EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/MultU64x32.asm

   1 ;/*++
   2 ;
   3 ;Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
   4 ;This program and the accompanying materials
   5 ;are licensed and made available under the terms and conditions of the BSD License
   6 ;which accompanies this distribution.  The full text of the license may be found at
   7 ;http://opensource.org/licenses/bsd-license.php
   8 ;
   9 ;THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  10 ;WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  11 ;
  12 ;Module Name:
  13 ;
  14 ;   MultU64x32.c
  15 ;
  16 ;Abstract:
  17 ;
  18 ;  64-bit Multiplication function for IA-32
  19 ;
  20 ;--*/
  21 ;---------------------------------------------------------------------------
  22     .686
  23     .model  flat,C
  24     .code
  25
  26 ;---------------------------------------------------------------------------
  27
  28 ;UINT64
  29 ;MultU64x32 (
  30 ;  IN UINT64   Multiplicand,
  31 ;  IN UINTN    Multiplier
  32 ;  )
  33 ;/*++
  34 ;
  35 ;Routine Description:
  36 ;
  37 ;  This routine allows a 64 bit value to be multiplied with a 32 bit
  38 ;  value returns 64bit result.
  39 ;  No checking if the result is greater than 64bits
  40 ;
  41 ;Arguments:
  42 ;
  43 ;  Multiplicand  - multiplicand
  44 ;  Multiplier    - multiplier
  45 ;
  46 ;Returns:
  47 ;
  48 ;  Multiplicand * Multiplier
  49 ;
  50 ;--*/
  51 MultU64x32 PROC
  52
  53     mov    eax, [esp + 4]; dword ptr Multiplicand[0]
  54     mul    dword ptr [esp + 0Ch] ; Multiplier
  55     push   eax
  56     push   edx
  57     mov    eax, [esp + 10h]; dword ptr Multiplicand[4]
  58     mul    dword ptr [esp + 14h]; Multiplier
  59     ;
  60     ; The value in edx stored by second multiplication overflows
  61     ; the output and should be discarded. So here we overwrite it
  62     ; with the edx value of first multiplication.
  63     ;
  64     pop    edx
  65     add    edx, eax
  66     pop    eax
  67
  68     ret
  69 MultU64x32 ENDP
  70         END