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  1. /*
  2.  * Copyright 2013 Marek Olšák <maraeo@gmail.com>
  3.  *
  4.  * Permission is hereby granted, free of charge, to any person obtaining a
  5.  * copy of this software and associated documentation files (the "Software"),
  6.  * to deal in the Software without restriction, including without limitation
  7.  * on the rights to use, copy, modify, merge, publish, distribute, sub
  8.  * license, and/or sell copies of the Software, and to permit persons to whom
  9.  * the Software is furnished to do so, subject to the following conditions:
  10.  *
  11.  * The above copyright notice and this permission notice (including the next
  12.  * paragraph) shall be included in all copies or substantial portions of the
  13.  * Software.
  14.  *
  15.  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16.  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17.  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  18.  * THE AUTHOR(S) AND/OR THEIR SUPPLIERS BE LIABLE FOR ANY CLAIM,
  19.  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  20.  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  21.  * USE OR OTHER DEALINGS IN THE SOFTWARE. */
  22.  
  23. /**
  24.  * @file
  25.  * 1D integer range, capable of the union and intersection operations.
  26.  *
  27.  * It only maintains a single interval which is extended when the union is
  28.  * done. This implementation is partially thread-safe (readers are not
  29.  * protected by a lock).
  30.  *
  31.  * @author Marek Olšák
  32.  */
  33.  
  34. #ifndef U_RANGE_H
  35. #define U_RANGE_H
  36.  
  37. #include "os/os_thread.h"
  38.  
  39. #include "util/u_math.h"
  40.  
  41. struct util_range {
  42.    unsigned start; /* inclusive */
  43.    unsigned end; /* exclusive */
  44.  
  45.    /* for the range to be consistent with multiple contexts: */
  46.    pipe_mutex write_mutex;
  47. };
  48.  
  49.  
  50. static INLINE void
  51. util_range_set_empty(struct util_range *range)
  52. {
  53.    range->start = ~0;
  54.    range->end = 0;
  55. }
  56.  
  57. /* This is like a union of two sets. */
  58. static INLINE void
  59. util_range_add(struct util_range *range, unsigned start, unsigned end)
  60. {
  61.    if (start < range->start || end > range->end) {
  62.       pipe_mutex_lock(range->write_mutex);
  63.       range->start = MIN2(start, range->start);
  64.       range->end = MAX2(end, range->end);
  65.       pipe_mutex_unlock(range->write_mutex);
  66.    }
  67. }
  68.  
  69. static INLINE boolean
  70. util_ranges_intersect(struct util_range *range, unsigned start, unsigned end)
  71. {
  72.    return MAX2(start, range->start) < MIN2(end, range->end);
  73. }
  74.  
  75.  
  76. /* Init/deinit */
  77.  
  78. static INLINE void
  79. util_range_init(struct util_range *range)
  80. {
  81.    pipe_mutex_init(range->write_mutex);
  82.    util_range_set_empty(range);
  83. }
  84.  
  85. static INLINE void
  86. util_range_destroy(struct util_range *range)
  87. {
  88.    pipe_mutex_destroy(range->write_mutex);
  89. }
  90.  
  91. #endif
  92.