transmission/libtransmission/bitfield.c

253 lines
5.5 KiB
C

/*
* This file Copyright (C) Mnemosyne LLC
*
* This file is licensed by the GPL version 2. Works owned by the
* Transmission project are granted a special exemption to clause 2(b)
* so that the bulk of its code can remain under the MIT license.
* This exemption does not extend to derived works not owned by
* the Transmission project.
*
* $Id$
*/
#include <assert.h>
#include <string.h> /* memset */
#include "transmission.h"
#include "bitfield.h"
#include "bitset.h"
#include "utils.h" /* tr_new0() */
const tr_bitfield TR_BITFIELD_INIT = { NULL, 0, 0 };
tr_bitfield*
tr_bitfieldConstruct( tr_bitfield * b, size_t bitCount )
{
b->bitCount = bitCount;
b->byteCount = ( bitCount + 7u ) / 8u;
b->bits = tr_new0( uint8_t, b->byteCount );
return b;
}
tr_bitfield*
tr_bitfieldDestruct( tr_bitfield * b )
{
if( b )
tr_free( b->bits );
return b;
}
tr_bitfield*
tr_bitfieldNew( size_t bitCount )
{
return tr_bitfieldConstruct( tr_new( tr_bitfield, 1 ), bitCount );
}
void
tr_bitfieldFree( tr_bitfield * b )
{
tr_free( tr_bitfieldDestruct( b ) );
}
void
tr_bitfieldClear( tr_bitfield * bitfield )
{
memset( bitfield->bits, 0, bitfield->byteCount );
}
int
tr_bitfieldAdd( tr_bitfield * bitfield,
size_t nth )
{
assert( bitfield );
assert( bitfield->bits );
if( nth >= bitfield->bitCount )
return -1;
bitfield->bits[nth >> 3u] |= ( 0x80 >> ( nth & 7u ) );
return 0;
}
/* Sets bit range [begin, end) to 1 */
int
tr_bitfieldAddRange( tr_bitfield * b,
size_t begin,
size_t end )
{
size_t sb, eb;
unsigned char sm, em;
end--;
if( ( end >= b->bitCount ) || ( begin > end ) )
return -1;
sb = begin >> 3;
sm = ~( 0xff << ( 8 - ( begin & 7 ) ) );
eb = end >> 3;
em = 0xff << ( 7 - ( end & 7 ) );
if( sb == eb )
{
b->bits[sb] |= ( sm & em );
}
else
{
b->bits[sb] |= sm;
b->bits[eb] |= em;
if( ++sb < eb )
memset ( b->bits + sb, 0xff, eb - sb );
}
return 0;
}
int
tr_bitfieldRem( tr_bitfield * bitfield,
size_t nth )
{
assert( bitfield );
assert( bitfield->bits );
if( nth >= bitfield->bitCount )
return -1;
bitfield->bits[nth >> 3u] &= ( 0xff7f >> ( nth & 7u ) );
return 0;
}
/* Clears bit range [begin, end) to 0 */
int
tr_bitfieldRemRange( tr_bitfield * b,
size_t begin,
size_t end )
{
size_t sb, eb;
unsigned char sm, em;
end--;
if( ( end >= b->bitCount ) || ( begin > end ) )
return -1;
sb = begin >> 3;
sm = 0xff << ( 8 - ( begin & 7 ) );
eb = end >> 3;
em = ~( 0xff << ( 7 - ( end & 7 ) ) );
if( sb == eb )
{
b->bits[sb] &= ( sm | em );
}
else
{
b->bits[sb] &= sm;
b->bits[eb] &= em;
if( ++sb < eb )
memset ( b->bits + sb, 0, eb - sb );
}
return 0;
}
tr_bitfield*
tr_bitfieldOr( tr_bitfield * a, const tr_bitfield * b )
{
uint8_t * ait = a->bits;
const uint8_t * aend = ait + a->byteCount;
const uint8_t * bit = b->bits;
const uint8_t * bend = bit + b->byteCount;
while( ait!=aend && bit!=bend )
*ait++ |= *bit++;
return a;
}
static const int trueBitCount[256] =
{
0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8
};
size_t
tr_bitfieldCountTrueBits( const tr_bitfield* b )
{
size_t ret = 0;
const uint8_t * it, *end;
if( !b )
return 0;
for( it = b->bits, end = it + b->byteCount; it != end; ++it )
ret += trueBitCount[*it];
return ret;
}
size_t
tr_bitfieldCountRange( const tr_bitfield * b, size_t begin, size_t end )
{
size_t ret = 0;
const int first_byte = begin >> 3u;
const int last_byte = ( end - 1 ) >> 3u;
assert( begin < end );
if( first_byte == last_byte )
{
int i;
uint8_t val = b->bits[first_byte];
i = begin - (first_byte * 8);
val <<= i;
val >>= i;
i = (last_byte+1)*8 - end;
val >>= i;
val <<= i;
ret += trueBitCount[val];
}
else
{
int i;
uint8_t val;
/* first byte */
i = begin - (first_byte * 8);
val = b->bits[first_byte];
val <<= i;
val >>= i;
ret += trueBitCount[val];
/* middle bytes */
for( i=first_byte+1; i<last_byte; ++i )
ret += trueBitCount[b->bits[i]];
/* last byte */
i = (last_byte+1)*8 - end;
val = b->bits[last_byte];
val >>= i;
val <<= i;
ret += trueBitCount[val];
}
assert( ret <= ( begin - end ) );
return ret;
}