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OpenBoard/thirdparty/mera/pdf-merger/ASCII85Decode.cpp

106 lines
2.5 KiB

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