MdePkg/Library/BaseLib/Ia32/RRotU64.c

   1 /** @file
   2   64-bit right 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
  11
  12 /**
  13   Rotates a 64-bit integer right between 0 and 63 bits, filling
  14   the high bits with the high low bits that were rotated.
  15
  16   This function rotates the 64-bit value Operand to the right by Count bits.
  17   The high Count bits are fill with the low Count bits of Operand. The rotated
  18   value is returned.
  19
  20   @param  Operand The 64-bit operand to rotate right.
  21   @param  Count   The number of bits to rotate right.
  22
  23   @return Operand >>> Count
  24
  25 **/
  26 UINT64
  27 EFIAPI
  28 InternalMathRRotU64 (
  29   IN      UINT64                    Operand,
  30   IN      UINTN                     Count
  31   )
  32 {
  33   _asm {
  34     mov     cl, byte ptr [Count]
  35     mov     eax, dword ptr [Operand + 0]
  36     mov     edx, dword ptr [Operand + 4]
  37     shrd    ebx, eax, cl
  38     shrd    eax, edx, cl
  39     rol     ebx, cl
  40     shrd    edx, ebx, cl
  41     test    cl, 32                      // Count >= 32?
  42     jz      L0
  43     mov     ecx, eax
  44     mov     eax, edx
  45     mov     edx, ecx
  46 L0:
  47   }
  48 }
  49