arch/i386/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 /*
  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" \
  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. */
  76 static 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! */
  91 static 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. */
 111 static 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 */