transmission/libtransmission/bitfield.c

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/*
* 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 <stdlib.h> /* realloc() */
#include <string.h> /* memset */
#include "transmission.h"
#include "bitfield.h"
#include "utils.h" /* tr_new0() */
const tr_bitfield TR_BITFIELD_INIT = { NULL, 0, 0, 0, false, false };
/****
*****
****/
static const int8_t 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
};
static size_t
countArray( const tr_bitfield * b )
{
size_t i;
size_t ret = 0;
for( i=0; i<b->alloc_count; ++i )
ret += trueBitCount[b->bits[i]];
return ret;
}
static size_t
countRange( const tr_bitfield * b, size_t begin, size_t end )
{
size_t ret = 0;
const size_t first_byte = begin >> 3u;
const size_t last_byte = ( end - 1 ) >> 3u;
if( !b->bit_count )
return 0;
if( first_byte >= b->alloc_count )
return 0;
assert( begin < end );
assert( b->bits != NULL );
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
{
size_t 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<b->alloc_count && i<last_byte; ++i )
ret += trueBitCount[b->bits[i]];
/* last byte */
if( last_byte < b->alloc_count ) {
i = (last_byte+1)*8 - end;
val = b->bits[last_byte];
val >>= i;
val <<= i;
ret += trueBitCount[val];
}
}
assert( ret <= ( begin - end ) );
return ret;
}
size_t
tr_bitfieldCountRange( const tr_bitfield * b, size_t begin, size_t end )
{
if( tr_bitfieldHasAll( b ) )
return end - begin;
if( tr_bitfieldHasNone( b ) )
return 0;
return countRange( b, begin, end );
}
/***
****
***/
static bool
tr_bitfieldIsValid( const tr_bitfield * b )
{
assert( b != NULL );
assert( ( b->alloc_count == 0 ) == ( b->bits == 0 ) );
assert( !b->bits || ( b->true_count == countArray ( b ) ) );
return true;
}
size_t
tr_bitfieldCountTrueBits( const tr_bitfield * b )
{
tr_bitfieldIsValid( b );
return b->true_count;
}
static size_t
get_bytes_needed( size_t bit_count )
{
return ( bit_count + 7u ) / 8u;
}
static void
set_all_true( uint8_t * array, size_t bit_count )
{
const uint8_t val = 0xFF;
const size_t n = get_bytes_needed( bit_count );
memset( array, val, n-1 );
array[n-1] = val << (n*8 - bit_count);
}
void*
tr_bitfieldGetRaw( const tr_bitfield * b, size_t * byte_count )
{
const size_t n = get_bytes_needed( b->bit_count );
uint8_t * bits = tr_new0( uint8_t, n );
assert( b->bit_count > 0 );
if( b->alloc_count )
memcpy( bits, b->bits, b->alloc_count );
else if( tr_bitfieldHasAll( b ) )
set_all_true( bits, b->bit_count );
*byte_count = n;
return bits;
}
static void
tr_bitfieldEnsureBitsAlloced( tr_bitfield * b, size_t nth )
{
size_t bytes_needed;
const bool has_all = tr_bitfieldHasAll( b );
assert( tr_bitfieldIsValid( b ) );
if( has_all )
bytes_needed = get_bytes_needed( MAX( nth, b->true_count ) + 1 );
else
bytes_needed = get_bytes_needed( nth + 1 );
if( b->alloc_count < bytes_needed )
{
const size_t old_count = countArray( b );
b->bits = tr_renew( uint8_t, b->bits, bytes_needed );
memset( b->bits + b->alloc_count, 0, bytes_needed - b->alloc_count );
b->alloc_count = bytes_needed;
assert( old_count == countArray( b ) );
if( has_all )
set_all_true( b->bits, b->true_count );
}
assert( tr_bitfieldIsValid( b ) );
}
static void
tr_bitfieldFreeArray( tr_bitfield * b )
{
tr_free( b->bits );
b->bits = NULL;
b->alloc_count = 0;
}
static void
tr_bitfieldSetTrueCount( tr_bitfield * b, size_t n )
{
b->true_count = n;
if( tr_bitfieldHasAll( b ) || tr_bitfieldHasNone( b ) )
tr_bitfieldFreeArray( b );
assert( tr_bitfieldIsValid( b ) );
}
static void
tr_bitfieldRebuildTrueCount( tr_bitfield * b )
{
tr_bitfieldSetTrueCount( b, countArray( b ) );
}
static void
tr_bitfieldIncTrueCount( tr_bitfield * b, int i )
{
tr_bitfieldSetTrueCount( b, b->true_count + i );
}
/****
*****
****/
void
tr_bitfieldConstruct( tr_bitfield * b, size_t bit_count )
{
b->bit_count = bit_count;
b->true_count = 0;
b->bits = NULL;
b->alloc_count = 0;
b->have_all_hint = false;
b->have_none_hint = false;
assert( tr_bitfieldIsValid( b ) );
}
void
tr_bitfieldSetHasNone( tr_bitfield * b )
{
tr_bitfieldFreeArray( b );
b->true_count = 0;
b->have_all_hint = false;
b->have_none_hint = true;
assert( tr_bitfieldIsValid( b ) );
}
void
tr_bitfieldSetHasAll( tr_bitfield * b )
{
tr_bitfieldFreeArray( b );
b->true_count = b->bit_count;
b->have_all_hint = true;
b->have_none_hint = false;
assert( tr_bitfieldIsValid( b ) );
}
void
tr_bitfieldSetFromBitfield( tr_bitfield * b, const tr_bitfield * src )
{
if( tr_bitfieldHasAll( src ) )
tr_bitfieldSetHasAll( b );
else if( tr_bitfieldHasNone( src ) )
tr_bitfieldSetHasNone( b );
else
tr_bitfieldSetRaw( b, src->bits, src->alloc_count );
}
void
tr_bitfieldSetRaw( tr_bitfield * b, const void * bits, size_t byte_count )
{
tr_bitfieldFreeArray( b );
b->true_count = 0;
b->bits = tr_memdup( bits, byte_count );
b->alloc_count = byte_count;
tr_bitfieldRebuildTrueCount( b );
}
void
tr_bitfieldAdd( tr_bitfield * b, size_t nth )
{
if( !tr_bitfieldHas( b, nth ) )
{
tr_bitfieldEnsureBitsAlloced( b, nth );
b->bits[nth >> 3u] |= ( 0x80 >> ( nth & 7u ) );
tr_bitfieldIncTrueCount( b, 1 );
}
}
/* Sets bit range [begin, end) to 1 */
void
tr_bitfieldAddRange( tr_bitfield * b, size_t begin, size_t end )
{
size_t sb, eb;
unsigned char sm, em;
const size_t diff = (end-begin) - tr_bitfieldCountRange( b, begin, end );
if( diff == 0 )
return;
end--;
if( ( end >= b->bit_count ) || ( begin > end ) )
return;
sb = begin >> 3;
sm = ~( 0xff << ( 8 - ( begin & 7 ) ) );
eb = end >> 3;
em = 0xff << ( 7 - ( end & 7 ) );
tr_bitfieldEnsureBitsAlloced( b, end );
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 );
}
tr_bitfieldIncTrueCount( b, diff );
}
void
tr_bitfieldRem( tr_bitfield * b, size_t nth )
{
assert( tr_bitfieldIsValid( b ) );
if( !tr_bitfieldHas( b, nth ) )
{
tr_bitfieldEnsureBitsAlloced( b, nth );
b->bits[nth >> 3u] &= ( 0xff7f >> ( nth & 7u ) );
tr_bitfieldIncTrueCount( b, -1 );
}
}
/* Clears bit range [begin, end) to 0 */
void
tr_bitfieldRemRange( tr_bitfield * b, size_t begin, size_t end )
{
size_t sb, eb;
unsigned char sm, em;
const size_t diff = tr_bitfieldCountRange( b, begin, end );
if( !diff )
return;
end--;
if( ( end >= b->bit_count ) || ( begin > end ) )
return;
sb = begin >> 3;
sm = 0xff << ( 8 - ( begin & 7 ) );
eb = end >> 3;
em = ~( 0xff << ( 7 - ( end & 7 ) ) );
tr_bitfieldEnsureBitsAlloced( b, end );
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 );
}
tr_bitfieldIncTrueCount( b, -diff );
}