/*Removes the free block pointer int the free_list*/
static void removeFromFree(void *bp){
if (GET_PREV_FREE(bp))
SET_NEXT_FREE(GET_PREV_FREE(bp), GET_NEXT_FREE(bp));
else
free_listp = GET_NEXT_FREE(bp);
SET_PREV_FREE(GET_NEXT_FREE(bp), GET_PREV_FREE(bp));
}
/*
* add_block - add a block to the list in order of address
*/
static void add_block(void *bp) {
int list = get_list(GET_SIZE(HDRP(bp)));
void *next = free_lists[list];
while (next != LIST_END) {
/* Insert bp in middle of list, or beginning if prev(next) is NULL */
if (next > bp) {
if (GET_PREV_FREE(next) == LIST_END)
free_lists[list] = bp; /* Update list head */
else
SET_NEXT_FREE(GET_PREV_FREE(next), bp);
SET_PREV_FREE(bp, GET_PREV_FREE(next));
SET_PREV_FREE(next, bp);
SET_NEXT_FREE(bp, next);
return;
/* Reached end of list, add bp to the end using saved block */
} else if (GET_NEXT_FREE(next) == LIST_END) {
SET_PREV_FREE(bp, next);
SET_NEXT_FREE(next, bp);
SET_NEXT_FREE(bp, LIST_END);
return;
}
next = GET_NEXT_FREE(next);
}
/* Edge case: list is empty, add bp */
SET_PREV_FREE(bp, LIST_END);
SET_NEXT_FREE(bp, LIST_END);
free_lists[list] = bp;
}
static void delete_free_block(void *ptr)
{
void *next_free = GET_NEXT_FREE(ptr);
void *prev_free = GET_PREV_FREE(ptr);
if (ptr == free_headp && ptr == free_tailp)
{
free_headp = NULL;
free_tailp = NULL;
}
else if (ptr == free_headp)
{
free_headp = next_free;
PUT_PREV_FREE(free_headp, NULL);
}
else if (ptr == free_tailp)
{
free_tailp = prev_free;
PUT_NEXT_FREE(free_tailp, NULL);
}
else
{
PUT_NEXT_FREE(prev_free, next_free);
PUT_PREV_FREE(next_free, prev_free);
}
}
/*
* delete_block - delete a block from the free list
*/
static void delete_block(void *bp) {
void *prev = GET_PREV_FREE(bp);
void *next = GET_NEXT_FREE(bp);
int list = get_list(GET_SIZE(HDRP(bp)));
/* Case 1: bp is the only block in list */
if ((prev == LIST_END) && (next == LIST_END)) {
free_lists[list] = NULL;
return;
/* Case 2: bp is the first block in the list */
} else if (prev == LIST_END) {
SET_PREV_FREE(next, LIST_END);
free_lists[list] = next;
return;
/* Case 3: bp is the last block in the list */
} else if (next == LIST_END) {
SET_NEXT_FREE(prev, LIST_END);
return;
/* Case 4: bp is in the middle of the list */
} else {
SET_NEXT_FREE(prev, next);
SET_PREV_FREE(next, prev);
return;
}
}
/*
* Scan the heap until we find a block large enough to fulfill the
* request.
*/
void *
malloc(unsigned sz)
{
block_header_t *header, *next;
/* Align the request. */
sz += MIN_REQUEST - 1;
sz &= ~(MIN_REQUEST - 1);
/* First fit. */
for (header = (block_header_t *) heap_start;
(char *) header < heap_end;
header = next) {
next = (block_header_t *)
((char *) header
+ sizeof(block_header_t)
+ GET_BLOCK_SIZE(*header));
if (GET_PREV_FREE(*next) && sz <= GET_BLOCK_SIZE(*header)) {
/* We can fit the request in this block. */
void *result = (void *)((char *) header + sizeof(block_header_t));
if (GET_BLOCK_SIZE(*header) < sz + sizeof(block_header_t) + MIN_REQUEST) {
/* We can't fit any other requests here, though. */
CLEAR_PREV_FREE(*next);
}
else {
/* Split the block. */
struct block_footer *footer =
(struct block_footer *)
((char *) next - sizeof(struct block_footer));
unsigned remaining = GET_BLOCK_SIZE(*header) - sz - sizeof(block_header_t);
SET_BLOCK_SIZE(*header, sz);
header = (block_header_t *)
((char *) header
+ sizeof(block_header_t)
+ sz);
ASSERT(remaining % 2 == 0, ("odd block size"));
INIT_BLOCK_HEADER(*header, remaining, 0);
footer->header = header;
}
return result;
}
}
/* Uh oh, couldn't allocate! */
panic();
return 0;
}
/*
* Free the block, coalescing with the previous and next blocks if
* possible.
*/
void
free(void *ptr)
{
block_header_t *header = (block_header_t *)
((char *) ptr - sizeof(block_header_t));
block_header_t *next = (block_header_t *)
((char *) ptr + GET_BLOCK_SIZE(*header));
block_header_t *next_next = (block_header_t *)
((char *) next + sizeof(block_header_t) + GET_BLOCK_SIZE(*next));
struct block_footer *footer;
unsigned size;
if ((char *) next_next < heap_end && GET_PREV_FREE(*next_next)) {
/* The block following us is free. */
next = next_next;
}
if (GET_PREV_FREE(*header)) {
/* The block prior to us is free. */
footer = (struct block_footer *)
((char *) header - sizeof(struct block_footer));
header = footer->header;
}
footer = (struct block_footer *)
((char *) next - sizeof(struct block_footer));
footer->header = header;
/* Expand the block to encompass the reclaimed space. */
size = (char *) next - (char *) header - sizeof(block_header_t);
ASSERT(size % 2 == 0, ("odd block size"));
SET_BLOCK_SIZE(*header, size);
/* Note in the header of the _next_ block that this block is free. */
MARK_PREV_FREE(*next);
}
/*
* Dump the heap to debug it.
*/
void
heap_walk()
{
block_header_t *header, *next;
printf("heap_begin=0x%p, heap_end=0x%p\n",
heap_start, heap_end);
for (header = (block_header_t *) heap_start;
(char *) header < heap_end;
header = next) {
next = (block_header_t *)
((char *) header
+ sizeof(block_header_t)
+ GET_BLOCK_SIZE(*header));
printf("%p heap_start+%04x size=%04x %s",
header,
(char *) header - heap_start,
GET_BLOCK_SIZE(*header),
GET_PREV_FREE(*next) ? "free" : "in use");
if (GET_PREV_FREE(*next)) {
struct block_footer *footer =
(struct block_footer *)
((char *) next - sizeof(struct block_footer));
if (footer->header != header) {
printf(" BAD FOOTER, footer->header=%p heap_start+%04x",
footer->header,
(char *) footer->header - heap_start);
}
}
printf("\n");
}
}
/*
* Return the amount of free space in the heap.
*/
int
heap_free()
{
int nfree = 0;
block_header_t *header, *next;
for (header = (block_header_t *) heap_start;
(char *) header < heap_end;
header = next) {
next = (block_header_t *)
((char *) header
+ sizeof(block_header_t)
+ GET_BLOCK_SIZE(*header));
if (GET_PREV_FREE(*next))
nfree += GET_BLOCK_SIZE(*header);
}
return nfree;
}
/*
* mm_check - TODO
*/
static int mm_check()
{
/* Check that the blocks are properly organized & that epilogue is present */
void *ptr = heap_listp;
int prev_alloced;
int freecount = 0;
while (ptr < mem_heap_hi())
{
size_t size = GET_SIZE(HDRP(ptr));
size_t size2 = GET_SIZE(FTRP(ptr));
int allocated = GET_ALLOC(HDRP(ptr));
int allocated2 = GET_ALLOC(FTRP(ptr));
if (size == 0)
{
if (ptr != mem_heap_hi() - WSIZE)
{
mm_log("mm_check error: ran into size 0 (epilogue) at %p, which is not heap_hi().\n",ptr);
return -1;
}
if (!allocated)
{
mm_log("mm_check error: epilogue at %p is marked as free\n",ptr);
return -1;
}
}
if (size != size2)
{
mm_log("mm_check error: %p size in header %d != footer %d\n", ptr, (int)size, (int)size2);
return -1;
}
if (allocated != allocated2)
{
mm_log("mm_check error: %p alloc in header %d != footer %d\n", ptr, allocated, allocated2);
return -1;
}
if (!allocated && !prev_alloced)
{
mm_log("mm_check error: two contiguous free blocks that should be coalesced. %p and prev.\n",ptr);
}
if (allocated)
{
//mm_log("block %p (%d,%d)\n", ptr, (int)size, allocated);
}
else
{
mm_log("block %p (%d,%d). prev=%p next=%p\n", ptr, (int)size, allocated, GET_PREV_FREE(ptr), GET_NEXT_FREE(ptr));
freecount++;
}
prev_alloced = allocated;
ptr += size;
}
/* Check the free list */
int count = 0;
ptr = free_headp;
void *prev = NULL;
while (ptr != NULL)
{
count++;
size_t bsize = GET_SIZE(HDRP(ptr));
if (GET_NEXT_FREE(ptr) && GET_PREV_FREE(GET_NEXT_FREE(ptr)) != ptr)
{
mm_log("mm_check error: prev of next of %p is %p\n", ptr, GET_PREV_FREE(GET_NEXT_FREE(ptr)));
return -1;
}
if (GET_PREV_FREE(ptr) && GET_NEXT_FREE(GET_PREV_FREE(ptr)) != ptr)
{
mm_log("mm_check error: next of prev of %p is %p\n", ptr, GET_NEXT_FREE(GET_PREV_FREE(ptr)));
return -1;
}
if (bsize == 0)
{
mm_log("mm_check error: block size 0 at %p\n", ptr);
return -1;
}
if (GET_ALLOC(HDRP(ptr)) || GET_ALLOC(FTRP(ptr)))
{
mm_log("mm_check error: block at %p on the freelist is marked allocated\n", ptr);
return -1;
}
if (GET_PREV_FREE(ptr) != prev)
{
mm_log("mm_check error: block at %p does not point to prev %p (points to %p)\n", ptr, prev, GET_PREV_FREE(ptr));
return -1;
}
prev = ptr;
ptr = GET_NEXT_FREE(ptr);
}
if (prev != free_tailp)
{
mm_log("mm_check error: last free block (%p) should == free_tailp (%p)\n", prev, free_tailp);
return -1;
}
if (freecount != count)
{
mm_log("mm_check error: found %d free blocks, but only %d on the freelist.\n",freecount, count);
return -1;
}
mm_log("mm_check says %d free block(s)\n",count);
return 0;
}
/*
* mm_checkheap - Check the heap for correctness. It prints a nice grid
* representation of the heap at the moment in time it is
* called, as well as the block pointer and epilogue
* pointer. It takes __LINE__ as input, allowing it to print
* the number of the line it is called at. It also silently
* checks for errors and exits the program if any error
* is found. If silent is 0, it will only print the results
* upon finding an error.
*
* NOTE: if mm_checkheap is called ANYWHERE besides malloc and
* free, it will find errors because of intermediate states
* that trigger error conditions. Therefore error_check should
* be 0 if you call it anywhere besides inside malloc and free.
*/
void mm_checkheap(int lineno)
{
char *bp;
char alloc_char;
char aligned;
char hef;
int payload;
int size;
int num_head = 0, num_tail = 0;
int link_error_flag = 0;
int alignment_flag = 0;
int error_flag = 0;
int error_check = 1; /* set to 0 if called outside malloc() and free() */
int silent = 1;
/* Silently check for errors */
if (error_check) {
for (bp = heap_listp; GET_SIZE(HDRP(bp)) > 0; bp = NEXT_BLKP(bp)) {
if (!ALIGNED(bp))
alignment_flag = 1;
if (!GET_ALLOC(HDRP(bp))) {
/* Check for linked list errors in free blocks */
if (GET_NEXT_FREE(bp) == NULL)
num_tail++;
else if (GET_PREV_FREE(GET_NEXT_FREE(bp)) != bp)
link_error_flag = 1;
if (GET_PREV_FREE(bp) == NULL)
num_head++;
else if (GET_NEXT_FREE(GET_PREV_FREE(bp)) != bp)
link_error_flag = 1;
}
if (num_tail > 1||num_head > 1||link_error_flag||alignment_flag)
error_flag = 1;
}
}
if (error_flag || !silent) {
printf("\n");
printf("========================================"
"==========================================\n");
printf(" HEAP CONSISTENCY CHECKER\n");
printf("========================================"
"==========================================\n");
printf("Line number = %d\n", lineno);
printf("Head of free list = %p\n",free_list);
printf("Epilogue pointer = %p\n", eptr);
printf("----------------------------------------"
"-----------------------------------------\n");
printf("T | Block pointer | Size |Payload|"
" Prev | Next |A|HEF\n");
printf("--|------------------|-------|-------|--"
"----------------|------------------|-|---\n");
for (bp = heap_listp; GET_SIZE(HDRP(bp)) > 0; bp = NEXT_BLKP(bp)) {
payload = FTRP(bp)-bp;
size = GET_SIZE(HDRP(bp));
alloc_char = ALLOC_CHAR(HDRP(bp));
aligned = ALIGNED_CHAR(bp); /* Check for alignment */
hef = HEF(bp); /* Check that header = footer */
if (GET_ALLOC(HDRP(bp))) {
printf("%c |%18p|%7d|%7d|%18s|%18s|%c| %c \n",
alloc_char,
bp,
size,
payload,
"",
"",
aligned,
hef);
} else {
printf("%c |%18p|%7d|%7d|%18p|%18p|%c| %c \n",
alloc_char,
bp,
size,
payload,
GET_PREV_FREE(bp),
GET_NEXT_FREE(bp),
aligned,
hef);
}
}
printf("----------------------------------------"
"-----------------------------------------\n");
printf("Key: T = (a)llocated or (f)ree. A = aligned to double word."
" HEF = H/F tags match.\n");
/* If there is a problem with the free list, print details and exit. */
if (error_flag) {
printf("----------------------------------------"
"-----------------------------------------\n");
printf("Heap integrity errors found:\n");
if (num_tail > 1)
printf(" [List error] More than one list tail.\n");
if (num_head > 1)
printf(" [List error] More than one list head.\n");
if (link_error_flag)
printf(" [List error] Links don't match up in "
"at least one block.\n");
if (alignment_flag)
printf(" [Alignment error] Unaligned block detected.\n");
printf("----------------------------------------"
"-----------------------------------------\n");
printf("\n");
exit(0);
}
}
}