),%%eax; movl %%eax,4(%%esi);\n"
 117               "movl %%ecx,%%eax; sbbl 8(%%esi),%%eax; movl %%eax,8(%%esi);\n"
 118               :"=g" (*x):"g" (x):"si","ax","cx");
 119}
 120
 121#endif /* _POLY_H */
 122