reactos/lib/rtl/i386/comparememory_asm.s

   1 /*
   2  * COPYRIGHT:       See COPYING in the top level directory
   3  * PROJECT:         ReactOS kernel
   4  * FILE:            comparememory_asm.S
   5  * PURPOSE:         Memory functions
   6  * PROGRAMMERS:     Patrick Baggett (baggett.patrick@gmail.com)
   7  *                  Alex Ionescu (alex@relsoft.net)
   8  *                  Magnus Olsen (magnusolsen@greatlord.com)
   9  */
  10
  11 .intel_syntax noprefix
  12
  13 /* GLOBALS ****************************************************************/
  14
  15 .globl  _RtlCompareMemory@12          // [4]  (no bug)
  16
  17 /* FUNCTIONS ***************************************************************/
  18
  19 _RtlCompareMemory@12:
  20      xor eax,eax       // count = 0
  21      mov ecx, dword [esp + 12 ]  // ecx = Length
  22          cmp ecx,0         // if (Length==0) goto .zero
  23          je 3f
  24
  25      push edi// register that does not to be save eax,ecx,edx to
  26      push ebx// the stack for protetion
  27
  28      mov edi, dword [esp + (4 + 8)]        // edi = Destination
  29      mov edx, dword [esp + (8 + 8)]        // edx = Source
  30
  31 1:
  32      mov bl,byte [edi + eax ]    //  if (src[count]!=des[count]) goto .pop_zero
  33      cmp byte [edx + eax ],bl
  34      jne 2f
  35
  36      inc eax //  count = count + 1
  37      dec ecx //  Length = Length - 1
  38      jnz 1b  //  if (Length!=0) goto .loop_1byte
  39
  40 2:
  41      pop ebx // restore regiester
  42      pop edi
  43 3:
  44      ret 12  // return count