arch/mn10300/lib/bitops.c

   1 /* MN10300 Non-trivial bit operations
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11 #include <linux/module.h>
  12 #include <asm/bitops.h>
  13 #include <asm/system.h>
  14
  15 /*
  16  * try flipping a bit using BSET and BCLR
  17  */
  18 void change_bit(unsigned long nr, volatile void *addr)
  19 {
  20         if (test_bit(nr, addr))
  21                 goto try_clear_bit;
  22
  23 try_set_bit:
  24         if (!test_and_set_bit(nr, addr))
  25                 return;
  26
  27 try_clear_bit:
  28         if (test_and_clear_bit(nr, addr))
  29                 return;
  30
  31         goto try_set_bit;
  32 }
  33
  34 /*
  35  * try flipping a bit using BSET and BCLR and returning the old value
  36  */
  37 int test_and_change_bit(unsigned long nr, volatile void *addr)
  38 {
  39         if (test_bit(nr, addr))
  40                 goto try_clear_bit;
  41
  42 try_set_bit:
  43         if (!test_and_set_bit(nr, addr))
  44                 return 0;
  45
  46 try_clear_bit:
  47         if (test_and_clear_bit(nr, addr))
  48                 return 1;
  49
  50         goto try_set_bit;
  51 }