MdePkg/Library/BaseLib/Ia32/LRotU64.c

   1 /** @file
   2   64-bit left rotation for Ia32
   3
   4   Copyright (c) 2006 - 2007, Intel Corporation<BR>
   5   All rights reserved. This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13 **/
  14
  15 //
  16 // Include common header file for this module.
  17 //
  18
  19
  20 /**
  21   Rotates a 64-bit integer left between 0 and 63 bits, filling
  22   the low bits with the high bits that were rotated.
  23
  24   This function rotates the 64-bit value Operand to the left by Count bits. The
  25   low Count bits are fill with the high Count bits of Operand. The rotated
  26   value is returned.
  27
  28   @param  Operand The 64-bit operand to rotate left.
  29   @param  Count   The number of bits to rotate left.
  30
  31   @return Operand <<< Count
  32
  33 **/
  34 UINT64
  35 EFIAPI
  36 InternalMathLRotU64 (
  37   IN      UINT64                    Operand,
  38   IN      UINTN                     Count
  39   )
  40 {
  41   _asm {
  42     mov     cl, byte ptr [Count]
  43     mov     edx, dword ptr [Operand + 4]
  44     mov     eax, dword ptr [Operand + 0]
  45     shld    ebx, edx, cl
  46     shld    edx, eax, cl
  47     ror     ebx, cl
  48     shld    eax, ebx, cl
  49     test    cl, 32                      ; Count >= 32?
  50     cmovnz  ecx, eax
  51     cmovnz  eax, edx
  52     cmovnz  edx, ecx
  53   }
  54 }
  55