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303 lines
7.5 KiB
C
303 lines
7.5 KiB
C
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/*
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* COPYRIGHT: GPL - See COPYING in the top level directory
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* PROJECT: 386/486 CPU Emulation Library
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* FILE: common.c
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* PURPOSE: Common functions used internally by Soft386.
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* PROGRAMMERS: Aleksandar Andrejevic <theflash AT sdf DOT lonestar DOT org>
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*/
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/* INCLUDES *******************************************************************/
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#include "common.h"
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/* PUBLIC FUNCTIONS ***********************************************************/
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inline
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BOOLEAN
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Soft386ReadMemory(PSOFT386_STATE State,
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INT SegmentReg,
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ULONG Offset,
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BOOLEAN InstFetch,
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PVOID Buffer,
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ULONG Size)
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{
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ULONG LinearAddress;
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PSOFT386_SEG_REG CachedDescriptor;
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ASSERT(SegmentReg < SOFT386_NUM_SEG_REGS);
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/* Get the cached descriptor */
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CachedDescriptor = &State->SegmentRegs[SegmentReg];
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if ((Offset + Size) >= CachedDescriptor->Limit)
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{
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/* Read beyond limit */
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// TODO: Generate exception #GP
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return FALSE;
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}
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/* Check for protected mode */
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if (State->ControlRegisters[0] & SOFT386_CR0_PE)
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{
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/* Privilege checks */
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if (!CachedDescriptor->Present)
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{
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// TODO: Generate exception #NP
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return FALSE;
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}
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if (GET_SEGMENT_DPL(CachedDescriptor->Selector) > CachedDescriptor->Dpl)
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{
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// TODO: Generate exception #GP
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return FALSE;
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}
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if (InstFetch)
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{
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if (!CachedDescriptor->Executable)
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{
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/* Data segment not executable */
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// TODO: Generate exception #GP
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return FALSE;
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}
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}
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else
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{
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if (CachedDescriptor->Executable && (!CachedDescriptor->ReadWrite))
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{
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/* Code segment not readable */
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// TODO: Generate exception #GP
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return FALSE;
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}
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}
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}
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/* Find the linear address */
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LinearAddress = CachedDescriptor->Base + Offset;
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// TODO: Paging support!
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/* Did the host provide a memory hook? */
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if (State->MemReadCallback)
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{
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/* Yes, call the host */
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State->MemReadCallback(State, LinearAddress, Buffer, Size);
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}
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else
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{
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/* Read the memory directly */
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RtlMoveMemory(Buffer, (LPVOID)LinearAddress, Size);
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}
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return TRUE;
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}
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inline
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BOOLEAN
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Soft386WriteMemory(PSOFT386_STATE State,
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INT SegmentReg,
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ULONG Offset,
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PVOID Buffer,
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ULONG Size)
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{
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ULONG LinearAddress;
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PSOFT386_SEG_REG CachedDescriptor;
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ASSERT(SegmentReg < SOFT386_NUM_SEG_REGS);
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/* Get the cached descriptor */
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CachedDescriptor = &State->SegmentRegs[SegmentReg];
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if ((Offset + Size) >= CachedDescriptor->Limit)
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{
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/* Write beyond limit */
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// TODO: Generate exception #GP
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return FALSE;
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}
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/* Check for protected mode */
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if (State->ControlRegisters[0] & SOFT386_CR0_PE)
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{
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/* Privilege checks */
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if (!CachedDescriptor->Present)
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{
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// TODO: Generate exception #NP
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return FALSE;
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}
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if (GET_SEGMENT_DPL(CachedDescriptor->Selector) > CachedDescriptor->Dpl)
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{
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// TODO: Generate exception #GP
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return FALSE;
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}
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if (CachedDescriptor->Executable)
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{
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/* Code segment not writable */
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// TODO: Generate exception #GP
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return FALSE;
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}
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else if (!CachedDescriptor->ReadWrite)
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{
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/* Data segment not writeable */
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// TODO: Generate exception #GP
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return FALSE;
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}
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}
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/* Find the linear address */
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LinearAddress = CachedDescriptor->Base + Offset;
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// TODO: Paging support!
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/* Did the host provide a memory hook? */
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if (State->MemWriteCallback)
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{
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/* Yes, call the host */
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State->MemWriteCallback(State, LinearAddress, Buffer, Size);
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}
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else
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{
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/* Write the memory directly */
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RtlMoveMemory((LPVOID)LinearAddress, Buffer, Size);
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}
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return TRUE;
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}
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inline
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BOOLEAN
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Soft386StackPush(PSOFT386_STATE State, ULONG Value)
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{
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BOOLEAN Size = State->SegmentRegs[SOFT386_REG_SS].Size;
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// TODO: Handle OPSIZE prefix.
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if (Size)
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{
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/* 32-bit size */
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/* Check if ESP is between 1 and 3 */
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if (State->GeneralRegs[SOFT386_REG_ESP].Long >= 1
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&& State->GeneralRegs[SOFT386_REG_ESP].Long <= 3)
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{
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// TODO: Exception #SS
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return FALSE;
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}
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/* Subtract ESP by 4 */
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State->GeneralRegs[SOFT386_REG_ESP].Long -= 4;
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/* Store the value in SS:ESP */
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return Soft386WriteMemory(State,
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SOFT386_REG_SS,
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State->GeneralRegs[SOFT386_REG_ESP].Long,
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&Value,
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sizeof(ULONG));
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}
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else
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{
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/* 16-bit size */
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USHORT ShortValue = LOWORD(Value);
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/* Check if SP is 1 */
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if (State->GeneralRegs[SOFT386_REG_ESP].Long == 1)
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{
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// TODO: Exception #SS
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return FALSE;
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}
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/* Subtract SP by 2 */
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State->GeneralRegs[SOFT386_REG_ESP].LowWord -= 2;
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/* Store the value in SS:SP */
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return Soft386WriteMemory(State,
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SOFT386_REG_SS,
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State->GeneralRegs[SOFT386_REG_ESP].LowWord,
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&ShortValue,
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sizeof(USHORT));
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}
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}
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inline
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BOOLEAN
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Soft386StackPop(PSOFT386_STATE State, PULONG Value)
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{
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ULONG LongValue;
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USHORT ShortValue;
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BOOLEAN Size = State->SegmentRegs[SOFT386_REG_SS].Size;
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// TODO: Handle OPSIZE prefix.
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if (Size)
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{
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/* 32-bit size */
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/* Check if ESP is 0xFFFFFFFF */
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if (State->GeneralRegs[SOFT386_REG_ESP].Long == 0xFFFFFFFF)
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{
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// TODO: Exception #SS
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return FALSE;
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}
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/* Read the value from SS:ESP */
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if (!Soft386ReadMemory(State,
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SOFT386_REG_SS,
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State->GeneralRegs[SOFT386_REG_ESP].Long,
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FALSE,
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&LongValue,
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sizeof(LongValue)))
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{
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/* An exception occurred */
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return FALSE;
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}
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/* Increment ESP by 4 */
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State->GeneralRegs[SOFT386_REG_ESP].Long += 4;
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/* Store the value in the result */
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*Value = LongValue;
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}
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else
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{
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/* 16-bit size */
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/* Check if SP is 0xFFFF */
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if (State->GeneralRegs[SOFT386_REG_ESP].LowWord == 0xFFFF)
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{
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// TODO: Exception #SS
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return FALSE;
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}
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/* Read the value from SS:SP */
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if (!Soft386ReadMemory(State,
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SOFT386_REG_SS,
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State->GeneralRegs[SOFT386_REG_ESP].LowWord,
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FALSE,
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&ShortValue,
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sizeof(ShortValue)))
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{
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/* An exception occurred */
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return FALSE;
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}
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/* Increment SP by 2 */
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State->GeneralRegs[SOFT386_REG_ESP].Long += 2;
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/* Store the value in the result */
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*Value = ShortValue;
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}
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return TRUE;
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}
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/* EOF */
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