arch/x86/math-emu/fpu_etc.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*---------------------------------------------------------------------------+
   3  |  fpu_etc.c                                                                |
   4  |                                                                           |
   5  | Implement a few FPU instructions.                                         |
   6  |                                                                           |
   7  | Copyright (C) 1992,1993,1994,1997                                         |
   8  |                       W. Metzenthen, 22 Parker St, Ormond, Vic 3163,      |
   9  |                       Australia.  E-mail   billm@suburbia.net             |
  10  |                                                                           |
  11  |                                                                           |
  12  +---------------------------------------------------------------------------*/
  13
  14 #include "fpu_system.h"
  15 #include "exception.h"
  16 #include "fpu_emu.h"
  17 #include "status_w.h"
  18 #include "reg_constant.h"
  19
  20 static void fchs(FPU_REG *st0_ptr, u_char st0tag)
  21 {
  22         if (st0tag ^ TAG_Empty) {
  23                 signbyte(st0_ptr) ^= SIGN_NEG;
  24                 clear_C1();
  25         } else
  26                 FPU_stack_underflow();
  27 }
  28
  29 static void fabs(FPU_REG *st0_ptr, u_char st0tag)
  30 {
  31         if (st0tag ^ TAG_Empty) {
  32                 setpositive(st0_ptr);
  33                 clear_C1();
  34         } else
  35                 FPU_stack_underflow();
  36 }
  37
  38 static void ftst_(FPU_REG *st0_ptr, u_char st0tag)
  39 {
  40         switch (st0tag) {
  41         case TAG_Zero:
  42                 setcc(SW_C3);
  43                 break;
  44         case TAG_Valid:
  45                 if (getsign(st0_ptr) == SIGN_POS)
  46                         setcc(0);
  47                 else
  48                         setcc(SW_C0);
  49                 break;
  50         case TAG_Special:
  51                 switch (FPU_Special(st0_ptr)) {
  52                 case TW_Denormal:
  53                         if (getsign(st0_ptr) == SIGN_POS)
  54                                 setcc(0);
  55                         else
  56                                 setcc(SW_C0);
  57                         if (denormal_operand() < 0) {
  58 #ifdef PECULIAR_486
  59                                 /* This is weird! */
  60                                 if (getsign(st0_ptr) == SIGN_POS)
  61                                         setcc(SW_C3);
  62 #endif /* PECULIAR_486 */
  63                                 return;
  64                         }
  65                         break;
  66                 case TW_NaN:
  67                         setcc(SW_C0 | SW_C2 | SW_C3);   /* Operand is not comparable */
  68                         EXCEPTION(EX_Invalid);
  69                         break;
  70                 case TW_Infinity:
  71                         if (getsign(st0_ptr) == SIGN_POS)
  72                                 setcc(0);
  73                         else
  74                                 setcc(SW_C0);
  75                         break;
  76                 default:
  77                         setcc(SW_C0 | SW_C2 | SW_C3);   /* Operand is not comparable */
  78                         EXCEPTION(EX_INTERNAL | 0x14);
  79                         break;
  80                 }
  81                 break;
  82         case TAG_Empty:
  83                 setcc(SW_C0 | SW_C2 | SW_C3);
  84                 EXCEPTION(EX_StackUnder);
  85                 break;
  86         }
  87 }
  88
  89 static void fxam(FPU_REG *st0_ptr, u_char st0tag)
  90 {
  91         int c = 0;
  92         switch (st0tag) {
  93         case TAG_Empty:
  94                 c = SW_C3 | SW_C0;
  95                 break;
  96         case TAG_Zero:
  97                 c = SW_C3;
  98                 break;
  99         case TAG_Valid:
 100                 c = SW_C2;
 101                 break;
 102         case TAG_Special:
 103                 switch (FPU_Special(st0_ptr)) {
 104                 case TW_Denormal:
 105                         c = SW_C2 | SW_C3;      /* Denormal */
 106                         break;
 107                 case TW_NaN:
 108                         /* We also use NaN for unsupported types. */
 109                         if ((st0_ptr->sigh & 0x80000000)
 110                             && (exponent(st0_ptr) == EXP_OVER))
 111                                 c = SW_C0;
 112                         break;
 113                 case TW_Infinity:
 114                         c = SW_C2 | SW_C0;
 115                         break;
 116                 }
 117         }
 118         if (getsign(st0_ptr) == SIGN_NEG)
 119                 c |= SW_C1;
 120         setcc(c);
 121 }
 122
 123 static FUNC_ST0 const fp_etc_table[] = {
 124         fchs, fabs, (FUNC_ST0) FPU_illegal, (FUNC_ST0) FPU_illegal,
 125         ftst_, fxam, (FUNC_ST0) FPU_illegal, (FUNC_ST0) FPU_illegal
 126 };
 127
 128 void FPU_etc(void)
 129 {
 130         (fp_etc_table[FPU_rm]) (&st(0), FPU_gettag0());
 131 }