MdePkg/Library/BaseLib/Ia32/DivU64x64Remainder.c

   1 /** @file
   2   Calculate the quotient of a 64-bit integer by a 64-bit integer and returns
   3   both the quotient and the remainderSet error flag for all division functions
   4
   5   Copyright (c) 2006, Intel Corporation<BR>
   6   All rights reserved. This program and the accompanying materials
   7   are licensed and made available under the terms and conditions of the BSD License
   8   which accompanies this distribution.  The full text of the license may be found at
   9   http://opensource.org/licenses/bsd-license.php
  10
  11   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  12   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13
  14 **/
  15
  16 #if _MSC_EXTENSIONS
  17
  18 UINT64
  19 EFIAPI
  20 InternalMathDivRemU64x64 (
  21   IN      UINT64                    Dividend,
  22   IN      UINT64                    Divisor,
  23   OUT     UINT64                    *Remainder    OPTIONAL
  24   )
  25 {
  26   _asm {
  27     mov     edx, dword ptr [Dividend + 4]
  28     mov     eax, dword ptr [Dividend + 0]   // edx:eax <- dividend
  29     mov     edi, edx
  30     mov     esi, eax                    // edi:esi <- dividend
  31     mov     ebx, dword ptr [Divisor + 0]   // ecx:ebx <- divisor
  32 BitLoop:
  33     shr     edx, 1
  34     rcr     eax, 1
  35     shrd    ebx, ecx, 1
  36     shr     ecx, 1
  37     jnz     BitLoop
  38     div     ebx
  39     mov     ebx, eax                    // ebx <- quotient
  40     mov     ecx, dword ptr [Divisor + 4]
  41     mul     dword ptr [Divisor]
  42     imul    ecx, ebx
  43     add     edx, ecx
  44     mov     ecx, Remainder
  45     jc      TooLarge                   // product > 2^64
  46     cmp     edi, edx                    // compare high 32 bits
  47     ja      Correct
  48     jb      TooLarge                   // product > dividend
  49     cmp     esi, eax
  50     jae     Correct                    // product <= dividend
  51 TooLarge:
  52     dec     ebx                         // adjust quotient by -1
  53     jecxz   Return                     // return if Remainder == NULL
  54     sub     eax, dword ptr [Divisor + 0]
  55     sbb     edx, dword ptr [Divisor + 4]
  56 Correct:
  57     jecxz   Return
  58     sub     esi, eax
  59     sbb     edi, edx                    // edi:esi <- remainder
  60     mov     [ecx], esi
  61     mov     [ecx + 4], edi
  62 Return:
  63     mov     eax, ebx                    // eax <- quotient
  64     xor     edx, edx
  65   }
  66 }
  67
  68 #endif