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557 lines
9.6 KiB
557 lines
9.6 KiB
/*++
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Copyright (c) 1994 Microsoft Corporation
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Module Name:
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utility.c
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Abstract:
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This module implements utility functions.
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Author:
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David N. Cutler (davec) 7-Sep-1994
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Environment:
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Kernel mode only.
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Revision History:
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--*/
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#include "nthal.h"
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#include "emulate.h"
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//
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// Define bit count array.
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//
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UCHAR XmBitCount[] = {0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4};
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ULONG
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XmComputeParity (
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IN ULONG Result
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)
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/*++
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Routine Description:
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This function computes the parity of the low byte of the specified
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result.
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Arguments:
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Result - Supplies the result for which the parity flag is computed.
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Return Value:
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The parity flag value.
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--*/
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{
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ULONG Count;
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//
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// Sum the bits in the result and return the complement of the low bit.
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//
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Count = XmBitCount[Result & 0xf];
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Count += XmBitCount[(Result >> 4) & 0xf];
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return (~Count) & 1;
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}
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UCHAR
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XmGetCodeByte (
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IN PRXM_CONTEXT P
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)
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/*++
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Routine Description:
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This function gets the next code byte from the instruction stream.
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Arguments:
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P - Supplies a pointer to an emulator context structure.
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Return Value:
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The next byte form the instruction stream.
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--*/
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{
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ULONG Offset;
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//
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// If the current IP is within the code segment, then return the
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// next byte from the instrcution stream and increment the IP value.
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// Otherwise, raise an exception.
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//
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Offset = P->Eip;
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if (Offset > P->SegmentLimit[CS]) {
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longjmp(&P->JumpBuffer[0], XM_SEGMENT_LIMIT_VIOLATION);
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}
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P->Ip += 1;
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return *(PUCHAR)((P->TranslateAddress)(P->SegmentRegister[CS], (USHORT)Offset));
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}
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UCHAR
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XmGetByteImmediate (
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IN PRXM_CONTEXT P
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)
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/*++
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Routine Description:
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This function gets an unsigned immediate byte operand from the
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code stream and returns a byte value.
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Arguments:
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P - Supplies a pointer to an emulator context structure.
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Return Value:
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The next byte from the instruction stream.
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--*/
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{
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UCHAR Byte;
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//
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// Get immediate byte from the code stream.
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//
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Byte = XmGetCodeByte(P);
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XmTraceInstruction(BYTE_DATA, (ULONG)Byte);
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return Byte;
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}
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USHORT
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XmGetByteImmediateToWord (
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IN PRXM_CONTEXT P
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)
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/*++
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Routine Description:
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This function gets an unsigned immediate byte operand from the
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code stream and returns a zero extended byte to word value.
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Arguments:
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P - Supplies a pointer to an emulator context structure.
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Return Value:
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The next byte from the instruction stream zero extended to a word.
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--*/
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{
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USHORT Word;
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//
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// Get immediate byte from the code stream.
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//
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Word = XmGetCodeByte(P);
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XmTraceInstruction(BYTE_DATA, (ULONG)((UCHAR)Word));
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return Word;
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}
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ULONG
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XmGetByteImmediateToLong (
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IN PRXM_CONTEXT P
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)
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/*++
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Routine Description:
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This function gets an unsigned immediate byte operand from the
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code stream and returns a zero extended byte to long value.
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Arguments:
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P - Supplies a pointer to an emulator context structure.
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Return Value:
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The next byte from the instruction stream zero extended to a long.
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--*/
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{
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ULONG Long;
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//
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// Get immediate byte from the code stream.
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//
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Long = XmGetCodeByte(P);
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XmTraceInstruction(BYTE_DATA, (ULONG)((UCHAR)Long));
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return Long;
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}
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USHORT
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XmGetSignedByteImmediateToWord (
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IN PRXM_CONTEXT P
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)
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/*++
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Routine Description:
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This function gets an unsigned immediate byte operand from the
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code stream and returns a sign extended byte to word value.
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Arguments:
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P - Supplies a pointer to an emulator context structure.
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Return Value:
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The next byte from the instruction stream sign extended to a word.
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--*/
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{
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USHORT Word;
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//
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// Get immediate byte from the code stream.
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//
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Word = (USHORT)((SHORT)((SCHAR)XmGetCodeByte(P)));
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XmTraceInstruction(BYTE_DATA, (ULONG)((UCHAR)Word));
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return Word;
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}
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ULONG
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XmGetSignedByteImmediateToLong (
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IN PRXM_CONTEXT P
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)
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/*++
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Routine Description:
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This function gets an unsigned immediate byte operand from the
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code stream and returns a sign extended byte to long value.
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Arguments:
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P - Supplies a pointer to an emulator context structure.
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Return Value:
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The next byte from the instruction stream sign extended to a long.
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--*/
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{
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ULONG Long;
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//
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// Get immediate byte from the code stream.
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//
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Long = (ULONG)((LONG)((SCHAR)XmGetCodeByte(P)));
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XmTraceInstruction(BYTE_DATA, (ULONG)((UCHAR)Long));
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return Long;
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}
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USHORT
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XmGetWordImmediate (
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IN PRXM_CONTEXT P
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)
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/*++
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Routine Description:
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This function gets an unsigned immediate word operand from the
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code stream and returns a word value.
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Arguments:
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P - Supplies a pointer to an emulator context structure.
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Return Value:
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The next word from the instruction stream.
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--*/
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{
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USHORT Word;
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//
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// Get immediate word from the code stream.
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//
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Word = XmGetCodeByte(P);
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Word += XmGetCodeByte(P) << 8;
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XmTraceInstruction(WORD_DATA, (ULONG)Word);
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return Word;
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}
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ULONG
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XmGetLongImmediate (
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IN PRXM_CONTEXT P
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)
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/*++
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Routine Description:
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This function gets an unsigned immediate long operand from the
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code stream and returns a long value.
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Arguments:
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P - Supplies a pointer to an emulator context structure.
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Return Value:
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The next long from the instruction stream.
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--*/
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{
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ULONG Long;
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//
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// Get immediate long from the code stream.
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//
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Long = XmGetCodeByte(P);
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Long += XmGetCodeByte(P) << 8;
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Long += XmGetCodeByte(P) << 16;
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Long += XmGetCodeByte(P) << 24;
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XmTraceInstruction(LONG_DATA, Long);
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return Long;
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}
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ULONG
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XmPopStack (
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IN PRXM_CONTEXT P
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)
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/*++
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Routine Description:
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This function pops an operand from the stack.
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Arguments:
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P - Supplies a pointer to the emulation context structure.
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Return Value:
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None.
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--*/
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{
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ULONG Offset;
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//
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// Compute the new stack address and compare against the segment limit.
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// If the new address is greater than the limit, then raise an exception.
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// Otherwise, perform the push operation.
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//
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Offset = P->Gpr[ESP].Exx;
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if (Offset > (ULONG)(P->SegmentLimit[SS] - P->DataType)) {
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longjmp(&P->JumpBuffer[0], XM_STACK_UNDERFLOW);
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}
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P->Gpr[ESP].Exx += (P->DataType + 1);
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XmSetSourceValue(P, (P->TranslateAddress)(P->SegmentRegister[SS], (USHORT)Offset));
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return P->SrcValue.Long;
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}
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VOID
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XmPushStack (
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IN PRXM_CONTEXT P,
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IN ULONG Value
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)
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/*++
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Routine Description:
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This function pushes an operand on the stack.
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Arguments:
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P - Supplies a pointer to the emulation context structure.
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Value - Supplies the value to be pushed.
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Return Value:
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None.
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--*/
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{
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ULONG Offset;
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//
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// Compute the new stack address and compare against the segment limit.
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// If the new address is greater than the limit, then raise an exception.
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// Otherwise, perform the push operation.
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//
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Offset = P->Gpr[ESP].Exx - P->DataType - 1;
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if (Offset > (ULONG)(P->SegmentLimit[SS] - P->DataType)) {
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longjmp(&P->JumpBuffer[0], XM_STACK_OVERFLOW);
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}
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P->Gpr[ESP].Exx = Offset;
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P->DstLong = (ULONG UNALIGNED *)((P->TranslateAddress)(P->SegmentRegister[SS],
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(USHORT)Offset));
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XmStoreResult(P, Value);
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return;
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}
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VOID
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XmSetDataType (
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IN PRXM_CONTEXT P
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)
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/*++
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Routine Description:
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This function sets the data type of the operation based on the width
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bit of the current opcode.
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Arguments:
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P - Supplies a pointer to an emulator context structure.
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Return Value:
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None.
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--*/
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{
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//
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// If the width bit is zero, then the data type is byte. Otherwise,
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// the datatype is determined by the presence of absence of a operand
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// size prefix.
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//
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if ((P->CurrentOpcode & WIDTH_BIT) == 0) {
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P->DataType = BYTE_DATA;
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} else if (P->OpsizePrefixActive != FALSE) {
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P->DataType = LONG_DATA;
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} else {
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P->DataType = WORD_DATA;
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}
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return;
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}
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VOID
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XmStoreResult (
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IN PRXM_CONTEXT P,
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IN ULONG Result
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)
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/*++
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Routine Description:
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This function stores the result of an operation.
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Arguments:
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P - Supplies a pointer to an emulator context structure.
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Result - Supplies the result value to store.
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Return Value:
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None.
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--*/
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{
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//
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// Store result of operation.
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//
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if (P->DataType == BYTE_DATA) {
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*P->DstByte = (UCHAR)Result;
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} else if (P->DataType == WORD_DATA) {
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if (((ULONG_PTR)P->DstWord & 0x1) == 0) {
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*((PUSHORT)(P->DstWord)) = (USHORT)Result;
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} else {
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*P->DstWord = (USHORT)Result;
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}
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} else {
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#ifdef _IA64_
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//
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// Hack to force the compiler to generate unaligned
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// accesses. We can remove it when the compiler is
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// fixed.
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//
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*P->DstLong = Result;
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#else
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if (((ULONG_PTR)P->DstLong & 0x3) == 0) {
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*((PULONG)(P->DstLong)) = Result;
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} else {
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*P->DstLong = Result;
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}
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#endif // #ifdef _IA64_
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}
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XmTraceResult(P, Result);
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return;
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}
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