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/** @file
64-bit left shift function for IA-32.
Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php.
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
/**
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?
cmovz eax, edx
cmovz edx, dword ptr [Operand + 4]
shld edx, eax, cl
shl eax, cl
}
}
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