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|
/*---------------------------------------------------------------------------+
| fpu_aux.c |
| |
| Code to implement some of the FPU auxiliary 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 "control_w.h"
static void fnop(void)
{
}
static void fclex(void)
{
partial_status &= ~(SW_Backward|SW_Summary|SW_Stack_Fault|SW_Precision|
SW_Underflow|SW_Overflow|SW_Zero_Div|SW_Denorm_Op|
SW_Invalid);
no_ip_update = 1;
}
/* Needs to be externally visible */
void finit(void)
{
control_word = 0x037f;
partial_status = 0;
top = 0; /* We don't keep top in the status word internally. */
fpu_tag_word = 0xffff;
/* The behaviour is different from that detailed in
Section 15.1.6 of the Intel manual */
operand_address.offset = 0;
operand_address.selector = 0;
instruction_address.offset = 0;
instruction_address.selector = 0;
instruction_address.opcode = 0;
no_ip_update = 1;
}
/*
* These are nops on the i387..
*/
#define feni fnop
#define fdisi fnop
#define fsetpm fnop
static FUNC const finit_table[] = {
feni, fdisi, fclex, finit,
fsetpm, FPU_illegal, FPU_illegal, FPU_illegal
};
void finit_(void)
{
(finit_table[FPU_rm])();
}
static void fstsw_ax(void)
{
*(short *) &FPU_EAX = status_word();
no_ip_update = 1;
}
static FUNC const fstsw_table[] = {
fstsw_ax, FPU_illegal, FPU_illegal, FPU_illegal,
FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
};
void fstsw_(void)
{
(fstsw_table[FPU_rm])();
}
static FUNC const fp_nop_table[] = {
fnop, FPU_illegal, FPU_illegal, FPU_illegal,
FPU_illegal, FPU_illegal, FPU_illegal, FPU_illegal
};
void fp_nop(void)
{
(fp_nop_table[FPU_rm])();
}
void fld_i_(void)
{
FPU_REG *st_new_ptr;
int i;
u_char tag;
if ( STACK_OVERFLOW )
{ FPU_stack_overflow(); return; }
/* fld st(i) */
i = FPU_rm;
if ( NOT_EMPTY(i) )
{
reg_copy(&st(i), st_new_ptr);
tag = FPU_gettagi(i);
push();
FPU_settag0(tag);
}
else
{
if ( control_word & CW_Invalid )
{
/* The masked response */
FPU_stack_underflow();
}
else
EXCEPTION(EX_StackUnder);
}
}
void fxch_i(void)
{
/* fxch st(i) */
FPU_REG t;
int i = FPU_rm;
FPU_REG *st0_ptr = &st(0), *sti_ptr = &st(i);
long tag_word = fpu_tag_word;
int regnr = top & 7, regnri = ((regnr + i) & 7);
u_char st0_tag = (tag_word >> (regnr*2)) & 3;
u_char sti_tag = (tag_word >> (regnri*2)) & 3;
if ( st0_tag == TAG_Empty )
{
if ( sti_tag == TAG_Empty )
{
FPU_stack_underflow();
FPU_stack_underflow_i(i);
return;
}
if ( control_word & CW_Invalid )
{
/* Masked response */
FPU_copy_to_reg0(sti_ptr, sti_tag);
}
FPU_stack_underflow_i(i);
return;
}
if ( sti_tag == TAG_Empty )
{
if ( control_word & CW_Invalid )
{
/* Masked response */
FPU_copy_to_regi(st0_ptr, st0_tag, i);
}
FPU_stack_underflow();
return;
}
clear_C1();
reg_copy(st0_ptr, &t);
reg_copy(sti_ptr, st0_ptr);
reg_copy(&t, sti_ptr);
tag_word &= ~(3 << (regnr*2)) & ~(3 << (regnri*2));
tag_word |= (sti_tag << (regnr*2)) | (st0_tag << (regnri*2));
fpu_tag_word = tag_word;
}
void ffree_(void)
{
/* ffree st(i) */
FPU_settagi(FPU_rm, TAG_Empty);
}
void ffreep(void)
{
/* ffree st(i) + pop - unofficial code */
FPU_settagi(FPU_rm, TAG_Empty);
FPU_pop();
}
void fst_i_(void)
{
/* fst st(i) */
FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
}
void fstp_i(void)
{
/* fstp st(i) */
FPU_copy_to_regi(&st(0), FPU_gettag0(), FPU_rm);
FPU_pop();
}
|
