contrib/FAQ/programs/fp-emu/fpemul/load_store.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  W. Metzenthen, 22 Parker St, Ormond,
 *                           Vic 3163, Australia.
 *                           E-mail apm233m@vaxc.cc.monash.edu.au
 * All rights reserved.
 *
 * This copyright notice covers the redistribution and use of the
 * FPU emulator developed by W. Metzenthen. It covers only its use
 * in the 386BSD operating system. Any other use is not permitted
 * under this copyright.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must include information specifying
 *    that source code for the emulator is freely available and include
 *    either:
 *      a) an offer to provide the source code for a nominal distribution
 *         fee, or
 *      b) list at least two alternative methods whereby the source
 *         can be obtained, e.g. a publically accessible bulletin board
 *         and an anonymous ftp site from which the software can be
 *         downloaded.
 * 3. All advertising materials specifically mentioning features or use of
 *    this emulator must acknowledge that it was developed by W. Metzenthen.
 * 4. The name of W. Metzenthen may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * W. METZENTHEN BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

/*---------------------------------------------------------------------------+
 | 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 "param.h"
#include "proc.h"
#include "systm.h"
#include "machine/cpu.h"
#include "machine/pcb.h"

#include "fpu_emu.h"
#include "fpu_system.h"
#include "exception.h"
#include "status_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 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_REG *pop_ptr;       /* We need a version of FPU_st0_ptr which
                                 * won't change. */

        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_:
                return Un_impl();
#ifdef PARANOID
        default:
                return EXCEPTION(EX_INTERNAL);
#endif                          /* PARANOID */
        }

        switch (type) {
        case 000:               /* fld m32real */
                reg_load_single();
                setcc(0);       /* Clear the SW_C1 bit, "other bits undefined" */
                reg_move(&FPU_loaded_data, pop_ptr);
                break;
        case 001:               /* fild m32int */
                reg_load_int32();
                setcc(0);       /* Clear the SW_C1 bit, "other bits undefined" */
                reg_move(&FPU_loaded_data, pop_ptr);
                break;
        case 002:               /* fld m64real */
                reg_load_double();
                setcc(0);       /* Clear the SW_C1 bit, "other bits undefined" */
                reg_move(&FPU_loaded_data, pop_ptr);
                break;
        case 003:               /* fild m16int */
                reg_load_int16();
                setcc(0);       /* Clear the SW_C1 bit, "other bits undefined" */
                reg_move(&FPU_loaded_data, pop_ptr);
                break;
        case 010:               /* fst m32real */
                reg_store_single();
                break;
        case 011:               /* fist m32int */
                reg_store_int32();
                break;
        case 012:               /* fst m64real */
                reg_store_double();
                break;
        case 013:               /* fist m16int */
                reg_store_int16();
                break;
        case 014:               /* fstp m32real */
                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 */
                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 */
                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 */
                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();
                break;
        case 022:               /* frstor m94/108byte */
                frstor();
                break;
        case 023:               /* fbld m80dec */
                reg_load_bcd();
                setcc(0);       /* Clear the SW_C1 bit, "other bits undefined" */
                reg_move(&FPU_loaded_data, pop_ptr);
                break;
        case 024:               /* fldcw */
                REENTRANT_CHECK(OFF);
                control_word = fuword((unsigned short *) FPU_data_address);
                REENTRANT_CHECK(ON);
#ifdef NO_UNDERFLOW_TRAP
                if (!(control_word & EX_Underflow)) {
                        control_word |= EX_Underflow;
                }
#endif
                FPU_data_address = (void *) data_operand_offset;        /* We want no net effect */
                FPU_entry_eip = ip_offset;      /* We want no net effect */
                break;
        case 025:               /* fld m80real */
                reg_load_extended();
                setcc(0);       /* Clear the SW_C1 bit, "other bits undefined" */
                reg_move(&FPU_loaded_data, pop_ptr);
                break;
        case 027:               /* fild m64int */
                reg_load_int64();
                setcc(0);       /* Clear the SW_C1 bit, "other bits undefined" */
                reg_move(&FPU_loaded_data, pop_ptr);
                break;
        case 030:               /* fstenv  m14/28byte */
                fstenv();
                FPU_data_address = (void *) data_operand_offset;        /* We want no net effect */
                FPU_entry_eip = ip_offset;      /* We want no net effect */
                break;
        case 032:               /* fsave */
                fsave();
                FPU_data_address = (void *) data_operand_offset;        /* We want no net effect */
                FPU_entry_eip = ip_offset;      /* We want no net effect */
                break;
        case 033:               /* fbstp m80dec */
                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 */
                REENTRANT_CHECK(OFF);
/*                  verify_area(VERIFY_WRITE, FPU_data_address, 2);*/
                suword( (short *) FPU_data_address,control_word);
                REENTRANT_CHECK(ON);
                FPU_data_address = (void *) data_operand_offset;        /* We want no net effect */
                FPU_entry_eip = ip_offset;      /* We want no net effect */
                break;
        case 035:               /* fstp m80real */
                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 */
                status_word &= ~SW_Top;
                status_word |= (top & 7) << SW_Top_Shift;
                REENTRANT_CHECK(OFF);
/*                  verify_area(VERIFY_WRITE, FPU_data_address, 2);*/
                suword( (short *) FPU_data_address,status_word);
                REENTRANT_CHECK(ON);
                FPU_data_address = (void *) data_operand_offset;        /* We want no net effect */
                FPU_entry_eip = ip_offset;      /* We want no net effect */
                break;
        case 037:               /* fistp m64int */
                if (reg_store_int64())
                        pop_0();/* pop only if the number was actually stored
                                 * (see the 80486 manual p16-28) */
                break;
        }
}