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1103 lines
32 KiB
C
1103 lines
32 KiB
C
/****************************************************************************
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*
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* Realmode X86 Emulator Library
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*
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* Copyright (C) 1996-1999 SciTech Software, Inc.
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* Copyright (C) David Mosberger-Tang
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* Copyright (C) 1999 Egbert Eich
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*
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* ========================================================================
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*
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* Permission to use, copy, modify, distribute, and sell this software and
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* its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and that
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* both that copyright notice and this permission notice appear in
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* supporting documentation, and that the name of the authors not be used
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* in advertising or publicity pertaining to distribution of the software
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* without specific, written prior permission. The authors makes no
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* representations about the suitability of this software for any purpose.
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* It is provided "as is" without express or implied warranty.
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*
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* THE AUTHORS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
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* EVENT SHALL THE AUTHORS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
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* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
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* USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
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* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*
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* ========================================================================
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*
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* Language: ANSI C
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* Environment: Any
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* Developer: Kendall Bennett
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*
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* Description: This file includes subroutines which are related to
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* instruction decoding and accessess of immediate data via IP. etc.
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*
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****************************************************************************/
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#include <stdlib.h>
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#if defined(__sun) && defined(CS) /* avoid conflicts with Solaris sys/regset.h */
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# undef CS
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# undef DS
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# undef SS
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# undef ES
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# undef FS
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# undef GS
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#endif
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#include "x86emu/x86emui.h"
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/*----------------------------- Implementation ----------------------------*/
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/****************************************************************************
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REMARKS:
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Handles any pending asychronous interrupts.
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****************************************************************************/
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static void
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x86emu_intr_handle(void)
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{
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u8 intno;
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if (M.x86.intr & INTR_SYNCH) {
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intno = M.x86.intno;
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if (_X86EMU_intrTab[intno]) {
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(*_X86EMU_intrTab[intno]) (intno);
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}
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else {
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push_word((u16) M.x86.R_FLG);
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CLEAR_FLAG(F_IF);
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CLEAR_FLAG(F_TF);
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push_word(M.x86.R_CS);
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M.x86.R_CS = mem_access_word(intno * 4 + 2);
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push_word(M.x86.R_IP);
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M.x86.R_IP = mem_access_word(intno * 4);
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M.x86.intr = 0;
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}
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}
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}
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/****************************************************************************
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PARAMETERS:
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intrnum - Interrupt number to raise
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REMARKS:
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Raise the specified interrupt to be handled before the execution of the
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next instruction.
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****************************************************************************/
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void
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x86emu_intr_raise(u8 intrnum)
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{
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M.x86.intno = intrnum;
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M.x86.intr |= INTR_SYNCH;
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}
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/****************************************************************************
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REMARKS:
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Main execution loop for the emulator. We return from here when the system
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halts, which is normally caused by a stack fault when we return from the
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original real mode call.
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****************************************************************************/
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void
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X86EMU_exec(void)
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{
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u8 op1;
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M.x86.intr = 0;
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DB(x86emu_end_instr();
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)
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for (;;) {
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DB(if (CHECK_IP_FETCH())
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x86emu_check_ip_access();)
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/* If debugging, save the IP and CS values. */
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SAVE_IP_CS(M.x86.R_CS, M.x86.R_IP);
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INC_DECODED_INST_LEN(1);
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if (M.x86.intr) {
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if (M.x86.intr & INTR_HALTED) {
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DB(if (M.x86.R_SP != 0) {
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printk("halted\n"); X86EMU_trace_regs();}
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else {
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if (M.x86.debug)
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printk("Service completed successfully\n");}
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)
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return;
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}
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if (((M.x86.intr & INTR_SYNCH) &&
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(M.x86.intno == 0 || M.x86.intno == 2)) ||
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!ACCESS_FLAG(F_IF)) {
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x86emu_intr_handle();
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}
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}
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op1 = (*sys_rdb) (((u32) M.x86.R_CS << 4) + (M.x86.R_IP++));
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(*x86emu_optab[op1]) (op1);
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if (M.x86.debug & DEBUG_EXIT) {
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M.x86.debug &= ~DEBUG_EXIT;
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return;
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}
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}
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}
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/****************************************************************************
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REMARKS:
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Halts the system by setting the halted system flag.
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****************************************************************************/
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void
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X86EMU_halt_sys(void)
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{
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M.x86.intr |= INTR_HALTED;
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}
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/****************************************************************************
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PARAMETERS:
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mod - Mod value from decoded byte
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regh - Reg h value from decoded byte
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regl - Reg l value from decoded byte
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REMARKS:
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Raise the specified interrupt to be handled before the execution of the
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next instruction.
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NOTE: Do not inline this function, as (*sys_rdb) is already inline!
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****************************************************************************/
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void
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fetch_decode_modrm(int *mod, int *regh, int *regl)
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{
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int fetched;
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DB(if (CHECK_IP_FETCH())
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x86emu_check_ip_access();)
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fetched = (*sys_rdb) (((u32) M.x86.R_CS << 4) + (M.x86.R_IP++));
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INC_DECODED_INST_LEN(1);
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*mod = (fetched >> 6) & 0x03;
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*regh = (fetched >> 3) & 0x07;
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*regl = (fetched >> 0) & 0x07;
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}
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/****************************************************************************
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RETURNS:
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Immediate byte value read from instruction queue
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REMARKS:
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This function returns the immediate byte from the instruction queue, and
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moves the instruction pointer to the next value.
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NOTE: Do not inline this function, as (*sys_rdb) is already inline!
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****************************************************************************/
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u8
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fetch_byte_imm(void)
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{
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u8 fetched;
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DB(if (CHECK_IP_FETCH())
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x86emu_check_ip_access();)
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fetched = (*sys_rdb) (((u32) M.x86.R_CS << 4) + (M.x86.R_IP++));
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INC_DECODED_INST_LEN(1);
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return fetched;
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}
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/****************************************************************************
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RETURNS:
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Immediate word value read from instruction queue
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REMARKS:
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This function returns the immediate byte from the instruction queue, and
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moves the instruction pointer to the next value.
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NOTE: Do not inline this function, as (*sys_rdw) is already inline!
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****************************************************************************/
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u16
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fetch_word_imm(void)
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{
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u16 fetched;
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DB(if (CHECK_IP_FETCH())
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x86emu_check_ip_access();)
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fetched = (*sys_rdw) (((u32) M.x86.R_CS << 4) + (M.x86.R_IP));
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M.x86.R_IP += 2;
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INC_DECODED_INST_LEN(2);
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return fetched;
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}
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/****************************************************************************
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RETURNS:
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Immediate lone value read from instruction queue
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REMARKS:
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This function returns the immediate byte from the instruction queue, and
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moves the instruction pointer to the next value.
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NOTE: Do not inline this function, as (*sys_rdw) is already inline!
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****************************************************************************/
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u32
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fetch_long_imm(void)
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{
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u32 fetched;
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DB(if (CHECK_IP_FETCH())
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x86emu_check_ip_access();)
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fetched = (*sys_rdl) (((u32) M.x86.R_CS << 4) + (M.x86.R_IP));
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M.x86.R_IP += 4;
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INC_DECODED_INST_LEN(4);
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return fetched;
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}
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/****************************************************************************
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RETURNS:
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Value of the default data segment
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REMARKS:
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Inline function that returns the default data segment for the current
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instruction.
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On the x86 processor, the default segment is not always DS if there is
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no segment override. Address modes such as -3[BP] or 10[BP+SI] all refer to
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addresses relative to SS (ie: on the stack). So, at the minimum, all
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decodings of addressing modes would have to set/clear a bit describing
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whether the access is relative to DS or SS. That is the function of the
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cpu-state-varible M.x86.mode. There are several potential states:
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repe prefix seen (handled elsewhere)
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repne prefix seen (ditto)
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cs segment override
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ds segment override
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es segment override
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fs segment override
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gs segment override
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ss segment override
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ds/ss select (in absence of override)
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Each of the above 7 items are handled with a bit in the mode field.
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****************************************************************************/
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_INLINE u32
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get_data_segment(void)
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{
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#define GET_SEGMENT(segment)
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switch (M.x86.mode & SYSMODE_SEGMASK) {
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case 0: /* default case: use ds register */
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case SYSMODE_SEGOVR_DS:
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case SYSMODE_SEGOVR_DS | SYSMODE_SEG_DS_SS:
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return M.x86.R_DS;
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case SYSMODE_SEG_DS_SS: /* non-overridden, use ss register */
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return M.x86.R_SS;
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case SYSMODE_SEGOVR_CS:
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case SYSMODE_SEGOVR_CS | SYSMODE_SEG_DS_SS:
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return M.x86.R_CS;
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case SYSMODE_SEGOVR_ES:
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case SYSMODE_SEGOVR_ES | SYSMODE_SEG_DS_SS:
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return M.x86.R_ES;
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case SYSMODE_SEGOVR_FS:
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case SYSMODE_SEGOVR_FS | SYSMODE_SEG_DS_SS:
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return M.x86.R_FS;
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case SYSMODE_SEGOVR_GS:
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case SYSMODE_SEGOVR_GS | SYSMODE_SEG_DS_SS:
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return M.x86.R_GS;
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case SYSMODE_SEGOVR_SS:
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case SYSMODE_SEGOVR_SS | SYSMODE_SEG_DS_SS:
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return M.x86.R_SS;
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default:
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#ifdef DEBUG
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printk("error: should not happen: multiple overrides.\n");
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#endif
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HALT_SYS();
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return 0;
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}
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}
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/****************************************************************************
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PARAMETERS:
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offset - Offset to load data from
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RETURNS:
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Byte value read from the absolute memory location.
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NOTE: Do not inline this function as (*sys_rdX) is already inline!
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****************************************************************************/
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u8
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fetch_data_byte(uint offset)
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{
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#ifdef DEBUG
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if (CHECK_DATA_ACCESS())
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x86emu_check_data_access((u16) get_data_segment(), offset);
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#endif
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return (*sys_rdb) ((get_data_segment() << 4) + offset);
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}
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/****************************************************************************
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PARAMETERS:
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offset - Offset to load data from
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RETURNS:
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Word value read from the absolute memory location.
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NOTE: Do not inline this function as (*sys_rdX) is already inline!
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****************************************************************************/
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u16
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fetch_data_word(uint offset)
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{
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#ifdef DEBUG
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if (CHECK_DATA_ACCESS())
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x86emu_check_data_access((u16) get_data_segment(), offset);
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#endif
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return (*sys_rdw) ((get_data_segment() << 4) + offset);
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}
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/****************************************************************************
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PARAMETERS:
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offset - Offset to load data from
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RETURNS:
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Long value read from the absolute memory location.
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NOTE: Do not inline this function as (*sys_rdX) is already inline!
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****************************************************************************/
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u32
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fetch_data_long(uint offset)
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{
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#ifdef DEBUG
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if (CHECK_DATA_ACCESS())
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x86emu_check_data_access((u16) get_data_segment(), offset);
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#endif
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return (*sys_rdl) ((get_data_segment() << 4) + offset);
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}
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/****************************************************************************
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PARAMETERS:
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segment - Segment to load data from
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offset - Offset to load data from
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RETURNS:
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Byte value read from the absolute memory location.
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NOTE: Do not inline this function as (*sys_rdX) is already inline!
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****************************************************************************/
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u8
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fetch_data_byte_abs(uint segment, uint offset)
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{
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#ifdef DEBUG
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if (CHECK_DATA_ACCESS())
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x86emu_check_data_access(segment, offset);
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#endif
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return (*sys_rdb) (((u32) segment << 4) + offset);
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}
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/****************************************************************************
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PARAMETERS:
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segment - Segment to load data from
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offset - Offset to load data from
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RETURNS:
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Word value read from the absolute memory location.
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NOTE: Do not inline this function as (*sys_rdX) is already inline!
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****************************************************************************/
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u16
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fetch_data_word_abs(uint segment, uint offset)
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{
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#ifdef DEBUG
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if (CHECK_DATA_ACCESS())
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x86emu_check_data_access(segment, offset);
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#endif
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return (*sys_rdw) (((u32) segment << 4) + offset);
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}
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/****************************************************************************
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PARAMETERS:
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segment - Segment to load data from
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offset - Offset to load data from
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RETURNS:
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Long value read from the absolute memory location.
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NOTE: Do not inline this function as (*sys_rdX) is already inline!
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****************************************************************************/
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u32
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fetch_data_long_abs(uint segment, uint offset)
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{
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#ifdef DEBUG
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if (CHECK_DATA_ACCESS())
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x86emu_check_data_access(segment, offset);
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#endif
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return (*sys_rdl) (((u32) segment << 4) + offset);
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}
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/****************************************************************************
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PARAMETERS:
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offset - Offset to store data at
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val - Value to store
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REMARKS:
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Writes a word value to an segmented memory location. The segment used is
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the current 'default' segment, which may have been overridden.
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NOTE: Do not inline this function as (*sys_wrX) is already inline!
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****************************************************************************/
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void
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store_data_byte(uint offset, u8 val)
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{
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#ifdef DEBUG
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if (CHECK_DATA_ACCESS())
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x86emu_check_data_access((u16) get_data_segment(), offset);
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#endif
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(*sys_wrb) ((get_data_segment() << 4) + offset, val);
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}
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/****************************************************************************
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PARAMETERS:
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offset - Offset to store data at
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val - Value to store
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REMARKS:
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Writes a word value to an segmented memory location. The segment used is
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the current 'default' segment, which may have been overridden.
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NOTE: Do not inline this function as (*sys_wrX) is already inline!
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****************************************************************************/
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void
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store_data_word(uint offset, u16 val)
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{
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#ifdef DEBUG
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if (CHECK_DATA_ACCESS())
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x86emu_check_data_access((u16) get_data_segment(), offset);
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#endif
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(*sys_wrw) ((get_data_segment() << 4) + offset, val);
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}
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|
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/****************************************************************************
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PARAMETERS:
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offset - Offset to store data at
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val - Value to store
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REMARKS:
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Writes a long value to an segmented memory location. The segment used is
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the current 'default' segment, which may have been overridden.
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NOTE: Do not inline this function as (*sys_wrX) is already inline!
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****************************************************************************/
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void
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store_data_long(uint offset, u32 val)
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{
|
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#ifdef DEBUG
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if (CHECK_DATA_ACCESS())
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x86emu_check_data_access((u16) get_data_segment(), offset);
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#endif
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(*sys_wrl) ((get_data_segment() << 4) + offset, val);
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}
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|
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/****************************************************************************
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PARAMETERS:
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segment - Segment to store data at
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offset - Offset to store data at
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val - Value to store
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REMARKS:
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Writes a byte value to an absolute memory location.
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NOTE: Do not inline this function as (*sys_wrX) is already inline!
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****************************************************************************/
|
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void
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store_data_byte_abs(uint segment, uint offset, u8 val)
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{
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#ifdef DEBUG
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if (CHECK_DATA_ACCESS())
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x86emu_check_data_access(segment, offset);
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#endif
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(*sys_wrb) (((u32) segment << 4) + offset, val);
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}
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|
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/****************************************************************************
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PARAMETERS:
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segment - Segment to store data at
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offset - Offset to store data at
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val - Value to store
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REMARKS:
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Writes a word value to an absolute memory location.
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NOTE: Do not inline this function as (*sys_wrX) is already inline!
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****************************************************************************/
|
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void
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store_data_word_abs(uint segment, uint offset, u16 val)
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{
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#ifdef DEBUG
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if (CHECK_DATA_ACCESS())
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x86emu_check_data_access(segment, offset);
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#endif
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(*sys_wrw) (((u32) segment << 4) + offset, val);
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}
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|
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/****************************************************************************
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PARAMETERS:
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segment - Segment to store data at
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offset - Offset to store data at
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val - Value to store
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REMARKS:
|
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Writes a long value to an absolute memory location.
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NOTE: Do not inline this function as (*sys_wrX) is already inline!
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****************************************************************************/
|
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void
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store_data_long_abs(uint segment, uint offset, u32 val)
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{
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#ifdef DEBUG
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if (CHECK_DATA_ACCESS())
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x86emu_check_data_access(segment, offset);
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#endif
|
|
(*sys_wrl) (((u32) segment << 4) + offset, val);
|
|
}
|
|
|
|
/****************************************************************************
|
|
PARAMETERS:
|
|
reg - Register to decode
|
|
|
|
RETURNS:
|
|
Pointer to the appropriate register
|
|
|
|
REMARKS:
|
|
Return a pointer to the register given by the R/RM field of the
|
|
modrm byte, for byte operands. Also enables the decoding of instructions.
|
|
****************************************************************************/
|
|
u8 *
|
|
decode_rm_byte_register(int reg)
|
|
{
|
|
switch (reg) {
|
|
case 0:
|
|
DECODE_PRINTF("AL");
|
|
return &M.x86.R_AL;
|
|
case 1:
|
|
DECODE_PRINTF("CL");
|
|
return &M.x86.R_CL;
|
|
case 2:
|
|
DECODE_PRINTF("DL");
|
|
return &M.x86.R_DL;
|
|
case 3:
|
|
DECODE_PRINTF("BL");
|
|
return &M.x86.R_BL;
|
|
case 4:
|
|
DECODE_PRINTF("AH");
|
|
return &M.x86.R_AH;
|
|
case 5:
|
|
DECODE_PRINTF("CH");
|
|
return &M.x86.R_CH;
|
|
case 6:
|
|
DECODE_PRINTF("DH");
|
|
return &M.x86.R_DH;
|
|
case 7:
|
|
DECODE_PRINTF("BH");
|
|
return &M.x86.R_BH;
|
|
}
|
|
HALT_SYS();
|
|
return NULL; /* NOT REACHED OR REACHED ON ERROR */
|
|
}
|
|
|
|
/****************************************************************************
|
|
PARAMETERS:
|
|
reg - Register to decode
|
|
|
|
RETURNS:
|
|
Pointer to the appropriate register
|
|
|
|
REMARKS:
|
|
Return a pointer to the register given by the R/RM field of the
|
|
modrm byte, for word operands. Also enables the decoding of instructions.
|
|
****************************************************************************/
|
|
u16 *
|
|
decode_rm_word_register(int reg)
|
|
{
|
|
switch (reg) {
|
|
case 0:
|
|
DECODE_PRINTF("AX");
|
|
return &M.x86.R_AX;
|
|
case 1:
|
|
DECODE_PRINTF("CX");
|
|
return &M.x86.R_CX;
|
|
case 2:
|
|
DECODE_PRINTF("DX");
|
|
return &M.x86.R_DX;
|
|
case 3:
|
|
DECODE_PRINTF("BX");
|
|
return &M.x86.R_BX;
|
|
case 4:
|
|
DECODE_PRINTF("SP");
|
|
return &M.x86.R_SP;
|
|
case 5:
|
|
DECODE_PRINTF("BP");
|
|
return &M.x86.R_BP;
|
|
case 6:
|
|
DECODE_PRINTF("SI");
|
|
return &M.x86.R_SI;
|
|
case 7:
|
|
DECODE_PRINTF("DI");
|
|
return &M.x86.R_DI;
|
|
}
|
|
HALT_SYS();
|
|
return NULL; /* NOTREACHED OR REACHED ON ERROR */
|
|
}
|
|
|
|
/****************************************************************************
|
|
PARAMETERS:
|
|
reg - Register to decode
|
|
|
|
RETURNS:
|
|
Pointer to the appropriate register
|
|
|
|
REMARKS:
|
|
Return a pointer to the register given by the R/RM field of the
|
|
modrm byte, for dword operands. Also enables the decoding of instructions.
|
|
****************************************************************************/
|
|
u32 *
|
|
decode_rm_long_register(int reg)
|
|
{
|
|
switch (reg) {
|
|
case 0:
|
|
DECODE_PRINTF("EAX");
|
|
return &M.x86.R_EAX;
|
|
case 1:
|
|
DECODE_PRINTF("ECX");
|
|
return &M.x86.R_ECX;
|
|
case 2:
|
|
DECODE_PRINTF("EDX");
|
|
return &M.x86.R_EDX;
|
|
case 3:
|
|
DECODE_PRINTF("EBX");
|
|
return &M.x86.R_EBX;
|
|
case 4:
|
|
DECODE_PRINTF("ESP");
|
|
return &M.x86.R_ESP;
|
|
case 5:
|
|
DECODE_PRINTF("EBP");
|
|
return &M.x86.R_EBP;
|
|
case 6:
|
|
DECODE_PRINTF("ESI");
|
|
return &M.x86.R_ESI;
|
|
case 7:
|
|
DECODE_PRINTF("EDI");
|
|
return &M.x86.R_EDI;
|
|
}
|
|
HALT_SYS();
|
|
return NULL; /* NOTREACHED OR REACHED ON ERROR */
|
|
}
|
|
|
|
/****************************************************************************
|
|
PARAMETERS:
|
|
reg - Register to decode
|
|
|
|
RETURNS:
|
|
Pointer to the appropriate register
|
|
|
|
REMARKS:
|
|
Return a pointer to the register given by the R/RM field of the
|
|
modrm byte, for word operands, modified from above for the weirdo
|
|
special case of segreg operands. Also enables the decoding of instructions.
|
|
****************************************************************************/
|
|
u16 *
|
|
decode_rm_seg_register(int reg)
|
|
{
|
|
switch (reg) {
|
|
case 0:
|
|
DECODE_PRINTF("ES");
|
|
return &M.x86.R_ES;
|
|
case 1:
|
|
DECODE_PRINTF("CS");
|
|
return &M.x86.R_CS;
|
|
case 2:
|
|
DECODE_PRINTF("SS");
|
|
return &M.x86.R_SS;
|
|
case 3:
|
|
DECODE_PRINTF("DS");
|
|
return &M.x86.R_DS;
|
|
case 4:
|
|
DECODE_PRINTF("FS");
|
|
return &M.x86.R_FS;
|
|
case 5:
|
|
DECODE_PRINTF("GS");
|
|
return &M.x86.R_GS;
|
|
case 6:
|
|
case 7:
|
|
DECODE_PRINTF("ILLEGAL SEGREG");
|
|
break;
|
|
}
|
|
HALT_SYS();
|
|
return NULL; /* NOT REACHED OR REACHED ON ERROR */
|
|
}
|
|
|
|
/*
|
|
*
|
|
* return offset from the SIB Byte
|
|
*/
|
|
u32
|
|
decode_sib_address(int sib, int mod)
|
|
{
|
|
u32 base = 0, i = 0, scale = 1;
|
|
|
|
switch (sib & 0x07) {
|
|
case 0:
|
|
DECODE_PRINTF("[EAX]");
|
|
base = M.x86.R_EAX;
|
|
break;
|
|
case 1:
|
|
DECODE_PRINTF("[ECX]");
|
|
base = M.x86.R_ECX;
|
|
break;
|
|
case 2:
|
|
DECODE_PRINTF("[EDX]");
|
|
base = M.x86.R_EDX;
|
|
break;
|
|
case 3:
|
|
DECODE_PRINTF("[EBX]");
|
|
base = M.x86.R_EBX;
|
|
break;
|
|
case 4:
|
|
DECODE_PRINTF("[ESP]");
|
|
base = M.x86.R_ESP;
|
|
M.x86.mode |= SYSMODE_SEG_DS_SS;
|
|
break;
|
|
case 5:
|
|
if (mod == 0) {
|
|
base = fetch_long_imm();
|
|
DECODE_PRINTF2("%08x", base);
|
|
}
|
|
else {
|
|
DECODE_PRINTF("[EBP]");
|
|
base = M.x86.R_ESP;
|
|
M.x86.mode |= SYSMODE_SEG_DS_SS;
|
|
}
|
|
break;
|
|
case 6:
|
|
DECODE_PRINTF("[ESI]");
|
|
base = M.x86.R_ESI;
|
|
break;
|
|
case 7:
|
|
DECODE_PRINTF("[EDI]");
|
|
base = M.x86.R_EDI;
|
|
break;
|
|
}
|
|
switch ((sib >> 3) & 0x07) {
|
|
case 0:
|
|
DECODE_PRINTF("[EAX");
|
|
i = M.x86.R_EAX;
|
|
break;
|
|
case 1:
|
|
DECODE_PRINTF("[ECX");
|
|
i = M.x86.R_ECX;
|
|
break;
|
|
case 2:
|
|
DECODE_PRINTF("[EDX");
|
|
i = M.x86.R_EDX;
|
|
break;
|
|
case 3:
|
|
DECODE_PRINTF("[EBX");
|
|
i = M.x86.R_EBX;
|
|
break;
|
|
case 4:
|
|
i = 0;
|
|
break;
|
|
case 5:
|
|
DECODE_PRINTF("[EBP");
|
|
i = M.x86.R_EBP;
|
|
break;
|
|
case 6:
|
|
DECODE_PRINTF("[ESI");
|
|
i = M.x86.R_ESI;
|
|
break;
|
|
case 7:
|
|
DECODE_PRINTF("[EDI");
|
|
i = M.x86.R_EDI;
|
|
break;
|
|
}
|
|
scale = 1 << ((sib >> 6) & 0x03);
|
|
if (((sib >> 3) & 0x07) != 4) {
|
|
if (scale == 1) {
|
|
DECODE_PRINTF("]");
|
|
}
|
|
else {
|
|
DECODE_PRINTF2("*%d]", scale);
|
|
}
|
|
}
|
|
return base + (i * scale);
|
|
}
|
|
|
|
/****************************************************************************
|
|
PARAMETERS:
|
|
rm - RM value to decode
|
|
|
|
RETURNS:
|
|
Offset in memory for the address decoding
|
|
|
|
REMARKS:
|
|
Return the offset given by mod=00 addressing. Also enables the
|
|
decoding of instructions.
|
|
|
|
NOTE: The code which specifies the corresponding segment (ds vs ss)
|
|
below in the case of [BP+..]. The assumption here is that at the
|
|
point that this subroutine is called, the bit corresponding to
|
|
SYSMODE_SEG_DS_SS will be zero. After every instruction
|
|
except the segment override instructions, this bit (as well
|
|
as any bits indicating segment overrides) will be clear. So
|
|
if a SS access is needed, set this bit. Otherwise, DS access
|
|
occurs (unless any of the segment override bits are set).
|
|
****************************************************************************/
|
|
u32
|
|
decode_rm00_address(int rm)
|
|
{
|
|
u32 offset;
|
|
int sib;
|
|
|
|
if (M.x86.mode & SYSMODE_PREFIX_ADDR) {
|
|
/* 32-bit addressing */
|
|
switch (rm) {
|
|
case 0:
|
|
DECODE_PRINTF("[EAX]");
|
|
return M.x86.R_EAX;
|
|
case 1:
|
|
DECODE_PRINTF("[ECX]");
|
|
return M.x86.R_ECX;
|
|
case 2:
|
|
DECODE_PRINTF("[EDX]");
|
|
return M.x86.R_EDX;
|
|
case 3:
|
|
DECODE_PRINTF("[EBX]");
|
|
return M.x86.R_EBX;
|
|
case 4:
|
|
sib = fetch_byte_imm();
|
|
return decode_sib_address(sib, 0);
|
|
case 5:
|
|
offset = fetch_long_imm();
|
|
DECODE_PRINTF2("[%08x]", offset);
|
|
return offset;
|
|
case 6:
|
|
DECODE_PRINTF("[ESI]");
|
|
return M.x86.R_ESI;
|
|
case 7:
|
|
DECODE_PRINTF("[EDI]");
|
|
return M.x86.R_EDI;
|
|
}
|
|
HALT_SYS();
|
|
}
|
|
else {
|
|
/* 16-bit addressing */
|
|
switch (rm) {
|
|
case 0:
|
|
DECODE_PRINTF("[BX+SI]");
|
|
return (M.x86.R_BX + M.x86.R_SI) & 0xffff;
|
|
case 1:
|
|
DECODE_PRINTF("[BX+DI]");
|
|
return (M.x86.R_BX + M.x86.R_DI) & 0xffff;
|
|
case 2:
|
|
DECODE_PRINTF("[BP+SI]");
|
|
M.x86.mode |= SYSMODE_SEG_DS_SS;
|
|
return (M.x86.R_BP + M.x86.R_SI) & 0xffff;
|
|
case 3:
|
|
DECODE_PRINTF("[BP+DI]");
|
|
M.x86.mode |= SYSMODE_SEG_DS_SS;
|
|
return (M.x86.R_BP + M.x86.R_DI) & 0xffff;
|
|
case 4:
|
|
DECODE_PRINTF("[SI]");
|
|
return M.x86.R_SI;
|
|
case 5:
|
|
DECODE_PRINTF("[DI]");
|
|
return M.x86.R_DI;
|
|
case 6:
|
|
offset = fetch_word_imm();
|
|
DECODE_PRINTF2("[%04x]", offset);
|
|
return offset;
|
|
case 7:
|
|
DECODE_PRINTF("[BX]");
|
|
return M.x86.R_BX;
|
|
}
|
|
HALT_SYS();
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/****************************************************************************
|
|
PARAMETERS:
|
|
rm - RM value to decode
|
|
|
|
RETURNS:
|
|
Offset in memory for the address decoding
|
|
|
|
REMARKS:
|
|
Return the offset given by mod=01 addressing. Also enables the
|
|
decoding of instructions.
|
|
****************************************************************************/
|
|
u32
|
|
decode_rm01_address(int rm)
|
|
{
|
|
int displacement = 0;
|
|
int sib;
|
|
|
|
/* Fetch disp8 if no SIB byte */
|
|
if (!((M.x86.mode & SYSMODE_PREFIX_ADDR) && (rm == 4)))
|
|
displacement = (s8) fetch_byte_imm();
|
|
|
|
if (M.x86.mode & SYSMODE_PREFIX_ADDR) {
|
|
/* 32-bit addressing */
|
|
switch (rm) {
|
|
case 0:
|
|
DECODE_PRINTF2("%d[EAX]", displacement);
|
|
return M.x86.R_EAX + displacement;
|
|
case 1:
|
|
DECODE_PRINTF2("%d[ECX]", displacement);
|
|
return M.x86.R_ECX + displacement;
|
|
case 2:
|
|
DECODE_PRINTF2("%d[EDX]", displacement);
|
|
return M.x86.R_EDX + displacement;
|
|
case 3:
|
|
DECODE_PRINTF2("%d[EBX]", displacement);
|
|
return M.x86.R_EBX + displacement;
|
|
case 4:
|
|
sib = fetch_byte_imm();
|
|
displacement = (s8) fetch_byte_imm();
|
|
DECODE_PRINTF2("%d", displacement);
|
|
return decode_sib_address(sib, 1) + displacement;
|
|
case 5:
|
|
DECODE_PRINTF2("%d[EBP]", displacement);
|
|
return M.x86.R_EBP + displacement;
|
|
case 6:
|
|
DECODE_PRINTF2("%d[ESI]", displacement);
|
|
return M.x86.R_ESI + displacement;
|
|
case 7:
|
|
DECODE_PRINTF2("%d[EDI]", displacement);
|
|
return M.x86.R_EDI + displacement;
|
|
}
|
|
HALT_SYS();
|
|
}
|
|
else {
|
|
/* 16-bit addressing */
|
|
switch (rm) {
|
|
case 0:
|
|
DECODE_PRINTF2("%d[BX+SI]", displacement);
|
|
return (M.x86.R_BX + M.x86.R_SI + displacement) & 0xffff;
|
|
case 1:
|
|
DECODE_PRINTF2("%d[BX+DI]", displacement);
|
|
return (M.x86.R_BX + M.x86.R_DI + displacement) & 0xffff;
|
|
case 2:
|
|
DECODE_PRINTF2("%d[BP+SI]", displacement);
|
|
M.x86.mode |= SYSMODE_SEG_DS_SS;
|
|
return (M.x86.R_BP + M.x86.R_SI + displacement) & 0xffff;
|
|
case 3:
|
|
DECODE_PRINTF2("%d[BP+DI]", displacement);
|
|
M.x86.mode |= SYSMODE_SEG_DS_SS;
|
|
return (M.x86.R_BP + M.x86.R_DI + displacement) & 0xffff;
|
|
case 4:
|
|
DECODE_PRINTF2("%d[SI]", displacement);
|
|
return (M.x86.R_SI + displacement) & 0xffff;
|
|
case 5:
|
|
DECODE_PRINTF2("%d[DI]", displacement);
|
|
return (M.x86.R_DI + displacement) & 0xffff;
|
|
case 6:
|
|
DECODE_PRINTF2("%d[BP]", displacement);
|
|
M.x86.mode |= SYSMODE_SEG_DS_SS;
|
|
return (M.x86.R_BP + displacement) & 0xffff;
|
|
case 7:
|
|
DECODE_PRINTF2("%d[BX]", displacement);
|
|
return (M.x86.R_BX + displacement) & 0xffff;
|
|
}
|
|
HALT_SYS();
|
|
}
|
|
return 0; /* SHOULD NOT HAPPEN */
|
|
}
|
|
|
|
/****************************************************************************
|
|
PARAMETERS:
|
|
rm - RM value to decode
|
|
|
|
RETURNS:
|
|
Offset in memory for the address decoding
|
|
|
|
REMARKS:
|
|
Return the offset given by mod=10 addressing. Also enables the
|
|
decoding of instructions.
|
|
****************************************************************************/
|
|
u32
|
|
decode_rm10_address(int rm)
|
|
{
|
|
u32 displacement = 0;
|
|
int sib;
|
|
|
|
/* Fetch disp16 if 16-bit addr mode */
|
|
if (!(M.x86.mode & SYSMODE_PREFIX_ADDR))
|
|
displacement = (u16) fetch_word_imm();
|
|
else {
|
|
/* Fetch disp32 if no SIB byte */
|
|
if (rm != 4)
|
|
displacement = (u32) fetch_long_imm();
|
|
}
|
|
|
|
if (M.x86.mode & SYSMODE_PREFIX_ADDR) {
|
|
/* 32-bit addressing */
|
|
switch (rm) {
|
|
case 0:
|
|
DECODE_PRINTF2("%08x[EAX]", displacement);
|
|
return M.x86.R_EAX + displacement;
|
|
case 1:
|
|
DECODE_PRINTF2("%08x[ECX]", displacement);
|
|
return M.x86.R_ECX + displacement;
|
|
case 2:
|
|
DECODE_PRINTF2("%08x[EDX]", displacement);
|
|
M.x86.mode |= SYSMODE_SEG_DS_SS;
|
|
return M.x86.R_EDX + displacement;
|
|
case 3:
|
|
DECODE_PRINTF2("%08x[EBX]", displacement);
|
|
return M.x86.R_EBX + displacement;
|
|
case 4:
|
|
sib = fetch_byte_imm();
|
|
displacement = (u32) fetch_long_imm();
|
|
DECODE_PRINTF2("%08x", displacement);
|
|
return decode_sib_address(sib, 2) + displacement;
|
|
break;
|
|
case 5:
|
|
DECODE_PRINTF2("%08x[EBP]", displacement);
|
|
return M.x86.R_EBP + displacement;
|
|
case 6:
|
|
DECODE_PRINTF2("%08x[ESI]", displacement);
|
|
return M.x86.R_ESI + displacement;
|
|
case 7:
|
|
DECODE_PRINTF2("%08x[EDI]", displacement);
|
|
return M.x86.R_EDI + displacement;
|
|
}
|
|
HALT_SYS();
|
|
}
|
|
else {
|
|
/* 16-bit addressing */
|
|
switch (rm) {
|
|
case 0:
|
|
DECODE_PRINTF2("%04x[BX+SI]", displacement);
|
|
return (M.x86.R_BX + M.x86.R_SI + displacement) & 0xffff;
|
|
case 1:
|
|
DECODE_PRINTF2("%04x[BX+DI]", displacement);
|
|
return (M.x86.R_BX + M.x86.R_DI + displacement) & 0xffff;
|
|
case 2:
|
|
DECODE_PRINTF2("%04x[BP+SI]", displacement);
|
|
M.x86.mode |= SYSMODE_SEG_DS_SS;
|
|
return (M.x86.R_BP + M.x86.R_SI + displacement) & 0xffff;
|
|
case 3:
|
|
DECODE_PRINTF2("%04x[BP+DI]", displacement);
|
|
M.x86.mode |= SYSMODE_SEG_DS_SS;
|
|
return (M.x86.R_BP + M.x86.R_DI + displacement) & 0xffff;
|
|
case 4:
|
|
DECODE_PRINTF2("%04x[SI]", displacement);
|
|
return (M.x86.R_SI + displacement) & 0xffff;
|
|
case 5:
|
|
DECODE_PRINTF2("%04x[DI]", displacement);
|
|
return (M.x86.R_DI + displacement) & 0xffff;
|
|
case 6:
|
|
DECODE_PRINTF2("%04x[BP]", displacement);
|
|
M.x86.mode |= SYSMODE_SEG_DS_SS;
|
|
return (M.x86.R_BP + displacement) & 0xffff;
|
|
case 7:
|
|
DECODE_PRINTF2("%04x[BX]", displacement);
|
|
return (M.x86.R_BX + displacement) & 0xffff;
|
|
}
|
|
HALT_SYS();
|
|
}
|
|
return 0;
|
|
/*NOTREACHED */
|
|
}
|