XCrAssoc.c   [plain text]

/* $XConsortium: XCrAssoc.c,v 10.17 91/01/06 12:04:57 rws Exp $ */
/* Copyright    Massachusetts Institute of Technology    1985	*/

/*
Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
the above copyright notice appear in all copies and that both that
copyright notice and this permission notice appear in supporting
documentation, and that the name of M.I.T. not be used in advertising or
publicity pertaining to distribution of the software without specific,
written prior permission.  M.I.T. makes no representations about the
suitability of this software for any purpose.  It is provided "as is"
without express or implied warranty.
*/

#include <config.h>
#include <X11/Xlib.h>
#include <errno.h>
#include "X10.h"

#ifndef NULL
#define NULL 0
#endif

extern int errno;

/*
 * XCreateAssocTable - Create an XAssocTable.  The size argument should be
 * a power of two for efficiency reasons.  Some size suggestions: use 32
 * buckets per 100 objects;  a reasonable maximum number of object per
 * buckets is 8.  If there is an error creating the XAssocTable, a NULL
 * pointer is returned.
 */
XAssocTable *XCreateAssocTable(size)
	register int size;		/* Desired size of the table. */
{
	register XAssocTable *table;	/* XAssocTable to be initialized. */
	register XAssoc *buckets;	/* Pointer to the first bucket in */
					/* the bucket array. */
	
	/* Malloc the XAssocTable. */
	if ((table = (XAssocTable *)malloc(sizeof(XAssocTable))) == NULL) {
		/* malloc call failed! */
		errno = ENOMEM;
		return(NULL);
	}
	
	/* calloc the buckets (actually just their headers). */
	buckets = (XAssoc *)calloc((unsigned)size, (unsigned)sizeof(XAssoc));
	if (buckets == NULL) {
		/* calloc call failed! */
		errno = ENOMEM;
		return(NULL);
	}

	/* Insert table data into the XAssocTable structure. */
	table->buckets = buckets;
	table->size = size;

	while (--size >= 0) {
		/* Initialize each bucket. */
		buckets->prev = buckets;
		buckets->next = buckets;
		buckets++;
	}

	return(table);
}