/*
* remove_freeblock - Removes the given free block pointed to by bp from the free list.
*
* The explicit free list is simply a doubly linked list. This function performs a removal
* of the block from the doubly linked free list.
*/
static void remove_freeblock(void *bp)
{
if(bp) {
if (PREV_FREE(bp))
NEXT_FREE(PREV_FREE(bp)) = NEXT_FREE(bp);
else
free_listp = NEXT_FREE(bp);
if(NEXT_FREE(bp) != NULL)
PREV_FREE(NEXT_FREE(bp)) = PREV_FREE(bp);
}
}
//Find free block size >= asize
void * find_fit(size_t asize){
char *bp;
//Scan free list, starting with freeStart and ending upon reaching the epilogue block
//Note that the epilogue block is the only memeber of the free list whose allocate bit is high
for (bp = freeStart; NEXT_FREE(bp) != NULL; bp = NEXT_FREE(bp)){
if (asize <= GET_SIZE(HDRP(bp))){
return bp;
}
}
return NULL; //no fit, BUG allways returning NULL
}
/*
* delBlkFromFreeList - Removes a block from the free list
* This function takes a block pointer of the block to remove, as a
* parameter. This is basically a rearrangement of the next
* and prev pointers.
*/
static void delBlkFromFreeList(void *bp)
{
if (bp == free_listp)
free_listp = NEXT_FREE(bp);
else
/* Set next pointer of previous free block
* to point to the next block(thereby skipping the current
* block). */
NEXT_FREE(PREV_FREE(bp)) = NEXT_FREE(bp);
/* The previous pointer of the next block points to
* the previous block thereby skipping the current block. */
PREV_FREE(NEXT_FREE(bp)) = PREV_FREE(bp);
}
/*
* checkFreeNodes - function that checks correctness of the blocks in
* the free list
*/
static void checkFreeNodes(void *bp)
{
/* Seperate condition for free_listp since it does not have a
* previous pointer.
*/
if(bp == free_listp)
{
/* Checking that free_listp indeed points to a free block. */
if(GET_ALLOC(HDRP(bp)))
printf("Error: Freelistp points to an allocated block.\n");
/* Free_listp must point to a valid block and must not be
* out of bounds */
if(!(bp > mem_heap_lo() && bp < mem_heap_hi()))
printf("Error: Free list pointer out of heap bounds.\n");
/* Previous pointer of free_listp
* must point nowhere (nil). */
if(PREV_FREE(bp) != 0 )
printf("Error: Free pointer is not null.\n");
return;
}
/* Checking that bp is indeed pointing to a free block */
if(GET_ALLOC(HDRP(bp)) != 0)
printf("Error: There exists an allocated block in the free list.\n");
/* Check that next and prev pointers in consecutive blocks are consistent
* Next pointer of previous block points to current block and previous pointer
* of next block points to current block */
// Split one print statement into 2 to not cross the 80 character limit.
if(PREV_FREE(bp) && NEXT_FREE(PREV_FREE(bp)) != bp)
{
printf("Error: Next pointer of previous free block ");
printf("not pointing to current block.\n");
}
if(NEXT_FREE(bp) && PREV_FREE(NEXT_FREE(bp)) != bp)
{
printf("Error: Previous pointer of next free block ");
printf("not pointing to current block.\n");
}
/* Check that coalescing was correct at the free block pointed to by
bp. The previous and next blocks must both be allocated.*/
if(!GET_ALLOC(HDRP(NEXT_BLKP(bp))) || !GET_ALLOC(HDRP(PREV_BLKP(bp))))
printf("Error: Contiguous free blocks in the heap\n");
}
/*
* find_fit - Attempts to find a free block of at least the given size in the free list.
*
* This function implements a first-fit search strategy for an explicit free list, which
* is simply a doubly linked list of free blocks.
*/
static void *find_fit(size_t size)
{
// First-fit search
void *bp;
/* Iterate through the free list and try to find a free block
* large enough */
for (bp = free_listp; GET_ALLOC(HDRP(bp)) == 0; bp = NEXT_FREE(bp)) {
if (size <= GET_SIZE(HDRP(bp)))
return bp;
}
// Otherwise no free block was large enough
return NULL;
}
/*
* coalesce - Coalesces the memory surrounding block bp using the Boundary Tag strategy
* proposed in the text (Page 851, Section 9.9.11).
*
* Adjancent blocks which are free are merged together and the aggregate free block
* is added to the free list. Any individual free blocks which were merged are removed
* from the free list.
*/
static void *coalesce(void *bp)
{
// Determine the current allocation state of the previous and next blocks
size_t prev_alloc = GET_ALLOC(FTRP(PREV_BLKP(bp))) || PREV_BLKP(bp) == bp;
size_t next_alloc = GET_ALLOC(HDRP(NEXT_BLKP(bp)));
// Get the size of the current free block
size_t size = GET_SIZE(HDRP(bp));
/* If the next block is free, then coalesce the current block
* (bp) and the next block */
if (prev_alloc && !next_alloc) { // Case 2 (in text)
size += GET_SIZE(HDRP(NEXT_BLKP(bp)));
remove_freeblock(NEXT_BLKP(bp));
PUT(HDRP(bp), PACK(size, 0));
PUT(FTRP(bp), PACK(size, 0));
}
/* If the previous block is free, then coalesce the current
* block (bp) and the previous block */
else if (!prev_alloc && next_alloc) { // Case 3 (in text)
size += GET_SIZE(HDRP(PREV_BLKP(bp)));
bp = PREV_BLKP(bp);
remove_freeblock(bp);
PUT(HDRP(bp), PACK(size, 0));
PUT(FTRP(bp), PACK(size, 0));
}
/* If the previous block and next block are free, coalesce
* both */
else if (!prev_alloc && !next_alloc) { // Case 4 (in text)
size += GET_SIZE(HDRP(PREV_BLKP(bp))) +
GET_SIZE(HDRP(NEXT_BLKP(bp)));
remove_freeblock(PREV_BLKP(bp));
remove_freeblock(NEXT_BLKP(bp));
bp = PREV_BLKP(bp);
PUT(HDRP(bp), PACK(size, 0));
PUT(FTRP(bp), PACK(size, 0));
}
// Insert the coalesced block at the front of the free list
NEXT_FREE(bp) = free_listp;
PREV_FREE(free_listp) = bp;
PREV_FREE(bp) = NULL;
free_listp = bp;
// Return the coalesced block
return bp;
}
static void delete_free_block(void * ptr){
//fix foward pointer of previous block
if (PREV_FREE(ptr) == NULL){ //then we're deleting the first element of the free list
PREV_FREE(NEXT_FREE(ptr)) = NULL; //fix backpointer
freeStart = NEXT_FREE(ptr); //fix freeStart
}
else if(PREV_FREE(ptr) != NULL && NEXT_FREE(ptr) != NULL){ //not at the beginning or end of the free list
PREV_FREE(NEXT_FREE(ptr)) = PREV_FREE(ptr);
NEXT_FREE(PREV_FREE(ptr)) = NEXT_FREE(ptr); //fix back pointer of next block
}
else{ //we are deleting the last element of the list
NEXT_FREE(PREV_FREE(ptr)) = NULL;
}
}
/*
* insertAtFront - Inserts a block pointed to
* by bp at the front of the free list
* (LIFO policy)
*/
static void insertAtFront(void *bp)
{
/* Make the next pointer of the block point to
* start of the list i.e. free_listp */
NEXT_FREE(bp) = free_listp;
/* Previous pointer of bp should not point
* anywhere. Set to 0 */
PREV_FREE(bp) = 0;
/* Set free_list prev to point to bp.
* This is how we include bp into the list.
* Since free_listp must always point to the
* first free block, and bp is the first free block,
* we set free_listp = bp */
PREV_FREE(free_listp) = bp;
free_listp = bp;
}
/*
* mm_checkheap - Checks the invariants of the heap
* This function checks the invariants of the heap such as header-footer match,
* absence of contiguous blocks of free memory and confirmation that the
* block pointers are within the heaps boundaries.
*/
void mm_checkheap(int verbose)
{
void *bp = heap_listp; //Points to the first block in the heap
verbose = verbose;
/* If first block's header's size or allocation bit is wrong,
* the prologue header is incorrect. */
if ((GET_SIZE(HDRP(heap_listp)) != MINBLOCKSIZE) ||
!GET_ALLOC(HDRP(heap_listp)))
printf("Bad prologue header\n");
checkblock(bp);
for (bp = heap_listp; GET_SIZE(HDRP(bp)) > 0; bp = NEXT_BLKP(bp))
{
if (verbose)
printblock(bp);
if(GET_SIZE(HDRP(bp)) == 0)
printf("Error: block has zero size\n");
checkblock(bp);
/* Checking to see if free block in the free list */
if(!GET_ALLOC(HDRP(bp)))
checkInFreeList(bp);
}
/* If last block's header's size or allocation bit is wrong,
* the epilogue's header is wrong. We also check the specific location
* of the epilogue header with respect to the last byte of the heap.
* mem_heap_hi() and bp(at this point) both point to the same word,
* but mem_heap_hi() points to the last byte and hence we must add 3 to
* the address of the header of bp to check this condition.
*/
if (GET_SIZE(HDRP(bp)) != 0 || (GET_ALLOC(HDRP(bp)) != 1)
|| (HDRP(bp) + WSIZE - 1) != mem_heap_hi())
printf("Bad epilogue header\n");
for(bp = free_listp; GET_ALLOC(HDRP(bp)) == 0; bp = NEXT_FREE(bp))
checkFreeNodes(bp);
}
/*
* findFit
* findFit finds a free block that has size at least asize bytes.
* It uses an algorithm that is a slight combination of best fit
* and first fit. The function traverses the list from the free_listp
* and once it hits a free block of large enough size we traverse a
* CONSTANT number of times. I used trial and error to find a constant
* that would give me the most throughput.
*/
static void *findFit(size_t asize)
{
void *bp = NULL;
void *temp = free_listp;
size_t minSize = mem_heapsize(); // maximum size
/* First fit search */
size_t size;
int counter = 0; /* counter for CONSTANT number of traversals */
int flag = 0; /* flag is set if we come across a fit. */
while(!GET_ALLOC(HDRP(temp))) /* While we are pointing to a free block */
{
if(asize <= (size = (size_t)GET_SIZE(HDRP(temp))) && size < minSize)
{
/* If we have a block that fits perfectly,
* then there is no point in searching for
* a smaller block because we have found the smallest possible one
*/
if(asize == size)
return temp;
bp = temp;
minSize = size;
flag = 1;
}
if(flag == 1)
counter++;
/* We have traversed enough. */
if(counter == CONSTANT)
return bp;
temp = NEXT_FREE(temp);
}
return bp;
}
/*FUNCTION*-----------------------------------------------------
*
* Function Name : _mem_alloc_internal_align
* Returned Value : pointer. NULL is returned upon error.
* Comments :
* Allocate a aligned block of memory for a task from the free list
*
*
*END*---------------------------------------------------------*/
pointer _mem_alloc_internal_align
(
/* [IN] the size of the memory block */
_mem_size requested_size,
/* [IN] requested alignement (e.g. 8 for alignement to 8 bytes) */
_mem_size req_align,
/* [IN] owner TD */
TD_STRUCT_PTR td_ptr,
/* [IN] which pool to allocate from */
MEMPOOL_STRUCT_PTR mem_pool_ptr,
/* [OUT] error code for operation */
_mqx_uint_ptr error_ptr
)
{ /* Body */
STOREBLOCK_STRUCT_PTR block_ptr, free_block_ptr;
STOREBLOCK_STRUCT_PTR next_block_ptr = NULL;
STOREBLOCK_STRUCT_PTR next_next_block_ptr;
_mem_size block_size;
_mem_size next_block_size;
_mem_size shift;
*error_ptr = MQX_OK;
/*
** Adjust message size to allow for block management overhead
** and force size to be aligned.
*/
requested_size += (_mem_size)(FIELD_OFFSET(STOREBLOCK_STRUCT,USER_AREA));
#if MQX_CHECK_ERRORS
if (requested_size < MQX_MIN_MEMORY_STORAGE_SIZE) {
requested_size = MQX_MIN_MEMORY_STORAGE_SIZE;
} /* Endif */
#endif
_MEMORY_ALIGN_VAL_LARGER(requested_size);
block_ptr = mem_pool_ptr->POOL_FREE_LIST_PTR;
while ( TRUE ) {
/*
** Save the current block pointer.
** We will be enabling access to higher priority tasks.
** A higher priority task may pre-empt the current task
** and may do a memory allocation. If this is true,
** the higher priority task will reset the POOL_ALLOC_CURRENT_BLOCK
** upon exit, and the current task will start the search over
** again.
*/
mem_pool_ptr->POOL_ALLOC_CURRENT_BLOCK = block_ptr;
/* allow pending interrupts */
_int_enable();
_int_disable();
/* Get block pointer in case reset by a higher priority task */
block_ptr = mem_pool_ptr->POOL_ALLOC_CURRENT_BLOCK;
if (block_ptr == NULL) { /* Null pointer */
mem_pool_ptr->POOL_BLOCK_IN_ERROR = block_ptr;
*error_ptr = MQX_OUT_OF_MEMORY;
return( NULL ); /* request failed */
} /* Endif */
#if MQX_CHECK_VALIDITY
if ( !_MEMORY_ALIGNED(block_ptr) || BLOCK_IS_USED(block_ptr) ) {
mem_pool_ptr->POOL_BLOCK_IN_ERROR = block_ptr;
*error_ptr = MQX_CORRUPT_STORAGE_POOL_FREE_LIST;
return((pointer)NULL);
}
if ( ! VALID_CHECKSUM(block_ptr) ) {
mem_pool_ptr->POOL_BLOCK_IN_ERROR = block_ptr;
*error_ptr = MQX_INVALID_CHECKSUM;
return((pointer)NULL);
}
#endif
block_size = block_ptr->BLOCKSIZE;
shift = (((_mem_size)&block_ptr->USER_AREA + req_align) & ~(req_align - 1)) - (_mem_size)&block_ptr->USER_AREA;
if (shift < (2 * MQX_MIN_MEMORY_STORAGE_SIZE)) {
shift = (((_mem_size)&block_ptr->USER_AREA + (3 * MQX_MIN_MEMORY_STORAGE_SIZE) + req_align) & ~(req_align - 1)) - (_mem_size)&block_ptr->USER_AREA;
}
if (block_size >= requested_size + shift) {
/* request fits into this block */
// create new free block
free_block_ptr = (STOREBLOCK_STRUCT_PTR)((char _PTR_)block_ptr);
block_ptr = (STOREBLOCK_STRUCT_PTR)(((char _PTR_)block_ptr) + shift);
block_ptr->PREVBLOCK = (STOREBLOCK_STRUCT_PTR)free_block_ptr;
next_block_size = block_size - requested_size - shift;
if (next_block_size >= (2 * MQX_MIN_MEMORY_STORAGE_SIZE) ) {
/*
** The current block is big enough to split.
** into 2 blocks.... the part to be allocated is one block,
** and the rest remains as a free block on the free list.
*/
next_block_ptr = (STOREBLOCK_STRUCT_PTR)((char _PTR_)block_ptr + requested_size);
/* Initialize the new physical block values */
next_block_ptr->BLOCKSIZE = next_block_size;
next_block_ptr->PREVBLOCK = (STOREBLOCK_STRUCT_PTR)block_ptr;
MARK_BLOCK_AS_FREE(next_block_ptr);
CALC_CHECKSUM(next_block_ptr);
/* Link new block into the free list */
next_block_ptr->NEXTBLOCK = free_block_ptr->NEXTBLOCK;
block_ptr->NEXTBLOCK = (pointer)next_block_ptr;
next_block_ptr->USER_AREA = (pointer)free_block_ptr;
if (next_block_ptr->NEXTBLOCK != NULL ) {
((STOREBLOCK_STRUCT_PTR)next_block_ptr->NEXTBLOCK)->USER_AREA = (pointer)next_block_ptr;
}
/*
** Modify the current block, to point to this newly created
** block which is now the next physical block.
*/
block_ptr->BLOCKSIZE = requested_size;
/*
** Modify the block on the other side of the next block
** (the next next block) so that it's previous block pointer
** correctly point to the next block.
*/
next_next_block_ptr = (STOREBLOCK_STRUCT_PTR)NEXT_PHYS(next_block_ptr);
PREV_PHYS(next_next_block_ptr) = next_block_ptr;
CALC_CHECKSUM(next_next_block_ptr);
} else {
/* Take the entire block */
requested_size = next_block_size;
} /* Endif */
/* modify the new physical block values */
free_block_ptr->BLOCKSIZE = shift;
free_block_ptr->NEXTBLOCK = (pointer)next_block_ptr;
//free_block_ptr->USER_AREA
MARK_BLOCK_AS_FREE(free_block_ptr);
CALC_CHECKSUM(free_block_ptr);
/* Set the size of the block */
block_ptr->BLOCKSIZE = requested_size;
block_ptr->PREVBLOCK = (STOREBLOCK_STRUCT_PTR)free_block_ptr;
block_ptr->MEM_TYPE = 0;
MARK_BLOCK_AS_USED(block_ptr, td_ptr->TASK_ID);
CALC_CHECKSUM(block_ptr);
/* Remember some statistics */
next_block_ptr = NEXT_PHYS(block_ptr);
if ( (char _PTR_)(next_block_ptr) > (char _PTR_)mem_pool_ptr->POOL_HIGHEST_MEMORY_USED )
{
mem_pool_ptr->POOL_HIGHEST_MEMORY_USED =
((char _PTR_)(next_block_ptr) - 1);
} /* Endif */
/* Link the block onto the task descriptor. */
block_ptr->NEXTBLOCK = td_ptr->MEMORY_RESOURCE_LIST;
td_ptr->MEMORY_RESOURCE_LIST = (pointer)(&block_ptr->USER_AREA);
block_ptr->MEM_POOL_PTR = (pointer)mem_pool_ptr;
#if MQX_CHECK_VALIDITY
/* Check that user area is aligned on a cache line boundary */
if ( !_MEMORY_ALIGNED(&block_ptr->USER_AREA) ) {
*error_ptr = MQX_INVALID_CONFIGURATION;
return((pointer)NULL);
} /* Endif */
#endif
return( (pointer)(&block_ptr->USER_AREA ) );
} else {
block_ptr = (STOREBLOCK_STRUCT_PTR)NEXT_FREE(block_ptr);
}
}
#ifdef lint
return( NULL ); /* to satisfy lint */
#endif
}
pointer _mem_alloc_internal
(
/* [IN] the size of the memory block */
_mem_size requested_size,
/* [IN] owner TD */
TD_STRUCT_PTR td_ptr,
/* [IN] which pool to allocate from */
MEMPOOL_STRUCT_PTR mem_pool_ptr,
/* [OUT] error code for operation */
_mqx_uint_ptr error_ptr
)
{ /* Body */
STOREBLOCK_STRUCT_PTR block_ptr;
STOREBLOCK_STRUCT_PTR next_block_ptr;
STOREBLOCK_STRUCT_PTR next_next_block_ptr;
_mem_size block_size;
_mem_size next_block_size;
*error_ptr = MQX_OK;
/*
** Adjust message size to allow for block management overhead
** and force size to be aligned.
*/
requested_size += (_mem_size)(FIELD_OFFSET(STOREBLOCK_STRUCT,USER_AREA));
#if MQX_CHECK_ERRORS
if (requested_size < MQX_MIN_MEMORY_STORAGE_SIZE) {
requested_size = MQX_MIN_MEMORY_STORAGE_SIZE;
} /* Endif */
#endif
_MEMORY_ALIGN_VAL_LARGER(requested_size);
block_ptr = mem_pool_ptr->POOL_FREE_LIST_PTR;
while ( TRUE ) {
/*
** Save the current block pointer.
** We will be enabling access to higher priority tasks.
** A higher priority task may pre-empt the current task
** and may do a memory allocation. If this is true,
** the higher priority task will reset the POOL_ALLOC_CURRENT_BLOCK
** upon exit, and the current task will start the search over
** again.
*/
mem_pool_ptr->POOL_ALLOC_CURRENT_BLOCK = block_ptr;
/* allow pending interrupts */
_int_enable();
_int_disable();
/* Get block pointer in case reset by a higher priority task */
block_ptr = mem_pool_ptr->POOL_ALLOC_CURRENT_BLOCK;
if (block_ptr == NULL) { /* Null pointer */
mem_pool_ptr->POOL_BLOCK_IN_ERROR = block_ptr;
*error_ptr = MQX_OUT_OF_MEMORY;
return( NULL ); /* request failed */
} /* Endif */
#if MQX_CHECK_VALIDITY
if ( !_MEMORY_ALIGNED(block_ptr) || BLOCK_IS_USED(block_ptr) ) {
mem_pool_ptr->POOL_BLOCK_IN_ERROR = block_ptr;
*error_ptr = MQX_CORRUPT_STORAGE_POOL_FREE_LIST;
return((pointer)NULL);
} /* Endif */
#endif
#if MQX_CHECK_VALIDITY
if ( ! VALID_CHECKSUM(block_ptr) ) {
mem_pool_ptr->POOL_BLOCK_IN_ERROR = block_ptr;
*error_ptr = MQX_INVALID_CHECKSUM;
return((pointer)NULL);
} /* Endif */
#endif
block_size = block_ptr->BLOCKSIZE;
if (block_size >= requested_size) {
/* request fits into this block */
next_block_size = block_size - requested_size;
if ( next_block_size >= (2 * MQX_MIN_MEMORY_STORAGE_SIZE) ) {
/*
** The current block is big enough to split.
** into 2 blocks.... the part to be allocated is one block,
** and the rest remains as a free block on the free list.
*/
next_block_ptr = (STOREBLOCK_STRUCT_PTR)
((char _PTR_)block_ptr + requested_size);
/* Initialize the new physical block values */
next_block_ptr->BLOCKSIZE = next_block_size;
next_block_ptr->PREVBLOCK = (STOREBLOCK_STRUCT_PTR)block_ptr;
MARK_BLOCK_AS_FREE(next_block_ptr);
CALC_CHECKSUM(next_block_ptr);
/* Link new block into the free list */
next_block_ptr->NEXTBLOCK = block_ptr->NEXTBLOCK;
block_ptr->NEXTBLOCK = (pointer)next_block_ptr;
next_block_ptr->USER_AREA = (pointer)block_ptr;
if ( next_block_ptr->NEXTBLOCK != NULL ) {
((STOREBLOCK_STRUCT_PTR)next_block_ptr->NEXTBLOCK)->
USER_AREA = (pointer)next_block_ptr;
} /* Endif */
/*
** Modify the block on the other side of the next block
** (the next next block) so that it's previous block pointer
** correctly point to the next block.
*/
next_next_block_ptr = (STOREBLOCK_STRUCT_PTR)
NEXT_PHYS(next_block_ptr);
PREV_PHYS(next_next_block_ptr) = next_block_ptr;
CALC_CHECKSUM(next_next_block_ptr);
} else {
/* Take the entire block */
requested_size = block_size;
} /* Endif */
/* Set the size of the block */
block_ptr->BLOCKSIZE = requested_size;
/* Indicate the block is in use */
MARK_BLOCK_AS_USED(block_ptr, td_ptr->TASK_ID);
block_ptr->MEM_TYPE = 0;
CALC_CHECKSUM(block_ptr);
/* Unlink the block from the free list */
if ( block_ptr == mem_pool_ptr->POOL_FREE_LIST_PTR ) {
/* At the head of the free list */
mem_pool_ptr->POOL_FREE_LIST_PTR = (STOREBLOCK_STRUCT_PTR)
NEXT_FREE(block_ptr);
if (mem_pool_ptr->POOL_FREE_LIST_PTR != NULL ) {
PREV_FREE(mem_pool_ptr->POOL_FREE_LIST_PTR) = 0;
} /* Endif */
} else {
/*
** NOTE: PREV_FREE guaranteed to be non-zero
** Have to make the PREV_FREE of this block
** point to the NEXT_FREE of this block
*/
NEXT_FREE(PREV_FREE(block_ptr)) = NEXT_FREE(block_ptr);
if ( NEXT_FREE(block_ptr) != NULL ) {
/*
** Now have to make the NEXT_FREE of this block
** point to the PREV_FREE of this block
*/
PREV_FREE(NEXT_FREE(block_ptr)) = PREV_FREE(block_ptr);
} /* Endif */
} /* Endif */
#if MQX_MEMORY_FREE_LIST_SORTED == 1
if ( block_ptr == mem_pool_ptr->POOL_FREE_CURRENT_BLOCK ) {
/* Reset the freelist insertion sort by _mem_free */
mem_pool_ptr->POOL_FREE_CURRENT_BLOCK = mem_pool_ptr->POOL_FREE_LIST_PTR;
} /* Endif */
#endif
/* Reset the __mem_test freelist pointer */
mem_pool_ptr->POOL_FREE_CHECK_BLOCK = mem_pool_ptr->POOL_FREE_LIST_PTR;
/*
** Set the curent pool block to the start of the free list, so
** that if this task pre-empted another that was performing a
** _mem_alloc, the other task will restart it's search for a block
*/
mem_pool_ptr->POOL_ALLOC_CURRENT_BLOCK = mem_pool_ptr->POOL_FREE_LIST_PTR;
/* Remember some statistics */
next_block_ptr = NEXT_PHYS(block_ptr);
if ( (char _PTR_)(next_block_ptr) > (char _PTR_)
mem_pool_ptr->POOL_HIGHEST_MEMORY_USED )
{
mem_pool_ptr->POOL_HIGHEST_MEMORY_USED =
((char _PTR_)(next_block_ptr) - 1);
} /* Endif */
/* Link the block onto the task descriptor. */
block_ptr->NEXTBLOCK = td_ptr->MEMORY_RESOURCE_LIST;
td_ptr->MEMORY_RESOURCE_LIST = (pointer)(&block_ptr->USER_AREA);
block_ptr->MEM_POOL_PTR = (pointer)mem_pool_ptr;
#if MQX_CHECK_VALIDITY
/* Check that user area is aligned on a cache line boundary */
if ( !_MEMORY_ALIGNED(&block_ptr->USER_AREA) ) {
*error_ptr = MQX_INVALID_CONFIGURATION;
return((pointer)NULL);
} /* Endif */
#endif
return( (pointer)(&block_ptr->USER_AREA ) );
} else {
block_ptr = (STOREBLOCK_STRUCT_PTR)NEXT_FREE(block_ptr);
} /* Endif */
} /* Endwhile */
#ifdef lint
return( NULL ); /* to satisfy lint */
#endif
} /* Endbody */
_mqx_uint _mem_extend_pool_internal
(
/* [IN] the address of the start of the memory pool addition */
pointer start_of_pool,
/* [IN] the size of the memory pool addition */
_mem_size size,
/* [IN] the memory pool to extend */
MEMPOOL_STRUCT_PTR mem_pool_ptr
)
{ /* Body */
KERNEL_DATA_STRUCT_PTR kernel_data;
STOREBLOCK_STRUCT_PTR block_ptr;
STOREBLOCK_STRUCT_PTR end_ptr;
STOREBLOCK_STRUCT_PTR free_ptr;
STOREBLOCK_STRUCT_PTR tmp_ptr;
MEMPOOL_EXTENSION_STRUCT_PTR ext_ptr;
uchar_ptr real_start_ptr;
uchar_ptr end_of_pool;
_mem_size block_size;
_mem_size real_size;
_mem_size free_block_size;
_GET_KERNEL_DATA(kernel_data);
#if MQX_CHECK_ERRORS
if (size < (_mem_size)(3*MQX_MIN_MEMORY_STORAGE_SIZE)) {
/* Pool must be big enough to hold at least 3 memory blocks */
return(MQX_INVALID_SIZE);
}/* Endif */
#endif
#if MQX_CHECK_VALIDITY
if (mem_pool_ptr->VALID != MEMPOOL_VALID) {
return(MQX_INVALID_COMPONENT_HANDLE);
}/* Endif */
#endif
ext_ptr = (MEMPOOL_EXTENSION_STRUCT_PTR)
_ALIGN_ADDR_TO_HIGHER_MEM(start_of_pool);
real_start_ptr = (uchar_ptr)ext_ptr + sizeof(MEMPOOL_EXTENSION_STRUCT);
real_start_ptr = (uchar_ptr)_ALIGN_ADDR_TO_HIGHER_MEM(real_start_ptr);
end_of_pool = (uchar_ptr)start_of_pool + size;
end_of_pool = (uchar_ptr)_ALIGN_ADDR_TO_LOWER_MEM(end_of_pool);
real_size = (_mem_size)(end_of_pool - real_start_ptr);
ext_ptr->START = start_of_pool;
ext_ptr->SIZE = size;
ext_ptr->REAL_START = real_start_ptr;
block_ptr = (STOREBLOCK_STRUCT_PTR)real_start_ptr;
block_size = MQX_MIN_MEMORY_STORAGE_SIZE;
free_ptr = (STOREBLOCK_STRUCT_PTR)((uchar_ptr)block_ptr + block_size);
free_block_size = real_size - (_mem_size)(2 * MQX_MIN_MEMORY_STORAGE_SIZE);
end_ptr = (STOREBLOCK_STRUCT_PTR)((uchar_ptr)free_ptr + free_block_size);
/*
** Make a small minimal sized memory block to be as
** the first block in the pool. This will be an in-use block
** and will thus avoid problems with memory co-allescing during
** memory frees
*/
block_ptr->BLOCKSIZE = block_size;
block_ptr->MEM_TYPE = 0;
block_ptr->USER_AREA = 0;
block_ptr->PREVBLOCK = (struct storeblock_struct _PTR_)NULL;
block_ptr->NEXTBLOCK = free_ptr;
MARK_BLOCK_AS_USED(block_ptr, SYSTEM_TASK_ID(kernel_data));
CALC_CHECKSUM(block_ptr);
/*
** Let the next block be the actual free block that will be added
** to the free list
*/
free_ptr->BLOCKSIZE = free_block_size;
free_ptr->MEM_TYPE = 0;
free_ptr->USER_AREA = 0;
free_ptr->PREVBLOCK = block_ptr;
free_ptr->NEXTBLOCK = end_ptr;
MARK_BLOCK_AS_FREE(free_ptr);
CALC_CHECKSUM(free_ptr);
/*
** Set up a minimal sized block at the end of the pool, and also
** mark it as being allocated. Again this is to comply with the
** _mem_free algorithm
*/
end_ptr->BLOCKSIZE = block_size;
end_ptr->MEM_TYPE = 0;
end_ptr->USER_AREA = 0;
end_ptr->PREVBLOCK = free_ptr;
end_ptr->NEXTBLOCK = NULL;
MARK_BLOCK_AS_USED(end_ptr, SYSTEM_TASK_ID(kernel_data));
CALC_CHECKSUM(end_ptr);
_int_disable(); /* Add the block to the free list */
tmp_ptr = mem_pool_ptr->POOL_FREE_LIST_PTR;
mem_pool_ptr->POOL_FREE_LIST_PTR = free_ptr;
if (tmp_ptr != NULL) {
PREV_FREE(tmp_ptr) = free_ptr;
} /* Endif */
PREV_FREE(free_ptr) = NULL;
NEXT_FREE(free_ptr) = tmp_ptr;
/* Reset the free list queue walker for some other task */
mem_pool_ptr->POOL_FREE_CURRENT_BLOCK = mem_pool_ptr->POOL_FREE_LIST_PTR;
/* Link in the extension */
_QUEUE_ENQUEUE(&mem_pool_ptr->EXT_LIST, &ext_ptr->LINK);
_int_enable();
return(MQX_OK);
} /* Endbody */
boolean _mem_check_coalesce_internal
(
/*
** [IN] the address of a memory block, whose neighbours have
** to be checked to see if they are free.
*/
STOREBLOCK_STRUCT_PTR passed_block_ptr
)
{ /* Body */
register STOREBLOCK_STRUCT_PTR block_ptr;
register STOREBLOCK_STRUCT_PTR prev_block_ptr;
register STOREBLOCK_STRUCT_PTR next_block_ptr;
MEMPOOL_STRUCT_PTR mem_pool_ptr;
boolean have_coalesced = FALSE;
block_ptr = passed_block_ptr;
mem_pool_ptr = (MEMPOOL_STRUCT_PTR)block_ptr->MEM_POOL_PTR;
/* Check the previous physical neighbour */
prev_block_ptr = PREV_PHYS(block_ptr);
if ((prev_block_ptr != NULL) && BLOCK_IS_FREE(prev_block_ptr)){
/* the block previous to this one is free */
/* make the current block a free block so it can't be freed again */
block_ptr->NEXTBLOCK = NULL;
MARK_BLOCK_AS_FREE(block_ptr);
/* Add the current block to the previous block */
prev_block_ptr->BLOCKSIZE += block_ptr->BLOCKSIZE;
/* Modify the next physical block to point to the previous block */
next_block_ptr = NEXT_PHYS(block_ptr);
PREV_PHYS(next_block_ptr) = prev_block_ptr;
CALC_CHECKSUM(prev_block_ptr);
CALC_CHECKSUM(next_block_ptr);
block_ptr = prev_block_ptr; /* Set up as the current block */
have_coalesced = TRUE;
} /* Endif */
/* Now, check the next block to see if it is free */
next_block_ptr = NEXT_PHYS(block_ptr);
if ( BLOCK_IS_FREE(next_block_ptr) ) {
/* the next block is free */
if ( mem_pool_ptr->POOL_ALLOC_CURRENT_BLOCK == next_block_ptr ) {
/* We must modify the _mem_alloc pointer to not point
** at the next block
*/
mem_pool_ptr->POOL_ALLOC_CURRENT_BLOCK = block_ptr;
} /* Endif */
if (have_coalesced) {
/* the current block is already on the free list */
/* Remove the block from the free list */
if ( block_ptr == mem_pool_ptr->POOL_FREE_LIST_PTR ) {
mem_pool_ptr->POOL_FREE_LIST_PTR =
(STOREBLOCK_STRUCT_PTR)NEXT_FREE(block_ptr);
if ( NEXT_FREE(block_ptr) != NULL ) {
PREV_FREE(NEXT_FREE(block_ptr)) = 0;
} /* Endif */
} else {
NEXT_FREE(PREV_FREE(block_ptr)) = NEXT_FREE(block_ptr);
if ( NEXT_FREE(block_ptr) != NULL ) {
PREV_FREE(NEXT_FREE(block_ptr)) = PREV_FREE(block_ptr);
} /* Endif */
} /* Endif */
} else {
/* Make the block a free block */
block_ptr->NEXTBLOCK = NULL;
MARK_BLOCK_AS_FREE(block_ptr);
} /* Endif */
/*
** The current block is now a free block not on the free list .
** the freelist pointers have to be modified so that the next
** block is removed from the list, replace with the current block.
*/
/* set the next free block to be the same as the one on the free list */
NEXT_FREE(block_ptr) = NEXT_FREE(next_block_ptr);
/*
** And set the back pointer of the block after the next free block
** to point back to the current block
*/
if ( NEXT_FREE(block_ptr) != NULL ) {
PREV_FREE(NEXT_FREE(block_ptr)) = (STOREBLOCK_STRUCT_PTR)block_ptr;
} /* Endif */
if (next_block_ptr == mem_pool_ptr->POOL_FREE_LIST_PTR) {
/*
** If the next block pointer was at the head of the free list,
** the kernel free list pointer must be updated
*/
mem_pool_ptr->POOL_FREE_LIST_PTR = block_ptr;
PREV_FREE(block_ptr) = NULL;
} else {
/*
** Otherwise we need to adjust the pointers of the block that
** was previous to the next block on the free list
*/
PREV_FREE(block_ptr) = PREV_FREE(next_block_ptr);
if ( PREV_FREE(block_ptr) != NULL ) {
NEXT_FREE(PREV_FREE(block_ptr)) = (pointer)block_ptr;
} /* Endif */
} /* Endif */
/* Add the next block onto the current block */
block_ptr->BLOCKSIZE += next_block_ptr->BLOCKSIZE;
/*
** Reset the previous physical block pointer of
** the block after the next block (ie the next next block)
*/
prev_block_ptr = NEXT_PHYS(next_block_ptr);
PREV_PHYS(prev_block_ptr) = block_ptr;
CALC_CHECKSUM(prev_block_ptr);
CALC_CHECKSUM(block_ptr);
have_coalesced = TRUE;
} /* Endif */
if (have_coalesced) {
/* Reset the _mem_test pointers */
mem_pool_ptr->POOL_PHYSICAL_CHECK_BLOCK =
(STOREBLOCK_STRUCT_PTR)mem_pool_ptr->POOL_PTR;
mem_pool_ptr->POOL_FREE_CHECK_BLOCK = mem_pool_ptr->POOL_FREE_LIST_PTR;
#if MQX_MEMORY_FREE_LIST_SORTED == 1
/*
** Reset the freelist current block pointer in case we pre-empted
** another task
*/
mem_pool_ptr->POOL_FREE_CURRENT_BLOCK = mem_pool_ptr->POOL_FREE_LIST_PTR;
#endif
} /* Endif */
return (have_coalesced);
} /* Endbody */
void moveStart(void *ptr){ //puts thing at pointer bp in front of free list
NEXT_FREE(ptr) = freeStart; //attach to old front of list
PREV_FREE(ptr) = NULL; //first element of free list has no predecessor
PREV_FREE(freeStart) = ptr;
freeStart = ptr; //ptr is now the start of the free list
}