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46 lines
1.0 KiB
C
46 lines
1.0 KiB
C
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/** @file
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64-bit left shift function for IA-32.
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Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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/**
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Shifts a 64-bit integer left between 0 and 63 bits. The low bits
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are filled with zeros. The shifted value is returned.
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This function shifts the 64-bit value Operand to the left by Count bits. The
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low Count bits are set to zero. The shifted value is returned.
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@param Operand The 64-bit operand to shift left.
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@param Count The number of bits to shift left.
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@return Operand << Count
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**/
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UINT64
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EFIAPI
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InternalMathLShiftU64 (
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IN UINT64 Operand,
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IN UINTN Count
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)
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{
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_asm {
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mov cl, byte ptr [Count]
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xor eax, eax
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mov edx, dword ptr [Operand + 0]
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test cl, 32 // Count >= 32?
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jnz L0
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mov eax, edx
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mov edx, dword ptr [Operand + 4]
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L0:
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shld edx, eax, cl
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shl eax, cl
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}
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}
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