144 lines
3.2 KiB
C
144 lines
3.2 KiB
C
/*---------------------------------------------------------------------------+
|
|
| fpu_etc.c |
|
|
| |
|
|
| Implement a few FPU instructions. |
|
|
| |
|
|
| Copyright (C) 1992,1993,1994,1997 |
|
|
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
|
|
| Australia. E-mail billm@suburbia.net |
|
|
| |
|
|
| |
|
|
+---------------------------------------------------------------------------*/
|
|
|
|
#include "fpu_system.h"
|
|
#include "exception.h"
|
|
#include "fpu_emu.h"
|
|
#include "status_w.h"
|
|
#include "reg_constant.h"
|
|
|
|
|
|
static void fchs(FPU_REG *st0_ptr, u_char st0tag)
|
|
{
|
|
if ( st0tag ^ TAG_Empty )
|
|
{
|
|
signbyte(st0_ptr) ^= SIGN_NEG;
|
|
clear_C1();
|
|
}
|
|
else
|
|
FPU_stack_underflow();
|
|
}
|
|
|
|
|
|
static void fabs(FPU_REG *st0_ptr, u_char st0tag)
|
|
{
|
|
if ( st0tag ^ TAG_Empty )
|
|
{
|
|
setpositive(st0_ptr);
|
|
clear_C1();
|
|
}
|
|
else
|
|
FPU_stack_underflow();
|
|
}
|
|
|
|
|
|
static void ftst_(FPU_REG *st0_ptr, u_char st0tag)
|
|
{
|
|
switch (st0tag)
|
|
{
|
|
case TAG_Zero:
|
|
setcc(SW_C3);
|
|
break;
|
|
case TAG_Valid:
|
|
if (getsign(st0_ptr) == SIGN_POS)
|
|
setcc(0);
|
|
else
|
|
setcc(SW_C0);
|
|
break;
|
|
case TAG_Special:
|
|
switch ( FPU_Special(st0_ptr) )
|
|
{
|
|
case TW_Denormal:
|
|
if (getsign(st0_ptr) == SIGN_POS)
|
|
setcc(0);
|
|
else
|
|
setcc(SW_C0);
|
|
if ( denormal_operand() < 0 )
|
|
{
|
|
#ifdef PECULIAR_486
|
|
/* This is weird! */
|
|
if (getsign(st0_ptr) == SIGN_POS)
|
|
setcc(SW_C3);
|
|
#endif /* PECULIAR_486 */
|
|
return;
|
|
}
|
|
break;
|
|
case TW_NaN:
|
|
setcc(SW_C0|SW_C2|SW_C3); /* Operand is not comparable */
|
|
EXCEPTION(EX_Invalid);
|
|
break;
|
|
case TW_Infinity:
|
|
if (getsign(st0_ptr) == SIGN_POS)
|
|
setcc(0);
|
|
else
|
|
setcc(SW_C0);
|
|
break;
|
|
default:
|
|
setcc(SW_C0|SW_C2|SW_C3); /* Operand is not comparable */
|
|
EXCEPTION(EX_INTERNAL|0x14);
|
|
break;
|
|
}
|
|
break;
|
|
case TAG_Empty:
|
|
setcc(SW_C0|SW_C2|SW_C3);
|
|
EXCEPTION(EX_StackUnder);
|
|
break;
|
|
}
|
|
}
|
|
|
|
|
|
static void fxam(FPU_REG *st0_ptr, u_char st0tag)
|
|
{
|
|
int c = 0;
|
|
switch (st0tag)
|
|
{
|
|
case TAG_Empty:
|
|
c = SW_C3|SW_C0;
|
|
break;
|
|
case TAG_Zero:
|
|
c = SW_C3;
|
|
break;
|
|
case TAG_Valid:
|
|
c = SW_C2;
|
|
break;
|
|
case TAG_Special:
|
|
switch ( FPU_Special(st0_ptr) )
|
|
{
|
|
case TW_Denormal:
|
|
c = SW_C2|SW_C3; /* Denormal */
|
|
break;
|
|
case TW_NaN:
|
|
/* We also use NaN for unsupported types. */
|
|
if ( (st0_ptr->sigh & 0x80000000) && (exponent(st0_ptr) == EXP_OVER) )
|
|
c = SW_C0;
|
|
break;
|
|
case TW_Infinity:
|
|
c = SW_C2|SW_C0;
|
|
break;
|
|
}
|
|
}
|
|
if ( getsign(st0_ptr) == SIGN_NEG )
|
|
c |= SW_C1;
|
|
setcc(c);
|
|
}
|
|
|
|
|
|
static FUNC_ST0 const fp_etc_table[] = {
|
|
fchs, fabs, (FUNC_ST0)FPU_illegal, (FUNC_ST0)FPU_illegal,
|
|
ftst_, fxam, (FUNC_ST0)FPU_illegal, (FUNC_ST0)FPU_illegal
|
|
};
|
|
|
|
void FPU_etc(void)
|
|
{
|
|
(fp_etc_table[FPU_rm])(&st(0), FPU_gettag0());
|
|
}
|