MdePkg/Library/BaseLib/Ia32/DivU64x32.c

   1 /** @file
   2   Calculate the quotient of a 64-bit integer by a 32-bit integer
   3
   4   Copyright (c) 2006 - 2007, Intel Corporation<BR>
   5   All rights reserved. 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 // Include common header file for this module.
  17 //
  18
  19
  20 /**
  21   Divides a 64-bit unsigned integer by a 32-bit unsigned integer and
  22   generates a 64-bit unsigned result.
  23
  24   This function divides the 64-bit unsigned value Dividend by the 32-bit
  25   unsigned value Divisor and generates a 64-bit unsigned quotient. This
  26   function returns the 64-bit unsigned quotient.
  27
  28    @param  Dividend  A 64-bit unsigned value.
  29   @param  Divisor   A 32-bit unsigned value.
  30
  31   @return Dividend / Divisor
  32
  33 **/
  34 UINT64
  35 EFIAPI
  36 InternalMathDivU64x32 (
  37   IN      UINT64                    Dividend,
  38   IN      UINT32                    Divisor
  39   )
  40 {
  41   _asm {
  42     mov     eax, dword ptr [Dividend + 4]
  43     mov     ecx, Divisor
  44     xor     edx, edx
  45     div     ecx
  46     push    eax                     ; save quotient on stack
  47     mov     eax, dword ptr [Dividend]
  48     div     ecx
  49     pop     edx                     ; restore high-order dword of the quotient
  50   }
  51 }
  52