git.oblomov.eu Git - linux-2.6/blob - arch/x86/math-emu/fpu_etc.c

   1 /*---------------------------------------------------------------------------+
   2  |  fpu_etc.c                                                                |
   3  |                                                                           |
   4  | Implement a few FPU instructions.                                         |
   5  |                                                                           |
   6  | Copyright (C) 1992,1993,1994,1997                                         |
   7  |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
   8  |                       Australia.  E-mail   billm@suburbia.net             |
   9  |                                                                           |
  10  |                                                                           |
  11  +---------------------------------------------------------------------------*/
  12
  13 #include "fpu_system.h"
  14 #include "exception.h"
  15 #include "fpu_emu.h"
  16 #include "status_w.h"
  17 #include "reg_constant.h"
  18
  19 static void fchs(FPU_REG *st0_ptr, u_char st0tag)
  20 {
  21         if (st0tag ^ TAG_Empty) {
  22                 signbyte(st0_ptr) ^= SIGN_NEG;
  23                 clear_C1();
  24         } else
  25                 FPU_stack_underflow();
  26 }
  27
  28 static void fabs(FPU_REG *st0_ptr, u_char st0tag)
  29 {
  30         if (st0tag ^ TAG_Empty) {
  31                 setpositive(st0_ptr);
  32                 clear_C1();
  33         } else
  34                 FPU_stack_underflow();
  35 }
  36
  37 static void ftst_(FPU_REG *st0_ptr, u_char st0tag)
  38 {
  39         switch (st0tag) {
  40         case TAG_Zero:
  41                 setcc(SW_C3);
  42                 break;
  43         case TAG_Valid:
  44                 if (getsign(st0_ptr) == SIGN_POS)
  45                         setcc(0);
  46                 else
  47                         setcc(SW_C0);
  48                 break;
  49         case TAG_Special:
  50                 switch (FPU_Special(st0_ptr)) {
  51                 case TW_Denormal:
  52                         if (getsign(st0_ptr) == SIGN_POS)
  53                                 setcc(0);
  54                         else
  55                                 setcc(SW_C0);
  56                         if (denormal_operand() < 0) {
  57 #ifdef PECULIAR_486
  58                                 /* This is weird! */
  59                                 if (getsign(st0_ptr) == SIGN_POS)
  60                                         setcc(SW_C3);
  61 #endif /* PECULIAR_486 */
  62                                 return;
  63                         }
  64                         break;
  65                 case TW_NaN:
  66                         setcc(SW_C0 | SW_C2 | SW_C3);   /* Operand is not comparable */
  67                         EXCEPTION(EX_Invalid);
  68                         break;
  69                 case TW_Infinity:
  70                         if (getsign(st0_ptr) == SIGN_POS)
  71                                 setcc(0);
  72                         else
  73                                 setcc(SW_C0);
  74                         break;
  75                 default:
  76                         setcc(SW_C0 | SW_C2 | SW_C3);   /* Operand is not comparable */
  77                         EXCEPTION(EX_INTERNAL | 0x14);
  78                         break;
  79                 }
  80                 break;
  81         case TAG_Empty:
  82                 setcc(SW_C0 | SW_C2 | SW_C3);
  83                 EXCEPTION(EX_StackUnder);
  84                 break;
  85         }
  86 }
  87
  88 static void fxam(FPU_REG *st0_ptr, u_char st0tag)
  89 {
  90         int c = 0;
  91         switch (st0tag) {
  92         case TAG_Empty:
  93                 c = SW_C3 | SW_C0;
  94                 break;
  95         case TAG_Zero:
  96                 c = SW_C3;
  97                 break;
  98         case TAG_Valid:
  99                 c = SW_C2;
 100                 break;
 101         case TAG_Special:
 102                 switch (FPU_Special(st0_ptr)) {
 103                 case TW_Denormal:
 104                         c = SW_C2 | SW_C3;      /* Denormal */
 105                         break;
 106                 case TW_NaN:
 107                         /* We also use NaN for unsupported types. */
 108                         if ((st0_ptr->sigh & 0x80000000)
 109                             && (exponent(st0_ptr) == EXP_OVER))
 110                                 c = SW_C0;
 111                         break;
 112                 case TW_Infinity:
 113                         c = SW_C2 | SW_C0;
 114                         break;
 115                 }
 116         }
 117         if (getsign(st0_ptr) == SIGN_NEG)
 118                 c |= SW_C1;
 119         setcc(c);
 120 }
 121
 122 static FUNC_ST0 const fp_etc_table[] = {
 123         fchs, fabs, (FUNC_ST0) FPU_illegal, (FUNC_ST0) FPU_illegal,
 124         ftst_, fxam, (FUNC_ST0) FPU_illegal, (FUNC_ST0) FPU_illegal
 125 };
 126
 127 void FPU_etc(void)
 128 {
 129         (fp_etc_table[FPU_rm]) (&st(0), FPU_gettag0());
 130 }