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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) { atomic_add(val, 1); }
  74.  
  75.  
  76. /** Atomic decrement.
  77.  *
  78.  * @param val Variable to be decremented.
  79.  */
  80. static inline void atomic_dec(atomic_t *val) { atomic_add(val, -1); }
  81.  
  82.  
  83. /** Atomic pre-increment.
  84.  *
  85.  * @param val Variable to be incremented.
  86.  * @return    Value after incrementation.
  87.  */
  88. static inline long atomic_preinc(atomic_t *val) { return atomic_add(val, 1); }
  89.  
  90.  
  91. /** Atomic pre-decrement.
  92.  *
  93.  * @param val Variable to be decremented.
  94.  * @return    Value after decrementation.
  95.  */
  96. static inline long atomic_predec(atomic_t *val) { return atomic_add(val, -1); }
  97.  
  98.  
  99. /** Atomic post-increment.
  100.  *
  101.  * @param val Variable to be incremented.
  102.  * @return    Value before incrementation.
  103.  */
  104. static inline long atomic_postinc(atomic_t *val) { return atomic_add(val, 1) - 1; }
  105.  
  106.  
  107. /** Atomic post-decrement.
  108.  *
  109.  * @param val Variable to be decremented.
  110.  * @return    Value before decrementation.
  111.  */
  112. static inline long atomic_postdec(atomic_t *val) { return atomic_add(val, -1) + 1; }
  113.  
  114.  
  115. #endif
  116.  
  117. /** @}
  118.  */
  119.