id.h

// SPDX-FileCopyrightText: 2023 Erin Catto
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include <stdint.h>
 
// Note: this file should be stand-alone


typedef struct b2WorldId
{
    uint16_t index1;
    uint16_t generation;
} b2WorldId;

typedef struct b2BodyId
{
    int32_t index1;
    uint16_t world0;
    uint16_t generation;
} b2BodyId;

typedef struct b2ShapeId
{
    int32_t index1;
    uint16_t world0;
    uint16_t generation;
} b2ShapeId;

typedef struct b2ChainId
{
    int32_t index1;
    uint16_t world0;
    uint16_t generation;
} b2ChainId;

typedef struct b2JointId
{
    int32_t index1;
    uint16_t world0;
    uint16_t generation;
} b2JointId;

typedef struct b2ContactId
{
    int32_t index1;
    uint16_t world0;
    int16_t padding;
    uint32_t generation;
} b2ContactId;
 
// clang-format off
#ifdef __cplusplus
#define B2_NULL_ID {}
#define B2_ID_INLINE inline
#else
#define B2_NULL_ID { 0 }
#define B2_ID_INLINE static inline
#endif
// clang-format on

static const b2WorldId b2_nullWorldId = B2_NULL_ID;
static const b2BodyId b2_nullBodyId = B2_NULL_ID;
static const b2ShapeId b2_nullShapeId = B2_NULL_ID;
static const b2ChainId b2_nullChainId = B2_NULL_ID;
static const b2JointId b2_nullJointId = B2_NULL_ID;
static const b2ContactId b2_nullContactId = B2_NULL_ID;

#define B2_IS_NULL( id ) ( ( id ).index1 == 0 )

#define B2_IS_NON_NULL( id ) ( ( id ).index1 != 0 )

#define B2_ID_EQUALS( id1, id2 )                                                                   \
    ( ( id1 ).index1 == ( id2 ).index1 && ( id1 ).world0 == ( id2 ).world0 &&                      \
      ( id1 ).generation == ( id2 ).generation )

B2_ID_INLINE uint32_t b2StoreWorldId( b2WorldId id )
{
    return ( (uint32_t)id.index1 << 16 ) | (uint32_t)id.generation;
}

B2_ID_INLINE b2WorldId b2LoadWorldId( uint32_t x )
{
    b2WorldId id = { (uint16_t)( x >> 16 ), (uint16_t)( x ) };
    return id;
}

B2_ID_INLINE uint64_t b2StoreBodyId( b2BodyId id )
{
    return ( (uint64_t)id.index1 << 32 ) | ( (uint64_t)id.world0 ) << 16 | (uint64_t)id.generation;
}

B2_ID_INLINE b2BodyId b2LoadBodyId( uint64_t x )
{
    b2BodyId id = { (int32_t)( x >> 32 ), (uint16_t)( x >> 16 ), (uint16_t)( x ) };
    return id;
}

B2_ID_INLINE uint64_t b2StoreShapeId( b2ShapeId id )
{
    return ( (uint64_t)id.index1 << 32 ) | ( (uint64_t)id.world0 ) << 16 | (uint64_t)id.generation;
}

B2_ID_INLINE b2ShapeId b2LoadShapeId( uint64_t x )
{
    b2ShapeId id = { (int32_t)( x >> 32 ), (uint16_t)( x >> 16 ), (uint16_t)( x ) };
    return id;
}

B2_ID_INLINE uint64_t b2StoreChainId( b2ChainId id )
{
    return ( (uint64_t)id.index1 << 32 ) | ( (uint64_t)id.world0 ) << 16 | (uint64_t)id.generation;
}

B2_ID_INLINE b2ChainId b2LoadChainId( uint64_t x )
{
    b2ChainId id = { (int32_t)( x >> 32 ), (uint16_t)( x >> 16 ), (uint16_t)( x ) };
    return id;
}

B2_ID_INLINE uint64_t b2StoreJointId( b2JointId id )
{
    return ( (uint64_t)id.index1 << 32 ) | ( (uint64_t)id.world0 ) << 16 | (uint64_t)id.generation;
}

B2_ID_INLINE b2JointId b2LoadJointId( uint64_t x )
{
    b2JointId id = { (int32_t)( x >> 32 ), (uint16_t)( x >> 16 ), (uint16_t)( x ) };
    return id;
}

B2_ID_INLINE void b2StoreContactId( b2ContactId id, uint32_t values[3] )
{
    values[0] = (uint32_t)id.index1;
    values[1] = (uint32_t)id.world0;
    values[2] = (uint32_t)id.generation;
}

B2_ID_INLINE b2ContactId b2LoadContactId( uint32_t values[3] )
{
    b2ContactId id;
    id.index1 = (int32_t)values[0];
    id.world0 = (uint16_t)values[1];
    id.padding = 0;
    id.generation = (uint32_t)values[2];
    return id;
}