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50 lines
1.1 KiB
C
50 lines
1.1 KiB
C
/** @file
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64-bit right rotation for Ia32
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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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Rotates a 64-bit integer right between 0 and 63 bits, filling
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the high bits with the high low bits that were rotated.
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This function rotates the 64-bit value Operand to the right by Count bits.
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The high Count bits are fill with the low Count bits of Operand. The rotated
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value is returned.
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@param Operand The 64-bit operand to rotate right.
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@param Count The number of bits to rotate right.
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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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InternalMathRRotU64 (
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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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mov eax, dword ptr [Operand + 0]
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mov edx, dword ptr [Operand + 4]
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shrd ebx, eax, cl
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shrd eax, edx, cl
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rol ebx, cl
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shrd edx, ebx, cl
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test cl, 32 // Count >= 32?
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jz L0
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mov ecx, eax
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mov eax, edx
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mov edx, ecx
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L0:
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}
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}
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