moved files around
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ejcoumans
257
jam-2.5/hash.c
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257
jam-2.5/hash.c
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/*
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* Copyright 1993, 1995 Christopher Seiwald.
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*
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* This file is part of Jam - see jam.c for Copyright information.
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*/
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/*
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* hash.c - simple in-memory hashing routines
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*
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* External routines:
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*
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* hashinit() - initialize a hash table, returning a handle
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* hashitem() - find a record in the table, and optionally enter a new one
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* hashdone() - free a hash table, given its handle
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*
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* Internal routines:
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*
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* hashrehash() - resize and rebuild hp->tab, the hash table
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*
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* 4/29/93 - ensure ITEM's are aligned
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* 11/04/02 (seiwald) - const-ing for string literals
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* 01/31/02 (seiwald) - keyval now unsigned (cray-ziness)
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*/
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# include "jam.h"
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# include "hash.h"
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/* Header attached to all data items entered into a hash table. */
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struct hashhdr {
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struct item *next;
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unsigned int keyval; /* for quick comparisons */
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} ;
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/* This structure overlays the one handed to hashenter(). */
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/* It's actual size is given to hashinit(). */
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struct hashdata {
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char *key;
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/* rest of user data */
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} ;
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typedef struct item {
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struct hashhdr hdr;
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struct hashdata data;
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} ITEM ;
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# define MAX_LISTS 32
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struct hash
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{
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/*
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* the hash table, just an array of item pointers
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*/
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struct {
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int nel;
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ITEM **base;
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} tab;
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int bloat; /* tab.nel / items.nel */
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int inel; /* initial number of elements */
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/*
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* the array of records, maintained by these routines
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* essentially a microallocator
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*/
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struct {
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int more; /* how many more ITEMs fit in lists[ list ] */
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char *next; /* where to put more ITEMs in lists[ list ] */
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int datalen; /* length of records in this hash table */
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int size; /* sizeof( ITEM ) + aligned datalen */
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int nel; /* total ITEMs held by all lists[] */
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int list; /* index into lists[] */
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struct {
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int nel; /* total ITEMs held by this list */
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char *base; /* base of ITEMs array */
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} lists[ MAX_LISTS ];
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} items;
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const char *name; /* just for hashstats() */
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} ;
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static void hashrehash( struct hash *hp );
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static void hashstat( struct hash *hp );
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/*
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* hashitem() - find a record in the table, and optionally enter a new one
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*/
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int
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hashitem(
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register struct hash *hp,
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HASHDATA **data,
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int enter )
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{
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ITEM **base;
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register ITEM *i;
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unsigned char *b = (unsigned char *)(*data)->key;
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unsigned int keyval;
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if( enter && !hp->items.more )
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hashrehash( hp );
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if( !enter && !hp->items.nel )
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return 0;
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keyval = *b;
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while( *b )
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keyval = keyval * 2147059363 + *b++;
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base = hp->tab.base + ( keyval % hp->tab.nel );
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for( i = *base; i; i = i->hdr.next )
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if( keyval == i->hdr.keyval &&
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!strcmp( i->data.key, (*data)->key ) )
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{
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*data = &i->data;
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return !0;
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}
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if( enter )
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{
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i = (ITEM *)hp->items.next;
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hp->items.next += hp->items.size;
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hp->items.more--;
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memcpy( (char *)&i->data, (char *)*data, hp->items.datalen );
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i->hdr.keyval = keyval;
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i->hdr.next = *base;
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*base = i;
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*data = &i->data;
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}
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return 0;
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}
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/*
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* hashrehash() - resize and rebuild hp->tab, the hash table
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*/
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static void hashrehash( register struct hash *hp )
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{
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int i = ++hp->items.list;
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hp->items.more = i ? 2 * hp->items.nel : hp->inel;
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hp->items.next = (char *)malloc( hp->items.more * hp->items.size );
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hp->items.lists[i].nel = hp->items.more;
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hp->items.lists[i].base = hp->items.next;
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hp->items.nel += hp->items.more;
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if( hp->tab.base )
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free( (char *)hp->tab.base );
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hp->tab.nel = hp->items.nel * hp->bloat;
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hp->tab.base = (ITEM **)malloc( hp->tab.nel * sizeof(ITEM **) );
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memset( (char *)hp->tab.base, '\0', hp->tab.nel * sizeof( ITEM * ) );
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for( i = 0; i < hp->items.list; i++ )
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{
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int nel = hp->items.lists[i].nel;
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char *next = hp->items.lists[i].base;
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for( ; nel--; next += hp->items.size )
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{
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register ITEM *i = (ITEM *)next;
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ITEM **ip = hp->tab.base + i->hdr.keyval % hp->tab.nel;
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i->hdr.next = *ip;
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*ip = i;
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}
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}
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}
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/* --- */
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# define ALIGNED(x) ( ( x + sizeof( ITEM ) - 1 ) & ~( sizeof( ITEM ) - 1 ) )
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/*
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* hashinit() - initialize a hash table, returning a handle
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*/
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struct hash *
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hashinit(
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int datalen,
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const char *name )
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{
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struct hash *hp = (struct hash *)malloc( sizeof( *hp ) );
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hp->bloat = 3;
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hp->tab.nel = 0;
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hp->tab.base = (ITEM **)0;
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hp->items.more = 0;
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hp->items.datalen = datalen;
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hp->items.size = sizeof( struct hashhdr ) + ALIGNED( datalen );
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hp->items.list = -1;
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hp->items.nel = 0;
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hp->inel = 11;
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hp->name = name;
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return hp;
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}
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/*
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* hashdone() - free a hash table, given its handle
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*/
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void
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hashdone( struct hash *hp )
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{
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int i;
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if( !hp )
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return;
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if( DEBUG_MEM )
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hashstat( hp );
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if( hp->tab.base )
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free( (char *)hp->tab.base );
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for( i = 0; i <= hp->items.list; i++ )
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free( hp->items.lists[i].base );
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free( (char *)hp );
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}
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/* ---- */
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static void
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hashstat( struct hash *hp )
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{
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ITEM **tab = hp->tab.base;
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int nel = hp->tab.nel;
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int count = 0;
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int sets = 0;
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int run = ( tab[ nel - 1 ] != (ITEM *)0 );
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int i, here;
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for( i = nel; i > 0; i-- )
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{
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if( here = ( *tab++ != (ITEM *)0 ) )
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count++;
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if( here && !run )
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sets++;
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run = here;
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}
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printf( "%s table: %d+%d+%d (%dK+%dK) items+table+hash, %f density\n",
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hp->name,
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count,
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hp->items.nel,
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hp->tab.nel,
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hp->items.nel * hp->items.size / 1024,
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hp->tab.nel * sizeof( ITEM ** ) / 1024,
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(float)count / (float)sets );
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}
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