новые иконки в OpenBoard
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
OpenBoard/thirdparty/mera/pdf-merger/RunLengthDecode.cpp

44 lines
1.1 KiB

#include "RunLengthDecode.h"
using namespace merge_lib;
/* The encoded data is a sequence of
runs, where each run consists of a length byte followed by 1 to 128 bytes of data. If
the length byte is in the range 0 to 127, the following length + 1 (1 to 128) bytes
are copied literally during decompression. If length is in the range 129 to 255, the
following single byte is to be copied 257 - length (2 to 128) times during decom-
pression. A length value of 128 denotes EOD. */
// Function performs RunLength Decoder for PDF, very simple
bool RunLengthDecode::decode(std::string & encoded)
{
std::string decoded;
for(unsigned enci = 0;enci < encoded.size();)
{
unsigned char c = encoded[enci++];
if( c == 128 )
{
break; //EOD
}
else if( c < 128 )
{
for(int j = 0; j < (c+1);j++)
{
decoded.append(1,encoded[enci]);
}
enci++;
}
else
{
for(int j = 0; j < (257 - c);j++)
{
decoded.append(1,encoded[enci]);
}
enci++;
}
}
return true;
}