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   SPDX-License-Identifier: BSD-2-Clause-Patent
   6
   7 **/
   8
   9 /**
  10   Rotates a 64-bit integer left between 0 and 63 bits, filling
  11   the low bits with the high bits that were rotated.
  12
  13   This function rotates the 64-bit value Operand to the left by Count bits. The
  14   low Count bits are fill with the high Count bits of Operand. The rotated
  15   value is returned.
  16
  17   @param  Operand The 64-bit operand to rotate left.
  18   @param  Count   The number of bits to rotate left.
  19
  20   @return Operand <<< Count
  21
  22 **/
  23 UINT64
  24 EFIAPI
  25 InternalMathLRotU64 (
  26   IN      UINT64  Operand,
  27   IN      UINTN   Count
  28   )
  29 {
  30   _asm {
  31     mov     cl, byte ptr [Count]
  32     mov     edx, dword ptr [Operand + 4]
  33     mov     eax, dword ptr [Operand + 0]
  34     shld    ebx, edx, cl
  35     shld    edx, eax, cl
  36     ror     ebx, cl
  37     shld    eax, ebx, cl
  38     test    cl, 32                      ; Count >= 32?
  39     jz      L0
  40     mov     ecx, eax
  41     mov     eax, edx
  42     mov     edx, ecx
  43     L0 :
  44   }
  45 }