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    */
  23 typedef struct {
  24         unsigned long lsw;
  25         unsigned long midw;
  26         unsigned long msw;
  27 } Xsig;
  28
  29 asmlinkage void mul64(unsigned long long const *a, unsigned long long const *b,
  30                       unsigned long long *result);
  31 asmlinkage void polynomial_Xsig(Xsig *, const unsigned long long *x,
  32                                 const unsigned long long terms[], const int n);
  33
  34 asmlinkage void mul32_Xsig(Xsig *, const unsigned long mult);
  35 asmlinkage void mul64_Xsig(Xsig *, const unsigned long long *mult);
  36 asmlinkage void mul_Xsig_Xsig(Xsig *dest, const Xsig *mult);
  37
  38 asmlinkage void shr_Xsig(Xsig *, const int n);
  39 asmlinkage int round_Xsig(Xsig *);
  40 asmlinkage int norm_Xsig(Xsig *);
  41 asmlinkage 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    Need to run gcc with optimizations on to get these to
  54    actually be in-line.
  55    */
  56
  57 /* Multiply two fixed-point 32 bit numbers, producing a 32 bit result.
  58    The answer is the ms word of the product. */
  59 /* Some versions of gcc make it difficult to stop eax from being clobbered.
  60    Merely specifying that it is used doesn't work...
  61  */
  62 static inline unsigned long mul_32_32(const unsigned long arg1,
  63                                       const unsigned long arg2)
  64 {
  65         int retval;
  66         asm volatile ("mull %2; movl %%edx,%%eax":"=a" (retval)
  67                       :"0"(arg1), "g"(arg2)
  68                       :"dx");
  69         return retval;
  70 }
  71
  72 /* Add the 12 byte Xsig x2 to Xsig dest, with no checks for overflow. */
  73 static inline void add_Xsig_Xsig(Xsig *dest, const Xsig *x2)
  74 {
  75         asm volatile ("movl %1,%%edi; movl %2,%%esi;\n"
  76                       "movl (%%esi),%%eax; addl %%eax,(%%edi);\n"
  77                       "movl 4(%%esi),%%eax; adcl %%eax,4(%%edi);\n"
  78                       "movl 8(%%esi),%%eax; adcl %%eax,8(%%edi);\n":"=g"
  79                       (*dest):"g"(dest), "g"(x2)
  80                       :"ax", "si", "di");
  81 }
  82
  83 /* Add the 12 byte Xsig x2 to Xsig dest, adjust exp if overflow occurs. */
  84 /* Note: the constraints in the asm statement didn't always work properly
  85    with gcc 2.5.8.  Changing from using edi to using ecx got around the
  86    problem, but keep fingers crossed! */
  87 static inline void add_two_Xsig(Xsig *dest, const Xsig *x2, long int *exp)
  88 {
  89         asm volatile ("movl %2,%%ecx; movl %3,%%esi;\n"
  90                       "movl (%%esi),%%eax; addl %%eax,(%%ecx);\n"
  91                       "movl 4(%%esi),%%eax; adcl %%eax,4(%%ecx);\n"
  92                       "movl 8(%%esi),%%eax; adcl %%eax,8(%%ecx);\n"
  93                       "jnc 0f;\n"
  94                       "rcrl 8(%%ecx); rcrl 4(%%ecx); rcrl (%%ecx)\n"
  95                       "movl %4,%%ecx; incl (%%ecx)\n"
  96                       "movl $1,%%eax; jmp 1f;\n"
  97                       "0: xorl %%eax,%%eax;\n" "1:\n":"=g" (*exp), "=g"(*dest)
  98                       :"g"(dest), "g"(x2), "g"(exp)
  99                       :"cx", "si", "ax");
 100 }
 101
 102 /* Negate (subtract from 1.0) the 12 byte Xsig */
 103 /* This is faster in a loop on my 386 than using the "neg" instruction. */
 104 static inline void negate_Xsig(Xsig *x)
 105 {
 106         asm volatile ("movl %1,%%esi;\n"
 107                       "xorl %%ecx,%%ecx;\n"
 108                       "movl %%ecx,%%eax; subl (%%esi),%%eax; movl %%eax,(%%esi);\n"
 109                       "movl %%ecx,%%eax; sbbl 4(%%esi),%%eax; movl %%eax,4(%%esi);\n"
 110                       "movl %%ecx,%%eax; sbbl 8(%%esi),%%eax; movl %%eax,8(%%esi);\n":"=g"
 111                       (*x):"g"(x):"si", "ax", "cx");
 112 }
 113
 114 #endif /* _POLY_H */