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108 lines
5.9 KiB
108 lines
5.9 KiB
#ifndef CACHE_GENERIC_H
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#define CACHE_GENERIC_H
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#include "generic_hash.h"
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#define CACHE_SIZE 512
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#define CACHE_NCYCLES (CACHE_SIZE/2)
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#define CACHE_BSIZE (((CACHE_SIZE+0x3f)&(~0x3f))>>6)
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#define CACHE_BRESET(b) for (int i = 0; i < CACHE_BSIZE; b[i++] = 0);
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#define CACHE_BSET(b, x) b[(x)>>6] |= (uint64_t)1<<((x)%64)
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#define CACHE_BTEST(b, x) (b[(x)>>6]&((uint64_t)1<<((x)%64)))
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// FIXME: this cache implementation is not really generic since it expects an unsigned
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// as the code and not a generic type
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// FIXME: when resetting the bitmap all references to overwritten elements are
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// invalidated, this really means that
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// 1) we get data mismatches
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// 2) this is not a good LRU cache
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#define CACHE_SET(c, x) \
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{ \
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if (++(c->cycles) > CACHE_NCYCLES) { \
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CACHE_BRESET(c->bitmap); \
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c->cycles=0;} \
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CACHE_BSET(c->bitmap, x); \
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}
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#define CACHE_DECL(name, type, hashfn, cmpfn) \
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HASH_DECL(name##table, uint32_t, uint32_t, hashfn, cmpfn) \
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struct name { \
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struct name##table_ref *table; \
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type *array; \
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uint64_t *bitmap; \
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int cycles; \
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}; \
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\
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\
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struct name name##_init(void) \
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{ \
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struct name##table_ref *t = name##table_create(CACHE_SIZE); \
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type *a = malloc(sizeof(type)*CACHE_SIZE); \
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uint64_t *b = malloc(sizeof(uint64_t)*CACHE_BSIZE); \
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CACHE_BRESET(b); \
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return (struct name){ .table = t, .array = a, .bitmap = b, 0}; \
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} \
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\
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\
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void name##_free(struct name *cache) \
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{ \
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if (cache) { \
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name##table_destroy(cache->table); \
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free(cache->array); \
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free(cache->bitmap); \
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} \
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} \
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\
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\
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const type * name##_search(struct name *cache, uint32_t code) \
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{ \
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if (!cache) return NULL; \
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struct name##table_entry *r; \
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r = name##table_search(cache->table, code); \
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/* MISS */ \
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if (!r || !cmpfn(code, r->code)) \
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return NULL; \
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/* HIT, set as recently used */ \
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CACHE_SET(cache, r->data); \
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return (&cache->array[r->data]); \
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} \
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\
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\
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int name##_get(struct name *cache) \
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{ \
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if (!cache) return -1; \
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int x = 0; \
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for (int b = 0; b < CACHE_BSIZE; b++) { \
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if (cache->bitmap[b] == 0) x = 64; \
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else x = __builtin_clzll(cache->bitmap[b]); \
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x = 64-x; \
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if (!CACHE_BTEST(cache->bitmap, x+64*b)) \
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return x+64*b; \
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} \
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return 0; \
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} \
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\
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\
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const type * name##_insert(struct name *cache, const type *g, uint32_t code, int x)\
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{ \
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if (!cache) return NULL; \
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type *spot = NULL; \
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/* x is the index to the cache array, it has to come from the user */ \
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/* check if the spot is free */ \
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if (x < 0 || CACHE_BTEST(cache->bitmap, x)) \
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return NULL; \
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CACHE_SET(cache, x) \
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spot = &(cache->array[x]); \
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*spot = *g; \
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struct name##table_entry e = { .code = code, .data = x}; \
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if (!name##table_insert(cache->table, &e)) \
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return NULL; \
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return spot; \
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} \
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#endif
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