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<h1>buffer.c</h1><a href="buffer_8c.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment">00001 <span class="comment">/*! \file buffer.c \brief Multipurpose byte buffer structure and methods. */</span>
00002 <span class="comment">//*****************************************************************************</span>
00003 <span class="comment">//</span>
00004 <span class="comment">// File Name : 'buffer.c'</span>
00005 <span class="comment">// Title : Multipurpose byte buffer structure and methods</span>
00006 <span class="comment">// Author : Pascal Stang - Copyright (C) 2001-2002</span>
00007 <span class="comment">// Created : 9/23/2001</span>
00008 <span class="comment">// Revised : 9/23/2001</span>
00009 <span class="comment">// Version : 1.0</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="buffer_8h.html">buffer.h</a>"</span>
00019 <span class="preprocessor">#include "<a class="code" href="global_8h.html">global.h</a>"</span>
00020 <span class="preprocessor">#include "avr/io.h"</span>
00021
00022 <span class="preprocessor">#ifndef CRITICAL_SECTION_START</span>
00023 <span class="preprocessor"></span><span class="preprocessor">#define CRITICAL_SECTION_START unsigned char _sreg = SREG; cli()</span>
00024 <span class="preprocessor"></span><span class="preprocessor">#define CRITICAL_SECTION_END SREG = _sreg</span>
00025 <span class="preprocessor"></span><span class="preprocessor">#endif</span>
00026 <span class="preprocessor"></span>
00027 <span class="comment">// global variables</span>
00028
00029 <span class="comment">// initialization</span>
00030
<a name="l00031"></a><a class="code" href="group__buffer.html#ga1">00031</a> <span class="keywordtype">void</span> <a class="code" href="group__buffer.html#ga1">bufferInit</a>(<a class="code" href="structstruct__cBuffer.html">cBuffer</a>* buffer, <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> *start, <span class="keywordtype">unsigned</span> <span class="keywordtype">short</span> size)
00032 {
00033 <span class="comment">// begin critical section</span>
00034 CRITICAL_SECTION_START;
00035 <span class="comment">// set start pointer of the buffer</span>
00036 buffer-><a class="code" href="structstruct__cBuffer.html#o0">dataptr</a> = start;
00037 buffer-><a class="code" href="structstruct__cBuffer.html#o1">size</a> = size;
00038 <span class="comment">// initialize index and length</span>
00039 buffer-><a class="code" href="structstruct__cBuffer.html#o3">dataindex</a> = 0;
00040 buffer-><a class="code" href="structstruct__cBuffer.html#o2">datalength</a> = 0;
00041 <span class="comment">// end critical section</span>
00042 CRITICAL_SECTION_END;
00043 }
00044
00045 <span class="comment">// access routines</span>
<a name="l00046"></a><a class="code" href="group__buffer.html#ga2">00046</a> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> <a class="code" href="group__buffer.html#ga2">bufferGetFromFront</a>(<a class="code" href="structstruct__cBuffer.html">cBuffer</a>* buffer)
00047 {
00048 <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> data = 0;
00049 <span class="comment">// begin critical section</span>
00050 CRITICAL_SECTION_START;
00051 <span class="comment">// check to see if there's data in the buffer</span>
00052 <span class="keywordflow">if</span>(buffer-><a class="code" href="structstruct__cBuffer.html#o2">datalength</a>)
00053 {
00054 <span class="comment">// get the first character from buffer</span>
00055 data = buffer-><a class="code" href="structstruct__cBuffer.html#o0">dataptr</a>[buffer-><a class="code" href="structstruct__cBuffer.html#o3">dataindex</a>];
00056 <span class="comment">// move index down and decrement length</span>
00057 buffer-><a class="code" href="structstruct__cBuffer.html#o3">dataindex</a>++;
00058 <span class="keywordflow">if</span>(buffer-><a class="code" href="structstruct__cBuffer.html#o3">dataindex</a> >= buffer-><a class="code" href="structstruct__cBuffer.html#o1">size</a>)
00059 {
00060 buffer-><a class="code" href="structstruct__cBuffer.html#o3">dataindex</a> -= buffer-><a class="code" href="structstruct__cBuffer.html#o1">size</a>;
00061 }
00062 buffer-><a class="code" href="structstruct__cBuffer.html#o2">datalength</a>--;
00063 }
00064 <span class="comment">// end critical section</span>
00065 CRITICAL_SECTION_END;
00066 <span class="comment">// return</span>
00067 <span class="keywordflow">return</span> data;
00068 }
00069
<a name="l00070"></a><a class="code" href="group__buffer.html#ga3">00070</a> <span class="keywordtype">void</span> <a class="code" href="group__buffer.html#ga3">bufferDumpFromFront</a>(<a class="code" href="structstruct__cBuffer.html">cBuffer</a>* buffer, <span class="keywordtype">unsigned</span> <span class="keywordtype">short</span> numbytes)
00071 {
00072 <span class="comment">// begin critical section</span>
00073 CRITICAL_SECTION_START;
00074 <span class="comment">// dump numbytes from the front of the buffer</span>
00075 <span class="comment">// are we dumping less than the entire buffer?</span>
00076 <span class="keywordflow">if</span>(numbytes < buffer-><a class="code" href="structstruct__cBuffer.html#o2">datalength</a>)
00077 {
00078 <span class="comment">// move index down by numbytes and decrement length by numbytes</span>
00079 buffer-><a class="code" href="structstruct__cBuffer.html#o3">dataindex</a> += numbytes;
00080 <span class="keywordflow">if</span>(buffer-><a class="code" href="structstruct__cBuffer.html#o3">dataindex</a> >= buffer-><a class="code" href="structstruct__cBuffer.html#o1">size</a>)
00081 {
00082 buffer-><a class="code" href="structstruct__cBuffer.html#o3">dataindex</a> -= buffer-><a class="code" href="structstruct__cBuffer.html#o1">size</a>;
00083 }
00084 buffer-><a class="code" href="structstruct__cBuffer.html#o2">datalength</a> -= numbytes;
00085 }
00086 <span class="keywordflow">else</span>
00087 {
00088 <span class="comment">// flush the whole buffer</span>
00089 buffer-><a class="code" href="structstruct__cBuffer.html#o2">datalength</a> = 0;
00090 }
00091 <span class="comment">// end critical section</span>
00092 CRITICAL_SECTION_END;
00093 }
00094
<a name="l00095"></a><a class="code" href="group__buffer.html#ga4">00095</a> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> <a class="code" href="group__buffer.html#ga4">bufferGetAtIndex</a>(<a class="code" href="structstruct__cBuffer.html">cBuffer</a>* buffer, <span class="keywordtype">unsigned</span> <span class="keywordtype">short</span> index)
00096 {
00097 <span class="comment">// begin critical section</span>
00098 CRITICAL_SECTION_START;
00099 <span class="comment">// return character at index in buffer</span>
00100 <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> data = buffer-><a class="code" href="structstruct__cBuffer.html#o0">dataptr</a>[(buffer-><a class="code" href="structstruct__cBuffer.html#o3">dataindex</a>+index)%(buffer-><a class="code" href="structstruct__cBuffer.html#o1">size</a>)];
00101 <span class="comment">// end critical section</span>
00102 CRITICAL_SECTION_END;
00103 <span class="keywordflow">return</span> data;
00104 }
00105
<a name="l00106"></a><a class="code" href="group__buffer.html#ga5">00106</a> <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> <a class="code" href="group__buffer.html#ga5">bufferAddToEnd</a>(<a class="code" href="structstruct__cBuffer.html">cBuffer</a>* buffer, <span class="keywordtype">unsigned</span> <span class="keywordtype">char</span> data)
00107 {
00108 <span class="comment">// begin critical section</span>
00109 CRITICAL_SECTION_START;
00110 <span class="comment">// make sure the buffer has room</span>
00111 <span class="keywordflow">if</span>(buffer-><a class="code" href="structstruct__cBuffer.html#o2">datalength</a> < buffer-><a class="code" href="structstruct__cBuffer.html#o1">size</a>)
00112 {
00113 <span class="comment">// save data byte at end of buffer</span>
00114 buffer-><a class="code" href="structstruct__cBuffer.html#o0">dataptr</a>[(buffer-><a class="code" href="structstruct__cBuffer.html#o3">dataindex</a> + buffer-><a class="code" href="structstruct__cBuffer.html#o2">datalength</a>) % buffer-><a class="code" href="structstruct__cBuffer.html#o1">size</a>] = data;
00115 <span class="comment">// increment the length</span>
00116 buffer-><a class="code" href="structstruct__cBuffer.html#o2">datalength</a>++;
00117 <span class="comment">// end critical section</span>
00118 CRITICAL_SECTION_END;
00119 <span class="comment">// return success</span>
00120 <span class="keywordflow">return</span> -1;
00121 }
00122 <span class="comment">// end critical section</span>
00123 CRITICAL_SECTION_END;
00124 <span class="comment">// return failure</span>
00125 <span class="keywordflow">return</span> 0;
00126 }
00127
<a name="l00128"></a><a class="code" href="group__buffer.html#ga6">00128</a> <span class="keywordtype">unsigned</span> <span class="keywordtype">short</span> <a class="code" href="group__buffer.html#ga6">bufferIsNotFull</a>(<a class="code" href="structstruct__cBuffer.html">cBuffer</a>* buffer)
00129 {
00130 <span class="comment">// begin critical section</span>
00131 CRITICAL_SECTION_START;
00132 <span class="comment">// check to see if the buffer has room</span>
00133 <span class="comment">// return true if there is room</span>
00134 <span class="keywordtype">unsigned</span> <span class="keywordtype">short</span> bytesleft = (buffer-><a class="code" href="structstruct__cBuffer.html#o1">size</a> - buffer-><a class="code" href="structstruct__cBuffer.html#o2">datalength</a>);
00135 <span class="comment">// end critical section</span>
00136 CRITICAL_SECTION_END;
00137 <span class="keywordflow">return</span> bytesleft;
00138 }
00139
<a name="l00140"></a><a class="code" href="group__buffer.html#ga7">00140</a> <span class="keywordtype">void</span> <a class="code" href="group__buffer.html#ga7">bufferFlush</a>(<a class="code" href="structstruct__cBuffer.html">cBuffer</a>* buffer)
00141 {
00142 <span class="comment">// begin critical section</span>
00143 CRITICAL_SECTION_START;
00144 <span class="comment">// flush contents of the buffer</span>
00145 buffer-><a class="code" href="structstruct__cBuffer.html#o2">datalength</a> = 0;
00146 <span class="comment">// end critical section</span>
00147 CRITICAL_SECTION_END;
00148 }
00149
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