arch/sh/lib/memset.S

   1 /* $Id: memset.S,v 1.1 2000/04/14 16:49:01 mjd Exp $
   2  *
   3  * "memset" implementation of SuperH
   4  *
   5  * Copyright (C) 1999  Niibe Yutaka
   6  *
   7  */
   8
   9 /*
  10  *            void *memset(void *s, int c, size_t n);
  11  */
  12
  13 #include <linux/linkage.h>
  14
  15 ENTRY(memset)
  16         tst     r6,r6
  17         bt/s    5f              ! if n=0, do nothing
  18          add    r6,r4
  19         mov     #12,r0
  20         cmp/gt  r6,r0
  21         bt/s    4f              ! if it's too small, set a byte at once
  22          mov    r4,r0
  23         and     #3,r0
  24         cmp/eq  #0,r0
  25         bt/s    2f              ! It's aligned
  26          sub    r0,r6
  27 1:
  28         dt      r0
  29         bf/s    1b
  30          mov.b  r5,@-r4
  31 2:                              ! make VVVV
  32         extu.b  r5,r5
  33         swap.b  r5,r0           !   V0
  34         or      r0,r5           !   VV
  35         swap.w  r5,r0           ! VV00
  36         or      r0,r5           ! VVVV
  37         !
  38         mov     r6,r0
  39         shlr2   r0
  40         shlr    r0              ! r0 = r6 >> 3
  41 3:
  42         dt      r0
  43         mov.l   r5,@-r4         ! set 8-byte at once
  44         bf/s    3b
  45          mov.l  r5,@-r4
  46         !
  47         mov     #7,r0
  48         and     r0,r6
  49         tst     r6,r6
  50         bt      5f
  51         ! fill bytes
  52 4:
  53         dt      r6
  54         bf/s    4b
  55          mov.b  r5,@-r4
  56 5:
  57         rts
  58          mov    r4,r0