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106 lines
2.5 KiB
106 lines
2.5 KiB
#include <iostream>
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#include "ASCII85Decode.h"
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using namespace merge_lib;
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static const unsigned long pow85[] = {
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85*85*85*85, 85*85*85, 85*85, 85, 1
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};
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void ASCII85Decode::_wput(std::string &cur,unsigned long tuple, int len)
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{
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switch (len)
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{
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case 4:
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cur+=static_cast<char>(tuple >> 24);
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cur+=static_cast<char>(tuple >> 16);
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cur+=static_cast<char>(tuple >> 8);
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cur+=static_cast<char>(tuple);
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break;
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case 3:
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cur+=static_cast<char>(tuple >> 24);
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cur+=static_cast<char>(tuple >> 16);
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cur+=static_cast<char>(tuple >> 8);
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break;
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case 2:
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cur+=static_cast<char>(tuple >> 24);
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cur+=static_cast<char>(tuple >> 16);
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break;
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case 1:
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cur+=static_cast<char>(tuple >> 24);
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break;
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default:
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std::cerr<<"Asci85Filter - unexpected len = "<<len<<"\n";
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break;
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}
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}
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bool ASCII85Decode::decode(std::string &encoded)
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{
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unsigned long tuple = 0;
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std::string decoded = "";
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int count = 0;
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int size = encoded.size();
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int i = 0;
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bool found = false;
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for(;size;)
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{
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char ch = encoded[i++];
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// sometimes <~ can present.
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switch(ch)
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{
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default:
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if( ch < '!' || ch > 'u' )
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{
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std::cerr<<"bag character in ascii85 block["<<ch<<"]\n";
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return false;
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}
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tuple += (unsigned long)(ch - '!') * pow85[count++];
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if( count == 5)
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{
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_wput(decoded,tuple,4);
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count = 0;
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tuple = 0;
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}
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break;
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case 'z':
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if( count != 0 )
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{
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std::cerr<<"Z inside of acii85 5-tuple!\n";
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return false;
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}
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decoded += "\0\0\0\0";
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break;
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case '~':
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if( --size )
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{
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ch = encoded[i++];
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if( ch == '>')
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{
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if( count > 0 )
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{
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count --;
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tuple += pow85[count];
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_wput(decoded,tuple,count);
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}
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}
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encoded = decoded;
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return true;
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}
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std::cerr<<"~ without > in ascii85 stream!\n = ["<<ch<<"]\n";
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encoded = decoded;
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return false;
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break;
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case '\n':
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case '\r':
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case '\t':
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case ' ':
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case '\0':
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case '\f':
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case '\b':
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case 0177:
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break;
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}
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--size;
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}
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return true;
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}
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