CryptoPkg/Library/BaseCryptLib/SysCall/Ia32/MathLShiftS64.c

   1 /** @file
   2   64-bit Math Worker Function.
   3   The 32-bit versions of C compiler generate calls to library routines
   4   to handle 64-bit math. These functions use non-standard calling conventions.
   5
   6 Copyright (c) 2009 - 2010, Intel Corporation. All rights reserved.<BR>
   7 This program and the accompanying materials
   8 are licensed and made available under the terms and conditions of the BSD License
   9 which accompanies this distribution.  The full text of the license may be found at
  10 http://opensource.org/licenses/bsd-license.php
  11
  12 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  13 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  14
  15 **/
  16
  17
  18 /*
  19  * Shifts a 64-bit signed value left by a particular number of bits.
  20  */
  21 __declspec(naked) void __cdecl _allshl (void)
  22 {
  23   _asm {
  24     ;
  25     ; Handle shifting of 64 or more bits (return 0)
  26     ;
  27     cmp     cl, 64
  28     jae     short ReturnZero
  29
  30     ;
  31     ; Handle shifting of between 0 and 31 bits
  32     ;
  33     cmp     cl, 32
  34     jae     short More32
  35     shld    edx, eax, cl
  36     shl     eax, cl
  37     ret
  38
  39     ;
  40     ; Handle shifting of between 32 and 63 bits
  41     ;
  42 More32:
  43     mov     edx, eax
  44     xor     eax, eax
  45     and     cl, 31
  46     shl     edx, cl
  47     ret
  48
  49 ReturnZero:
  50     xor     eax,eax
  51     xor     edx,edx
  52     ret
  53   }
  54 }