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  1. /*
  2.  * Copyright (C) 2006 Josef Cejka
  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. #include <key_buffer.h>
  30. #include <futex.h>
  31.  
  32. atomic_t keybuffer_futex = FUTEX_INITIALIZER;
  33.  
  34. /** Clear key buffer.
  35.  */
  36. void keybuffer_free(keybuffer_t *keybuffer)
  37. {
  38.     futex_down(&keybuffer_futex);
  39.     keybuffer->head = 0;
  40.     keybuffer->tail = 0;
  41.     keybuffer->items = 0;
  42.     futex_up(&keybuffer_futex);
  43. }
  44.  
  45. /** Key buffer initialization.
  46.  *
  47.  */
  48. void keybuffer_init(keybuffer_t *keybuffer)
  49. {
  50.     keybuffer_free(keybuffer);
  51. }
  52.  
  53. /** Get free space in buffer.
  54.  * This function is useful for processing some scancodes that are translated
  55.  * to more than one character.
  56.  * @return empty buffer space
  57.  */
  58. int keybuffer_available(keybuffer_t *keybuffer)
  59. {
  60.     return KEYBUFFER_SIZE - keybuffer->items;
  61. }
  62.  
  63. /**
  64.  * @return nonzero, if buffer is not empty.
  65.  */
  66. int keybuffer_empty(keybuffer_t *keybuffer)
  67. {
  68.     return (keybuffer->items == 0);
  69. }
  70.  
  71. /** Push key to key buffer.
  72.  * If buffer is full, character is ignored.
  73.  * @param key code of stored key
  74.  */
  75. void keybuffer_push(keybuffer_t *keybuffer, char key)
  76. {
  77.     futex_down(&keybuffer_futex);
  78.     if (keybuffer->items < KEYBUFFER_SIZE) {
  79.         keybuffer->fifo[keybuffer->tail] = key;
  80.         keybuffer->tail = (keybuffer->tail + 1) % KEYBUFFER_SIZE;
  81.         keybuffer->items++;
  82.     }
  83.     futex_up(&keybuffer_futex);
  84. }
  85.  
  86. /** Pop character from buffer.
  87.  * @param c pointer to space where to store character from buffer.
  88.  * @return zero on empty buffer, nonzero else
  89.  */
  90. int keybuffer_pop(keybuffer_t *keybuffer, char *c)
  91. {
  92.     futex_down(&keybuffer_futex);
  93.     if (keybuffer->items > 0) {
  94.         keybuffer->items--;
  95.         *c = keybuffer->fifo[keybuffer->head];
  96.         keybuffer->head = (keybuffer->head + 1) % KEYBUFFER_SIZE;
  97.         futex_up(&keybuffer_futex);
  98.         return 1;
  99.     }
  100.     futex_up(&keybuffer_futex);
  101.     return 0;
  102. }
  103.  
  104.  
  105.