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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 <libadt/fifo.h>
  31.  
  32. #define KBD_BUFFER_SIZE 128 /**< Size of buffer for pressed keys */
  33.  
  34. FIFO_INITIALIZE_STATIC(buffer, char, KBD_BUFFER_SIZE);  /**< Fifo for storing pressed keys */
  35. fifo_count_t buffer_items;  /**< Counter of used items for prevent fifo overflow */
  36.  
  37. /** Clear key buffer.
  38.  */
  39. void key_buffer_free(void)
  40. {
  41.     buffer_items = 0;
  42.     buffer.head = buffer.tail = 0;
  43. }
  44.  
  45. /** Key buffer initialization.
  46.  *
  47.  */
  48. void key_buffer_init(void)
  49. {
  50.     key_buffer_free();
  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 key_buffer_available(void)
  59. {
  60.     return KBD_BUFFER_SIZE - buffer_items;
  61. }
  62.  
  63. /**
  64.  * @return nonzero, if buffer is not empty.
  65.  */
  66. int key_buffer_empty(void)
  67. {
  68.     return (buffer_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 key_buffer_push(char key)
  76. {
  77.     if (buffer_items < KBD_BUFFER_SIZE) {
  78.         fifo_push(buffer, key);
  79.         buffer_items++;
  80.     }
  81. }
  82.  
  83. /** Pop character from buffer.
  84.  * @param c pointer to space where to store character from buffer.
  85.  * @return zero on empty buffer, nonzero else
  86.  */
  87. int key_buffer_pop(char *c)
  88. {
  89.     if (buffer_items > 0) {
  90.         buffer_items--;
  91.         *c = fifo_pop(buffer);
  92.         return 1;
  93.     }
  94.     return 0;
  95. }
  96.  
  97.  
  98.