/* Allocate a block of size size and return a pointer to it. */
void * mm_malloc (size_t size) {
size_t reqSize;
BlockInfo * ptrFreeBlock = NULL;
//Zero-size requests get NULL;
if (size == 0){
return NULL;
}
//Add one word for the initial size header.
//Note that we don't need to boundary tag when the block is used!
if (size <= MIN_BLOCK_SIZE) {
// Make sure we allocate enough space for a blockInfo in case we
// free this block (when we free this block, we'll need to use the
// next pointer, the prev pointer, and the boundary tag).
reqSize = MIN_BLOCK_SIZE;
} else {
// Round up for correct alignment
reqSize = ALIGNMENT * ((size + ALIGNMENT - 1) / ALIGNMENT);
}
printf("Begin malloc of reqSize: %zd \n", reqSize);
printf("Free list head: %p\n", FREE_LIST_HEAD);
examine_heap();
while ((ptrFreeBlock = searchFreeList(reqSize)) == NULL){
requestMoreSpace(reqSize);
printf("Finished space request\n");
}
removeFreeBlock(ptrFreeBlock);
placeBlock(ptrFreeBlock, reqSize);
printf("Completed malloc\n");
printf("Pointer free block: %p\n", ptrFreeBlock);
examine_heap();
return UNSCALED_POINTER_ADD(ptrFreeBlock, WORD_SIZE);
}
/* Allocate a block of size size and return a pointer to it. */
void* mm_malloc (size_t size)
{
size_t reqSize;
BlockInfo * ptrFreeBlock = NULL, * head;
size_t blockSize;
size_t precedingBlockUseTag;
size_t extendsize; /* Amount to extend heap if no fit */
// Zero-size requests get NULL.
if (size == 0) {
return NULL;
}
// Add one word for the initial size header.
// Note that we don't need to boundary tag when the block is used!
size += WORD_SIZE;
if (size <= MIN_BLOCK_SIZE) {
// Make sure we allocate enough space for a blockInfo in case we
// free this block (when we free this block, we'll need to use the
// next pointer, the prev pointer, and the boundary tag).
reqSize = MIN_BLOCK_SIZE;
}
else {
// Round up for correct alignment
reqSize = ALIGNMENT * ((size + ALIGNMENT - 1) / ALIGNMENT);
}
// Implement mm_malloc. You can change or remove any of the above
// code. It is included as a suggestion of where to start.
// You will want to replace this return statement...
//head = FREE_LIST_HEAD;
//printf("\nSo we were requested %d (%d). Free list head was 0x%x %d 0x%x 0x%x\n",
// size, reqSize, head, head->sizeAndTags, head->next, head->prev );
// half-arsed fix
reqSize=reqSize+ALIGNMENT;
if ( ptrFreeBlock = searchFreeList(reqSize) )
{
precedingBlockUseTag = ptrFreeBlock->sizeAndTags & TAG_PRECEDING_USED;
placeBlock( ptrFreeBlock, reqSize, precedingBlockUseTag );
}
else
{
//printf("But there wasn't big enough free block, we requsted extension %d\n", extendsize);
requestMoreSpace( reqSize );
ptrFreeBlock = searchFreeList(reqSize);
//printf("We got ourselves new pointer to free block after 0x%x %d 0x%x 0x%x\n",
// (int*)ptrFreeBlock, (int)ptrFreeBlock->sizeAndTags, (int*)ptrFreeBlock->next, (int*)ptrFreeBlock->prev);
precedingBlockUseTag = TAG_PRECEDING_USED;
placeBlock( ptrFreeBlock, reqSize, precedingBlockUseTag );
}
return ((void*) POINTER_ADD(ptrFreeBlock, WORD_SIZE));
}
/* Allocate a block of size size and return a pointer to it. */
void* mm_malloc (size_t size) {
size_t reqSize;
BlockInfo * ptrFreeBlock = NULL;
size_t precedingBlockUseTag;
// Zero-size requests get NULL.
if (size == 0) {
return NULL;
}
// Add one word for the initial size header.
// Note that we don't need to boundary tag when the block is used!
size += WORD_SIZE;
if (size <= MIN_BLOCK_SIZE) {
// Make sure we allocate enough space for a blockInfo in case we
// free this block (when we free this block, we'll need to use the
// next pointer, the prev pointer, and the boundary tag).
reqSize = MIN_BLOCK_SIZE;
}
else {
// Round up for correct alignment
reqSize = ALIGNMENT * ((size + ALIGNMENT - 1) / ALIGNMENT);
}
ptrFreeBlock = searchFreeList(reqSize); //test for available block
if(ptrFreeBlock != NULL){ //if block of correct size available:
precedingBlockUseTag = (ptrFreeBlock)->sizeAndTags & (TAG_PRECEDING_USED); //test to see if block preceeding the block to be allocated is allocated
setBlock(ptrFreeBlock, reqSize, precedingBlockUseTag);//call to helper function, setBlock
}
else{
requestMoreSpace(reqSize); //request a freeBlock of the appropriate size
ptrFreeBlock = searchFreeList(reqSize);//search the free list now that we know the free block is there
precedingBlockUseTag = TAG_PRECEDING_USED;
setBlock(ptrFreeBlock, reqSize, precedingBlockUseTag);//call to helper function, setBlock
}
return UNSCALED_POINTER_ADD(ptrFreeBlock, WORD_SIZE);
}
/* Allocate a block of size size and return a pointer to it. */
void* mm_malloc (size_t size) {
size_t reqSize;
BlockInfo * ptrFreeBlock = NULL;
size_t blockSize;
size_t precedingBlockUseTag;
// Zero-size requests get NULL.
if (size == 0) {
return NULL;
}
// Add one word for the initial size header.
// Note that we don't need to boundary tag when the block is used!
size += WORD_SIZE;
if (size <= MIN_BLOCK_SIZE) {
// Make sure we allocate enough space for a blockInfo in case we
// free this block (when we free this block, we'll need to use the
// next pointer, the prev pointer, and the boundary tag).
reqSize = MIN_BLOCK_SIZE;
} else {
// Round up for correct alignment
reqSize = ALIGNMENT * ((size + ALIGNMENT - 1) / ALIGNMENT);
}
// Implement mm_malloc. You can change or remove any of the above
// code. It is included as a suggestion of where to start.
// You will want to replace this return statement...
// Search the free list for a fit
ptrFreeBlock = searchFreeList(reqSize);
// No fit found. Get more memory
if (ptrFreeBlock == NULL) {
requestMoreSpace(reqSize);
ptrFreeBlock = searchFreeList(reqSize);
}
// place the acquired block and split excessive part as needed
removeFreeBlock(ptrFreeBlock);
blockSize = SIZE(ptrFreeBlock->sizeAndTags);
precedingBlockUseTag = ptrFreeBlock->sizeAndTags & TAG_PRECEDING_USED;
if (blockSize - reqSize >= MIN_BLOCK_SIZE) {
size_t newFreeBlockSize = blockSize - reqSize;
BlockInfo *newPtrFreeBlock = (BlockInfo*)POINTER_ADD(ptrFreeBlock, reqSize);
newPtrFreeBlock->sizeAndTags = newFreeBlockSize | TAG_PRECEDING_USED; // !TAG_USED
// update the boundary tag
*((size_t*)POINTER_ADD(newPtrFreeBlock, newFreeBlockSize - WORD_SIZE)) =
newFreeBlockSize | TAG_PRECEDING_USED; // !TAG_USED
// insert the new free block into free list
insertFreeBlock(newPtrFreeBlock);
blockSize = reqSize;
} else {
// do not need to split the block, but need to update the status of following block
BlockInfo *followingBlock = (BlockInfo*)POINTER_ADD(ptrFreeBlock, blockSize);
size_t followingBlockSize = SIZE(followingBlock->sizeAndTags);
size_t followingBlockUsed = followingBlock->sizeAndTags & TAG_USED;
followingBlock->sizeAndTags = followingBlockSize | TAG_PRECEDING_USED | followingBlockUsed;
if (followingBlockUsed != TAG_USED) {
*((size_t*)POINTER_ADD(followingBlock, followingBlockSize - WORD_SIZE)) = followingBlock->sizeAndTags;
}
}
ptrFreeBlock->sizeAndTags = blockSize | precedingBlockUseTag | TAG_USED;
// we do not care about the boundary tag of used block!
return POINTER_ADD(ptrFreeBlock, WORD_SIZE);
}
/* Allocate a block of size size and return a pointer to it. */
void* mm_malloc (size_t size) {
size_t reqSize;
BlockInfo * ptrFreeBlock = NULL;
size_t blockSize;
size_t precedingBlockUseTag;
BlockInfo * nextBlock = NULL;
BlockInfo * newBlock = NULL;
// Zero-size requests get NULL.
if (size == 0) {
return NULL;
}
// Add one word for the initial size header.
// Note that we don't need to boundary tag when the block is used!
size += WORD_SIZE;
if (size <= MIN_BLOCK_SIZE) {
// Make sure we allocate enough space for a blockInfo in case we
// free this block (when we free this block, we'll need to use the
// next pointer, the prev pointer, and the boundary tag).
reqSize = MIN_BLOCK_SIZE;
} else {
// Round up for correct alignment
reqSize = ALIGNMENT * ((size + ALIGNMENT - 1) / ALIGNMENT);
}
// Implement mm_malloc. You can change or remove any of the above
// code. It is included as a suggestion of where to start.
// You will want to replace this return statement...
/*
ptrFreeBlock = searchFreeList(reqSize);
if( ptrFreeBlock != NULL) {
blockSize = SIZE(ptrFreeBlock->sizeAndTags);
nextBlock = (BlockInfo* )POINTER_ADD(ptrFreeBlock, blockSize);
nextBlock->sizeAndTags = nextBlock->sizeAndTags | TAG_PRECEDING_USED;
removeFreeBlock(ptrFreeBlock);
ptrFreeBlock->sizeAndTags = ptrFreeBlock->sizeAndTags | TAG_USED;
return POINTER_ADD( ptrFreeBlock, WORD_SIZE);
}
requestMoreSpace(reqSize);
ptrFreeBlock = searchFreeList(reqSize);
if( ptrFreeBlock != NULL) {
blockSize = SIZE(ptrFreeBlock->sizeAndTags);
nextBlock = (BlockInfo* )POINTER_ADD(ptrFreeBlock, blockSize);
nextBlock->sizeAndTags = nextBlock->sizeAndTags | TAG_PRECEDING_USED;
removeFreeBlock(ptrFreeBlock);
ptrFreeBlock->sizeAndTags = ptrFreeBlock->sizeAndTags | TAG_USED;
return POINTER_ADD( ptrFreeBlock, WORD_SIZE);
}
*/
ptrFreeBlock = searchFreeList(reqSize);
if( ptrFreeBlock == NULL){
requestMoreSpace(reqSize);
ptrFreeBlock = searchFreeList(reqSize);
}
blockSize = SIZE(ptrFreeBlock->sizeAndTags);
if( (blockSize - reqSize) >= MIN_BLOCK_SIZE ){
precedingBlockUseTag = ptrFreeBlock->sizeAndTags & TAG_PRECEDING_USED;
ptrFreeBlock->sizeAndTags = reqSize | precedingBlockUseTag | TAG_USED ;
removeFreeBlock(ptrFreeBlock);
newBlock = (BlockInfo* )POINTER_ADD(ptrFreeBlock, reqSize);
newBlock->sizeAndTags = blockSize - reqSize;
newBlock->sizeAndTags = newBlock->sizeAndTags | TAG_PRECEDING_USED;
*((size_t*)POINTER_ADD(newBlock, blockSize - reqSize - WORD_SIZE ) ) = newBlock->sizeAndTags;
insertFreeBlock(newBlock);
}else{
nextBlock = (BlockInfo* )POINTER_ADD(ptrFreeBlock, blockSize);
nextBlock->sizeAndTags = nextBlock->sizeAndTags | TAG_PRECEDING_USED;
ptrFreeBlock->sizeAndTags = ptrFreeBlock->sizeAndTags | TAG_USED;
removeFreeBlock(ptrFreeBlock);
}
return POINTER_ADD( ptrFreeBlock, WORD_SIZE);
}
/* Allocate a block of size size and return a pointer to it. */
void* mm_malloc (size_t size) {
size_t reqSize;
BlockInfo * ptrFreeBlock = NULL;
BlockInfo * splitBlock;
size_t blockSize;
size_t precedingBlockUseTag;
// Zero-size requests get NULL.
if (size == 0) {
return NULL;
}
// Add one word for the initial size header.
// Note that we don't need to boundary tag when the block is used!
size += WORD_SIZE;
if (size <= MIN_BLOCK_SIZE) {
// Make sure we allocate enough space for a blockInfo in case we
// free this block (when we free this block, we'll need to use the
// next pointer, the prev pointer, and the boundary tag).
reqSize = MIN_BLOCK_SIZE;
} else {
// Round up for correct alignment
reqSize = ALIGNMENT * ((size + ALIGNMENT - 1) / ALIGNMENT);
}
// Implement mm_malloc. You can change or remove any of the above
// code. It is included as a suggestion of where to start.
// You will want to replace this return statement...
// find free block of reqSize
ptrFreeBlock = searchFreeList(reqSize);
while ( ptrFreeBlock == NULL ) {
requestMoreSpace(1 << 14);
ptrFreeBlock = searchFreeList(reqSize);
}
// check free block size vs reqSize vs alignment requirements,
// split if necessary. If split, reformat newly created free
// block (add header, set bits, add footer).
blockSize = SIZE(ptrFreeBlock->sizeAndTags);
if ( blockSize - reqSize >= MIN_BLOCK_SIZE ) {
// Split, set size and tags of new block
splitBlock = (BlockInfo*) POINTER_ADD(ptrFreeBlock, reqSize);
blockSize -= reqSize;
splitBlock->sizeAndTags = blockSize | TAG_PRECEDING_USED;
splitBlock->sizeAndTags &= ~0 << 1; // turn off use bit - preserve others
// set footer equal to header. Current ptr + blockSize - one word = boundary
// tag of current block (word prior to start of next block)
*((size_t*) POINTER_ADD(splitBlock, blockSize- WORD_SIZE))=
splitBlock->sizeAndTags;
insertFreeBlock(splitBlock);
// set size of ptrFreeBlock to exclude size of newBlock
blockSize = reqSize;
} else { // if we didnt split, set the next block's preceding tag to 1
*((size_t*) POINTER_ADD(ptrFreeBlock, SIZE(ptrFreeBlock->sizeAndTags))) |=
TAG_PRECEDING_USED;
}
removeFreeBlock(ptrFreeBlock);
precedingBlockUseTag = ptrFreeBlock->sizeAndTags & TAG_PRECEDING_USED;
// if the preceding block is used as well, set lower two bits. Else, set only
// used bit.
if ( precedingBlockUseTag ) {
ptrFreeBlock->sizeAndTags = blockSize | (TAG_PRECEDING_USED + TAG_USED);
} else {
ptrFreeBlock->sizeAndTags = blockSize | TAG_USED;
}
// return pointer to block (beginning of payload)
// if null, return null. else return 8 after start of block (ie skip header,
// return ptr to payload region)
if ( ptrFreeBlock == NULL) { return NULL; }
else { return (void*) POINTER_ADD(ptrFreeBlock, WORD_SIZE); }
}
