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 ret = 0;
ssize_t i = b->alloc_count;
while (--i >= 0)
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;
const size_t walk_end = MIN (b->alloc_count, last_byte);
/* 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<walk_end; ++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);
}
bool
tr_bitfieldHas (const tr_bitfield * b, size_t n)
{
if (tr_bitfieldHasAll (b))
return true;
if (tr_bitfieldHasNone (b))
return false;
if (n>>3u >= b->alloc_count)
return false;
return (b->bits[n>>3u] << (n & 7u) & 0x80) != 0;
}
/***
****
***/
static bool
tr_bitfieldIsValid (const tr_bitfield * b UNUSED)
{
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)
{
assert (b->alloc_count <= n);
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 n)
{
size_t bytes_needed;
const bool has_all = tr_bitfieldHasAll (b);
if (has_all)
bytes_needed = get_bytes_needed (MAX (n, b->true_count));
else
bytes_needed = get_bytes_needed (n);
if (b->alloc_count < bytes_needed)
{
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;
if (has_all)
set_all_true (b->bits, b->true_count);
}
}
static void
tr_bitfieldEnsureNthBitAlloced (tr_bitfield * b, size_t nth)
{
/* count is zero-based, so we need to allocate nth+1 bits before setting the nth */
tr_bitfieldEnsureBitsAlloced (b, nth + 1);
}
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, true);
}
void
tr_bitfieldSetRaw (tr_bitfield * b, const void * bits, size_t byte_count, bool bounded)
{
tr_bitfieldFreeArray (b);
b->true_count = 0;
if (bounded)
byte_count = MIN (byte_count, get_bytes_needed (b->bit_count));
b->bits = tr_memdup (bits, byte_count);
b->alloc_count = byte_count;
if (bounded)
{
/* ensure the excess bits are set to '0' */
const int excess_bit_count = byte_count*8 - b->bit_count;
assert (excess_bit_count >= 0);
assert (excess_bit_count <= 7);
if (excess_bit_count)
b->bits[b->alloc_count-1] &= ((0xff) << excess_bit_count);
}
tr_bitfieldRebuildTrueCount (b);
}
void
tr_bitfieldSetFromFlags (tr_bitfield * b, const bool * flags, size_t n)
{
size_t i;
size_t trueCount = 0;
tr_bitfieldFreeArray (b);
tr_bitfieldEnsureBitsAlloced (b, n);
for (i=0; i<n; ++i)
{
if (flags[i])
{
++trueCount;
b->bits[i >> 3u] |= (0x80 >> (i & 7u));
}
}
tr_bitfieldSetTrueCount (b, trueCount);
}
void
tr_bitfieldAdd (tr_bitfield * b, size_t nth)
{
if (!tr_bitfieldHas (b, nth))
{
tr_bitfieldEnsureNthBitAlloced (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_bitfieldEnsureNthBitAlloced (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_bitfieldEnsureNthBitAlloced (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_bitfieldEnsureNthBitAlloced (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);
}