EdkCompatibilityPkg/Foundation/Library/EfiCommonLib/Ia32/DivU64x32.asm

;---------------------------------------------------------------------------
;/*++
;
;Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
;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:
;
;  DivU64x32.c
;
;Abstract:
;
;  64-bit division function for IA-32
;
;--*/

;---------------------------------------------------------------------------
    .386
    .model  flat,C
    .code

;---------------------------------------------------------------------------
;UINT64
;DivU64x32 (
;  IN UINT64   Dividend,
;  IN UINTN    Divisor,
;  OUT UINTN   *Remainder OPTIONAL
;  )
;/*++

;Routine Description:

;  This routine allows a 64 bit value to be divided with a 32 bit value returns 
;  64bit result and the Remainder.
;
;Arguments:

;  Dividend  - dividend
;  Divisor   - divisor
;  Remainder - buffer for remainder
;  
;Returns:

;  Dividend  / Divisor
;  Remainder = Dividend mod Divisor
;  
;N.B. only works for 31bit divisors!!
;
;--*/
;---------------------------------------------------------------------------

DivU64x32 PROC
    push ebp
    mov ebp, esp
    xor edx, edx                    ; Clear EDX

    mov eax, [ebp + 0Ch]              ; Put high 32 bits of 64-bit dividend in EAX
    mov ecx, [ebp + 10h]            ; Put 32 bits divisor in ECX
    div ecx                         ; Dividend   Divisor  Quoitent...Remainder
                                    ;  0:EAX  /  ECX   =  EAX      EDX   

    push eax                        ; Push quoitent in stack

    mov eax, [ebp + 8]              ; Put low 32 bits of 64-bit dividend in EAX              
    div ecx                         ; Leave the REMAINDER in EDX as High 32-bit of new dividend
                                    ; Dividend   Divisor  Quoitent...Remainder              
                                    ;  EDX:EAX  /  ECX   =  EAX      EDX               

    mov ecx, [ebp + 14h]             ; Put &REMAINDER to ecx

    jecxz Label1                    ; If ecx == 0, no remainder exist, return with quoitent in EDX directly 
    mov dword ptr [ecx], edx        ; Put EDX through REMAINDER pointer in ECX 

Label1:
    pop edx                         ; Pop High 32-bit QUOITENT to EDX
    pop ebp

    ret

DivU64x32 ENDP
    END