lib/rtl/amd64/rtlmem.S

   1 /*
   2  * COPYRIGHT:         See COPYING in the top level directory
   3  * PROJECT:           ReactOS Run-Time Library
   4  * PURPOSE:           Memory functions for amd64
   5  * FILE:              lib/rtl/i386/rtlswap.S
   6  * PROGRAMER:         Timo Kreuzer (timo.kreuzer@reactos.org)
   7  */
   8
   9 /* INCLUDES ******************************************************************/
  10
  11 #include <reactos/asm.h>
  12 #include <ndk/amd64/asm.h>
  13
  14 /* FUNCTIONS *****************************************************************/
  15
  16 .code64
  17
  18 /* SIZE_T
  19  * RtlCompareMemory(
  20  *   IN CONST VOID *Source1, <rcx>
  21  *   IN CONST VOID *Source2, <rdx>
  22  *   IN SIZE_T  Length <r8>
  23  * );
  24  */
  25 .proc RtlCompareMemory
  26
  27     /* Save registers */
  28     push rsi
  29     .pushreg rsi
  30     push rdi
  31     .pushreg rdi
  32     .ENDPROLOG
  33
  34     /* Setup registers for compare */
  35     mov rsi, rcx
  36     mov rdi, rdx
  37
  38     /* Clear direction flag */
  39     cli
  40
  41     /* Get number of qwords */
  42     mov rcx, r8
  43     shr rcx, 3
  44     jz RtlCompareMemory2
  45
  46     /* Compare qwords */
  47     repe cmpsq
  48     jnz RtlCompareMemory4
  49
  50 RtlCompareMemory2:
  51     /* Compare rest */
  52     mov rcx, r8
  53     and rcx, 7
  54     jz RtlCompareMemory3
  55
  56     repe cmpsb
  57     jnz RtlCompareMemory5
  58
  59 RtlCompareMemory3:
  60     /* All equal */
  61     /* Return the full count */
  62     mov rax, rcx
  63     jmp RtlCompareMemory6
  64
  65 RtlCompareMemory4:
  66     /* Not equal after comparing qwords */
  67     /* Compare the last qword */
  68     sub rsi, 8
  69     sub rdi, 8
  70     mov rcx, 8
  71     repe cmpsb
  72
  73 RtlCompareMemory5:
  74     /* Not equal after comparing bytes */
  75     /* Return difference */
  76     sub rdi, rdx
  77     dec rdi
  78     mov rax, rdi
  79
  80 RtlCompareMemory6:
  81    /* Cleanup and return */
  82     pop rdi
  83     pop rsi
  84     ret
  85 .endp RtlCompareMemory
  86
  87 END
  88