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  1. /*
  2.  * Copyright (C) 2005 Jakub Jermar
  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. #ifndef __sparc64_ATOMIC_H__
  30. #define __sparc64_ATOMIC_H__
  31.  
  32. #include <arch/types.h>
  33. #include <typedefs.h>
  34.  
  35. /** Atomic add operation.
  36.  *
  37.  * Use atomic compare and swap operation to atomically add signed value.
  38.  *
  39.  * @param val Atomic variable.
  40.  * @param i Signed value to be added.
  41.  *
  42.  * @return Value of the atomic variable as it existed before addition.
  43.  */
  44. static inline long atomic_add(atomic_t *val, int i)
  45. {
  46.     __u64 a, b;
  47.     volatile __u64 x = (__u64) &val->count;
  48.  
  49.     __asm__ volatile (
  50.         "0:\n"
  51.         "ldx %0, %1\n"
  52.         "add %1, %3, %2\n"
  53.         "casx %0, %1, %2\n"
  54.         "cmp %1, %2\n"
  55.         "bne 0b\n"      /* The operation failed and must be attempted again if a != b. */
  56.         "nop\n"
  57.         : "=m" (*((__u64 *)x)), "=r" (a), "=r" (b)
  58.         : "r" (i)
  59.     );
  60.  
  61.     return a;
  62. }
  63.  
  64. static inline long atomic_preinc(atomic_t *val)
  65. {
  66.     return atomic_add(val, 1) + 1;
  67. }
  68.  
  69. static inline long atomic_postinc(atomic_t *val)
  70. {
  71.     return atomic_add(val, 1);
  72. }
  73.  
  74. static inline long atomic_predec(atomic_t *val)
  75. {
  76.     return atomic_add(val, -1) - 1;
  77. }
  78.  
  79. static inline long atomic_postdec(atomic_t *val)
  80. {
  81.     return atomic_add(val, -1);
  82. }
  83.  
  84. static inline void atomic_inc(atomic_t *val)
  85. {
  86.     (void) atomic_add(val, 1);
  87. }
  88.  
  89. static inline void atomic_dec(atomic_t *val)
  90. {
  91.     (void) atomic_add(val, -1);
  92. }
  93.  
  94. #endif
  95.