int main() {
void *bitset = Create_Bit_Set(100);
assert(Find_First_Free_Bit(bitset,100) == 0);
Set_Bit(bitset, 0);
assert(Find_First_Free_Bit(bitset,100) == 1);
Set_Bit(bitset, 1);
assert(Find_First_Free_Bit(bitset,100) == 2);
Set_Bit(bitset, 3);
assert(Find_First_Free_Bit(bitset,100) == 2);
Set_Bit(bitset, 4);
Set_Bit(bitset, 5);
Set_Bit(bitset, 6);
Set_Bit(bitset, 7);
assert(Find_First_Free_Bit(bitset,100) == 2);
Set_Bit(bitset, 2);
assert(Find_First_Free_Bit(bitset,100) == 8);
Clear_Bit(bitset, 2);
assert(Find_First_Free_Bit(bitset,100) == 2);
}
/*
* Get a PFAT_File object representing the file whose directory entry
* is given.
*/
static struct PFAT_File *Get_PFAT_File(struct PFAT_Instance *instance, directoryEntry *entry)
{
ulong_t numBlocks;
struct PFAT_File *pfatFile = 0;
char *fileDataCache = 0;
struct Bit_Set *validBlockSet = 0;
KASSERT(entry != 0);
KASSERT(instance != 0);
Mutex_Lock(&instance->lock);
/*
* See if this file has already been opened.
* If so, use the existing PFAT_File object.
*/
for (pfatFile = Get_Front_Of_PFAT_File_List(&instance->fileList);
pfatFile != 0;
pfatFile = Get_Next_In_PFAT_File_List(pfatFile)) {
if (pfatFile->entry == entry)
break;
}
if (pfatFile == 0) {
/* Determine size of data block cache for file. */
numBlocks = Round_Up_To_Block(entry->fileSize) / SECTOR_SIZE;
/*
* Allocate File object, PFAT_File object, file block data cache,
* and valid cache block bitset
*/
if ((pfatFile = (struct PFAT_File *) Malloc(sizeof(*pfatFile))) == 0 ||
(fileDataCache = Malloc(numBlocks * SECTOR_SIZE)) == 0 ||
(validBlockSet = Create_Bit_Set(numBlocks)) == 0) {
goto memfail;
}
/* Populate PFAT_File */
pfatFile->entry = entry;
pfatFile->numBlocks = numBlocks;
pfatFile->fileDataCache = fileDataCache;
pfatFile->validBlockSet = validBlockSet;
Mutex_Init(&pfatFile->lock);
/* Add to instance's list of PFAT_File objects. */
Add_To_Back_Of_PFAT_File_List(&instance->fileList, pfatFile);
KASSERT(pfatFile->nextPFAT_File_List == 0);
}
/* Success! */
goto done;
memfail:
if (pfatFile != 0)
Free(pfatFile);
if (fileDataCache != 0)
Free(fileDataCache);
if (validBlockSet != 0)
Free(validBlockSet);
done:
Mutex_Unlock(&instance->lock);
return pfatFile;
}
