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      1 ;---------------------------------------------------------------------------
      2 ;/*++
      3 ;
      4 ;Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
      5 ;This program and the accompanying materials                          
      6 ;are licensed and made available under the terms and conditions of the BSD License         
      7 ;which accompanies this distribution.  The full text of the license may be found at        
      8 ;http://opensource.org/licenses/bsd-license.php                                            
      9 ;                                                                                          
     10 ;THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,                     
     11 ;WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.             
     12 ;
     13 ;Module Name:
     14 ;
     15 ;  DivU64x32.c
     16 ;
     17 ;Abstract:
     18 ;
     19 ;  64-bit division function for IA-32
     20 ;
     21 ;--*/
     22 
     23 ;---------------------------------------------------------------------------
     24     .386
     25     .model  flat,C
     26     .code
     27 
     28 ;---------------------------------------------------------------------------
     29 ;UINT64
     30 ;DivU64x32 (
     31 ;  IN UINT64   Dividend,
     32 ;  IN UINTN    Divisor,
     33 ;  OUT UINTN   *Remainder OPTIONAL
     34 ;  )
     35 ;/*++
     36 
     37 ;Routine Description:
     38 
     39 ;  This routine allows a 64 bit value to be divided with a 32 bit value returns 
     40 ;  64bit result and the Remainder.
     41 ;
     42 ;Arguments:
     43 
     44 ;  Dividend  - dividend
     45 ;  Divisor   - divisor
     46 ;  Remainder - buffer for remainder
     47 ;  
     48 ;Returns:
     49 
     50 ;  Dividend  / Divisor
     51 ;  Remainder = Dividend mod Divisor
     52 ;  
     53 ;N.B. only works for 31bit divisors!!
     54 ;
     55 ;--*/
     56 ;---------------------------------------------------------------------------
     57 
     58 DivU64x32 PROC
     59     push ebp
     60     mov ebp, esp
     61     xor edx, edx                    ; Clear EDX
     62 
     63     mov eax, [ebp + 0Ch]              ; Put high 32 bits of 64-bit dividend in EAX
     64     mov ecx, [ebp + 10h]            ; Put 32 bits divisor in ECX
     65     div ecx                         ; Dividend   Divisor  Quoitent...Remainder
     66                                     ;  0:EAX  /  ECX   =  EAX      EDX   
     67 
     68     push eax                        ; Push quoitent in stack
     69 
     70     mov eax, [ebp + 8]              ; Put low 32 bits of 64-bit dividend in EAX              
     71     div ecx                         ; Leave the REMAINDER in EDX as High 32-bit of new dividend
     72                                     ; Dividend   Divisor  Quoitent...Remainder              
     73                                     ;  EDX:EAX  /  ECX   =  EAX      EDX               
     74 
     75     mov ecx, [ebp + 14h]             ; Put &REMAINDER to ecx
     76 
     77     jecxz Label1                    ; If ecx == 0, no remainder exist, return with quoitent in EDX directly 
     78     mov dword ptr [ecx], edx        ; Put EDX through REMAINDER pointer in ECX 
     79 
     80 Label1:
     81     pop edx                         ; Pop High 32-bit QUOITENT to EDX
     82     pop ebp
     83 
     84     ret
     85 
     86 DivU64x32 ENDP
     87     END
     88