/*
*
* Create a new hash table
*
* nrows : number of rows in hash table, primes are best.
* > 0 => we use the nearest prime internally
* < 0 => we use the magnitude as nrows.
* keysize : > 0 => bytes in each key, keys are binary bytes,
* all keys are the same size.
* ==0 => keys are strings and are null terminated,
* allowing random key lengths.
* userkeys : > 0 => indicates user owns the key data
* and we should not allocate or free space for it,
* nor should we attempt to free the user key. We just
* save the pointer to the key.
* ==0 => we should copy the keys and manage them internally
* userfree : routine to free users data, null if we should not
* free user data in sfghash_delete(). The routine
* should be of the form 'void userfree(void * userdata)',
* 'free' works for simple allocations.
*/
SFGHASH * sfghash_new( int nrows, int keysize, int userkeys, void (*userfree)(void*p) )
{
int i;
SFGHASH * h;
if( nrows > 0 ) /* make sure we have a prime number */
{
nrows = sf_nearest_prime( nrows );
}
else /* use the magnitude or nrows as is */
{
nrows = -nrows;
}
h = (SFGHASH*)s_alloc( sizeof(SFGHASH) );
if( !h )
return 0;
memset( h, 0, sizeof(SFGHASH) );
h->sfhashfcn = sfhashfcn_new( nrows );
if( !h->sfhashfcn )
{
free(h);
return 0;
}
h->table = (SFGHASH_NODE**) s_alloc( sizeof(SFGHASH_NODE*) * nrows );
if( !h->table )
{
free(h->sfhashfcn);
free(h);
return 0;
}
for( i=0; i<nrows; i++ )
{
h->table[i] = 0;
}
h->userkey = userkeys;
h->keysize = keysize;
h->nrows = nrows;
h->count = 0;
h->userfree = userfree;
h->crow = 0; // findfirst/next current row
h->cnode = 0; // findfirst/next current node ptr
return h;
}
SFHASHFCN * sfhashfcn_new( int m )
{
SFHASHFCN * p;
static int one=1;
if( one ) /* one time init */
{
srand( (unsigned) time(0) );
one = 0;
}
// This can make all of the hashing static for testing.
//#define rand() 0
p = (SFHASHFCN*) calloc( 1,sizeof(SFHASHFCN) );
if( !p )
return 0;
#ifdef STATIC_HASH
#ifndef DYNAMIC_PREPROC_CONTEXT
if (ScStaticHash())
{
sfhashfcn_static(p);
}
else
#endif
#endif
{
p->seed = sf_nearest_prime( (rand()%m)+3191 );
p->scale = sf_nearest_prime( (rand()%m)+709 );
p->hardener = (rand()*rand()) + 133824503;
}
p->hash_fcn = &sfhashfcn_hash;
p->keycmp_fcn = &memcmp;
return p;
}
