arch/i386/math-emu/fpu_tags.c

   1 /*---------------------------------------------------------------------------+
   2  |  fpu_tags.c                                                               |
   3  |                                                                           |
   4  |  Set FPU register tags.                                                   |
   5  |                                                                           |
   6  | Copyright (C) 1997                                                        |
   7  |                  W. Metzenthen, 22 Parker St, Ormond, Vic 3163, Australia |
   8  |                  E-mail   billm@jacobi.maths.monash.edu.au                |
   9  |                                                                           |
  10  |                                                                           |
  11  +---------------------------------------------------------------------------*/
  12
  13 #include "fpu_emu.h"
  14 #include "fpu_system.h"
  15 #include "exception.h"
  16
  17
  18 void FPU_pop(void)
  19 {
  20   fpu_tag_word |= 3 << ((top & 7)*2);
  21   top++;
  22 }
  23
  24
  25 int FPU_gettag0(void)
  26 {
  27   return (fpu_tag_word >> ((top & 7)*2)) & 3;
  28 }
  29
  30
  31 int FPU_gettagi(int stnr)
  32 {
  33   return (fpu_tag_word >> (((top+stnr) & 7)*2)) & 3;
  34 }
  35
  36
  37 int FPU_gettag(int regnr)
  38 {
  39   return (fpu_tag_word >> ((regnr & 7)*2)) & 3;
  40 }
  41
  42
  43 void FPU_settag0(int tag)
  44 {
  45   int regnr = top;
  46   regnr &= 7;
  47   fpu_tag_word &= ~(3 << (regnr*2));
  48   fpu_tag_word |= (tag & 3) << (regnr*2);
  49 }
  50
  51
  52 void FPU_settagi(int stnr, int tag)
  53 {
  54   int regnr = stnr+top;
  55   regnr &= 7;
  56   fpu_tag_word &= ~(3 << (regnr*2));
  57   fpu_tag_word |= (tag & 3) << (regnr*2);
  58 }
  59
  60
  61 void FPU_settag(int regnr, int tag)
  62 {
  63   regnr &= 7;
  64   fpu_tag_word &= ~(3 << (regnr*2));
  65   fpu_tag_word |= (tag & 3) << (regnr*2);
  66 }
  67
  68
  69 int FPU_Special(FPU_REG const *ptr)
  70 {
  71   int exp = exponent(ptr);
  72
  73   if ( exp == EXP_BIAS+EXP_UNDER )
  74     return TW_Denormal;
  75   else if ( exp != EXP_BIAS+EXP_OVER )
  76     return TW_NaN;
  77   else if ( (ptr->sigh == 0x80000000) && (ptr->sigl == 0) )
  78     return TW_Infinity;
  79   return TW_NaN;
  80 }
  81
  82
  83 int isNaN(FPU_REG const *ptr)
  84 {
  85   return ( (exponent(ptr) == EXP_BIAS+EXP_OVER)
  86            && !((ptr->sigh == 0x80000000) && (ptr->sigl == 0)) );
  87 }
  88
  89
  90 int FPU_empty_i(int stnr)
  91 {
  92   int regnr = (top+stnr) & 7;
  93
  94   return ((fpu_tag_word >> (regnr*2)) & 3) == TAG_Empty;
  95 }
  96
  97
  98 int FPU_stackoverflow(FPU_REG **st_new_ptr)
  99 {
 100   *st_new_ptr = &st(-1);
 101
 102   return ((fpu_tag_word >> (((top - 1) & 7)*2)) & 3) != TAG_Empty;
 103 }
 104
 105
 106 void FPU_copy_to_regi(FPU_REG const *r, u_char tag, int stnr)
 107 {
 108   reg_copy(r, &st(stnr));
 109   FPU_settagi(stnr, tag);
 110 }
 111
 112 void FPU_copy_to_reg1(FPU_REG const *r, u_char tag)
 113 {
 114   reg_copy(r, &st(1));
 115   FPU_settagi(1, tag);
 116 }
 117
 118 void FPU_copy_to_reg0(FPU_REG const *r, u_char tag)
 119 {
 120   int regnr = top;
 121   regnr &= 7;
 122
 123   reg_copy(r, &st(0));
 124
 125   fpu_tag_word &= ~(3 << (regnr*2));
 126   fpu_tag_word |= (tag & 3) << (regnr*2);
 127 }