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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.  *  @brief Atomic operations.
  34.  */
  35.  
  36. #ifndef LIBC_arm32_ATOMIC_H_
  37. #define LIBC_arm32_ATOMIC_H_
  38.  
  39. /** Atomic addition.
  40.  *
  41.  * @param val Where to add.
  42.  * @param i   Value to be added.
  43.  *
  44.  * @return Value after addition.
  45.  */
  46. static inline long atomic_add(atomic_t *val, int i)
  47. {
  48.     int ret;
  49.     volatile long * mem = &(val->count);
  50.  
  51.     asm volatile (
  52.     "1:\n"
  53.         "ldr r2, [%1]\n"
  54.         "add r3, r2, %2\n"
  55.         "str r3, %0\n"
  56.         "swp r3, r3, [%1]\n"
  57.         "cmp r3, r2\n"
  58.         "bne 1b\n"
  59.  
  60.         : "=m" (ret)
  61.         : "r" (mem), "r" (i)
  62.         : "r3", "r2"
  63.     );
  64.  
  65.     return ret;
  66. }
  67.  
  68.  
  69. /** Atomic increment.
  70.  *
  71.  * @param val Variable to be incremented.
  72.  */
  73. static inline void atomic_inc(atomic_t *val)
  74. {
  75.     atomic_add(val, 1);
  76. }
  77.  
  78.  
  79. /** Atomic decrement.
  80.  *
  81.  * @param val Variable to be decremented.
  82.  */
  83. static inline void atomic_dec(atomic_t *val)
  84. {
  85.     atomic_add(val, -1);
  86. }
  87.  
  88.  
  89. /** Atomic pre-increment.
  90.  *
  91.  * @param val Variable to be incremented.
  92.  * @return    Value after incrementation.
  93.  */
  94. static inline long atomic_preinc(atomic_t *val)
  95. {
  96.     return atomic_add(val, 1);
  97. }
  98.  
  99.  
  100. /** Atomic pre-decrement.
  101.  *
  102.  * @param val Variable to be decremented.
  103.  * @return    Value after decrementation.
  104.  */
  105. static inline long atomic_predec(atomic_t *val)
  106. {
  107.     return atomic_add(val, -1);
  108. }
  109.  
  110.  
  111. /** Atomic post-increment.
  112.  *
  113.  * @param val Variable to be incremented.
  114.  * @return    Value before incrementation.
  115.  */
  116. static inline long atomic_postinc(atomic_t *val)
  117. {
  118.     return atomic_add(val, 1) - 1;
  119. }
  120.  
  121.  
  122. /** Atomic post-decrement.
  123.  *
  124.  * @param val Variable to be decremented.
  125.  * @return    Value before decrementation.
  126.  */
  127. static inline long atomic_postdec(atomic_t *val)
  128. {
  129.     return atomic_add(val, -1) + 1;
  130. }
  131.  
  132.  
  133. #endif
  134.  
  135. /** @}
  136.  */
  137.