id.h

// SPDX-FileCopyrightText: 2026 Erin Catto
// SPDX-License-Identifier: MIT
 
#pragma once
 
#include <stdint.h>
 
// Note: this file should be stand-alone


typedef struct b3WorldId
{
    uint16_t index1;
    uint16_t generation;
} b3WorldId;

typedef struct b3BodyId
{
    int32_t index1;
    uint16_t world0;
    uint16_t generation;
} b3BodyId;

typedef struct b3ShapeId
{
    int32_t index1;
    uint16_t world0;
    uint16_t generation;
} b3ShapeId;

typedef struct b3JointId
{
    int32_t index1;
    uint16_t world0;
    uint16_t generation;
} b3JointId;

typedef struct b3ContactId
{
    int32_t index1;
    uint16_t world0;
    int16_t padding;
    uint32_t generation;
} b3ContactId;
 
// clang-format off
#ifdef __cplusplus
    #define B3_NULL_ID {}
    #define B3_ID_INLINE inline
#else
    #define B3_NULL_ID { 0 }

    #define B3_ID_INLINE static inline
#endif
// clang-format on

static const b3WorldId b3_nullWorldId = B3_NULL_ID;
static const b3BodyId b3_nullBodyId = B3_NULL_ID;
static const b3ShapeId b3_nullShapeId = B3_NULL_ID;
static const b3JointId b3_nullJointId = B3_NULL_ID;
static const b3ContactId b3_nullContactId = B3_NULL_ID;

#define B3_IS_NULL( id ) ( id.index1 == 0 )

#define B3_IS_NON_NULL( id ) ( id.index1 != 0 )

#define B3_ID_EQUALS( id1, id2 ) ( id1.index1 == id2.index1 && id1.world0 == id2.world0 && id1.generation == id2.generation )

B3_ID_INLINE uint32_t b3StoreWorldId( b3WorldId id )
{
    return ( (uint32_t)id.index1 << 16 ) | (uint32_t)id.generation;
}

B3_ID_INLINE b3WorldId b3LoadWorldId( uint32_t x )
{
    b3WorldId id = { (uint16_t)( x >> 16 ), (uint16_t)( x ) };
    return id;
}

B3_ID_INLINE uint64_t b3StoreBodyId( b3BodyId id )
{
    return ( (uint64_t)id.index1 << 32 ) | ( (uint64_t)id.world0 ) << 16 | (uint64_t)id.generation;
}

B3_ID_INLINE b3BodyId b3LoadBodyId( uint64_t x )
{
    b3BodyId id = { (int32_t)( x >> 32 ), (uint16_t)( x >> 16 ), (uint16_t)( x ) };
    return id;
}

B3_ID_INLINE uint64_t b3StoreShapeId( b3ShapeId id )
{
    return ( (uint64_t)id.index1 << 32 ) | ( (uint64_t)id.world0 ) << 16 | (uint64_t)id.generation;
}

B3_ID_INLINE b3ShapeId b3LoadShapeId( uint64_t x )
{
    b3ShapeId id = { (int32_t)( x >> 32 ), (uint16_t)( x >> 16 ), (uint16_t)( x ) };
    return id;
}

B3_ID_INLINE uint64_t b3StoreJointId( b3JointId id )
{
    return ( (uint64_t)id.index1 << 32 ) | ( (uint64_t)id.world0 ) << 16 | (uint64_t)id.generation;
}

B3_ID_INLINE b3JointId b3LoadJointId( uint64_t x )
{
    b3JointId id = { (int32_t)( x >> 32 ), (uint16_t)( x >> 16 ), (uint16_t)( x ) };
    return id;
}

B3_ID_INLINE void b3StoreContactId( b3ContactId id, uint32_t values[3] )
{
    values[0] = (uint32_t)id.index1;
    values[1] = (uint32_t)id.world0;
    values[2] = (uint32_t)id.generation;
}

B3_ID_INLINE b3ContactId b3LoadContactId( uint32_t values[3] )
{
    b3ContactId id;
    id.index1 = (int32_t)values[0];
    id.world0 = (uint16_t)values[1];
    id.padding = 0;
    id.generation = (uint32_t)values[2];
    return id;
}