void coalesceWithNextBlock(void* newAddr, uint32_t newSize, struct freeBlockLinks *successorBlockLinks)
{
struct blockHeader *newBlock = newAddr;
newBlock->attribute = newSize;
// Update links to freenodes.
void* blockLinks = ADDRESS_PLUS_OFFSET(newAddr, blockHeader);
struct freeBlockLinks *newBlockLinks = INIT_STRUCT(freeBlockLinks, blockLinks);
PREV_BLOCK(newBlockLinks) = PREV_BLOCK(successorBlockLinks);
NEXT_BLOCK(newBlockLinks) = NEXT_BLOCK(successorBlockLinks);
// Prev block.
void* prevLinks = ADDRESS_PLUS_OFFSET(PREV_BLOCK(newBlockLinks), blockHeader);
struct freeBlockLinks *prevBlockLinks = INIT_STRUCT(freeBlockLinks, prevLinks);
NEXT_BLOCK(prevBlockLinks) = newAddr;
// Next block.
void* nextLinks = ADDRESS_PLUS_OFFSET(NEXT_BLOCK(newBlockLinks), blockHeader);
struct freeBlockLinks *nextBlockLinks = INIT_STRUCT(freeBlockLinks, nextLinks);
PREV_BLOCK(prevBlockLinks) = newAddr;
uint64_t sizeOffset = WORDS_TO_BYTES(newSize);
setFooterBlockOnCoalescing(newAddr, sizeOffset, newSize);
updateNextBlockOnCoalescing(newAddr, sizeOffset);
}
// Remove allocated block from free list.
void removeAllocatedBlock(struct freeBlockLinks *blockToBeRemovedLinks)
{
void* prevBlock = PREV_BLOCK(blockToBeRemovedLinks);
void* prevLinks = ADDRESS_PLUS_OFFSET(prevBlock, blockHeader);
struct freeBlockLinks *prevBlockLinks = INIT_STRUCT(freeBlockLinks, prevLinks);
NEXT_BLOCK(prevBlockLinks) = NEXT_BLOCK(blockToBeRemovedLinks);
void* nextBlock = NEXT_BLOCK(blockToBeRemovedLinks);
void* nextLinks = ADDRESS_PLUS_OFFSET(nextBlock, blockHeader);
struct freeBlockLinks *nextBlockLinks = INIT_STRUCT(freeBlockLinks, nextLinks);
PREV_BLOCK(nextBlockLinks) = PREV_BLOCK(blockToBeRemovedLinks);
}
// Insert new free block into the free list
void insertFreeBlock(void* newBlock, struct freeBlockLinks *prevBlockLinks)
{
void* usableArea = ADDRESS_PLUS_OFFSET(newBlock, blockHeader);
struct freeBlockLinks *newBlockLinks = INIT_STRUCT(freeBlockLinks, usableArea);
void* next = NEXT_BLOCK(newBlockLinks) + sizeof(blockHeader);
struct freeBlockLinks *nextBlock = INIT_STRUCT(freeBlockLinks, next);
PREV_BLOCK(nextBlock) = newBlock;
void* prev = PREV_BLOCK(newBlockLinks) + sizeof(blockHeader);
struct freeBlockLinks *prevBlock = INIT_STRUCT(freeBlockLinks, prev);
NEXT_BLOCK(prevBlock) = newBlock;
}
/*
* mm_check - heap consistency checker. return 0 if something is wrong, 1 otherwise.
*/
int mm_check(void)
{
void *cur, *end;
if(!rb_check_preorder()){
return 0;
}
cur = mem_heap_lo() + MIN_BLOCK_SIZE;
end = mem_heap_hi() - 3;
while(cur < end){
if(CUR_FREE(cur)){ // cur is free block
if(PREV_FREE(cur)){ // contiguous free block
printf("%p, %p are consecutive, but both are free.\n",
PREV_BLOCK(cur, CUR_SIZE_MASKED(cur)), cur);
return 0;
}
if(IS_IN_RB(cur) && !rb_find_exact(cur)){ // cur is not in Red-black tree
printf("%p is free block, but is not in Red-black tree.\n", cur);
return 0;
}
}else{ // cur is allocated block
}
cur = NEXT_BLOCK(cur, CUR_SIZE_MASKED(cur));
}
return 1;
}
// size in words.
// Flag one means block is free.
void initialiseFreeBlock(void* freeRegion, uint32_t size, void* prevFreeRegion,
void* nextFreeRegion, bool flag, bool setHeader)
{
totalFreeSpace += WORDS_TO_BYTES(size); // Stats
// Update largest free region.
if (size > largestFreeBlock) {
largestFreeBlock = WORDS_TO_BYTES(size);
}
if (setHeader) {
struct blockHeader *header = INIT_STRUCT(blockHeader, freeRegion);
header->attribute = size; // Set size. Size is max 2^30. Flag is 0 by default.
if (flag)
header->attribute |= MSB_TO_ONE; // Set flag to 1.
}
void* usableArea = ADDRESS_PLUS_OFFSET(freeRegion, blockHeader);
struct freeBlockLinks *blockLinks = INIT_STRUCT(freeBlockLinks, usableArea);
PREV_BLOCK(blockLinks) = prevFreeRegion;
NEXT_BLOCK(blockLinks) = nextFreeRegion;
// Set footer free region.
uint64_t sizeOffset = WORDS_TO_BYTES(size);
void* footer = ADDRESS_MINUS_OFFSET(usableArea + sizeOffset, freeBlockFooter);
struct freeBlockFooter *blockFooter = INIT_STRUCT(freeBlockFooter, footer);
blockFooter->size = size;
}
// Split a large block into two sub-blocks.
// spaceLeft and size are in words
void *splitFreeBlock(void* blockToSplit, uint64_t spaceLeft,
uint32_t size, void* currentFreeBlock,
struct freeBlockLinks *currentBlockLinks)
{
// Reinitialise header of first sub-block.
void* block = ADDRESS_MINUS_OFFSET(blockToSplit, blockHeader);
struct blockHeader *allocatedBlock = INIT_STRUCT(blockHeader, block);
allocatedBlock->attribute = size;
// Create and initialise new node.
uint32_t sizeNewNode = spaceLeft - BYTES_TO_WORDS(sizeof(blockHeader));
uint64_t sizeOffset = WORDS_TO_BYTES(size);
void* endUserRequestedBlock = blockToSplit + sizeOffset;
// initialise new block.
void* prevBlock = PREV_BLOCK(currentBlockLinks);
totalFreeSpace -= WORDS_TO_BYTES(spaceLeft);
totalFreeSpace -= WORDS_TO_BYTES(size); // Stats
initialiseFreeBlock(endUserRequestedBlock, sizeNewNode,
prevBlock, currentFreeBlock, false, true);
insertFreeBlock(endUserRequestedBlock, currentBlockLinks);
return endUserRequestedBlock;
}
// size free region in bytes
void initialiseFreeMmapRegion(void* beginningFreeRegion, uint64_t sizeFreeRegion)
{
uint32_t sizeFreeRegionInWords = BYTES_TO_WORDS(sizeFreeRegion); // headerMmapsize in words.
if(!freeList) {
freeList = beginningFreeRegion; // Initialise the free list.
initialiseFreeBlock(beginningFreeRegion, sizeFreeRegionInWords,
beginningFreeRegion, beginningFreeRegion, false, true);
} else {
// Add to free list.
void *currentBlock = freeList;
void* links = ADDRESS_PLUS_OFFSET(currentBlock, blockHeader);
struct freeBlockLinks *currentBlockLinks = INIT_STRUCT(freeBlockLinks, links);
void* prevBlock = PREV_BLOCK(currentBlockLinks);
initialiseFreeBlock(beginningFreeRegion, sizeFreeRegionInWords,
prevBlock, currentBlock, false, true);
// Tell next block that its previous one is NOW free.
uint64_t sizeOffset = WORDS_TO_BYTES(sizeFreeRegionInWords);
updateNextBlockOnCoalescing(beginningFreeRegion, sizeFreeRegion);
insertFreeBlock(beginningFreeRegion, currentBlockLinks);
}
}
/* TBD: Make this function force inline */
static inline void prvInsertBlockIntoFreeList( xBlockLink * pxBlockToInsert )
{
xBlockLink *pxIterator;
xBlockLink *xBlockToMerge;
size_t xBlockSize;
ASSERT(IS_FREE_BLOCK(pxBlockToInsert));
/* We have a block which we are about to declare as a free block.
* Lets find out if there is a free block in front of us and back
* of us
*/
/*
TRACE("pxBlockToInsert->pxNextFreeBlock: %x ->pxPrev = %x\n\r",
pxBlockToInsert->pxNextFreeBlock, pxBlockToInsert->pxPrev);
*/
/* Check for front merge */
if ( !IS_LAST_BLOCK( pxBlockToInsert ) ) {
if ( IS_FREE_BLOCK(NEXT_BLOCK( pxBlockToInsert ) ) ) {
xBlockToMerge = NEXT_BLOCK( pxBlockToInsert );
/* Find out xBlockToMerge's location on the free list.*/
for( pxIterator = &xStart;
pxIterator->pxNextFreeBlock != xBlockToMerge &&
pxIterator->pxNextFreeBlock != NULL;
pxIterator = pxIterator->pxNextFreeBlock ) {}
#ifdef DEBUG_HEAP
if(! ( pxIterator->pxNextFreeBlock == xBlockToMerge ) ) {
/*
* This is not a good situation. The
* problem is that data structures here are
* showing that the next block is free. But
* ths free block could not be found in the
* free list.
*/
ATRACE("Target block dump :\n\r");
ATRACE("pxNextFreeBlock : 0x%x\n\r",
xBlockToMerge->pxNextFreeBlock);
ATRACE("pxPrev : 0x%x\n\r",
xBlockToMerge->pxPrev);
ATRACE("xBlockSize : %d (0x%x)\n\r",
xBlockToMerge->xBlockSize, xBlockToMerge->xBlockSize);
#ifdef DEBUG_HEAP_EXTRA
ATRACE("xActualBlockSize: %d\n\r",
xBlockToMerge->xActualBlockSize);
#endif /* DEBUG_HEAP_EXTRA */
ATRACE("Panic\n\r");
while(1) {}
}
#endif /* DEBUG_HEAP */
ASSERT( pxIterator->pxNextFreeBlock == xBlockToMerge );
//TRACE("Merge: F\n\r");
/* Delete node from Free list */
pxIterator->pxNextFreeBlock = xBlockToMerge->pxNextFreeBlock;
/* Delete xBlockToMerge node from Serial List */
if( ! IS_LAST_BLOCK( xBlockToMerge ) )
NEXT_BLOCK( xBlockToMerge )->pxPrev = pxBlockToInsert;
/* Update node size */
pxBlockToInsert->xBlockSize += BLOCK_SIZE( xBlockToMerge );
/* Now forget about xBlockToMerge */
}
}
/* Check for back merge */
if ( ! IS_FIRST_BLOCK(pxBlockToInsert) ) {
if ( IS_FREE_BLOCK( PREV_BLOCK(pxBlockToInsert ))) {
xBlockToMerge = PREV_BLOCK(pxBlockToInsert);
/* Find out xBlockToMerge's location on the free list */
for( pxIterator = &xStart;
pxIterator->pxNextFreeBlock != xBlockToMerge &&
pxIterator->pxNextFreeBlock != NULL;
pxIterator = pxIterator->pxNextFreeBlock ) {}
ASSERT( pxIterator->pxNextFreeBlock == xBlockToMerge );
//TRACE("Merge: R\n\r");
/* Delete xBlockToMerge node from Free list */
pxIterator->pxNextFreeBlock = xBlockToMerge->pxNextFreeBlock;
/* Delete _ pxBlockToInsert _ node from Serial List */
if( ! IS_LAST_BLOCK( pxBlockToInsert ) )
NEXT_BLOCK( pxBlockToInsert )->pxPrev = xBlockToMerge;
/* Update node size */
xBlockToMerge->xBlockSize += BLOCK_SIZE( pxBlockToInsert );
/* Now forget about pxBlockToInsert */
pxBlockToInsert = xBlockToMerge;
}
}
xBlockSize = pxBlockToInsert->xBlockSize;
/* Iterate through the list until a block is found that has a larger size */
/* than the block we are inserting. */
for( pxIterator = &xStart; pxIterator->pxNextFreeBlock->xBlockSize < xBlockSize;
pxIterator = pxIterator->pxNextFreeBlock )
{
/* There is nothing to do here - just iterate to the correct position. */
}
/* Update the list to include the block being inserted in the correct */
/* position. */
pxBlockToInsert->pxNextFreeBlock = pxIterator->pxNextFreeBlock;
pxIterator->pxNextFreeBlock = pxBlockToInsert;
}
/*
* mm_free - Coalesce with surrounding blocks, and put it to Red-black tree
*/
void mm_free(void *ptr)
{
size_t size, new_size;
void *prev, *cur, *next, *new_block;
cur = ptr - HEADER_SIZE;
/* double free */
if(CUR_FREE(cur)){
printf("try to free a freed memory block(%p) is detected.\n", cur);
return ;
}
new_block = cur;
new_size = CUR_SIZE_MASKED(cur);
/* coalesce with the previous block if free */
if(PREV_FREE(cur)){
size = PREV_SIZE_MASKED(cur);
prev = PREV_BLOCK(cur, size);
if(IS_IN_RB(prev)){
rb_delete(prev);
}
new_block = prev;
new_size += size;
}
/* coalesce with the next block if exists and free */
size = CUR_SIZE_MASKED(cur);
next = NEXT_BLOCK(cur, size);
if(next + 4 <= mem_heap_hi() && CUR_FREE(next)){
size = CUR_SIZE_MASKED(next);
if(IS_IN_RB(next)){
rb_delete(next);
}
new_size += size;
}
/* new free block setting */
CUR_SIZE(new_block) = PREV_SIZE(NEXT_BLOCK(new_block, new_size)) = new_size | 1;
if(IS_IN_RB(new_block)){
rb_insert(new_block);
}
#ifdef DEBUG
printf("mm_free(%p) called\n", ptr);
printf("new_block = %p\n", new_block);
rb_print_preorder();
printf("\n");
#endif /* DEBUG */
#ifdef CHECK
if(!mm_check()){
rb_print_preorder();
exit(0);
}
#endif /* CHECK */
/* DON't MODIFY THIS STAGE AND LEAVE IT AS IT WAS */
if (gl_ranges)
remove_range(gl_ranges, ptr);
}
void coalescingAndFree(void* block)
{
struct blockHeader *header = INIT_STRUCT(blockHeader, block);
uint32_t size = GET_SIZE(header->attribute); // in words
uint32_t flag = GET_FLAG(header->attribute);
NEIGHBOUR_BLOCKS state = NEIGHBOUR_BLOCKS_NOT_FREE;
struct freeBlockLinks *successorBlockLinks = NULL; // update only if necessary
// Initialise addr and size for no change.
void* newAddr = block;
uint32_t newSize = size;
uint64_t sizeOffset;
// Is precedent block free?
if (flag == MSB_TO_ONE) {
state = NEIGHBOUR_BLOCKS_PRECEDENT_FREE;
// In this case it's just about updating the size of the prev free block
// and removing the successive one if free.
void* footer = ADDRESS_MINUS_OFFSET(block, freeBlockFooter);
struct freeBlockFooter *prevBlockFooter = INIT_STRUCT(freeBlockFooter, footer);
sizeOffset = WORDS_TO_BYTES(prevBlockFooter->size); // Footer has no flag.
newAddr = block - sizeOffset - sizeof(blockHeader);
newSize = prevBlockFooter->size + BYTES_TO_WORDS(sizeof(blockHeader)) + size;
}
// Is successive block free?
sizeOffset = WORDS_TO_BYTES(size);
void* nextBlock = ADDRESS_PLUS_OFFSET(block + sizeOffset, blockHeader);
struct blockHeader *nextHeader = INIT_STRUCT(blockHeader, nextBlock);
if (nextHeader->attribute != MSB_TO_ZERO) { // check if next block is mmap footer or not.
uint32_t nextSize = GET_SIZE(nextHeader->attribute);
sizeOffset = WORDS_TO_BYTES(nextSize);
void* nextNextBlock = ADDRESS_PLUS_OFFSET(nextBlock + sizeOffset, blockHeader);
struct blockHeader *nextNextHeader = INIT_STRUCT(blockHeader, nextNextBlock);
if (nextNextHeader->attribute != MSB_TO_ZERO) {
flag = GET_FLAG(nextNextHeader->attribute);
if (flag == MSB_TO_ONE) {
if (!state) {
state = NEIGHBOUR_BLOCKS_SUCCESSIVE_FREE;
// Do not change address, but Increase size
newSize = size + BYTES_TO_WORDS(sizeof(blockHeader)) + nextSize;
} else {
state = NEIGHBOUR_BLOCKS_BOTH_FREE;
newSize = newSize + BYTES_TO_WORDS(sizeof(blockHeader)) + nextSize;
}
successorBlockLinks = nextBlock + sizeof(blockHeader);
// IF NO PREV block is free:
// Just update the pointers of the prev and next blocks
// relative to this block AND the size.
}
}
} // Otherwise it's next block is the mmap footer.
switch(state)
{
case NEIGHBOUR_BLOCKS_NOT_FREE:
{
void *currentBlock = freeList;
struct freeBlockLinks *currentBlockLinks = ADDRESS_PLUS_OFFSET(currentBlock, blockHeader);
void* prevBlock = PREV_BLOCK(currentBlockLinks);
initialiseFreeBlock(newAddr, newSize,
prevBlock, currentBlock, false, false);
// Tell next block that its previous one is NOW free.
sizeOffset = WORDS_TO_BYTES(size);
updateNextBlockOnCoalescing(newAddr, sizeOffset);
insertFreeBlock(newAddr, currentBlockLinks);
numberFreeBlocks++;
break;
}
case NEIGHBOUR_BLOCKS_PRECEDENT_FREE:
{
coalesceWithPrevBlock(newAddr, newSize);
break;
}
case NEIGHBOUR_BLOCKS_SUCCESSIVE_FREE:
{
coalesceWithNextBlock(newAddr, newSize, successorBlockLinks);
break;
}
case NEIGHBOUR_BLOCKS_BOTH_FREE:
{
coalesceWithNeighbours(newAddr, newSize, successorBlockLinks);
break;
}
default:
{
fprintf(stderr, "memoryManagement.coalescingAndFree - NEIGHBOUR_BLOCKS state unknown\n");
exit(-1);
}
} // end switch
// Update total free space
// When state == 0, the totalFreeSpace is updated when the block is initialised.
totalFreeSpace += WORDS_TO_BYTES(size); // Stats
if (state != NEIGHBOUR_BLOCKS_NOT_FREE)
totalFreeSpace += sizeof(blockHeader);
// Largest free region
if (newSize > largestFreeBlock)
largestFreeBlock = newSize;
freeList = newAddr;
}
