259 lines
7.6 KiB
C
259 lines
7.6 KiB
C
/*
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* Emulation of priviledged instructions
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*
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* Copyright 1995 Alexandre Julliard
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*/
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#include <stdio.h>
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#include "windows.h"
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#include "ldt.h"
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#include "miscemu.h"
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#include "registers.h"
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/***********************************************************************
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* INSTR_EmulateInstruction
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*
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* Emulate a priviledged instruction. Returns TRUE if emulation successful.
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*/
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BOOL INSTR_EmulateInstruction( struct sigcontext_struct *context )
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{
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int prefix, segprefix, repX, long_op, long_addr;
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BYTE *instr;
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long_op = long_addr = (GET_SEL_FLAGS(CS_reg(context)) & LDT_FLAGS_32BIT) != 0;
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instr = (BYTE *) PTR_SEG_OFF_TO_LIN( CS_reg(context), EIP_reg(context) );
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/* First handle any possible prefix */
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segprefix = -1; /* no prefix */
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prefix = 1;
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repX = 0;
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while(prefix)
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{
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switch(*instr)
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{
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case 0x2e:
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segprefix = CS_reg(context);
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break;
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case 0x36:
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segprefix = SS_reg(context);
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break;
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case 0x3e:
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segprefix = DS_reg(context);
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break;
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case 0x26:
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segprefix = ES_reg(context);
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break;
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case 0x64:
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segprefix = FS_reg(context);
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break;
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case 0x65:
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segprefix = GS_reg(context);
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break;
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case 0x66:
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long_op = !long_op; /* opcode size prefix */
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break;
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case 0x67:
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long_addr = !long_addr; /* addr size prefix */
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break;
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case 0xf0: /* lock */
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break;
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case 0xf2: /* repne */
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repX = 1;
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break;
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case 0xf3: /* repe */
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repX = 2;
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break;
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default:
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prefix = 0; /* no more prefixes */
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break;
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}
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if (prefix)
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{
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instr++;
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EIP_reg(context)++;
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}
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}
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/* Now look at the actual instruction */
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switch(*instr)
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{
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case 0xcd: /* int <XX> */
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if (long_op)
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{
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fprintf(stderr, "int xx from 32-bit code is not supported.\n");
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return FALSE; /* Unable to emulate it */
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}
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else
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{
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SEGPTR addr = INT_GetHandler( instr[1] );
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/* FIXME: should check the stack 'big' bit */
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WORD *stack = (WORD *)PTR_SEG_OFF_TO_LIN( SS_reg(context),
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SP_reg(context) );
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/* Push the flags and return address on the stack */
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*(--stack) = FL_reg(context);
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*(--stack) = CS_reg(context);
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*(--stack) = IP_reg(context) + 2;
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SP_reg(context) -= 3 * sizeof(WORD);
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/* Jump to the interrupt handler */
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CS_reg(context) = HIWORD(addr);
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EIP_reg(context) = LOWORD(addr);
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}
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break;
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case 0xcf: /* iret */
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if (long_op)
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{
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/* FIXME: should check the stack 'big' bit */
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DWORD *stack = (DWORD *)PTR_SEG_OFF_TO_LIN( SS_reg(context),
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SP_reg(context) );
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EIP_reg(context) = *stack++;
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CS_reg(context) = *stack++;
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EFL_reg(context) = *stack;
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SP_reg(context) += 3*sizeof(DWORD); /* Pop the return address and flags */
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}
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else
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{
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/* FIXME: should check the stack 'big' bit */
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WORD *stack = (WORD *)PTR_SEG_OFF_TO_LIN( SS_reg(context),
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SP_reg(context) );
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EIP_reg(context) = *stack++;
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CS_reg(context) = *stack++;
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FL_reg(context) = *stack;
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SP_reg(context) += 3*sizeof(WORD); /* Pop the return address and flags */
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}
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break;
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case 0xe4: /* inb al,XX */
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AL_reg(context) = inport( instr[1], 1 );
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EIP_reg(context) += 2;
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break;
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case 0xe5: /* in (e)ax,XX */
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if (long_op) EAX_reg(context) = inport( instr[1], 4 );
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else AX_reg(context) = inport( instr[1], 2 );
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EIP_reg(context) += 2;
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break;
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case 0xe6: /* outb XX,al */
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outport( instr[1], 1, AL_reg(context) );
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EIP_reg(context) += 2;
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break;
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case 0xe7: /* out XX,(e)ax */
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if (long_op) outport( instr[1], 4, EAX_reg(context) );
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else outport( instr[1], 2, AX_reg(context) );
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EIP_reg(context) += 2;
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break;
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case 0xec: /* inb al,dx */
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AL_reg(context) = inport( DX_reg(context), 1 );
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EIP_reg(context)++;
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break;
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case 0xed: /* in (e)ax,dx */
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if (long_op) EAX_reg(context) = inport( DX_reg(context), 4 );
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else AX_reg(context) = inport( DX_reg(context), 2 );
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EIP_reg(context)++;
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break;
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case 0xee: /* outb dx,al */
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outport( DX_reg(context), 1, AL_reg(context) );
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EIP_reg(context)++;
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break;
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case 0xef: /* out dx,(e)ax */
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if (long_op) outport( DX_reg(context), 4, EAX_reg(context) );
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else outport( DX_reg(context), 2, AX_reg(context) );
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EIP_reg(context)++;
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break;
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case 0xfa: /* cli, ignored */
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EIP_reg(context)++;
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break;
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case 0xfb: /* sti, ignored */
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EIP_reg(context)++;
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break;
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case 0x6c: /* insb */
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case 0x6d: /* insw/d */
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case 0x6e: /* outsb */
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case 0x6f: /* outsw/d */
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{
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int typ = *instr; /* Just in case it's overwritten. */
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int outp = (typ >= 0x6e);
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unsigned long count = repX ?
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(long_addr ? ECX_reg(context) : CX_reg(context)) : 1;
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int opsize = (typ & 1) ? (long_op ? 4 : 2) : 1;
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int step = (EFL_reg(context) & 0x400) ? -opsize : +opsize;
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int seg = outp ? (segprefix >= 0 ? segprefix : DS_reg(context))
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: ES_reg(context);
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if (outp)
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/* FIXME: Check segment readable. */
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;
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else
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/* FIXME: Check segment writeable. */
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;
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if (repX)
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if (long_addr)
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ECX_reg(context) = 0;
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else
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CX_reg(context) = 0;
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while (count-- > 0)
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{
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void *data;
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if (outp)
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{
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data = PTR_SEG_OFF_TO_LIN (seg,
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long_addr ? ESI_reg(context) : SI_reg(context));
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if (long_addr) ESI_reg(context) += step;
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else SI_reg(context) += step;
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}
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else
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{
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data = PTR_SEG_OFF_TO_LIN (seg,
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long_addr ? EDI_reg(context) : DI_reg(context));
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if (long_addr) EDI_reg(context) += step;
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else DI_reg(context) += step;
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}
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switch (typ)
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{
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case 0x6c:
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*((BYTE *)data) = inport( DX_reg(context), 1);
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break;
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case 0x6d:
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if (long_op)
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*((DWORD *)data) = inport( DX_reg(context), 4);
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else
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*((WORD *)data) = inport( DX_reg(context), 2);
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break;
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case 0x6e:
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outport( DX_reg(context), 1, *((BYTE *)data));
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break;
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case 0x6f:
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if (long_op)
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outport( DX_reg(context), 4, *((DWORD *)data));
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else
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outport( DX_reg(context), 2, *((WORD *)data));
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break;
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}
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}
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EIP_reg(context)++;
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break;
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}
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default:
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fprintf(stderr, "Unexpected Windows program segfault"
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" - opcode = %x\n", *instr);
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return FALSE; /* Unable to emulate it */
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}
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return TRUE;
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}
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