box2d_sys 0.2.1

Bindings for Box2D v3.0
Documentation 
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// SPDX-FileCopyrightText: 2023 Erin Catto
// SPDX-License-Identifier: MIT

#include "bitset.h"

#include <string.h>

b2BitSet b2CreateBitSet( uint32_t bitCapacity )
{
	b2BitSet bitSet = { 0 };

	bitSet.blockCapacity = ( bitCapacity + sizeof( uint64_t ) * 8 - 1 ) / ( sizeof( uint64_t ) * 8 );
	bitSet.blockCount = 0;
	bitSet.bits = b2Alloc( bitSet.blockCapacity * sizeof( uint64_t ) );
	memset( bitSet.bits, 0, bitSet.blockCapacity * sizeof( uint64_t ) );
	return bitSet;
}

void b2DestroyBitSet( b2BitSet* bitSet )
{
	b2Free( bitSet->bits, bitSet->blockCapacity * sizeof( uint64_t ) );
	bitSet->blockCapacity = 0;
	bitSet->blockCount = 0;
	bitSet->bits = NULL;
}

void b2SetBitCountAndClear( b2BitSet* bitSet, uint32_t bitCount )
{
	uint32_t blockCount = ( bitCount + sizeof( uint64_t ) * 8 - 1 ) / ( sizeof( uint64_t ) * 8 );
	if ( bitSet->blockCapacity < blockCount )
	{
		b2DestroyBitSet( bitSet );
		uint32_t newBitCapacity = bitCount + ( bitCount >> 1 );
		*bitSet = b2CreateBitSet( newBitCapacity );
	}

	bitSet->blockCount = blockCount;
	memset( bitSet->bits, 0, bitSet->blockCount * sizeof( uint64_t ) );
}

void b2GrowBitSet( b2BitSet* bitSet, uint32_t blockCount )
{
	B2_ASSERT( blockCount > bitSet->blockCount );
	if ( blockCount > bitSet->blockCapacity )
	{
		uint32_t oldCapacity = bitSet->blockCapacity;
		bitSet->blockCapacity = blockCount + blockCount / 2;
		uint64_t* newBits = b2Alloc( bitSet->blockCapacity * sizeof( uint64_t ) );
		memset( newBits, 0, bitSet->blockCapacity * sizeof( uint64_t ) );
		B2_ASSERT( bitSet->bits != NULL );
		memcpy( newBits, bitSet->bits, oldCapacity * sizeof( uint64_t ) );
		b2Free( bitSet->bits, oldCapacity * sizeof( uint64_t ) );
		bitSet->bits = newBits;
	}

	bitSet->blockCount = blockCount;
}

void b2InPlaceUnion( b2BitSet* B2_RESTRICT setA, const b2BitSet* B2_RESTRICT setB )
{
	B2_ASSERT( setA->blockCount == setB->blockCount );
	uint32_t blockCount = setA->blockCount;
	for ( uint32_t i = 0; i < blockCount; ++i )
	{
		setA->bits[i] |= setB->bits[i];
	}
}