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  1. /*
  2.  * Copyright (c) 2007 Michal Kebrt
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup libcarm32  
  30.  * @{
  31.  */
  32. /** @file
  33.  */
  34.  
  35. #ifndef LIBC_arm32_ATOMIC_H_
  36. #define LIBC_arm32_ATOMIC_H_
  37.  
  38. /** Atomic addition.
  39.  *
  40.  * @param val "Atomic variable".
  41.  * @param i Value to add.
  42.  *
  43.  * @return Value after addition.
  44.  */
  45. static inline long atomic_add(atomic_t *val, int i)
  46. {
  47.     int ret;
  48.     volatile long * mem = &(val->count);
  49.  
  50.     asm volatile (
  51.         "1:                 \n"
  52.         "ldr r2, [%1]       \n"
  53.         "add r3, r2, %2     \n"
  54.         "str r3, %0         \n"
  55.         "swp r3, r3, [%1]   \n"
  56.         "cmp r3, r2         \n"
  57.         "bne 1b             \n"
  58.  
  59.         : "=m" (ret)
  60.         : "r" (mem), "r" (i)
  61.         : "r3", "r2"
  62.     );
  63.  
  64.     return ret;
  65. }
  66.  
  67. static inline void atomic_inc(atomic_t *val) { atomic_add(val, 1); }
  68. static inline void atomic_dec(atomic_t *val) { atomic_add(val, -1); }
  69.  
  70. static inline long atomic_preinc(atomic_t *val) { return atomic_add(val, 1); }
  71. static inline long atomic_predec(atomic_t *val) { return atomic_add(val, -1); }
  72.  
  73. static inline long atomic_postinc(atomic_t *val) { return atomic_add(val, 1) - 1; }
  74. static inline long atomic_postdec(atomic_t *val) { return atomic_add(val, -1) + 1; }
  75.  
  76. #endif
  77.  
  78. /** @}
  79.  */
  80.