shithub: femtolisp

ref: 008d2886ab8f7bd5138019ec48b75bbaf88fc769
dir: /htable.inc/

//-*- mode:c -*-

/*
  include this file and call HTIMPL to generate an implementation
*/

#define hash_size(h) ((h)->size/2)

// compute empirical max-probe for a given size
#define max_probe(size) ((size) <= (HT_N_INLINE*2) ? (HT_N_INLINE/2) : (size)>>3)

#define HTIMPL(HTNAME, HFUNC, EQFUNC) \
static void ** \
HTNAME##_lookup_bp(htable_t *h, void *key) \
{ \
	value_t hv; \
	size_t i, orig, index, iter; \
	size_t newsz, sz = hash_size(h); \
	size_t maxprobe = max_probe(sz); \
	void **tab = h->table; \
	void **ol; \
 \
	hv = HFUNC((uintptr_t)key); \
retry_bp: \
	iter = 0; \
	index = (hv & (sz-1)) * 2; \
	sz *= 2; \
	orig = index; \
 \
	do{ \
		if(tab[index+1] == HT_NOTFOUND){ \
			tab[index] = key; \
			return &tab[index+1]; \
		} \
		if(EQFUNC(key, tab[index])) \
			return &tab[index+1]; \
		index = (index+2) & (sz-1); \
		iter++; \
		if(iter > maxprobe) \
			break; \
	}while(index != orig); \
 \
	/* table full */ \
	/* quadruple size, rehash, retry the insert */ \
	/* it's important to grow the table really fast; otherwise we waste */ \
	/* lots of time rehashing all the keys over and over. */ \
	sz = h->size; \
	ol = h->table; \
	if(sz >= (1<<19) || (sz <= (1<<8))) \
		newsz = sz<<1; \
	else if(sz <= HT_N_INLINE) \
		newsz = HT_N_INLINE; \
	else \
		newsz = sz<<2; \
	tab = (void**)MEM_ALLOC(newsz*sizeof(void*)); \
	if(tab == nil) \
		return nil; \
	for(i = 0; i < newsz; i++) \
		tab[i] = HT_NOTFOUND; \
	h->table = tab; \
	h->size = newsz; \
	for(i = 0; i < sz; i += 2) { \
		if(ol[i+1] != HT_NOTFOUND) \
			(*HTNAME##_lookup_bp(h, ol[i])) = ol[i+1]; \
	} \
	if(ol != &h->_space[0]) \
		MEM_FREE(ol); \
	sz = hash_size(h); \
	maxprobe = max_probe(sz); \
	tab = h->table; \
	goto retry_bp; \
}                                                                       \
 \
void \
HTNAME##_put(htable_t *h, void *key, void *val) \
{ \
    void **bp = HTNAME##_lookup_bp(h, key); \
    *bp = val; \
} \
 \
void ** \
HTNAME##_bp(htable_t *h, void *key) \
{ \
    return HTNAME##_lookup_bp(h, key); \
} \
 \
/* returns bp if key is in hash, otherwise nil */ \
/* if return is non-nil and *bp == HT_NOTFOUND then key was deleted */ \
static void ** \
HTNAME##_peek_bp(htable_t *h, void *key) \
{ \
    size_t sz = hash_size(h); \
    size_t maxprobe = max_probe(sz); \
    void **tab = h->table; \
    size_t index = (HFUNC((uintptr_t)key) & (sz-1)) * 2; \
    sz *= 2; \
    size_t orig = index; \
    size_t iter = 0; \
 \
    do { \
        if(tab[index] == HT_NOTFOUND) \
            return nil; \
        if(EQFUNC(key, tab[index])) \
            return &tab[index+1]; \
 \
        index = (index+2) & (sz-1); \
        iter++; \
        if(iter > maxprobe) \
            break; \
    }while(index != orig); \
 \
    return nil; \
} \
 \
void *\
HTNAME##_get(htable_t *h, void *key) \
{ \
    void **bp = HTNAME##_peek_bp(h, key); \
    if(bp == nil) \
        return HT_NOTFOUND; \
    return *bp; \
} \
 \
int \
HTNAME##_has(htable_t *h, void *key) \
{ \
    return HTNAME##_get(h, key) != HT_NOTFOUND; \
} \
 \
int \
HTNAME##_remove(htable_t *h, void *key) \
{ \
    void **bp = HTNAME##_peek_bp(h, key); \
    if(bp != nil){ \
        *bp = HT_NOTFOUND; \
        return 1; \
    } \
    return 0; \
} \
 \
void \
HTNAME##_adjoin(htable_t *h, void *key, void *val) \
{ \
    void **bp = HTNAME##_lookup_bp(h, key); \
    if(*bp == HT_NOTFOUND) \
        *bp = val; \
}