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

   1 ;---------------------------------------------------------------------------
   2 ;/*++
   3 ;
   4 ;Copyright (c) 2006, Intel Corporation
   5 ;All rights reserved. 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