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Filename : LOAD_STO.C

/*---------------------------------------------------------------------------+
| load_store.c |
| |
| This file contains most of the code to interpret the FPU instructions |
| which load and store from user memory. |
| |
| Copyright (C) 1992,1993,1994 |
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
| Australia. E-mail [email protected] |
| |
| |
+---------------------------------------------------------------------------*/

/*---------------------------------------------------------------------------+
| Note: |
| The file contains code which accesses user memory. |
| Emulator static data may change when user memory is accessed, due to |
| other processes using the emulator while swapping is in progress. |
+---------------------------------------------------------------------------*/

#include

#include "fpu_system.h"
#include "exception.h"
#include "fpu_emu.h"
#include "status_w.h"
#include "control_w.h"


#define _NONE_ 0 /* FPU_st0_ptr etc not needed */
#define _REG0_ 1 /* Will be storing st(0) */
#define _PUSH_ 3 /* Need to check for space to push onto stack */
#define _null_ 4 /* Function illegal or not implemented */

#define pop_0() { pop_ptr->tag = TW_Empty; top++; }


static unsigned char const type_table[32] = {
_PUSH_, _PUSH_, _PUSH_, _PUSH_,
_null_, _null_, _null_, _null_,
_REG0_, _REG0_, _REG0_, _REG0_,
_REG0_, _REG0_, _REG0_, _REG0_,
_NONE_, _null_, _NONE_, _PUSH_,
_NONE_, _PUSH_, _null_, _PUSH_,
_NONE_, _null_, _NONE_, _REG0_,
_NONE_, _REG0_, _NONE_, _REG0_
};

void load_store_instr(char type, fpu_addr_modes addr_modes)
{
FPU_REG *pop_ptr; /* We need a version of FPU_st0_ptr which won't
change if the emulator is re-entered. */

pop_ptr = NULL; /* Initialized just to stop compiler warnings. */
switch ( type_table[(int) (unsigned) type] )
{
case _NONE_:
break;
case _REG0_:
pop_ptr = &st(0); /* Some of these instructions pop after
storing */

FPU_st0_ptr = pop_ptr; /* Set the global variables. */
FPU_st0_tag = FPU_st0_ptr->tag;
break;
case _PUSH_:
{
pop_ptr = &st(-1);
if ( pop_ptr->tag != TW_Empty )
{ stack_overflow(); return; }
top--;
}
break;
case _null_:
FPU_illegal();
return;
#ifdef PARANOID
default:
EXCEPTION(EX_INTERNAL);
return;
#endif PARANOID
}

switch ( type )
{
case 000: /* fld m32real */
clear_C1();
reg_load_single();
if ( (FPU_loaded_data.tag == TW_NaN) &&
real_2op_NaN(&FPU_loaded_data, &FPU_loaded_data, &FPU_loaded_data) )
{
top++;
break;
}
reg_move(&FPU_loaded_data, pop_ptr);
break;
case 001: /* fild m32int */
clear_C1();
reg_load_int32();
reg_move(&FPU_loaded_data, pop_ptr);
break;
case 002: /* fld m64real */
clear_C1();
reg_load_double();
if ( (FPU_loaded_data.tag == TW_NaN) &&
real_2op_NaN(&FPU_loaded_data, &FPU_loaded_data, &FPU_loaded_data) )
{
top++;
break;
}
reg_move(&FPU_loaded_data, pop_ptr);
break;
case 003: /* fild m16int */
clear_C1();
reg_load_int16();
reg_move(&FPU_loaded_data, pop_ptr);
break;
case 010: /* fst m32real */
clear_C1();
reg_store_single();
break;
case 011: /* fist m32int */
clear_C1();
reg_store_int32();
break;
case 012: /* fst m64real */
clear_C1();
reg_store_double();
break;
case 013: /* fist m16int */
clear_C1();
reg_store_int16();
break;
case 014: /* fstp m32real */
clear_C1();
if ( reg_store_single() )
pop_0(); /* pop only if the number was actually stored
(see the 80486 manual p16-28) */
break;
case 015: /* fistp m32int */
clear_C1();
if ( reg_store_int32() )
pop_0(); /* pop only if the number was actually stored
(see the 80486 manual p16-28) */
break;
case 016: /* fstp m64real */
clear_C1();
if ( reg_store_double() )
pop_0(); /* pop only if the number was actually stored
(see the 80486 manual p16-28) */
break;
case 017: /* fistp m16int */
clear_C1();
if ( reg_store_int16() )
pop_0(); /* pop only if the number was actually stored
(see the 80486 manual p16-28) */
break;
case 020: /* fldenv m14/28byte */
fldenv(addr_modes);
break;
case 022: /* frstor m94/108byte */
frstor(addr_modes);
break;
case 023: /* fbld m80dec */
clear_C1();
reg_load_bcd();
reg_move(&FPU_loaded_data, pop_ptr);
break;
case 024: /* fldcw */
RE_ENTRANT_CHECK_OFF;
FPU_verify_area(VERIFY_READ, FPU_data_address, 2);
control_word = get_fs_word((unsigned short *) FPU_data_address);
RE_ENTRANT_CHECK_ON;
if ( partial_status & ~control_word & CW_Exceptions )
partial_status |= (SW_Summary | SW_Backward);
else
partial_status &= ~(SW_Summary | SW_Backward);
#ifdef PECULIAR_486
control_word |= 0x40; /* An 80486 appears to always set this bit */
#endif PECULIAR_486
NO_NET_DATA_EFFECT;
NO_NET_INSTR_EFFECT;
break;
case 025: /* fld m80real */
clear_C1();
reg_load_extended();
reg_move(&FPU_loaded_data, pop_ptr);
break;
case 027: /* fild m64int */
clear_C1();
reg_load_int64();
reg_move(&FPU_loaded_data, pop_ptr);
break;
case 030: /* fstenv m14/28byte */
fstenv(addr_modes);
NO_NET_DATA_EFFECT;
break;
case 032: /* fsave */
fsave(addr_modes);
NO_NET_DATA_EFFECT;
break;
case 033: /* fbstp m80dec */
clear_C1();
if ( reg_store_bcd() )
pop_0(); /* pop only if the number was actually stored
(see the 80486 manual p16-28) */
break;
case 034: /* fstcw m16int */
RE_ENTRANT_CHECK_OFF;
FPU_verify_area(VERIFY_WRITE,FPU_data_address,2);
put_fs_word(control_word, (short *) FPU_data_address);
RE_ENTRANT_CHECK_ON;
NO_NET_DATA_EFFECT;
NO_NET_INSTR_EFFECT;
break;
case 035: /* fstp m80real */
clear_C1();
if ( reg_store_extended() )
pop_0(); /* pop only if the number was actually stored
(see the 80486 manual p16-28) */
break;
case 036: /* fstsw m2byte */
RE_ENTRANT_CHECK_OFF;
FPU_verify_area(VERIFY_WRITE,FPU_data_address,2);
put_fs_word(status_word(),(short *) FPU_data_address);
RE_ENTRANT_CHECK_ON;
NO_NET_DATA_EFFECT;
NO_NET_INSTR_EFFECT;
break;
case 037: /* fistp m64int */
clear_C1();
if ( reg_store_int64() )
pop_0(); /* pop only if the number was actually stored
(see the 80486 manual p16-28) */
break;
}
}