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

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/*---------------------------------------------------------------------------+
   3 |  poly.h                                                                   |
   4 |                                                                           |
   5 |  Header file for the FPU-emu poly*.c source files.                        |
   6 |                                                                           |
   7 | Copyright (C) 1994,1999                                                   |
   8 |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
   9 |                       Australia.  E-mail   billm@melbpc.org.au            |
  10 |                                                                           |
  11 | Declarations and definitions for functions operating on Xsig (12-byte     |
  12 | extended-significand) quantities.                                         |
  13 |                                                                           |
  14 +---------------------------------------------------------------------------*/
  15
  16#ifndef _POLY_H
  17#define _POLY_H
  18
  19/* This 12-byte structure is used to improve the accuracy of computation
  20   of transcendental functions.
  21   Intended to be used to get results better than 8-byte computation
  22   allows. 9-byte would probably be sufficient.
  23   */
  24typedef struct {
  25        unsigned long lsw;
  26        unsigned long midw;
  27        unsigned long msw;
  28} Xsig;
  29
  30asmlinkage void mul64(unsigned long long const *a, unsigned long long const *b,
  31                      unsigned long long *result);
  32asmlinkage void polynomial_Xsig(Xsig *, const unsigned long long *x,
  33                                const unsigned long long terms[], const int n);
  34
  35asmlinkage void mul32_Xsig(Xsig *, const unsigned long mult);
  36asmlinkage void mul64_Xsig(Xsig *, const unsigned long long *mult);
  37asmlinkage void mul_Xsig_Xsig(Xsig *dest, const Xsig *mult);
  38
  39asmlinkage void shr_Xsig(Xsig *, const int n);
  40asmlinkage int round_Xsig(Xsig *);
  41asmlinkage int norm_Xsig(Xsig *);
  42asmlinkage void div_Xsig(Xsig *x1, const Xsig *x2, const Xsig *dest);
  43
  44/* Macro to extract the most significant 32 bits from a long long */
  45#define LL_MSW(x)     (((unsigned long *)&x)[1])
  46
  47/* Macro to initialize an Xsig struct */
  48#define MK_XSIG(a,b,c)     { c, b, a }
  49
  50/* Macro to access the 8 ms bytes of an Xsig as a long long */
  51#define XSIG_LL(x)         (*(unsigned long long *)&x.midw)
  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":"=a" (retval)
  68                      :"0"(arg1), "g"(arg2)
  69                      :"dx");
  70        return retval;
  71}
  72
  73/* Add the 12 byte Xsig x2 to Xsig dest, with no checks for overflow. */
  74static inline void add_Xsig_Xsig(Xsig *dest, const Xsig *x2)
  75{
  76        asm volatile ("movl %1,%%edi; movl %2,%%esi;\n"
  77                      "movl (%%esi),%%eax; addl %%eax,(%%edi);\n"
  78                      "movl 4(%%esi),%%eax; adcl %%eax,4(%%edi);\n"
  79                      "movl 8(%%esi),%%eax; adcl %%eax,8(%%edi);\n":"=g"
  80                      (*dest):"g"(dest), "g"(x2)
  81                      :"ax", "si", "di");
  82}
  83
  84/* Add the 12 byte Xsig x2 to Xsig dest, adjust exp if overflow occurs. */
  85/* Note: the constraints in the asm statement didn't always work properly
  86   with gcc 2.5.8.  Changing from using edi to using ecx got around the
  87   problem, but keep fingers crossed! */
  88static inline void add_two_Xsig(Xsig *dest, const Xsig *x2, long int *exp)
  89{
  90        asm volatile ("movl %2,%%ecx; movl %3,%%esi;\n"
  91                      "movl (%%esi),%%eax; addl %%eax,(%%ecx);\n"
  92                      "movl 4(%%esi),%%eax; adcl %%eax,4(%%ecx);\n"
  93                      "movl 8(%%esi),%%eax; adcl %%eax,8(%%ecx);\n"
  94                      "jnc 0f;\n"
  95                      "rcrl 8(%%ecx); rcrl 4(%%ecx); rcrl (%%ecx)\n"
  96                      "movl %4,%%ecx; incl (%%ecx)\n"
  97                      "movl $1,%%eax; jmp 1f;\n"
  98                      "0: xorl %%eax,%%eax;\n" "1:\n":"=g" (*exp), "=g"(*dest)
  99                      :"g"(dest), "g"(x2), "g"(exp)
 100                      :"cx", "si", "ax");
 101}
 102
 103/* Negate (subtract from 1.0) the 12 byte Xsig */
 104/* This is faster in a loop on my 386 than using the "neg" instruction. */
 105static inline void negate_Xsig(Xsig *x)
 106{
 107        asm volatile ("movl %1,%%esi;\n"
 108                      "xorl %%ecx,%%ecx;\n"
 109                      "movl %%ecx,%%eax; subl (%%esi),%%eax; movl %%eax,(%%esi);\n"
 110                      "movl %%ecx,%%eax; sbbl 4(%%esi),%%eax; movl %%eax,4(%%esi);\n"
 111                      "movl %%ecx,%%eax; sbbl 8(%%esi),%%eax; movl %%eax,8(%%esi);\n":"=g"
 112                      (*x):"g"(x):"si", "ax", "cx");
 113}
 114
 115#endif /* _POLY_H */
 116