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  1. /*
  2.  * Copyright (c) 2001-2004 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. /** @addtogroup ia32   
  30.  * @{
  31.  */
  32. /** @file
  33.  */
  34.  
  35. #ifndef KERN_ia32_ATOMIC_H_
  36. #define KERN_ia32_ATOMIC_H_
  37.  
  38. #include <arch/types.h>
  39. #include <arch/barrier.h>
  40. #include <preemption.h>
  41. #include <typedefs.h>
  42.  
  43. static inline void atomic_inc(atomic_t *val) {
  44. #ifdef CONFIG_SMP
  45.     asm volatile ("lock incl %0\n" : "=m" (val->count));
  46. #else
  47.     asm volatile ("incl %0\n" : "=m" (val->count));
  48. #endif /* CONFIG_SMP */
  49. }
  50.  
  51. static inline void atomic_dec(atomic_t *val) {
  52. #ifdef CONFIG_SMP
  53.     asm volatile ("lock decl %0\n" : "=m" (val->count));
  54. #else
  55.     asm volatile ("decl %0\n" : "=m" (val->count));
  56. #endif /* CONFIG_SMP */
  57. }
  58.  
  59. static inline long atomic_postinc(atomic_t *val)
  60. {
  61.     long r = 1;
  62.  
  63.     asm volatile (
  64.         "lock xaddl %1, %0\n"
  65.         : "=m" (val->count), "+r" (r)
  66.     );
  67.  
  68.     return r;
  69. }
  70.  
  71. static inline long atomic_postdec(atomic_t *val)
  72. {
  73.     long r = -1;
  74.    
  75.     asm volatile (
  76.         "lock xaddl %1, %0\n"
  77.         : "=m" (val->count), "+r"(r)
  78.     );
  79.    
  80.     return r;
  81. }
  82.  
  83. #define atomic_preinc(val) (atomic_postinc(val)+1)
  84. #define atomic_predec(val) (atomic_postdec(val)-1)
  85.  
  86. static inline uint32_t test_and_set(atomic_t *val) {
  87.     uint32_t v;
  88.    
  89.     asm volatile (
  90.         "movl $1, %0\n"
  91.         "xchgl %0, %1\n"
  92.         : "=r" (v),"=m" (val->count)
  93.     );
  94.    
  95.     return v;
  96. }
  97.  
  98. /** ia32 specific fast spinlock */
  99. static inline void atomic_lock_arch(atomic_t *val)
  100. {
  101.     uint32_t tmp;
  102.  
  103.     preemption_disable();
  104.     asm volatile (
  105.         "0:;"
  106. #ifdef CONFIG_HT
  107.         "pause;" /* Pentium 4's HT love this instruction */
  108. #endif
  109.         "mov %0, %1;"
  110.         "testl %1, %1;"
  111.         "jnz 0b;"       /* Lightweight looping on locked spinlock */
  112.        
  113.         "incl %1;"      /* now use the atomic operation */
  114.         "xchgl %0, %1;"
  115.         "testl %1, %1;"
  116.         "jnz 0b;"
  117.                 : "=m"(val->count),"=r"(tmp)
  118.         );
  119.     /*
  120.      * Prevent critical section code from bleeding out this way up.
  121.      */
  122.     CS_ENTER_BARRIER();
  123. }
  124.  
  125. #endif
  126.  
  127. /** @}
  128.  */
  129.