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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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| 142 | </body> |
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| 143 | </html> |
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