Subversion Repositories HelenOS-historic

Rev

Rev 475 | Go to most recent revision | Blame | Last modification | View Log | Download | RSS feed

  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. #ifndef __mips32_ATOMIC_H__
  30. #define __mips32_ATOMIC_H__
  31.  
  32. #include <arch/types.h>
  33.  
  34. #define atomic_inc(x)   (a_add(x,1))
  35. #define atomic_dec(x)   (a_sub(x,1))
  36.  
  37. #define atomic_inc_pre(x) (a_add(x,1)-1)
  38. #define atomic_dec_pre(x) (a_sub(x,1)+1)
  39.  
  40. #define atomic_inc_post(x) (a_add(x,1))
  41. #define atomic_dec_post(x) (a_sub(x,1))
  42.  
  43.  
  44. typedef volatile __u32 atomic_t;
  45.  
  46. /*
  47.  * Atomic addition
  48.  *
  49.  * This case is harder, and we have to use the special LL and SC operations
  50.  * to achieve atomicity. The instructions are similar to LW (load) and SW
  51.  * (store), except that the LL (load-linked) instruction loads the address
  52.  * of the variable to a special register and if another process writes to
  53.  * the same location, the SC (store-conditional) instruction fails.
  54.  
  55.  Returns (*val)+i
  56.  
  57.  */
  58. static inline atomic_t a_add(atomic_t *val, int i)
  59. {
  60.     atomic_t tmp, tmp2;
  61.  
  62.     asm volatile (
  63.         "   .set    push\n"
  64.         "   .set    noreorder\n"
  65.         "   nop\n"
  66.         "1:\n"
  67.         "   ll  %0, %1\n"
  68.         "   addu    %0, %0, %3\n"
  69.         "       move    %2, %0\n"
  70.         "   sc  %0, %1\n"
  71.         "   beq %0, 0x0, 1b\n"
  72.         "   move    %0, %2\n"
  73.         "   .set    pop\n"
  74.         : "=&r" (tmp), "=o" (*val), "=r" (tmp2)
  75.         : "r" (i)
  76.         );
  77.     return tmp;
  78. }
  79.  
  80.  
  81. /*
  82.  * Atomic subtraction
  83.  *
  84.  * Implemented in the same manner as a_add, except we substract the value.
  85.  
  86.  Returns (*val)-i
  87.  
  88.  */
  89. static inline atomic_t a_sub(atomic_t *val, int i)
  90.  
  91. {
  92.     atomic_t tmp, tmp2;
  93.  
  94.     asm volatile (
  95.         "   .set    push\n"
  96.         "   .set    noreorder\n"
  97.         "   nop\n"
  98.         "1:\n"
  99.         "   ll  %0, %1\n"
  100.         "   subu    %0, %0, %3\n"
  101.         "       move    %2, %0\n"
  102.         "   sc  %0, %1\n"
  103.         "   beq %0, 0x0, 1b\n"
  104.         "       move    %0, %2\n"
  105.         "   .set    pop\n"
  106.         : "=&r" (tmp), "=o" (*val), "=r" (tmp2)
  107.         : "r" (i)
  108.         );
  109.     return tmp;
  110. }
  111.  
  112.  
  113. #endif
  114.