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

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