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Codechange: Deduplicate and simplify tile hash arithmetic.

pull/12131/head
frosch 2025-04-25 17:35:05 +02:00 committed by frosch
parent b4d4d730a5
commit ac3ed9f3ad
1 changed files with 49 additions and 22 deletions
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71
src/vehicle.cpp
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@ -382,23 +382,54 @@ Vehicle::Vehicle(VehicleType type)
/* Size of the hash, 6 = 64 x 64, 7 = 128 x 128. Larger sizes will (in theory) reduce hash
* lookup times at the expense of memory usage. */
const int HASH_BITS = 7;
const int HASH_SIZE = 1 << HASH_BITS;
const int HASH_MASK = HASH_SIZE - 1;
const int TOTAL_HASH_SIZE = 1 << (HASH_BITS * 2);
const int TOTAL_HASH_MASK = TOTAL_HASH_SIZE - 1;
constexpr uint TILE_HASH_BITS = 7;
constexpr uint TILE_HASH_SIZE = 1 << TILE_HASH_BITS;
constexpr uint TILE_HASH_MASK = TILE_HASH_SIZE - 1;
constexpr uint TOTAL_TILE_HASH_SIZE = 1 << (TILE_HASH_BITS * 2);
/* Resolution of the hash, 0 = 1*1 tile, 1 = 2*2 tiles, 2 = 4*4 tiles, etc.
* Profiling results show that 0 is fastest. */
const int HASH_RES = 0;
constexpr uint TILE_HASH_RES = 0;
static std::array<Vehicle *, TOTAL_HASH_SIZE> _vehicle_tile_hash{};
static Vehicle *VehicleFromTileHash(int xl, int yl, int xu, int yu, void *data, VehicleFromPosProc *proc, bool find_first)
/**
* Compute hash for 1D tile coordinate.
*/
static inline uint GetTileHash1D(uint p)
{
for (int y = yl; ; y = (y + (1 << HASH_BITS)) & (HASH_MASK << HASH_BITS)) {
for (int x = xl; ; x = (x + 1) & HASH_MASK) {
Vehicle *v = _vehicle_tile_hash[(x + y) & TOTAL_HASH_MASK];
return GB(p, TILE_HASH_RES, TILE_HASH_BITS);
}
/**
* Increment 1D hash to next bucket.
*/
static inline uint IncTileHash1D(uint h)
{
return (h + 1) & TILE_HASH_MASK;
}
/**
* Compose two 1D hashes into 2D hash.
*/
static inline uint ComposeTileHash(uint hx, uint hy)
{
return hx | hy << TILE_HASH_BITS;
}
/**
* Compute hash for tile coordinate.
*/
static inline uint GetTileHash(uint x, uint y)
{
return ComposeTileHash(GetTileHash1D(x), GetTileHash1D(y));
}
static std::array<Vehicle *, TOTAL_TILE_HASH_SIZE> _vehicle_tile_hash{};
static Vehicle *VehicleFromTileHash(uint xl, uint yl, uint xu, uint yu, void *data, VehicleFromPosProc *proc, bool find_first)
{
for (uint y = yl; ; y = IncTileHash1D(y)) {
for (uint x = xl; ; x = IncTileHash1D(x)) {
Vehicle *v = _vehicle_tile_hash[ComposeTileHash(x, y)];
for (; v != nullptr; v = v->hash_tile_next) {
Vehicle *a = proc(v, data);
if (find_first && a != nullptr) return a;
@ -428,10 +459,10 @@ static Vehicle *VehicleFromPosXY(int x, int y, void *data, VehicleFromPosProc *p
const int COLL_DIST = 6;
/* Hash area to scan is from xl,yl to xu,yu */
int xl = GB((x - COLL_DIST) / TILE_SIZE, HASH_RES, HASH_BITS);
int xu = GB((x + COLL_DIST) / TILE_SIZE, HASH_RES, HASH_BITS);
int yl = GB((y - COLL_DIST) / TILE_SIZE, HASH_RES, HASH_BITS) << HASH_BITS;
int yu = GB((y + COLL_DIST) / TILE_SIZE, HASH_RES, HASH_BITS) << HASH_BITS;
uint xl = GetTileHash1D((x - COLL_DIST) / TILE_SIZE);
uint xu = GetTileHash1D((x + COLL_DIST) / TILE_SIZE);
uint yl = GetTileHash1D((y - COLL_DIST) / TILE_SIZE);
uint yu = GetTileHash1D((y + COLL_DIST) / TILE_SIZE);
return VehicleFromTileHash(xl, yl, xu, yu, data, proc, find_first);
}
@ -477,9 +508,7 @@ bool HasVehicleOnPosXY(int x, int y, void *data, VehicleFromPosProc *proc)
*/
VehiclesOnTile::Iterator::Iterator(TileIndex tile) : tile(tile)
{
int x = GB(TileX(tile), HASH_RES, HASH_BITS);
int y = GB(TileY(tile), HASH_RES, HASH_BITS) << HASH_BITS;
this->current = _vehicle_tile_hash[(x + y) & TOTAL_HASH_MASK];
this->current = _vehicle_tile_hash[GetTileHash(TileX(tile), TileY(tile))];
this->SkipFalseMatches();
}
@ -578,9 +607,7 @@ static void UpdateVehicleTileHash(Vehicle *v, bool remove)
if (remove) {
new_hash = nullptr;
} else {
int x = GB(TileX(v->tile), HASH_RES, HASH_BITS);
int y = GB(TileY(v->tile), HASH_RES, HASH_BITS) << HASH_BITS;
new_hash = &_vehicle_tile_hash[(x + y) & TOTAL_HASH_MASK];
new_hash = &_vehicle_tile_hash[GetTileHash(TileX(v->tile), TileY(v->tile))];
}
if (old_hash == new_hash) return;