#include "X11.h" // this module provides functions for freely associating data to IDs // XSaveContext, XFindContext, XDeleteContext // see lib/x11/Context.c // see xlib.pdf 16.10 // TODO: use original file and move to Xmisc /* 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. */ #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. */ HMTX linfo; } 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) register DB db; { DBUG_ENTER("ResizeTable") 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; DBUG_VOID_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); DBUG_VOID_RETURN; } static void _XFreeContextDB(display) Display *display; { DBUG_ENTER("_XFreeContextDB") 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); EbCloseMutexSem(db->linfo); Xfree((char *) db); } DBUG_VOID_RETURN; } /* 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. */ #if NeedFunctionPrototypes int XSaveContext( Display *display, register XID rid, register XContext context, _Xconst char* data) #else int XSaveContext(display, rid, context, data) Display *display; register XID rid; register XContext context; XPointer data; #endif { DBUG_ENTER("XSaveContext") 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) DBUG_RETURN(XCNOMEM); db->mask = INITHASHMASK; db->table = (TableEntry *)Xcalloc(db->mask + 1, sizeof(TableEntry)); if (!db->table) { Xfree((char *)db); DBUG_RETURN(XCNOMEM); } db->numentries = 0; EbCreateMutexSem(&db->linfo); #ifdef MOTIFBC if (!display) *pdb = db; else #endif { LockDisplay(display); *pdb = db; display->free_funcs->context_db = _XFreeContextDB; UnlockDisplay(display); } } EbLockMutexSem(db->linfo); head = &Hash(db, rid, context); EbReleaseMutexSem(db->linfo); for (entry = *head; entry; entry = entry->next) { if (entry->rid == rid && entry->context == context) { entry->data = (XPointer)data; DBUG_RETURN(0); } } entry = (TableEntry) Xmalloc(sizeof(TableEntryRec)); if (!entry) DBUG_RETURN(XCNOMEM); entry->rid = rid; entry->context = context; entry->data = (XPointer)data; entry->next = *head; *head = entry; EbLockMutexSem(db->linfo); db->numentries++; if (db->numentries > (db->mask << 2)) ResizeTable(db); EbReleaseMutexSem(db->linfo); DBUG_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 */ { DBUG_ENTER("XFindContext") register DB db; register TableEntry entry; #ifdef MOTIFBC if (!display) db = NullDB; else #endif { LockDisplay(display); db = display->context_db; UnlockDisplay(display); } if (!db) DBUG_RETURN(XCNOENT); EbLockMutexSem(db->linfo); for (entry = Hash(db, rid, context); entry; entry = entry->next) { if (entry->rid == rid && entry->context == context) { *data = (XPointer)entry->data; EbReleaseMutexSem(db->linfo); DBUG_RETURN(0); } } EbReleaseMutexSem(db->linfo); DBUG_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; { DBUG_ENTER("XDeleteContext") 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) DBUG_RETURN(XCNOENT); EbLockMutexSem(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); EbReleaseMutexSem(db->linfo); DBUG_RETURN(0); } } EbReleaseMutexSem(db->linfo); DBUG_RETURN(XCNOENT); }