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    */
  24 typedef struct {
  25         unsigned long lsw;
  26         unsigned long midw;
  27         unsigned long msw;
  28 } Xsig;
  29
  30 asmlinkage void mul64(unsigned long long const *a, unsigned long long const *b,
  31                       unsigned long long *result);
  32 asmlinkage void polynomial_Xsig(Xsig *, const unsigned long long *x,
  33                                 const unsigned long long terms[], const int n);
  34
  35 asmlinkage void mul32_Xsig(Xsig *, const unsigned long mult);
  36 asmlinkage void mul64_Xsig(Xsig *, const unsigned long long *mult);
  37 asmlinkage void mul_Xsig_Xsig(Xsig *dest, const Xsig *mult);
  38
  39 asmlinkage void shr_Xsig(Xsig *, const int n);
  40 asmlinkage int round_Xsig(Xsig *);
  41 asmlinkage int norm_Xsig(Xsig *);
  42 asmlinkage 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  */
  63 static 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. */
  74 static 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! */
  88 static 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. */
 105 static 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 */