257 lines
3.5 KiB
C
257 lines
3.5 KiB
C
/*++
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Copyright (c) 1994 Microsoft Corporation
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Module Name:
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bitops.c
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Abstract:
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This module implements the code to emulate the bit opcodes.
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Author:
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David N. Cutler (davec) 12-Nov-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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VOID
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XmBsfOp (
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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 emulates an bsf opcode.
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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 Result;
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ULONG Source;
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//
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// If the source operand is zero, then set ZF and set the destination
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// to zero, Otherwise, find the first bit set scanning from right to
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// left.
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//
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Result = 0;
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Source = P->SrcValue.Long;
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P->Eflags.EFLAG_ZF = 1;
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while (Source != 0) {
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if ((Source & 1) != 0) {
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P->Eflags.EFLAG_ZF = 0;
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break;
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}
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Result += 1;
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Source >>= 1;
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};
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XmStoreResult(P, Result);
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return;
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}
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VOID
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XmBsrOp (
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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 emulates an bsr opcode.
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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 Result;
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ULONG Source;
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//
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// If the source operand is zero, then set ZF and set the destination
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// to zero, Otherwise, find the first bit set scanning from left to
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// right.
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//
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Result = ((P->DataType + 1) << 3) - 1;
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Source = P->SrcValue.Long;
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P->Eflags.EFLAG_ZF = 1;
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while (Source != 0) {
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if (((Source >> Result) & 1) != 0) {
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P->Eflags.EFLAG_ZF = 0;
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break;
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}
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Result -= 1;
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};
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XmStoreResult(P, Result);
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return;
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}
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VOID
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XmBtOp (
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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 emulates an bt opcode.
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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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//
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// Test the specified bit and store the bit in CF.
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//
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P->Eflags.EFLAG_CF = P->DstValue.Long >> P->SrcValue.Long;
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return;
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}
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VOID
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XmBtsOp (
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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 emulates an bts opcode.
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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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//
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// Test and set the specified bit and store the bit in CF.
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//
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//
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P->Eflags.EFLAG_CF = P->DstValue.Long >> P->SrcValue.Long;
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P->DstValue.Long |= (1 << P->SrcValue.Long);
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XmStoreResult(P, P->DstValue.Long);
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return;
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}
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VOID
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XmBtrOp (
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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 emulates an btr opcode.
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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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//
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// Test and reset the specified bit and store the bit in CF.
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//
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//
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P->Eflags.EFLAG_CF = P->DstValue.Long >> P->SrcValue.Long;
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P->DstValue.Long &= ~(1 << P->SrcValue.Long);
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XmStoreResult(P, P->DstValue.Long);
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return;
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}
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VOID
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XmBtcOp (
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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 emulates an btc opcode.
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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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//
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// Test and reset the specified bit and store the bit in CF.
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//
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//
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P->Eflags.EFLAG_CF = P->DstValue.Long >> P->SrcValue.Long;
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P->DstValue.Long ^= (1 << P->SrcValue.Long);
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XmStoreResult(P, P->DstValue.Long);
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return;
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}
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