sprite_cache.h

#ifndef SPRITE_CACHE_H
#define SPRITE_CACHE_H

#include <stdint.h>

typedef struct SpriteCacheEntry_s SpriteCacheEntry;

// A sprite cache.
typedef struct {
	int sprite_size;                // size of a sprite in bytes
	int max_sprites;                // maximum number of sprites in cache
	int num_buckets;                // number of hash table buckets (should be pow2)
	int32_t cur_tick;               // current tick (frame counter)
	int32_t tick_cutoff;            // tick which marks sprites old enough to remove with sprite_cache_pop                 
	uint8_t *sprites;               // pixel memory (for all sprites)
	uint16_t *free_sprite_indices;
	int num_sprites;				// number of sprites currently in cache
	SpriteCacheEntry *buckets;      // hashtable of the sprite entries
} SpriteCache;

void sprite_cache_init(SpriteCache *c, int sprite_size, int max_sprites);
void sprite_cache_reset(SpriteCache *c);
void sprite_cache_tick(SpriteCache *c);
uint8_t* sprite_cache_lookup(SpriteCache *c, uint32_t key);
uint8_t* sprite_cache_insert(SpriteCache *c, uint32_t key);
void sprite_cache_pop(SpriteCache *c);

#endif /* SPRITE_CACHE_H */