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<hr><h1>swcomprs.cpp</h1><div class="fragment"><pre>00001 <font class="comment">/******************************************************************************</font>
00002 <font class="comment"> * swcomprs.cpp - code for class 'SWCompress'- a driver class that provides</font>
00003 <font class="comment"> * compression utilities.</font>
00004 <font class="comment"> */</font>
00005
00006 <font class="preprocessor">#include <string.h></font>
00007 <font class="preprocessor">#include <stdlib.h></font>
00008 <font class="preprocessor">#include <swcomprs.h></font>
00009
00010
00011 <font class="comment">/******************************************************************************</font>
00012 <font class="comment"> * SWCompress Constructor - Initializes data for instance of SWCompress</font>
00013 <font class="comment"> *</font>
00014 <font class="comment"> */</font>
00015
00016 SWCompress::SWCompress()
00017 {
00018 buf = zbuf = 0;
00019 Init();
00020 }
00021
00022
00023 <font class="comment">/******************************************************************************</font>
00024 <font class="comment"> * SWCompress Destructor - Cleans up instance of SWCompress</font>
00025 <font class="comment"> */</font>
00026
00027 SWCompress::~SWCompress()
00028 {
00029 <font class="keywordflow">if</font> (zbuf)
00030 free(zbuf);
00031
00032 <font class="keywordflow">if</font> (buf)
00033 free(buf);
00034 }
00035
00036
00037 <font class="keywordtype">void</font> SWCompress::Init()
00038 {
00039 <font class="keywordflow">if</font> (buf)
00040 free(buf);
00041
00042 <font class="keywordflow">if</font> (zbuf)
00043 free(zbuf);
00044
00045 buf = 0;
00046 zbuf = 0;
00047 direct = 0;
00048 zlen = 0;
00049 slen = 0;
00050 zpos = 0;
00051 pos = 0;
00052 }
00053
00054
00055 <font class="keywordtype">char</font> *SWCompress::Buf(<font class="keyword">const</font> <font class="keywordtype">char</font> *ibuf, <font class="keywordtype">unsigned</font> <font class="keywordtype">long</font> *len) {
00056 <font class="comment">// setting an uncompressed buffer</font>
00057 <font class="keywordflow">if</font> (ibuf) {
00058 Init();
00059 slen = (len) ? *len : strlen(ibuf);
00060 buf = (<font class="keywordtype">char</font> *) calloc(slen + 1, 1);
00061 memcpy(buf, ibuf, slen);
00062 }
00063
00064 <font class="comment">// getting an uncompressed buffer</font>
00065 <font class="keywordflow">if</font> (!buf) {
00066 buf = (<font class="keywordtype">char</font> *)calloc(1,1); <font class="comment">// be sure we at least allocate an empty buf for return;</font>
00067 direct = 1;
00068 Decode();
00069 <font class="comment">// slen = strlen(buf);</font>
00070 <font class="keywordflow">if</font> (len)
00071 *len = slen;
00072 }
00073 <font class="keywordflow">return</font> buf;
00074 }
00075
00076
00077 <font class="keywordtype">char</font> *SWCompress::zBuf(<font class="keywordtype">unsigned</font> <font class="keywordtype">long</font> *len, <font class="keywordtype">char</font> *ibuf)
00078 {
00079 <font class="comment">// setting a compressed buffer</font>
00080 <font class="keywordflow">if</font> (ibuf) {
00081 Init();
00082 zbuf = (<font class="keywordtype">char</font> *) malloc(*len);
00083 memcpy(zbuf, ibuf, *len);
00084 zlen = *len;
00085 }
00086
00087 <font class="comment">// getting a compressed buffer</font>
00088 <font class="keywordflow">if</font> (!zbuf) {
00089 direct = 0;
00090 Encode();
00091 }
00092
00093 *len = zlen;
00094 <font class="keywordflow">return</font> zbuf;
00095 }
00096
00097
00098 <font class="keywordtype">unsigned</font> <font class="keywordtype">long</font> SWCompress::GetChars(<font class="keywordtype">char</font> *ibuf, <font class="keywordtype">unsigned</font> <font class="keywordtype">long</font> len)
00099 {
00100 <font class="keywordflow">if</font> (direct) {
00101 len = (((zlen - zpos) > (unsigned)len) ? len : zlen - zpos);
00102 <font class="keywordflow">if</font> (len > 0) {
00103 memmove(ibuf, &zbuf[zpos], len);
00104 zpos += len;
00105 }
00106 }
00107 <font class="keywordflow">else</font> {
00108 <font class="comment">// slen = strlen(buf);</font>
00109 len = (((slen - pos) > (unsigned)len) ? len : slen - pos);
00110 <font class="keywordflow">if</font> (len > 0) {
00111 memmove(ibuf, &buf[pos], len);
00112 pos += len;
00113 }
00114 }
00115 <font class="keywordflow">return</font> len;
00116 }
00117
00118
00119 <font class="keywordtype">unsigned</font> <font class="keywordtype">long</font> SWCompress::SendChars(<font class="keywordtype">char</font> *ibuf, <font class="keywordtype">unsigned</font> <font class="keywordtype">long</font> len)
00120 {
00121 <font class="keywordflow">if</font> (direct) {
00122 <font class="keywordflow">if</font> (buf) {
00123 <font class="comment">// slen = strlen(buf);</font>
00124 <font class="keywordflow">if</font> ((pos + len) > (unsigned)slen) {
00125 buf = (<font class="keywordtype">char</font> *) realloc(buf, pos + len + 1024);
00126 memset(&buf[pos], 0, len + 1024);
00127 }
00128 }
00129 <font class="keywordflow">else</font> buf = (<font class="keywordtype">char</font> *)calloc(1, len + 1024);
00130 memmove(&buf[pos], ibuf, len);
00131 pos += len;
00132 }
00133 <font class="keywordflow">else</font> {
00134 <font class="keywordflow">if</font> (zbuf) {
00135 <font class="keywordflow">if</font> ((zpos + len) > zlen) {
00136 zbuf = (<font class="keywordtype">char</font> *) realloc(zbuf, zpos + len + 1024);
00137 zlen = zpos + len + 1024;
00138 }
00139 }
00140 <font class="keywordflow">else</font> {
00141 zbuf = (<font class="keywordtype">char</font> *)calloc(1, len + 1024);
00142 zlen = len + 1024;
00143 }
00144 memmove(&zbuf[zpos], ibuf, len);
00145 zpos += len;
00146 }
00147 <font class="keywordflow">return</font> len;
00148 }
00149
00150
00151 <font class="comment">/******************************************************************************</font>
00152 <font class="comment"> * SWCompress::Encode - This function "encodes" the input stream into the</font>
00153 <font class="comment"> * output stream.</font>
00154 <font class="comment"> * The GetChars() and SendChars() functions are</font>
00155 <font class="comment"> * used to separate this method from the actual</font>
00156 <font class="comment"> * i/o.</font>
00157 <font class="comment"> */</font>
00158
00159 <font class="keywordtype">void</font> SWCompress::Encode(<font class="keywordtype">void</font>)
00160 {
00161 cycleStream();
00162 }
00163
00164
00165 <font class="comment">/******************************************************************************</font>
00166 <font class="comment"> * SWCompress::Decode - This function "decodes" the input stream into the</font>
00167 <font class="comment"> * output stream.</font>
00168 <font class="comment"> * The GetChars() and SendChars() functions are</font>
00169 <font class="comment"> * used to separate this method from the actual</font>
00170 <font class="comment"> * i/o.</font>
00171 <font class="comment"> */</font>
00172
00173 <font class="keywordtype">void</font> SWCompress::Decode(<font class="keywordtype">void</font>)
00174 {
00175 cycleStream();
00176 }
00177
00178
00179 <font class="keywordtype">void</font> SWCompress::cycleStream() {
00180 <font class="keywordtype">char</font> buf[1024];
00181 <font class="keywordtype">unsigned</font> <font class="keywordtype">long</font> len, totlen = 0;
00182
00183 <font class="keywordflow">do</font> {
00184 len = GetChars(buf, 1024);
00185 <font class="keywordflow">if</font> (len)
00186 totlen += SendChars(buf, len);
00187 } <font class="keywordflow">while</font> (len == 1024);
00188
00189 zlen = slen = totlen;
00190 }
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