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/arch/i386/math-emu/fpu_etc.c

https://bitbucket.org/evzijst/gittest
C | 143 lines | 118 code | 12 blank | 13 comment | 20 complexity | 2c98167827ffc38ff9779a35887e62c4 MD5 | raw file
  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
 20static void fchs(FPU_REG *st0_ptr, u_char st0tag)
 21{
 22  if ( st0tag ^ TAG_Empty )
 23    {
 24      signbyte(st0_ptr) ^= SIGN_NEG;
 25      clear_C1();
 26    }
 27  else
 28    FPU_stack_underflow();
 29}
 30
 31
 32static void fabs(FPU_REG *st0_ptr, u_char st0tag)
 33{
 34  if ( st0tag ^ TAG_Empty )
 35    {
 36      setpositive(st0_ptr);
 37      clear_C1();
 38    }
 39  else
 40    FPU_stack_underflow();
 41}
 42
 43
 44static void ftst_(FPU_REG *st0_ptr, u_char st0tag)
 45{
 46  switch (st0tag)
 47    {
 48    case TAG_Zero:
 49      setcc(SW_C3);
 50      break;
 51    case TAG_Valid:
 52      if (getsign(st0_ptr) == SIGN_POS)
 53        setcc(0);
 54      else
 55        setcc(SW_C0);
 56      break;
 57    case TAG_Special:
 58      switch ( FPU_Special(st0_ptr) )
 59	{
 60	case TW_Denormal:
 61	  if (getsign(st0_ptr) == SIGN_POS)
 62	    setcc(0);
 63	  else
 64	    setcc(SW_C0);
 65	  if ( denormal_operand() < 0 )
 66	    {
 67#ifdef PECULIAR_486
 68	      /* This is weird! */
 69	      if (getsign(st0_ptr) == SIGN_POS)
 70		setcc(SW_C3);
 71#endif /* PECULIAR_486 */
 72	      return;
 73	    }
 74	  break;
 75	case TW_NaN:
 76	  setcc(SW_C0|SW_C2|SW_C3);   /* Operand is not comparable */ 
 77	  EXCEPTION(EX_Invalid);
 78	  break;
 79	case TW_Infinity:
 80	  if (getsign(st0_ptr) == SIGN_POS)
 81	    setcc(0);
 82	  else
 83	    setcc(SW_C0);
 84	  break;
 85	default:
 86	  setcc(SW_C0|SW_C2|SW_C3);   /* Operand is not comparable */ 
 87	  EXCEPTION(EX_INTERNAL|0x14);
 88	  break;
 89	}
 90      break;
 91    case TAG_Empty:
 92      setcc(SW_C0|SW_C2|SW_C3);
 93      EXCEPTION(EX_StackUnder);
 94      break;
 95    }
 96}
 97
 98
 99static void fxam(FPU_REG *st0_ptr, u_char st0tag)
100{
101  int c = 0;
102  switch (st0tag)
103    {
104    case TAG_Empty:
105      c = SW_C3|SW_C0;
106      break;
107    case TAG_Zero:
108      c = SW_C3;
109      break;
110    case TAG_Valid:
111      c = SW_C2;
112      break;
113    case TAG_Special:
114      switch ( FPU_Special(st0_ptr) )
115	{
116	case TW_Denormal:
117	  c = SW_C2|SW_C3;  /* Denormal */
118	  break;
119	case TW_NaN:
120	  /* We also use NaN for unsupported types. */
121	  if ( (st0_ptr->sigh & 0x80000000) && (exponent(st0_ptr) == EXP_OVER) )
122	    c = SW_C0;
123	  break;
124	case TW_Infinity:
125	  c = SW_C2|SW_C0;
126	  break;
127	}
128    }
129  if ( getsign(st0_ptr) == SIGN_NEG )
130    c |= SW_C1;
131  setcc(c);
132}
133
134
135static FUNC_ST0 const fp_etc_table[] = {
136  fchs, fabs, (FUNC_ST0)FPU_illegal, (FUNC_ST0)FPU_illegal,
137  ftst_, fxam, (FUNC_ST0)FPU_illegal, (FUNC_ST0)FPU_illegal
138};
139
140void FPU_etc(void)
141{
142  (fp_etc_table[FPU_rm])(&st(0), FPU_gettag0());
143}