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+/* $Xorg: Context.c,v 1.5 2001/02/09 02:03:31 xorgcvs Exp $ */
+
+/***********************************************************
+Copyright 1987, 1988, 1990 by Digital Equipment Corporation, Maynard,
+
+ All Rights Reserved
+
+Permission to use, copy, modify, and distribute this software and its
+documentation for any purpose and without fee is hereby granted,
+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 Digital not be
+used in advertising or publicity pertaining to distribution of the
+software without specific, written prior permission.
+
+DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
+ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL
+DIGITAL BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
+ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION,
+ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+SOFTWARE.
+
+******************************************************************/
+
+/*
+
+Copyright 1987, 1988, 1990, 1994, 1998 The Open Group
+
+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.
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+Except as contained in this notice, the name of The Open Group shall
+not be used in advertising or otherwise to promote the sale, use or
+other dealings in this Software without prior written authorization
+from The Open Group.
+
+*/
+/* $XFree86: xc/lib/X11/Context.c,v 1.5 2001/12/14 19:53:58 dawes Exp $ */
+
+/* This module implements a simple sparse array.
+
+ XSaveContext(a,b,c,d) will store d in position (a,b,c) of the array.
+ XFindContext(a,b,c,&d) will set d to be the value in position (a,b,c).
+ XDeleteContext(a,b,c) will delete the entry in (a,b,c).
+
+ a is a display id, b is a resource id, and c is a Context. d is just an
+ XPointer. This code will work with any range of parameters, but is geared
+ to be most efficient with very few (one or two) different a's.
+
+*/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include "Xlibint.h"
+#include "Xutil.h"
+#ifdef XTHREADS
+#include "locking.h"
+#endif
+
+#define INITHASHMASK 63 /* Number of entries originally in the hash table. */
+
+typedef struct _TableEntryRec { /* Stores one entry. */
+ XID rid;
+ XContext context;
+ XPointer data;
+ struct _TableEntryRec *next;
+} TableEntryRec, *TableEntry;
+
+typedef struct _XContextDB { /* Stores hash table for one display. */
+ TableEntry *table; /* Pointer to array of hash entries. */
+ int mask; /* Current size of hash table minus 1. */
+ int numentries; /* Number of entries currently in table. */
+#ifdef XTHREADS
+ LockInfoRec linfo;
+#endif
+} DBRec, *DB;
+
+#ifdef MOTIFBC
+static DB NullDB = (DB)0;
+#endif
+
+/* Given an XID and a context, returns a value between 0 and HashSize-1.
+ Currently, this requires that HashSize be a power of 2.
+*/
+
+#define Hash(db,rid,context) \
+ (db)->table[(((rid) << 1) + context) & (db)->mask]
+
+/* Resize the given db */
+
+static void ResizeTable(DB db)
+{
+ TableEntry *otable;
+ register TableEntry entry, next, *pold, *head;
+ register int i, j;
+
+ otable = db->table;
+ for (i = INITHASHMASK+1; (i + i) < db->numentries; )
+ i += i;
+ db->table = (TableEntry *) Xcalloc((unsigned)i, sizeof(TableEntry));
+ if (!db->table) {
+ db->table = otable;
+ return;
+ }
+ j = db->mask + 1;
+ db->mask = i - 1;
+ for (pold = otable ; --j >= 0; pold++) {
+ for (entry = *pold; entry; entry = next) {
+ next = entry->next;
+ head = &Hash(db, entry->rid, entry->context);
+ entry->next = *head;
+ *head = entry;
+ }
+ }
+ Xfree((char *) otable);
+}
+
+static void _XFreeContextDB(Display *display)
+{
+ register DB db;
+ register int i;
+ register TableEntry *pentry, entry, next;
+
+ db = display->context_db;
+ if (db) {
+ for (i = db->mask + 1, pentry = db->table ; --i >= 0; pentry++) {
+ for (entry = *pentry; entry; entry = next) {
+ next = entry->next;
+ Xfree((char *)entry);
+ }
+ }
+ Xfree((char *) db->table);
+ _XFreeMutex(&db->linfo);
+ Xfree((char *) db);
+ }
+}
+
+/* Public routines. */
+
+/* Save the given value of data to correspond with the keys XID and context.
+ Returns nonzero error code if an error has occured, 0 otherwise.
+ Possible errors are Out-of-memory.
+*/
+
+int XSaveContext(
+ Display *display,
+ register XID rid,
+ register XContext context,
+ _Xconst char* data)
+{
+ DB *pdb;
+ register DB db;
+ TableEntry *head;
+ register TableEntry entry;
+
+#ifdef MOTIFBC
+ if (!display) {
+ pdb = &NullDB;
+ db = *pdb;
+ } else
+#endif
+ {
+ LockDisplay(display);
+ pdb = &display->context_db;
+ db = *pdb;
+ UnlockDisplay(display);
+ }
+ if (!db) {
+ db = (DB) Xmalloc(sizeof(DBRec));
+ if (!db)
+ return XCNOMEM;
+ db->mask = INITHASHMASK;
+ db->table = (TableEntry *)Xcalloc(db->mask + 1, sizeof(TableEntry));
+ if (!db->table) {
+ Xfree((char *)db);
+ return XCNOMEM;
+ }
+ db->numentries = 0;
+ _XCreateMutex(&db->linfo);
+#ifdef MOTIFBC
+ if (!display) *pdb = db; else
+#endif
+ {
+ LockDisplay(display);
+ *pdb = db;
+ display->free_funcs->context_db = _XFreeContextDB;
+ UnlockDisplay(display);
+ }
+ }
+ _XLockMutex(&db->linfo);
+ head = &Hash(db, rid, context);
+ _XUnlockMutex(&db->linfo);
+ for (entry = *head; entry; entry = entry->next) {
+ if (entry->rid == rid && entry->context == context) {
+ entry->data = (XPointer)data;
+ return 0;
+ }
+ }
+ entry = (TableEntry) Xmalloc(sizeof(TableEntryRec));
+ if (!entry)
+ return XCNOMEM;
+ entry->rid = rid;
+ entry->context = context;
+ entry->data = (XPointer)data;
+ entry->next = *head;
+ *head = entry;
+ _XLockMutex(&db->linfo);
+ db->numentries++;
+ if (db->numentries > (db->mask << 2))
+ ResizeTable(db);
+ _XUnlockMutex(&db->linfo);
+ return 0;
+}
+
+
+
+/* Given an XID and context, returns the associated data. Note that data
+ here is a pointer since it is a return value. Returns nonzero error code
+ if an error has occured, 0 otherwise. Possible errors are Entry-not-found.
+*/
+
+int XFindContext(display, rid, context, data)
+ Display *display;
+ register XID rid;
+ register XContext context;
+ XPointer *data; /* RETURN */
+{
+ register DB db;
+ register TableEntry entry;
+
+#ifdef MOTIFBC
+ if (!display) db = NullDB; else
+#endif
+ {
+ LockDisplay(display);
+ db = display->context_db;
+ UnlockDisplay(display);
+ }
+ if (!db)
+ return XCNOENT;
+ _XLockMutex(&db->linfo);
+ for (entry = Hash(db, rid, context); entry; entry = entry->next)
+ {
+ if (entry->rid == rid && entry->context == context) {
+ *data = (XPointer)entry->data;
+ _XUnlockMutex(&db->linfo);
+ return 0;
+ }
+ }
+ _XUnlockMutex(&db->linfo);
+ return XCNOENT;
+}
+
+
+
+/* Deletes the entry for the given XID and context from the datastructure.
+ This returns the same thing that FindContext would have returned if called
+ with the same arguments.
+*/
+
+int XDeleteContext(display, rid, context)
+ Display *display;
+ register XID rid;
+ register XContext context;
+{
+ register DB db;
+ register TableEntry entry, *prev;
+
+#ifdef MOTIFBC
+ if (!display) db = NullDB; else
+#endif
+ {
+ LockDisplay(display);
+ db = display->context_db;
+ UnlockDisplay(display);
+ }
+ if (!db)
+ return XCNOENT;
+ _XLockMutex(&db->linfo);
+ for (prev = &Hash(db, rid, context);
+ (entry = *prev);
+ prev = &entry->next) {
+ if (entry->rid == rid && entry->context == context) {
+ *prev = entry->next;
+ Xfree((char *) entry);
+ db->numentries--;
+ if (db->numentries < db->mask && db->mask > INITHASHMASK)
+ ResizeTable(db);
+ _XUnlockMutex(&db->linfo);
+ return 0;
+ }
+ }
+ _XUnlockMutex(&db->linfo);
+ return XCNOENT;
+}
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