arch/x86/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 void FPU_pop(void)
  18 {
  19         fpu_tag_word |= 3 << ((top & 7) * 2);
  20         top++;
  21 }
  22
  23 int FPU_gettag0(void)
  24 {
  25         return (fpu_tag_word >> ((top & 7) * 2)) & 3;
  26 }
  27
  28 int FPU_gettagi(int stnr)
  29 {
  30         return (fpu_tag_word >> (((top + stnr) & 7) * 2)) & 3;
  31 }
  32
  33 int FPU_gettag(int regnr)
  34 {
  35         return (fpu_tag_word >> ((regnr & 7) * 2)) & 3;
  36 }
  37
  38 void FPU_settag0(int tag)
  39 {
  40         int regnr = top;
  41         regnr &= 7;
  42         fpu_tag_word &= ~(3 << (regnr * 2));
  43         fpu_tag_word |= (tag & 3) << (regnr * 2);
  44 }
  45
  46 void FPU_settagi(int stnr, int tag)
  47 {
  48         int regnr = stnr + top;
  49         regnr &= 7;
  50         fpu_tag_word &= ~(3 << (regnr * 2));
  51         fpu_tag_word |= (tag & 3) << (regnr * 2);
  52 }
  53
  54 void FPU_settag(int regnr, int tag)
  55 {
  56         regnr &= 7;
  57         fpu_tag_word &= ~(3 << (regnr * 2));
  58         fpu_tag_word |= (tag & 3) << (regnr * 2);
  59 }
  60
  61 int FPU_Special(FPU_REG const *ptr)
  62 {
  63         int exp = exponent(ptr);
  64
  65         if (exp == EXP_BIAS + EXP_UNDER)
  66                 return TW_Denormal;
  67         else if (exp != EXP_BIAS + EXP_OVER)
  68                 return TW_NaN;
  69         else if ((ptr->sigh == 0x80000000) && (ptr->sigl == 0))
  70                 return TW_Infinity;
  71         return TW_NaN;
  72 }
  73
  74 int isNaN(FPU_REG const *ptr)
  75 {
  76         return ((exponent(ptr) == EXP_BIAS + EXP_OVER)
  77                 && !((ptr->sigh == 0x80000000) && (ptr->sigl == 0)));
  78 }
  79
  80 int FPU_empty_i(int stnr)
  81 {
  82         int regnr = (top + stnr) & 7;
  83
  84         return ((fpu_tag_word >> (regnr * 2)) & 3) == TAG_Empty;
  85 }
  86
  87 int FPU_stackoverflow(FPU_REG ** st_new_ptr)
  88 {
  89         *st_new_ptr = &st(-1);
  90
  91         return ((fpu_tag_word >> (((top - 1) & 7) * 2)) & 3) != TAG_Empty;
  92 }
  93
  94 void FPU_copy_to_regi(FPU_REG const *r, u_char tag, int stnr)
  95 {
  96         reg_copy(r, &st(stnr));
  97         FPU_settagi(stnr, tag);
  98 }
  99
 100 void FPU_copy_to_reg1(FPU_REG const *r, u_char tag)
 101 {
 102         reg_copy(r, &st(1));
 103         FPU_settagi(1, tag);
 104 }
 105
 106 void FPU_copy_to_reg0(FPU_REG const *r, u_char tag)
 107 {
 108         int regnr = top;
 109         regnr &= 7;
 110
 111         reg_copy(r, &st(0));
 112
 113         fpu_tag_word &= ~(3 << (regnr * 2));
 114         fpu_tag_word |= (tag & 3) << (regnr * 2);
 115 }