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compress_variable_byte.h
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compress_variable_byte.h
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/*
COMPRESS_VARIABLE_BYTE.H
------------------------
*/
#ifndef COMPRESS_VARIABLE_BYTE_H_
#define COMPRESS_VARIABLE_BYTE_H_
#include "compress.h"
/*
class ANT_COMPRESS_VARIABLE_BYTE
--------------------------------
*/
class ANT_compress_variable_byte : public ANT_compress
{
public:
ANT_compress_variable_byte() {}
virtual ~ANT_compress_variable_byte() {}
virtual long long compress(unsigned char *destination, long long destination_length, uint32_t *source, long long source_integers);
virtual void decompress(uint32_t *destination, unsigned char *source, long long destination_integers);
static inline long compress_bytes_needed(long long docno);
static inline void compress_into(unsigned char *dest, long long docno);
} ;
/*
ANT_COMPRESS_VARIABLE_BYTE::COMPRESS_BYTES_NEEDED()
---------------------------------------------------
*/
inline long ANT_compress_variable_byte::compress_bytes_needed(long long docno)
{
if (docno < ((long long)1 << 7))
return 1;
else if (docno < ((long long)1 << 14))
return 2;
else if (docno < ((long long)1 << 21))
return 3;
else if (docno < ((long long)1 << 28))
return 4;
else if (docno < ((long long)1 << 35))
return 5;
else if (docno < ((long long)1 << 42))
return 6;
else if (docno < ((long long)1 << 49))
return 7;
else if (docno < ((long long)1 << 56))
return 8;
else
return 9;
}
/*
ANT_COMPRESS_VARIABLE_BYTE::COMPRESS_INTO()
-------------------------------------------
*/
inline void ANT_compress_variable_byte::compress_into(unsigned char *dest, long long docno)
{
if (docno < ((long long)1 << 7))
goto one;
else if (docno < ((long long)1 << 14))
goto two;
else if (docno < ((long long)1 << 21))
goto three;
else if (docno < ((long long)1 << 28))
goto four;
else if (docno < ((long long)1 << 35))
goto five;
else if (docno < ((long long)1 << 42))
goto six;
else if (docno < ((long long)1 << 49))
goto seven;
else if (docno < ((long long)1 << 56))
goto eight;
/*
Else we are a nine byte compressed integer
*/
*dest++ = (docno >> 56) & 0x7F;
eight:
*dest++ = (docno >> 49) & 0x7F;
seven:
*dest++ = (docno >> 42) & 0x7F;
six:
*dest++ = (docno >> 35) & 0x7F;
five:
*dest++ = (docno >> 28) & 0x7F;
four:
*dest++ = (docno >> 21) & 0x7F;
three:
*dest++ = (docno >> 14) & 0x7F;
two:
*dest++ = (docno >> 7) & 0x7F;
one:
*dest++ = (docno & 0x7F) | 0x80;
}
#endif /* COMPRESS_VARIABLE_BYTE_H_ */