transmission/libtransmission/bitfield.cc

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/*
* This file Copyright (C) 2008-2014 Mnemosyne LLC
*
* It may be used under the GNU GPL versions 2 or 3
* or any future license endorsed by Mnemosyne LLC.
*
*/
#include <algorithm>
#include <cstring> /* memset */
#include "transmission.h"
#include "bitfield.h"
#include "tr-assert.h"
#include "utils.h" /* tr_new0() */
/****
*****
****/
static constexpr int8_t const 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 constexpr size_t countArray(tr_bitfield const* b)
{
size_t ret = 0;
size_t i = b->alloc_count;
while (i > 0)
{
ret += trueBitCount[b->bits[--i]];
}
return ret;
}
static constexpr size_t countRange(tr_bitfield const* b, size_t begin, size_t end)
{
size_t ret = 0;
size_t const first_byte = begin >> 3U;
size_t const last_byte = (end - 1) >> 3U;
if (b->bit_count == 0)
{
return 0;
}
if (first_byte >= b->alloc_count)
{
return 0;
}
TR_ASSERT(begin < end);
TR_ASSERT(b->bits != nullptr);
if (first_byte == last_byte)
{
uint8_t val = b->bits[first_byte];
int 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 const walk_end = std::min(b->alloc_count, last_byte);
/* first byte */
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size_t const first_shift = begin - (first_byte * 8);
uint8_t val = b->bits[first_byte];
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val <<= first_shift;
val >>= first_shift;
ret += trueBitCount[val];
/* middle bytes */
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for (size_t i = first_byte + 1; i < walk_end; ++i)
{
ret += trueBitCount[b->bits[i]];
}
/* last byte */
if (last_byte < b->alloc_count)
{
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size_t const last_shift = (last_byte + 1) * 8 - end;
val = b->bits[last_byte];
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val >>= last_shift;
val <<= last_shift;
ret += trueBitCount[val];
}
}
TR_ASSERT(ret <= (begin - end));
return ret;
}
size_t tr_bitfieldCountRange(tr_bitfield const* 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(tr_bitfield const* 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;
}
/***
****
***/
#ifdef TR_ENABLE_ASSERTS
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static bool tr_bitfieldIsValid(tr_bitfield const* b)
{
TR_ASSERT(b != nullptr);
TR_ASSERT((b->alloc_count == 0) == (b->bits == nullptr));
TR_ASSERT(b->bits == nullptr || b->true_count == countArray(b));
return true;
}
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#endif
size_t tr_bitfieldCountTrueBits(tr_bitfield const* b)
{
TR_ASSERT(tr_bitfieldIsValid(b));
return b->true_count;
}
static constexpr size_t get_bytes_needed(size_t bit_count)
{
return (bit_count >> 3) + ((bit_count & 7) != 0 ? 1 : 0);
}
static void set_all_true(uint8_t* array, size_t bit_count)
{
uint8_t const val = 0xFF;
size_t const n = get_bytes_needed(bit_count);
if (n > 0)
{
memset(array, val, n - 1);
array[n - 1] = val << (n * 8 - bit_count);
}
}
void* tr_bitfieldGetRaw(tr_bitfield const* b, size_t* byte_count)
{
TR_ASSERT(b->bit_count > 0);
size_t const n = get_bytes_needed(b->bit_count);
uint8_t* bits = tr_new0(uint8_t, n);
if (b->alloc_count != 0)
{
TR_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;
bool const has_all = tr_bitfieldHasAll(b);
if (has_all)
{
bytes_needed = get_bytes_needed(std::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 bool tr_bitfieldEnsureNthBitAlloced(tr_bitfield* b, size_t nth)
{
/* count is zero-based, so we need to allocate nth+1 bits before setting the nth */
if (nth == SIZE_MAX)
{
return false;
}
tr_bitfieldEnsureBitsAlloced(b, nth + 1);
return true;
}
static void tr_bitfieldFreeArray(tr_bitfield* b)
{
tr_free(b->bits);
b->bits = nullptr;
b->alloc_count = 0;
}
static void tr_bitfieldSetTrueCount(tr_bitfield* b, size_t n)
{
TR_ASSERT(b->bit_count == 0 || n <= b->bit_count);
b->true_count = n;
if (tr_bitfieldHasAll(b) || tr_bitfieldHasNone(b))
{
tr_bitfieldFreeArray(b);
}
TR_ASSERT(tr_bitfieldIsValid(b));
}
static void tr_bitfieldRebuildTrueCount(tr_bitfield* b)
{
tr_bitfieldSetTrueCount(b, countArray(b));
}
static void tr_bitfieldIncTrueCount(tr_bitfield* b, size_t i)
{
TR_ASSERT(b->bit_count == 0 || i <= b->bit_count);
TR_ASSERT(b->bit_count == 0 || b->true_count <= b->bit_count - i);
tr_bitfieldSetTrueCount(b, b->true_count + i);
}
static void tr_bitfieldDecTrueCount(tr_bitfield* b, size_t i)
{
TR_ASSERT(b->bit_count == 0 || i <= b->bit_count);
TR_ASSERT(b->bit_count == 0 || b->true_count >= 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 = nullptr;
b->alloc_count = 0;
b->have_all_hint = false;
b->have_none_hint = false;
TR_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;
TR_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;
TR_ASSERT(tr_bitfieldIsValid(b));
}
void tr_bitfieldSetFromBitfield(tr_bitfield* b, tr_bitfield const* 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, void const* bits, size_t byte_count, bool bounded)
{
tr_bitfieldFreeArray(b);
b->true_count = 0;
if (bounded)
{
byte_count = std::min(byte_count, get_bytes_needed(b->bit_count));
}
b->bits = static_cast<uint8_t*>(tr_memdup(bits, byte_count));
b->alloc_count = byte_count;
if (bounded)
{
/* ensure the excess bits are set to '0' */
int const excess_bit_count = byte_count * 8 - b->bit_count;
TR_ASSERT(excess_bit_count >= 0);
TR_ASSERT(excess_bit_count <= 7);
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if (excess_bit_count != 0)
{
b->bits[b->alloc_count - 1] &= 0xff << excess_bit_count;
}
}
tr_bitfieldRebuildTrueCount(b);
}
void tr_bitfieldSetFromFlags(tr_bitfield* b, bool const* flags, size_t n)
{
size_t trueCount = 0;
tr_bitfieldFreeArray(b);
tr_bitfieldEnsureBitsAlloced(b, n);
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for (size_t i = 0; i < n; ++i)
{
if (flags[i] && b->bits != nullptr)
{
++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))
{
size_t const offset = nth >> 3U;
if ((b->bits != nullptr) && (offset < b->alloc_count))
{
b->bits[offset] |= 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;
size_t eb;
unsigned char sm;
unsigned char em;
size_t const 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));
if (!tr_bitfieldEnsureNthBitAlloced(b, end))
{
return;
}
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)
{
TR_ASSERT(tr_bitfieldIsValid(b));
if (tr_bitfieldHas(b, nth) && tr_bitfieldEnsureNthBitAlloced(b, nth))
{
b->bits[nth >> 3U] &= 0xff7f >> (nth & 7U);
tr_bitfieldDecTrueCount(b, 1);
}
}
/* Clears bit range [begin, end) to 0 */
void tr_bitfieldRemRange(tr_bitfield* b, size_t begin, size_t end)
{
size_t sb;
size_t eb;
unsigned char sm;
unsigned char em;
size_t const diff = 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)));
if (!tr_bitfieldEnsureNthBitAlloced(b, end))
{
return;
}
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_bitfieldDecTrueCount(b, diff);
}