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  1. /*
  2.  * Copyright (C) 2005 Ondrej Palkovsky
  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 libcmips32
  30.  * @{
  31.  */
  32. /** @file
  33.  */
  34.  
  35. #ifndef __mips32_ATOMIC_H__
  36. #define __mips32_ATOMIC_H__
  37.  
  38. #define atomic_inc(x)   ((void) atomic_add(x, 1))
  39. #define atomic_dec(x)   ((void) atomic_add(x, -1))
  40.  
  41. #define atomic_postinc(x) (atomic_add(x, 1) - 1)
  42. #define atomic_postdec(x) (atomic_add(x, -1) + 1)
  43.  
  44. #define atomic_preinc(x) atomic_add(x, 1)
  45. #define atomic_predec(x) atomic_add(x, -1)
  46.  
  47. /* Atomic addition of immediate value.
  48.  *
  49.  * @param val Memory location to which will be the immediate value added.
  50.  * @param i Signed immediate that will be added to *val.
  51.  *
  52.  * @return Value after addition.
  53.  */
  54. static inline long atomic_add(atomic_t *val, int i)
  55. {
  56.     long tmp, v;
  57.  
  58.     __asm__ volatile (
  59.         "1:\n"
  60.         "   ll %0, %1\n"
  61.         "   addiu %0, %0, %3\n" /* same as addi, but never traps on overflow */
  62.         "       move %2, %0\n"
  63.         "   sc %0, %1\n"
  64.         "   beq %0, %4, 1b\n"   /* if the atomic operation failed, try again */
  65.         /*  nop */      /* nop is inserted automatically by compiler */
  66.         : "=r" (tmp), "=m" (val->count), "=r" (v)
  67.         : "i" (i), "i" (0)
  68.         );
  69.  
  70.     return v;
  71. }
  72.  
  73. #endif
  74.  
  75.  /** @}
  76.  */
  77.  
  78.