arch/arm64/lib/memchr.S

   1 /*
   2  * Based on arch/arm/lib/memchr.S
   3  *
   4  * Copyright (C) 1995-2000 Russell King
   5  * Copyright (C) 2013 ARM Ltd.
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <linux/linkage.h>
  21 #include <asm/assembler.h>
  22
  23 /*
  24  * Find a character in an area of memory.
  25  *
  26  * Parameters:
  27  *      x0 - buf
  28  *      x1 - c
  29  *      x2 - n
  30  * Returns:
  31  *      x0 - address of first occurrence of 'c' or 0
  32  */
  33 ENTRY(memchr)
  34         and     w1, w1, #0xff
  35 1:      subs    x2, x2, #1
  36         b.mi    2f
  37         ldrb    w3, [x0], #1
  38         cmp     w3, w1
  39         b.ne    1b
  40         sub     x0, x0, #1
  41         ret
  42 2:      mov     x0, #0
  43         ret
  44 ENDPIPROC(memchr)