MdePkg/Library/BaseLib/Ia32/LRotU64.c

   1 /** @file
   2   64-bit left rotation for Ia32
   3
   4   Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
   5   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
  17
  18 /**
  19   Rotates a 64-bit integer left between 0 and 63 bits, filling
  20   the low bits with the high bits that were rotated.
  21
  22   This function rotates the 64-bit value Operand to the left by Count bits. The
  23   low Count bits are fill with the high Count bits of Operand. The rotated
  24   value is returned.
  25
  26   @param  Operand The 64-bit operand to rotate left.
  27   @param  Count   The number of bits to rotate left.
  28
  29   @return Operand <<< Count
  30
  31 **/
  32 UINT64
  33 EFIAPI
  34 InternalMathLRotU64 (
  35   IN      UINT64                    Operand,
  36   IN      UINTN                     Count
  37   )
  38 {
  39   _asm {
  40     mov     cl, byte ptr [Count]
  41     mov     edx, dword ptr [Operand + 4]
  42     mov     eax, dword ptr [Operand + 0]
  43     shld    ebx, edx, cl
  44     shld    edx, eax, cl
  45     ror     ebx, cl
  46     shld    eax, ebx, cl
  47     test    cl, 32                      ; Count >= 32?
  48     jz      L0
  49     mov     ecx, eax
  50     mov     eax, edx
  51     mov     edx, ecx
  52 L0:
  53   }
  54 }
  55