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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
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