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1 /*
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2 * SpanDSP - a series of DSP components for telephony
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3 *
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4 * queue.h - simple in process message queuing
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5 *
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6 * Written by Steve Underwood <steveu@coppice.org>
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7 *
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8 * Copyright (C) 2004 Steve Underwood
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9 *
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10 * All rights reserved.
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11 *
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12 * This program is free software; you can redistribute it and/or modify
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13 * it under the terms of the GNU General Public License version 2, as
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14 * published by the Free Software Foundation.
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15 *
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16 * This program is distributed in the hope that it will be useful,
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17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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19 * GNU General Public License for more details.
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20 *
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21 * You should have received a copy of the GNU General Public License
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22 * along with this program; if not, write to the Free Software
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23 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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24 *
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25 * $Id: queue.h,v 1.4 2006/10/24 13:45:28 steveu Exp $
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26 */
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27
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28 /*! \file */
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29
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30 /*! \page queue_page Queuing
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31 \section queue_page_sec_1 What does it do?
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32 ???.
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33
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34 \section queue_page_sec_2 How does it work?
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35 ???.
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36 */
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37
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38 #if !defined(_QUEUE_H_)
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39 #define _QUEUE_H_
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40
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41 #define QUEUE_READ_ATOMIC 0x0001
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42 #define QUEUE_WRITE_ATOMIC 0x0002
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43
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44 typedef struct
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45 {
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46 int len;
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47 int iptr;
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48 int optr;
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49 int flags;
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50 uint8_t *data;
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51 } queue_t;
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52
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53 #ifdef __cplusplus
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54 extern "C" {
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55 #endif
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56
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57 /*! Check if a queue is empty.
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58 \brief Check if a queue is empty.
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59 \param p The queue context.
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60 \return TRUE if empty, else FALSE. */
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61 int queue_empty(queue_t *p);
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62
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63 /*! Check the available free space in a queue's buffer.
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64 \brief Check available free space.
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65 \param p The queue context.
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66 \return The number of bytes of free space. */
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67 int queue_free_space(queue_t *p);
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68
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69 /*! Check the contents of a queue.
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70 \brief Check the contents of a queue.
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71 \param p The queue context.
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72 \return The number of bytes in the queue. */
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73 int queue_contents(queue_t *p);
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74
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75 /*! Flush the contents of a queue.
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76 \brief Flush the contents of a queue.
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77 \param p The queue context. */
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78 void queue_flush(queue_t *p);
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79
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80 /*! Copy bytes from a queue. This is similar to queue_read, but
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81 the data remains in the queue.
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82 \brief Copy bytes from a queue.
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83 \param p The queue context.
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84 \param buf The buffer into which the bytes will be read.
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85 \param len The length of the buffer.
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86 \return the number of bytes returned. */
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87 int queue_view(queue_t *p, uint8_t *buf, int len);
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88
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89 /*! Read bytes from a queue.
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90 \brief Read bytes from a queue.
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91 \param p The queue context.
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92 \param buf The buffer into which the bytes will be read.
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93 \param len The length of the buffer.
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94 \return the number of bytes returned. */
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95 int queue_read(queue_t *p, uint8_t *buf, int len);
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96
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97 /*! Write bytes to a queue.
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98 \brief Write bytes to a queue.
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99 \param p The queue context.
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100 \param buf The buffer containing the bytes to be written.
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101 \param len The length of the buffer.
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102 \return the number of bytes actually written. */
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103 int queue_write(queue_t *p, const uint8_t *buf, int len);
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104
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105 /*! Test the length of the message at the head of a queue.
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106 \brief Test message length.
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107 \param p The queue context.
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108 \return The length of the next message, in byte. If there are
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109 no messages in the queue, -1 is returned. */
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110 int queue_test_msg(queue_t *p);
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111
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112 /*! Read a message from a queue. If the message is longer than the buffer
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113 provided, only the first len bytes of the message will be returned. The
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114 remainder of the message will be discarded.
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115 \brief Read a message from a queue.
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116 \param p The queue context.
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117 \param buf The buffer into which the message will be read.
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118 \param len The length of the buffer.
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119 \return The number of bytes returned. If there are
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120 no messages in the queue, -1 is returned. */
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121 int queue_read_msg(queue_t *p, uint8_t *buf, int len);
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122
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123 /*! Write a message to a queue.
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124 \brief Write a message to a queue.
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125 \param p The queue context.
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126 \param buf The buffer from which the message will be written.
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127 \param len The length of the message.
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128 \return The number of bytes actually written. */
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129 int queue_write_msg(queue_t *p, const uint8_t *buf, int len);
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130
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131 /*! Create a queue.
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132 \brief Create a queue.
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133 \param p The queue context.
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134 \param len The length of the queue's buffer.
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135 \param flags Flags controlling the operation of the queue.
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136 Valid flags are QUEUE_READ_ATOMIC and QUEUE_WRITE_ATOMIC.
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137 \return 0 if created OK, else -1. */
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138 int queue_create(queue_t *p, int len, int flags);
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139
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140 /*! Delete a queue.
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141 \brief Delete a queue.
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142 \param p The queue context.
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143 \return 0 if deleted OK, else -1. */
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144 int queue_delete(queue_t *p);
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145
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146 #ifdef __cplusplus
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147 }
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148 #endif
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149
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150 #endif
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151 /*- End of file ------------------------------------------------------------*/
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