/**
* Free unused memory.
*/
void BITSET_Trim(BitSet * bs)
{
if (bs->alloc > bs->inuse) {
if (bs->inuse == 0) {
ASSERT(bs->storage.units);
MEM_Free(bs->storage.units);
bs->storage.units = NULL;
bs->alloc = 0;
} else {
BitUnit * savebuf = bs->storage.units;
size_t size = sizeof(BitUnit) * bs->inuse;
#ifdef NO_REALLOC
bs->storage.units = (BitUnit*)MEM_Alloc(size);
if (bs->storage.units) {
memcpy(bs->storage.units, savebuf, size);
MEM_Free(bs->storage.units);
}
#else
bs->storage.units = (BitUnit*)MEM_Realloc(savebuf, size);
#endif /* NO_REALLOC */
if (bs->storage.units) {
bs->alloc = bs->inuse;
} else {
bs->storage.units = savebuf;
}
}
}
}
/**
* Returns available RWEntry for the calling thread. Reallocates array
* of thread entries if necessary. Obviously, this function must be called
* under synchronization. Returns NULL only if we run out of thread entries
* and memory allocation fails.
*/
STATIC RWEntry * RWLOCK_GetEntry(RWLock * lock)
{
int i;
ThrID self = THREAD_Self();
RWEntry * empty = NULL; /* vacant empty entry */
/*
* try to find existing entry for this thread. At the same time
* pick up the first available empty slot.
*/
for (i=0; i<lock->entriesInUse; i++) {
RWEntry * entry = GET_ENTRY(lock,i);
if (entry->id == self) {
return entry;
} else if (!empty && !entry->id) {
empty = entry;
}
}
/*
* we didn't find existing slot for the calling thread.
* We have to find an empty slot.
*/
if (!empty) {
for (; i<lock->numEntries; i++) {
RWEntry * entry = GET_ENTRY(lock,i);
if (!entry->id) {
empty = entry;
break;
}
}
/*
* looks like we are out of luck. We need to reallocate the array
* of thread entries.
*/
if (!empty) {
int count = lock->numEntries + STATIC_ENTRIES;
size_t size = count * sizeof(RWEntry);
RWEntry * newEntries = (RWEntry*)
MEM_Realloc(lock->moreEntries, size);
if (!newEntries) {
return NULL;
}
lock->moreEntries = newEntries;
lock->numEntries = count;
empty = lock->moreEntries + i - STATIC_ENTRIES;
memset(empty, 0, sizeof(RWEntry) * STATIC_ENTRIES);
}
lock->entriesInUse = i + 1;
}
lock->entriesActive++;
/*
* initialize the empty entry.
*/
empty->id = self;
empty->read = empty->write = 0L;
return empty;
}
