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

   1 #/*++
   2 #
   3 #Copyright (c) 2006, Intel Corporation
   4 #All rights reserved. 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 #include "EfiBind.h"
  22 #---------------------------------------------------------------------------
  23     .686:
  24     #.MODEL flat,C
  25     .code:
  26
  27 #---------------------------------------------------------------------------
  28 .globl ASM_PFX(MultU64x32)
  29 #UINT64
  30 #MultU64x32 (
  31 #  IN UINT64   Multiplicand,
  32 #  IN UINTN    Multiplier
  33 #  )
  34 #/*++
  35 #
  36 #Routine Description:
  37 #
  38 #  This routine allows a 64 bit value to be multiplied with a 32 bit
  39 #  value returns 64bit result.
  40 #  No checking if the result is greater than 64bits
  41 #
  42 #Arguments:
  43 #
  44 #  Multiplicand  - multiplicand
  45 #  Multiplier    - multiplier
  46 #
  47 #Returns:
  48 #
  49 #  Multiplicand * Multiplier
  50 #
  51 #--*/
  52 ASM_PFX(MultU64x32):
  53
  54     movl   4(%esp), %eax # dword ptr Multiplicand[0]
  55     mull   0xC(%esp)             # Multiplier
  56     pushl  %eax
  57     pushl  %edx
  58     movl   0x10(%esp), %eax # dword ptr Multiplicand[4]
  59     mull   0x14(%esp)           # Multiplier
  60     #
  61     # The value in edx stored by second multiplication overflows
  62     # the output and should be discarded. So here we overwrite it
  63     # with the edx value of first multiplication.
  64     #
  65     popl   %edx
  66     addl   %eax, %edx
  67     popl   %eax
  68
  69     ret
  70 #MultU64x32 ENDP
  71