arch/arm/lib/strnlen_user.S

   1 /*
   2  *  linux/arch/arm/lib/strnlen_user.S
   3  *
   4  *  Copyright (C) 1995-2000 Russell King
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/linkage.h>
  11 #include <asm/assembler.h>
  12 #include <asm/errno.h>
  13
  14         .text
  15         .align  5
  16
  17 /* Prototype: unsigned long __arch_strnlen_user(const char *str, long n)
  18  * Purpose  : get length of a string in user memory
  19  * Params   : str - address of string in user memory
  20  * Returns  : length of string *including terminator*
  21  *            or zero on exception, or n + 1 if too long
  22  */
  23 ENTRY(__arch_strnlen_user)
  24         save_lr
  25         mov     r2, r0
  26 1:
  27 USER(   ldrbt   r3, [r0], #1)
  28         teq     r3, #0
  29         beq     2f
  30         subs    r1, r1, #1
  31         bne     1b
  32         add     r0, r0, #1
  33 2:      sub     r0, r0, r2
  34         restore_pc
  35
  36         .section .fixup,"ax"
  37         .align  0
  38 9001:   mov     r0, #0
  39         restore_pc
  40         .previous