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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html;charset=iso-8859-1"><title>Procyon AVRlib: bitbuf.c Source File</title><link href="dox.css" rel="stylesheet" type="text/css"></head><body><!-- Generated by Doxygen 1.3.6 --><div class="qindex"><a class="qindex" href="main.html">Main Page</a> | <a class="qindex" href="modules.html">Modules</a> | <a class="qindex" href="annotated.html">Data Structures</a> | <a class="qindex" href="files.html">File List</a> | <a class="qindex" href="functions.html">Data Fields</a> | <a class="qindex" href="globals.html">Globals</a></div><h1>bitbuf.c</h1><a href="bitbuf_8c.html">Go to the documentation of this file.</a><div class="fragment"><pre>00001 <span class="comment">/*! \file bitbuf.c \brief Multipurpose bit buffer structure and methods. */</span>00002 <span class="comment">//*****************************************************************************</span>00003 <span class="comment">//</span>00004 <span class="comment">// File Name : 'bitbuf.c'</span>00005 <span class="comment">// Title : Multipurpose bit buffer structure and methods</span>00006 <span class="comment">// Author : Pascal Stang - Copyright (C) 2001-2002</span>00007 <span class="comment">// Created : 7/10/2002</span>00008 <span class="comment">// Revised : 7/10/2002</span>00009 <span class="comment">// Version : 0.5</span>00010 <span class="comment">// Target MCU : any</span>00011 <span class="comment">// Editor Tabs : 4</span>00012 <span class="comment">//</span>00013 <span class="comment">// This code is distributed under the GNU Public License</span>00014 <span class="comment">// which can be found at http://www.gnu.org/licenses/gpl.txt</span>00015 <span class="comment">//</span>00016 <span class="comment">//*****************************************************************************</span>00017 00018 <span class="preprocessor">#include "<a class="code" href="bitbuf_8h.html">bitbuf.h</a>"</span>00019 00020 <span class="comment">// global variables</span>00021 <span class="comment"></span>00022 <span class="comment">//! Initialize the bit buffer</span>00023 <span class="comment"></span><span class="comment">// sets the start location and size of the buffer in memory</span><a name="l00024"></a><a class="code" href="bitbuf_8h.html#a1">00024</a> <span class="keywordtype">void</span> <a class="code" href="bitbuf_8h.html#a1">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)00025 {00026 <span class="comment">// set start pointer of the buffer</span>00027 bitBuffer->dataptr = start;00028 bitBuffer->size = bytesize;00029 <span class="comment">// initialize indexing and length</span>00030 bitBuffer->dataindex = 0;00031 <a class="code" href="bitbuf_8h.html#a7">bitbufFlush</a>(bitBuffer);00032 }00033 00034 <span class="comment">// access routines</span>00035 <span class="comment"></span>00036 <span class="comment">//! Get a bit from the current position in the buffer</span>00037 <span class="comment"></span><span class="comment">// returns the bit at the current position in the buffer</span>00038 <span class="comment">// and increments the bit position</span><a name="l00039"></a><a class="code" href="bitbuf_8h.html#a2">00039</a> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> <a class="code" href="bitbuf_8h.html#a2">bitbufGet</a>(BitBuf* bitBuffer)00040 {00041 <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> byte;00042 <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> bit;00043 00044 <span class="comment">// get current working byte</span>00045 byte = bitBuffer->dataptr[bitBuffer->bytePos];00046 <span class="comment">// read data bit</span>00047 bit = (byte & (1<<bitBuffer->bitPos))?(1):(0);00048 00049 <span class="comment">// increment bit counter</span>00050 <span class="keywordflow">if</span>(bitBuffer->bitPos < 7)00051 {00052 bitBuffer->bitPos++;00053 }00054 <span class="keywordflow">else</span>00055 {00056 <span class="comment">// increment byte counter</span>00057 bitBuffer->bitPos = 0;00058 bitBuffer->bytePos++;00059 }00060 00061 <span class="comment">// return bit value</span>00062 <span class="keywordflow">return</span> bit;00063 }00064 <span class="comment"></span>00065 <span class="comment">//! Get a bit from a given index into the buffer</span>00066 <span class="comment"></span><span class="comment">// returns the bit at position [bitIndex] in the buffer</span><a name="l00067"></a><a class="code" href="bitbuf_8h.html#a3">00067</a> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> <a class="code" href="bitbuf_8h.html#a3">bitbufGetAtIndex</a>(BitBuf* bitBuffer, <span class="keywordtype">unsigned</span> <span class="keywordtype">short</span> bitIndex)00068 {00069 <span class="comment">// return bit at index in buffer</span>00070 <span class="keywordflow">return</span> (bitBuffer->dataptr[bitIndex>>3] & (1<<(bitIndex & 0x07)))?(1):(0);00071 }00072 <span class="comment"></span>00073 <span class="comment">//! Store a bit at the current position in the buffer</span>00074 <span class="comment"></span><span class="comment">// stores the bit at the current position in the buffer</span>00075 <span class="comment">// and increments the bit position</span><a name="l00076"></a><a class="code" href="bitbuf_8h.html#a4">00076</a> <span class="keywordtype">void</span> <a class="code" href="bitbuf_8h.html#a4">bitbufStore</a>(BitBuf* bitBuffer, <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> bit)00077 {00078 <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> byte;00079 <span class="comment">// get current working byte</span>00080 byte = bitBuffer->dataptr[bitBuffer->bytePos];00081 <span class="comment">// apply data bit</span>00082 <span class="keywordflow">if</span>(bit)00083 byte |= (1<<bitBuffer->bitPos);00084 <span class="keywordflow">else</span>00085 byte &= ~(1<<bitBuffer->bitPos);00086 <span class="comment">// store data</span>00087 bitBuffer->dataptr[bitBuffer->bytePos] = byte;00088 bitBuffer->datalength++;00089 00090 <span class="comment">// increment bit counter</span>00091 <span class="keywordflow">if</span>(bitBuffer->bitPos < 7)00092 {00093 bitBuffer->bitPos++;00094 }00095 <span class="keywordflow">else</span>00096 {00097 <span class="comment">// increment byte counter</span>00098 bitBuffer->bitPos = 0;00099 bitBuffer->bytePos++;00100 }00101 }00102 <a name="l00103"></a><a class="code" href="bitbuf_8h.html#a6">00103</a> <span class="keywordtype">void</span> <a class="code" href="bitbuf_8h.html#a6">bitbufReset</a>(BitBuf* bitBuffer)00104 {00105 <span class="comment">// reset counters</span>00106 bitBuffer->bytePos = 0;00107 bitBuffer->bitPos = 0;00108 }00109 <a name="l00110"></a><a class="code" href="bitbuf_8h.html#a7">00110</a> <span class="keywordtype">void</span> <a class="code" href="bitbuf_8h.html#a7">bitbufFlush</a>(BitBuf* bitBuffer)00111 {00112 <span class="comment">// flush contents of the buffer</span>00113 bitBuffer->datalength = 0;00114 <span class="comment">// reset indexing</span>00115 <a class="code" href="bitbuf_8h.html#a6">bitbufReset</a>(bitBuffer);00116 }00117 <a name="l00118"></a><a class="code" href="bitbuf_8h.html#a5">00118</a> <span class="keywordtype">unsigned</span> <span class="keywordtype">short</span> <a class="code" href="bitbuf_8h.html#a5">bitbufGetDataLength</a>(BitBuf* bitBuffer)00119 {00120 <span class="keywordflow">return</span> bitBuffer->datalength;00121 }00122 00123 <span class="comment">/*</span>00124 <span class="comment">unsigned char bitbufIsNotFull(cBuffer* buffer)</span>00125 <span class="comment">{</span>00126 <span class="comment"> // check to see if the buffer has room</span>00127 <span class="comment"> // return true if there is room</span>00128 <span class="comment"> return (buffer->datalength < buffer->size);</span>00129 <span class="comment">}</span>00130 <span class="comment">*/</span>00131 </pre></div><hr size="1"><address style="align: right;"><small>Generated on Fri Oct 15 03:50:21 2004 for Procyon AVRlib by<a href="http://www.doxygen.org/index.html"><img src="doxygen.png" alt="doxygen" align="middle" border=0 > </a>1.3.6 </small></address></body></html>?? 快捷鍵說明
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