TITLE   MultU64x32.asm: 64-bit Multiplication function for IA-32
      
;------------------------------------------------------------------------------
;
; Copyright (c) 2004, Intel Corporation                                                         
; All rights reserved. This program and the accompanying materials                          
; are licensed and made available under the terms and conditions of the BSD License         
; which accompanies this distribution.  The full text of the license may be found at        
; http://opensource.org/licenses/bsd-license.php                                            
;                                                                                           
; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     
; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.             
; 
; Module Name:
;
;   MultU64x32.asm
; 
; Abstract:
; 
;   64-bit Multiplication function for IA-32
;
;------------------------------------------------------------------------------

  .686P
  .XMM
  .MODEL SMALL, C
  .CODE

MultU64x32 PROTO C  Multiplicand: QWORD, Multiplier: DWORD

MultU64x32 PROC C   Multiplicand: QWORD, Multiplier: DWORD

;------------------------------------------------------------------------------
; UINT64
; MultU64x32 (
;   IN UINT64   Multiplicand,
;   IN UINTN    Multiplier
;   )
;
; Routine Description:
;
;   This routine allows a 64 bit value to be multiplied with a 32 bit 
;   value returns 64bit result.
;   No checking if the result is greater than 64bits
;
; Arguments:
;
;   Multiplicand  - multiplicand
;   Multiplier    - multiplier
;
; Returns:
;
;   Multiplicand * Multiplier
;------------------------------------------------------------------------------

  mov    eax, dword ptr Multiplicand[0]
  mul    Multiplier
  push   eax
  push   edx
  mov    eax, dword ptr Multiplicand[4]
  mul    Multiplier
  ;
  ; The value in edx stored by second multiplication overflows
  ; the output and should be discarded. So here we overwrite it
  ; with the edx value of first multiplication.
  ;
  pop    edx
  add    edx, eax
  pop    eax
  ret

MultU64x32 ENDP

END