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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.  
  34. typedef struct { volatile __u64 count; } atomic_t;
  35.  
  36. /** Atomic add operation.
  37.  *
  38.  * Use atomic compare and swap operation to atomically add signed value.
  39.  *
  40.  * @param val Atomic variable.
  41.  * @param i Signed value to be added.
  42.  *
  43.  * @return Value of the atomic variable as it existed before addition.
  44.  */
  45. static inline count_t atomic_add(atomic_t *val, int i)
  46. {
  47.     __u64 a, b;
  48.     volatile __u64 x = (__u64) &val->count;
  49.  
  50.     __asm__ volatile (
  51.         "0:\n"
  52.         "ldx %0, %1\n"
  53.         "add %1, %3, %2\n"
  54.         "casx %0, %1, %2\n"
  55.         "cmp %1, %2\n"
  56.         "bne 0b\n"      /* The operation failed and must be attempted again if a != b. */
  57.         "nop\n"
  58.         : "=m" (*((__u64 *)x)), "=r" (a), "=r" (b)
  59.         : "r" (i)
  60.     );
  61.  
  62.     return a;
  63. }
  64.  
  65. static inline void atomic_inc(atomic_t *val)
  66. {
  67.     (void) atomic_add(val, 1);
  68. }
  69.  
  70. static inline void atomic_dec(atomic_t *val)
  71. {
  72.     (void) atomic_add(val, -1);
  73. }
  74.  
  75. static inline void atomic_set(atomic_t *val, __u64 i)
  76. {
  77.     val->count = i;
  78. }
  79.  
  80. static inline __u64 atomic_get(atomic_t *val)
  81. {
  82.     return val->count;
  83. }
  84.  
  85. #endif
  86.