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