#include <u.h>
#include <libc.h>
#include <flate.h>
#include "hash.h"

static ulong *crctab;

void
inithash(void)
{
	crctab = mkcrctab(0xEDB88320);
}

Hash*
newhash(void)
{
	Hash *h;

	h = mallocz(sizeof(*h), 1);
	h->sz = 128;
	h->items = mallocz(h->sz * sizeof(HashItem*), 1);
	return h;
}

void
freehash(Hash *h)
{
	if(h == nil)
		return;
	free(h->items);
	h->sz = 0;
	free(h);
}

int
lenhash(Hash *h)
{
	return h->nitems;
}

void
puthash(Hash *h, char *str, HashItem *item)
{
	ulong crc;

	crc = blockcrc(crctab, 0, str, strlen(str));

	item->crc = crc;
	strncpy(item->key, str, sizeof(item->key)-1);

	crc %= h->sz;
	item->next = h->items[crc];
	h->items[crc] = item;
	h->nitems++;
}

void*
gethash(Hash *h, char *str)
{
	ulong crc, idx;
	HashItem *i;

	crc = blockcrc(crctab, 0, str, strlen(str));

	idx = crc % h->sz;
	for(i = h->items[idx]; i != nil; i = i->next){
		if(i->crc == crc){
			return i;
		}
	}
	return nil;
}

void*
delhash(Hash *h, char *str)
{
	ulong crc, idx;
	HashItem *i, *prev;

	prev = nil;

	crc = blockcrc(crctab, 0, str, strlen(str));
	idx = crc % h->sz;

	for(i = h->items[idx]; i != nil; i = i->next){
		if(i->crc == crc){
			if(i == h->items[idx]){
				h->items[idx] = i->next;
			} else {
				prev->next = i->next;
			}
			h->nitems--;
			return i;
		} else {
			prev = i->next;
		}
	}

	return nil;
}

void
forhash(Hash *h, void (*f)(void*))
{
	int i;
	HashItem *c;

	for(i = 0; i < h->sz; i++){
		for(c = h->items[i]; c != nil; c = c->next){
			f(c);
		}
	}
}