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1 /* |
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2 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER. |
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3 * |
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4 * Copyright 2017 Mike Becker, Olaf Wintermann All rights reserved. |
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5 * |
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6 * Redistribution and use in source and binary forms, with or without |
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7 * modification, are permitted provided that the following conditions are met: |
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8 * |
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9 * 1. Redistributions of source code must retain the above copyright |
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10 * notice, this list of conditions and the following disclaimer. |
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11 * |
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12 * 2. Redistributions in binary form must reproduce the above copyright |
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13 * notice, this list of conditions and the following disclaimer in the |
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14 * documentation and/or other materials provided with the distribution. |
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15 * |
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16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
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17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
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20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
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21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
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22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
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23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
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24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
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25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
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26 * POSSIBILITY OF SUCH DAMAGE. |
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27 */ |
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28 |
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29 /** |
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30 * @file buffer.h |
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31 * |
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32 * Advanced buffer implementation. |
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33 * |
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34 * Instances of UcxBuffer can be used to read from or to write to like one |
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35 * would do with a stream. This allows the use of ucx_stream_copy() to copy |
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36 * contents from one buffer to another. |
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37 * |
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38 * Some features for convenient use of the buffer |
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39 * can be enabled. See the documentation of the macro constants for more |
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40 * information. |
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41 * |
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42 * @author Mike Becker |
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43 * @author Olaf Wintermann |
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44 */ |
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45 |
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46 #ifndef UCX_BUFFER_H |
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47 #define UCX_BUFFER_H |
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48 |
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49 #include "ucx.h" |
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50 #include <sys/types.h> |
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51 #include <stdio.h> |
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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 /** |
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58 * No buffer features enabled (all flags cleared). |
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59 */ |
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60 #define UCX_BUFFER_DEFAULT 0x00 |
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61 |
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62 /** |
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63 * If this flag is enabled, the buffer will automatically free its contents. |
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64 */ |
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65 #define UCX_BUFFER_AUTOFREE 0x01 |
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66 |
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67 /** |
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68 * If this flag is enabled, the buffer will automatically extends its capacity. |
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69 */ |
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70 #define UCX_BUFFER_AUTOEXTEND 0x02 |
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71 |
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72 /** UCX Buffer. */ |
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73 typedef struct { |
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74 /** A pointer to the buffer contents. */ |
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75 char *space; |
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76 /** Current position of the buffer. */ |
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77 size_t pos; |
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78 /** Current capacity (i.e. maximum size) of the buffer. */ |
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79 size_t capacity; |
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80 /** Current size of the buffer content. */ |
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81 size_t size; |
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82 /** |
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83 * Flag register for buffer features. |
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84 * @see #UCX_BUFFER_DEFAULT |
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85 * @see #UCX_BUFFER_AUTOFREE |
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86 * @see #UCX_BUFFER_AUTOEXTEND |
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87 */ |
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88 int flags; |
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89 } UcxBuffer; |
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90 |
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91 /** |
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92 * Creates a new buffer. |
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93 * |
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94 * <b>Note:</b> you may provide <code>NULL</code> as argument for |
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95 * <code>space</code>. Then this function will allocate the space and enforce |
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96 * the #UCX_BUFFER_AUTOFREE flag. |
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97 * |
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98 * @param space pointer to the memory area, or <code>NULL</code> to allocate |
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99 * new memory |
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100 * @param capacity the capacity of the buffer |
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101 * @param flags buffer features (see UcxBuffer.flags) |
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102 * @return the new buffer |
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103 */ |
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104 UcxBuffer *ucx_buffer_new(void *space, size_t capacity, int flags); |
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105 |
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106 /** |
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107 * Destroys a buffer. |
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108 * |
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109 * If the #UCX_BUFFER_AUTOFREE feature is enabled, the contents of the buffer |
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110 * are also freed. |
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111 * |
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112 * @param buffer the buffer to destroy |
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113 */ |
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114 void ucx_buffer_free(UcxBuffer* buffer); |
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115 |
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116 /** |
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117 * Creates a new buffer and fills it with extracted content from another buffer. |
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118 * |
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119 * <b>Note:</b> the #UCX_BUFFER_AUTOFREE feature is enforced for the new buffer. |
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120 * |
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121 * @param src the source buffer |
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122 * @param start the start position of extraction |
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123 * @param length the count of bytes to extract (must not be zero) |
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124 * @param flags feature mask for the new buffer |
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125 * @return a new buffer containing the extraction |
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126 */ |
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127 UcxBuffer* ucx_buffer_extract(UcxBuffer *src, |
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128 size_t start, size_t length, int flags); |
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129 |
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130 /** |
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131 * A shorthand macro for the full extraction of the buffer. |
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132 * |
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133 * @param src the source buffer |
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134 * @param flags feature mask for the new buffer |
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135 * @return a new buffer with the extracted content |
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136 */ |
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137 #define ucx_buffer_clone(src,flags) \ |
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138 ucx_buffer_extract(src, 0, (src)->capacity, flags) |
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139 |
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140 |
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141 /** |
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142 * Shifts the contents of the buffer by the given offset. |
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143 * |
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144 * If the offset is positive, the contents are shifted to the right. |
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145 * If auto extension is enabled, the buffer grows, if necessary. |
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146 * In case the auto extension fails, this function returns a non-zero value and |
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147 * no contents are changed. |
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148 * If auto extension is disabled, the contents that do not fit into the buffer |
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149 * are discarded. |
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150 * |
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151 * If the offset is negative, the contents are shifted to the left where the |
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152 * first <code>shift</code> bytes are discarded. |
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153 * The new size of the buffer is the old size minus |
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154 * the absolute shift value. |
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155 * If this value is larger than the buffer size, the buffer is emptied (but |
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156 * not cleared, see the security note below). |
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157 * |
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158 * The buffer position gets shifted alongside with the content but is kept |
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159 * within the boundaries of the buffer. |
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160 * |
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161 * <b>Security note:</b> the shifting operation does <em>not</em> erase the |
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162 * previously occupied memory cells. You can easily do that manually, e.g. by |
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163 * calling <code>memset(buffer->space, 0, shift)</code> for a right shift or |
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164 * <code>memset(buffer->size, 0, buffer->capacity-buffer->size)</code> |
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165 * for a left shift. |
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166 * |
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167 * @param buffer the buffer |
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168 * @param shift the shift offset (negative means left shift) |
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169 * @return 0 on success, non-zero if a required auto-extension fails |
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170 */ |
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171 int ucx_buffer_shift(UcxBuffer* buffer, off_t shift); |
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172 |
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173 /** |
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174 * Shifts the buffer to the right. |
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175 * See ucx_buffer_shift() for details. |
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176 * |
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177 * @param buffer the buffer |
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178 * @param shift the shift offset |
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179 * @return 0 on success, non-zero if a required auto-extension fails |
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180 * @see ucx_buffer_shift() |
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181 */ |
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182 int ucx_buffer_shift_right(UcxBuffer* buffer, size_t shift); |
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183 |
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184 /** |
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185 * Shifts the buffer to the left. |
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186 * |
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187 * See ucx_buffer_shift() for details. Note, however, that this method expects |
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188 * a positive shift offset. |
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189 * |
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190 * Since a left shift cannot fail due to memory allocation problems, this |
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191 * function always returns zero. |
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192 * |
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193 * @param buffer the buffer |
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194 * @param shift the shift offset |
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195 * @return always zero |
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196 * @see ucx_buffer_shift() |
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197 */ |
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198 int ucx_buffer_shift_left(UcxBuffer* buffer, size_t shift); |
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199 |
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200 |
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201 /** |
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202 * Moves the position of the buffer. |
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203 * |
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204 * The new position is relative to the <code>whence</code> argument. |
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205 * |
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206 * SEEK_SET marks the start of the buffer. |
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207 * SEEK_CUR marks the current position. |
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208 * SEEK_END marks the end of the buffer. |
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209 * |
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210 * With an offset of zero, this function sets the buffer position to zero |
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211 * (SEEK_SET), the buffer size (SEEK_END) or leaves the buffer position |
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212 * unchanged (SEEK_CUR). |
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213 * |
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214 * @param buffer |
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215 * @param offset position offset relative to <code>whence</code> |
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216 * @param whence one of SEEK_SET, SEEK_CUR or SEEK_END |
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217 * @return 0 on success, non-zero if the position is invalid |
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218 * |
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219 */ |
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220 int ucx_buffer_seek(UcxBuffer *buffer, off_t offset, int whence); |
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221 |
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222 /** |
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223 * Clears the buffer by resetting the position and deleting the data. |
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224 * |
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225 * The data is deleted by a zeroing it with call to <code>memset()</code>. |
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226 * |
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227 * @param buffer the buffer to be cleared |
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228 */ |
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229 #define ucx_buffer_clear(buffer) memset((buffer)->space, 0, (buffer)->size); \ |
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230 (buffer)->size = 0; (buffer)->pos = 0; |
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231 |
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232 /** |
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233 * Tests, if the buffer position has exceeded the buffer capacity. |
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234 * |
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235 * @param buffer the buffer to test |
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236 * @return non-zero, if the current buffer position has exceeded the last |
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237 * available byte of the buffer. |
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238 */ |
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239 int ucx_buffer_eof(UcxBuffer *buffer); |
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240 |
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241 |
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242 /** |
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243 * Extends the capacity of the buffer. |
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244 * |
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245 * <b>Note:</b> The buffer capacity increased by a power of two. I.e. |
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246 * the buffer capacity is doubled, as long as it would not hold the current |
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247 * content plus the additional required bytes. |
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248 * |
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249 * <b>Attention:</b> the argument provided is the number of <i>additional</i> |
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250 * bytes the buffer shall hold. It is <b>NOT</b> the total number of bytes the |
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251 * buffer shall hold. |
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252 * |
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253 * @param buffer the buffer to extend |
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254 * @param additional_bytes the number of additional bytes the buffer shall |
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255 * <i>at least</i> hold |
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256 * @return 0 on success or a non-zero value on failure |
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257 */ |
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258 int ucx_buffer_extend(UcxBuffer *buffer, size_t additional_bytes); |
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259 |
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260 /** |
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261 * Writes data to a UcxBuffer. |
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262 * |
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263 * The position of the buffer is increased by the number of bytes written. |
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264 * |
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265 * @param ptr a pointer to the memory area containing the bytes to be written |
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266 * @param size the length of one element |
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267 * @param nitems the element count |
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268 * @param buffer the UcxBuffer to write to |
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269 * @return the total count of bytes written |
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270 */ |
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271 size_t ucx_buffer_write(const void *ptr, size_t size, size_t nitems, |
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272 UcxBuffer *buffer); |
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273 |
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274 /** |
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275 * Reads data from a UcxBuffer. |
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276 * |
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277 * The position of the buffer is increased by the number of bytes read. |
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278 * |
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279 * @param ptr a pointer to the memory area where to store the read data |
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280 * @param size the length of one element |
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281 * @param nitems the element count |
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282 * @param buffer the UcxBuffer to read from |
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283 * @return the total number of elements read |
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284 */ |
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285 size_t ucx_buffer_read(void *ptr, size_t size, size_t nitems, |
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286 UcxBuffer *buffer); |
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287 |
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288 /** |
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289 * Writes a character to a buffer. |
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290 * |
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291 * The least significant byte of the argument is written to the buffer. If the |
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292 * end of the buffer is reached and #UCX_BUFFER_AUTOEXTEND feature is enabled, |
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293 * the buffer capacity is extended by ucx_buffer_extend(). If the feature is |
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294 * disabled or buffer extension fails, <code>EOF</code> is returned. |
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295 * |
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296 * On successful write the position of the buffer is increased. |
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297 * |
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298 * @param buffer the buffer to write to |
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299 * @param c the character to write as <code>int</code> value |
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300 * @return the byte that has bean written as <code>int</code> value or |
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301 * <code>EOF</code> when the end of the stream is reached and automatic |
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302 * extension is not enabled or not possible |
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303 */ |
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304 int ucx_buffer_putc(UcxBuffer *buffer, int c); |
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305 |
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306 /** |
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307 * Gets a character from a buffer. |
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308 * |
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309 * The current position of the buffer is increased after a successful read. |
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310 * |
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311 * @param buffer the buffer to read from |
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312 * @return the character as <code>int</code> value or <code>EOF</code>, if the |
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313 * end of the buffer is reached |
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314 */ |
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315 int ucx_buffer_getc(UcxBuffer *buffer); |
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316 |
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317 /** |
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318 * Writes a string to a buffer. |
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319 * |
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320 * @param buffer the buffer |
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321 * @param str the string |
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322 * @return the number of bytes written |
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323 */ |
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324 size_t ucx_buffer_puts(UcxBuffer *buffer, const char *str); |
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325 |
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326 /** |
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327 * Returns the complete buffer content as sstr_t. |
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328 * @param buffer the buffer |
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329 * @return the result of <code>sstrn()</code> with the buffer space and size |
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330 * as arguments |
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331 */ |
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332 #define ucx_buffer_to_sstr(buffer) sstrn((buffer)->space, (buffer)->size) |
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333 |
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334 #ifdef __cplusplus |
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335 } |
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336 #endif |
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337 |
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338 #endif /* UCX_BUFFER_H */ |
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339 |