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