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 - 2010, Intel Corporation. All rights reserved.<BR>
   5   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
  17
  18 /**
  19   Divides a 64-bit unsigned integer by a 32-bit unsigned integer and
  20   generates a 64-bit unsigned result.
  21
  22   This function divides the 64-bit unsigned value Dividend by the 32-bit
  23   unsigned value Divisor and generates a 64-bit unsigned quotient. This
  24   function returns the 64-bit unsigned quotient.
  25
  26   @param  Dividend  A 64-bit unsigned value.
  27   @param  Divisor   A 32-bit unsigned value.
  28
  29   @return Dividend / Divisor
  30
  31 **/
  32 UINT64
  33 EFIAPI
  34 InternalMathDivU64x32 (
  35   IN      UINT64                    Dividend,
  36   IN      UINT32                    Divisor
  37   )
  38 {
  39   _asm {
  40     mov     eax, dword ptr [Dividend + 4]
  41     mov     ecx, Divisor
  42     xor     edx, edx
  43     div     ecx
  44     push    eax                     ; save quotient on stack
  45     mov     eax, dword ptr [Dividend]
  46     div     ecx
  47     pop     edx                     ; restore high-order dword of the quotient
  48   }
  49 }
  50