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<h1>adler32.cpp</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">// adler32.cpp - written and placed in the public domain by Wei Dai</span>
<a name="l00002"></a>00002
<a name="l00003"></a>00003 <span class="preprocessor">#include "pch.h"</span>
<a name="l00004"></a>00004 <span class="preprocessor">#include "adler32.h"</span>
<a name="l00005"></a>00005
<a name="l00006"></a>00006 NAMESPACE_BEGIN(CryptoPP)
<a name="l00007"></a>00007
<a name="l00008"></a><a class="code" href="class_adler32.html#a84c3d47f039beab76b5f902ff558ac49">00008</a> void <a class="code" href="class_adler32.html" title="ADLER-32 checksum calculations.">Adler32</a>::Update(const byte *input, <span class="keywordtype">size_t</span> length)
<a name="l00009"></a>00009 {
<a name="l00010"></a>00010 <span class="keyword">const</span> <span class="keywordtype">unsigned</span> <span class="keywordtype">long</span> <a class="code" href="class_b_a_s_e.html">BASE</a> = 65521;
<a name="l00011"></a>00011
<a name="l00012"></a>00012 <span class="keywordtype">unsigned</span> <span class="keywordtype">long</span> s1 = m_s1;
<a name="l00013"></a>00013 <span class="keywordtype">unsigned</span> <span class="keywordtype">long</span> s2 = m_s2;
<a name="l00014"></a>00014
<a name="l00015"></a>00015 <span class="keywordflow">if</span> (length % 8 != 0)
<a name="l00016"></a>00016 {
<a name="l00017"></a>00017 <span class="keywordflow">do</span>
<a name="l00018"></a>00018 {
<a name="l00019"></a>00019 s1 += *input++;
<a name="l00020"></a>00020 s2 += s1;
<a name="l00021"></a>00021 length--;
<a name="l00022"></a>00022 } <span class="keywordflow">while</span> (length % 8 != 0);
<a name="l00023"></a>00023
<a name="l00024"></a>00024 <span class="keywordflow">if</span> (s1 >= BASE)
<a name="l00025"></a>00025 s1 -= BASE;
<a name="l00026"></a>00026 s2 %= BASE;
<a name="l00027"></a>00027 }
<a name="l00028"></a>00028
<a name="l00029"></a>00029 <span class="keywordflow">while</span> (length > 0)
<a name="l00030"></a>00030 {
<a name="l00031"></a>00031 s1 += input[0]; s2 += s1;
<a name="l00032"></a>00032 s1 += input[1]; s2 += s1;
<a name="l00033"></a>00033 s1 += input[2]; s2 += s1;
<a name="l00034"></a>00034 s1 += input[3]; s2 += s1;
<a name="l00035"></a>00035 s1 += input[4]; s2 += s1;
<a name="l00036"></a>00036 s1 += input[5]; s2 += s1;
<a name="l00037"></a>00037 s1 += input[6]; s2 += s1;
<a name="l00038"></a>00038 s1 += input[7]; s2 += s1;
<a name="l00039"></a>00039
<a name="l00040"></a>00040 length -= 8;
<a name="l00041"></a>00041 input += 8;
<a name="l00042"></a>00042
<a name="l00043"></a>00043 <span class="keywordflow">if</span> (s1 >= BASE)
<a name="l00044"></a>00044 s1 -= BASE;
<a name="l00045"></a>00045 <span class="keywordflow">if</span> (length % 0x8000 == 0)
<a name="l00046"></a>00046 s2 %= BASE;
<a name="l00047"></a>00047 }
<a name="l00048"></a>00048
<a name="l00049"></a>00049 assert(s1 < BASE);
<a name="l00050"></a>00050 assert(s2 < BASE);
<a name="l00051"></a>00051
<a name="l00052"></a>00052 m_s1 = (word16)s1;
<a name="l00053"></a>00053 m_s2 = (word16)s2;
<a name="l00054"></a>00054 }
<a name="l00055"></a>00055
<a name="l00056"></a><a class="code" href="class_adler32.html#ae6c17afdf6aeb8b58d771932551b07fa">00056</a> <span class="keywordtype">void</span> <a class="code" href="class_adler32.html#ae6c17afdf6aeb8b58d771932551b07fa" title="truncated version of Final()">Adler32::TruncatedFinal</a>(byte *hash, <span class="keywordtype">size_t</span> size)
<a name="l00057"></a>00057 {
<a name="l00058"></a>00058 ThrowIfInvalidTruncatedSize(size);
<a name="l00059"></a>00059
<a name="l00060"></a>00060 <span class="keywordflow">switch</span> (size)
<a name="l00061"></a>00061 {
<a name="l00062"></a>00062 <span class="keywordflow">default</span>:
<a name="l00063"></a>00063 hash[3] = byte(m_s1);
<a name="l00064"></a>00064 <span class="keywordflow">case</span> 3:
<a name="l00065"></a>00065 hash[2] = byte(m_s1 >> 8);
<a name="l00066"></a>00066 <span class="keywordflow">case</span> 2:
<a name="l00067"></a>00067 hash[1] = byte(m_s2);
<a name="l00068"></a>00068 <span class="keywordflow">case</span> 1:
<a name="l00069"></a>00069 hash[0] = byte(m_s2 >> 8);
<a name="l00070"></a>00070 <span class="keywordflow">case</span> 0:
<a name="l00071"></a>00071 ;
<a name="l00072"></a>00072 }
<a name="l00073"></a>00073
<a name="l00074"></a>00074 Reset();
<a name="l00075"></a>00075 }
<a name="l00076"></a>00076
<a name="l00077"></a>00077 NAMESPACE_END
</pre></div></div>
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