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3 | <title>Procyon AVRlib: bitbuf.c Source File</title> |
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8 | <h1>bitbuf.c</h1><a href="bitbuf_8c.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment">00001 <span class="comment">/*! \file bitbuf.c \brief Multipurpose bit buffer structure and methods. */</span> |
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9 | 00002 <span class="comment">//*****************************************************************************</span> |
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10 | 00003 <span class="comment">//</span> |
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11 | 00004 <span class="comment">// File Name : 'bitbuf.c'</span> |
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12 | 00005 <span class="comment">// Title : Multipurpose bit buffer structure and methods</span> |
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13 | 00006 <span class="comment">// Author : Pascal Stang - Copyright (C) 2001-2002</span> |
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14 | 00007 <span class="comment">// Created : 7/10/2002</span> |
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15 | 00008 <span class="comment">// Revised : 7/10/2002</span> |
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16 | 00009 <span class="comment">// Version : 0.5</span> |
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17 | 00010 <span class="comment">// Target MCU : any</span> |
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18 | 00011 <span class="comment">// Editor Tabs : 4</span> |
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19 | 00012 <span class="comment">//</span> |
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20 | 00013 <span class="comment">// This code is distributed under the GNU Public License</span> |
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21 | 00014 <span class="comment">// which can be found at http://www.gnu.org/licenses/gpl.txt</span> |
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22 | 00015 <span class="comment">//</span> |
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23 | 00016 <span class="comment">//*****************************************************************************</span> |
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24 | 00017 |
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25 | 00018 <span class="preprocessor">#include "<a class="code" href="bitbuf_8h.html">bitbuf.h</a>"</span> |
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26 | 00019 |
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27 | 00020 <span class="comment">// global variables</span> |
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28 | 00021 <span class="comment"></span> |
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29 | 00022 <span class="comment">//! Initialize the bit buffer</span> |
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30 | 00023 <span class="comment"></span><span class="comment">// sets the start location and size of the buffer in memory</span> |
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31 | <a name="l00024"></a><a class="code" href="group__bitbuf.html#ga1">00024</a> <span class="keywordtype">void</span> <a class="code" href="group__bitbuf.html#ga1">bitbufInit</a>(BitBuf* bitBuffer, <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> *start, <span class="keywordtype">unsigned</span> <span class="keywordtype">short</span> bytesize) |
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32 | 00025 { |
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33 | 00026 <span class="comment">// set start pointer of the buffer</span> |
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34 | 00027 bitBuffer->dataptr = start; |
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35 | 00028 bitBuffer->size = bytesize; |
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36 | 00029 <span class="comment">// initialize indexing and length</span> |
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37 | 00030 bitBuffer->dataindex = 0; |
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38 | 00031 <a class="code" href="group__bitbuf.html#ga7">bitbufFlush</a>(bitBuffer); |
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39 | 00032 } |
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40 | 00033 |
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41 | 00034 <span class="comment">// access routines</span> |
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42 | 00035 <span class="comment"></span> |
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43 | 00036 <span class="comment">//! Get a bit from the current position in the buffer</span> |
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44 | 00037 <span class="comment"></span><span class="comment">// returns the bit at the current position in the buffer</span> |
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45 | 00038 <span class="comment">// and increments the bit position</span> |
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46 | <a name="l00039"></a><a class="code" href="group__bitbuf.html#ga2">00039</a> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> <a class="code" href="group__bitbuf.html#ga2">bitbufGet</a>(BitBuf* bitBuffer) |
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47 | 00040 { |
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48 | 00041 <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> byte; |
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49 | 00042 <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> bit; |
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50 | 00043 |
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51 | 00044 <span class="comment">// get current working byte</span> |
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52 | 00045 byte = bitBuffer->dataptr[bitBuffer->bytePos]; |
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53 | 00046 <span class="comment">// read data bit</span> |
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54 | 00047 bit = (byte & (1<<bitBuffer->bitPos))?(1):(0); |
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55 | 00048 |
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56 | 00049 <span class="comment">// increment bit counter</span> |
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57 | 00050 <span class="keywordflow">if</span>(bitBuffer->bitPos < 7) |
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58 | 00051 { |
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59 | 00052 bitBuffer->bitPos++; |
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60 | 00053 } |
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61 | 00054 <span class="keywordflow">else</span> |
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62 | 00055 { |
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63 | 00056 <span class="comment">// increment byte counter</span> |
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64 | 00057 bitBuffer->bitPos = 0; |
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65 | 00058 bitBuffer->bytePos++; |
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66 | 00059 } |
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67 | 00060 |
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68 | 00061 <span class="comment">// return bit value</span> |
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69 | 00062 <span class="keywordflow">return</span> bit; |
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70 | 00063 } |
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71 | 00064 <span class="comment"></span> |
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72 | 00065 <span class="comment">//! Get a bit from a given index into the buffer</span> |
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73 | 00066 <span class="comment"></span><span class="comment">// returns the bit at position [bitIndex] in the buffer</span> |
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74 | <a name="l00067"></a><a class="code" href="group__bitbuf.html#ga3">00067</a> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> <a class="code" href="group__bitbuf.html#ga3">bitbufGetAtIndex</a>(BitBuf* bitBuffer, <span class="keywordtype">unsigned</span> <span class="keywordtype">short</span> bitIndex) |
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75 | 00068 { |
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76 | 00069 <span class="comment">// return bit at index in buffer</span> |
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77 | 00070 <span class="keywordflow">return</span> (bitBuffer->dataptr[bitIndex>>3] & (1<<(bitIndex & 0x07)))?(1):(0); |
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78 | 00071 } |
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79 | 00072 <span class="comment"></span> |
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80 | 00073 <span class="comment">//! Store a bit at the current position in the buffer</span> |
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81 | 00074 <span class="comment"></span><span class="comment">// stores the bit at the current position in the buffer</span> |
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82 | 00075 <span class="comment">// and increments the bit position</span> |
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83 | <a name="l00076"></a><a class="code" href="group__bitbuf.html#ga4">00076</a> <span class="keywordtype">void</span> <a class="code" href="group__bitbuf.html#ga4">bitbufStore</a>(BitBuf* bitBuffer, <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> bit) |
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84 | 00077 { |
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85 | 00078 <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> byte; |
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86 | 00079 <span class="comment">// get current working byte</span> |
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87 | 00080 byte = bitBuffer->dataptr[bitBuffer->bytePos]; |
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88 | 00081 <span class="comment">// apply data bit</span> |
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89 | 00082 <span class="keywordflow">if</span>(bit) |
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90 | 00083 byte |= (1<<bitBuffer->bitPos); |
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91 | 00084 <span class="keywordflow">else</span> |
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92 | 00085 byte &= ~(1<<bitBuffer->bitPos); |
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93 | 00086 <span class="comment">// store data</span> |
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94 | 00087 bitBuffer->dataptr[bitBuffer->bytePos] = byte; |
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95 | 00088 bitBuffer->datalength++; |
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96 | 00089 |
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97 | 00090 <span class="comment">// increment bit counter</span> |
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98 | 00091 <span class="keywordflow">if</span>(bitBuffer->bitPos < 7) |
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99 | 00092 { |
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100 | 00093 bitBuffer->bitPos++; |
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101 | 00094 } |
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102 | 00095 <span class="keywordflow">else</span> |
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103 | 00096 { |
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104 | 00097 <span class="comment">// increment byte counter</span> |
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105 | 00098 bitBuffer->bitPos = 0; |
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106 | 00099 bitBuffer->bytePos++; |
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107 | 00100 } |
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108 | 00101 } |
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109 | 00102 |
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110 | <a name="l00103"></a><a class="code" href="group__bitbuf.html#ga6">00103</a> <span class="keywordtype">void</span> <a class="code" href="group__bitbuf.html#ga6">bitbufReset</a>(BitBuf* bitBuffer) |
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111 | 00104 { |
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112 | 00105 <span class="comment">// reset counters</span> |
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113 | 00106 bitBuffer->bytePos = 0; |
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114 | 00107 bitBuffer->bitPos = 0; |
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115 | 00108 } |
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116 | 00109 |
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117 | <a name="l00110"></a><a class="code" href="group__bitbuf.html#ga7">00110</a> <span class="keywordtype">void</span> <a class="code" href="group__bitbuf.html#ga7">bitbufFlush</a>(BitBuf* bitBuffer) |
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118 | 00111 { |
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119 | 00112 <span class="comment">// flush contents of the buffer</span> |
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120 | 00113 bitBuffer->datalength = 0; |
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121 | 00114 <span class="comment">// reset indexing</span> |
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122 | 00115 <a class="code" href="group__bitbuf.html#ga6">bitbufReset</a>(bitBuffer); |
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123 | 00116 } |
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124 | 00117 |
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125 | <a name="l00118"></a><a class="code" href="group__bitbuf.html#ga5">00118</a> <span class="keywordtype">unsigned</span> <span class="keywordtype">short</span> <a class="code" href="group__bitbuf.html#ga5">bitbufGetDataLength</a>(BitBuf* bitBuffer) |
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126 | 00119 { |
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127 | 00120 <span class="keywordflow">return</span> bitBuffer->datalength; |
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128 | 00121 } |
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129 | 00122 |
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130 | 00123 <span class="comment">/*</span> |
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131 | 00124 <span class="comment">unsigned char bitbufIsNotFull(cBuffer* buffer)</span> |
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132 | 00125 <span class="comment">{</span> |
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133 | 00126 <span class="comment"> // check to see if the buffer has room</span> |
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134 | 00127 <span class="comment"> // return true if there is room</span> |
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135 | 00128 <span class="comment"> return (buffer->datalength < buffer->size);</span> |
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136 | 00129 <span class="comment">}</span> |
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137 | 00130 <span class="comment">*/</span> |
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138 | 00131 |
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139 | </pre></div><hr size="1"><address style="align: right;"><small>Generated on Sun Oct 29 03:41:06 2006 for Procyon AVRlib by |
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140 | <a href="http://www.doxygen.org/index.html"> |
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141 | <img src="doxygen.png" alt="doxygen" align="middle" border="0"></a> 1.4.2 </small></address> |
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