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1339 cejka 1
/*
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 * Copyright (C) 2006 Josef Cejka
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#include <key_buffer.h>
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#include <libadt/fifo.h>
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#define KBD_BUFFER_SIZE 128 /**< Size of buffer for pressed keys */
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FIFO_INITIALIZE_STATIC(buffer, char, KBD_BUFFER_SIZE);  /**< Fifo for storing pressed keys */
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fifo_count_t buffer_items;  /**< Counter of used items for prevent fifo overflow */
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/** Clear key buffer.
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 */
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void key_buffer_free(void)
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{
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    buffer_items = 0;
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    buffer.head = buffer.tail = 0;
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}
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/** Key buffer initialization.
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 *
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 */
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void key_buffer_init(void)
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{
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    key_buffer_free();
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}
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/** Get free space in buffer.
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 * This function is useful for processing some scancodes that are translated
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 * to more than one character.
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 * @return empty buffer space
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 */
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int key_buffer_available(void)
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{
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    return KBD_BUFFER_SIZE - buffer_items;
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}
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/**
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 * @return nonzero, if buffer is not empty.
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 */
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int key_buffer_empty(void)
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{
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    return (buffer_items == 0);
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}
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/** Push key to key buffer.
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 * If buffer is full, character is ignored.
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 * @param key code of stored key
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 */
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void key_buffer_push(char key)
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{
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    if (buffer_items < KBD_BUFFER_SIZE) {
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        fifo_push(buffer, key);
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        buffer_items++;
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    }
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}
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/** Pop character from buffer.
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 * @param c pointer to space where to store character from buffer.
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 * @return zero on empty buffer, nonzero else
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 */
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int key_buffer_pop(char *c)
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{
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    if (buffer_items > 0) {
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        buffer_items--;
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        *c = fifo_pop(buffer);
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        return 1;
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    }
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    return 0;
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}
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