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not_empty, coalesce

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Felicia Seo 2022-11-12 08:47:17 -05:00
parent 08198ed242
commit 9637fb3db3
1 changed files with 22 additions and 18 deletions
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40
mm.c
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@ -52,7 +52,7 @@ static size_t list_sizes[NUM_LISTS];
/* Function prototypes for internal helper routines */ /* Function prototypes for internal helper routines */
static struct block *extend_heap(size_t words, int realloc); static struct block *extend_heap(size_t words, int realloc);
static void place(struct block *blck, size_t asize); static void place(struct block *blck, size_t asize);
static struct list* find_list(size_t size); static struct list* find_list(int not_empty, size_t size);
static struct block *find_fit(size_t num_words); static struct block *find_fit(size_t num_words);
//~ static void coalesce_free_lists(); //~ static void coalesce_free_lists();
static struct block *coalesce(struct block *bp); static struct block *coalesce(struct block *bp);
@ -196,7 +196,7 @@ void mm_free(void *bp)
set_block_free(blk, size); set_block_free(blk, size);
list_push_front(find_list(size), &blk->elem); list_push_front(find_list(0, size), &blk->elem);
coalesce(blk); coalesce(blk);
} }
@ -255,30 +255,31 @@ static struct block *coalesce(struct block *bp)
else if (prev_alloc && !next_alloc) { /* Case 2 */ else if (prev_alloc && !next_alloc) { /* Case 2 */
// combine this block and next block by extending it // combine this block and next block by extending it
list_remove(&bp->elem); list_remove(&bp->elem);
set_block_free(bp, size + blk_size(next_blk(bp)));
list_remove(&next_blk(bp)->elem); list_remove(&next_blk(bp)->elem);
list_push_front(find_list(size + blk_size(next_blk(bp))), &bp->elem); size_t new_size = size + blk_size(next_blk(bp));
set_block_free(bp, new_size);
list_push_front(find_list(0, new_size), &bp->elem);
} }
else if (!prev_alloc && next_alloc) { /* Case 3 */ else if (!prev_alloc && next_alloc) { /* Case 3 */
// combine previous and this block by extending previous // combine previous and this block by extending previous
list_remove(&prev_blk(bp)->elem);
list_remove(&bp->elem); list_remove(&bp->elem);
size_t new_size = blk_size(prev_blk(bp)) + size;
bp = prev_blk(bp); bp = prev_blk(bp);
set_block_free(bp, size + blk_size(bp)); set_block_free(bp, new_size);
list_remove(&bp->elem); list_push_front(find_list(0, new_size), &bp->elem);
list_push_front(find_list(size + blk_size(next_blk(bp))), &bp->elem);
} }
else { /* Case 4 */ else { /* Case 4 */
// combine all previous, this, and next block into one // combine all previous, this, and next block into one
list_remove(&bp->elem); list_remove(&prev_blk(bp)->elem);
set_block_free(prev_blk(bp),
size + blk_size(next_blk(bp)) + blk_size(prev_blk(bp)));
bp = prev_blk(bp);
list_remove(&bp->elem); list_remove(&bp->elem);
list_remove(&next_blk(bp)->elem); list_remove(&next_blk(bp)->elem);
list_push_front(find_list(size + blk_size(next_blk(bp))), &bp->elem); size_t new_size = blk_size(prev_blk(bp)) + size + blk_size(next_blk(bp));
bp = prev_blk(bp);
set_block_free(bp, new_size);
list_push_front(find_list(0, new_size), &bp->elem);
} }
return bp; return bp;
} }
@ -302,7 +303,7 @@ static struct block *extend_heap(size_t words, int realloc)
if (realloc) { if (realloc) {
return blk; return blk;
} }
list_push_front(find_list(words), &blk->elem); list_push_front(find_list(0, words), &blk->elem);
return coalesce(blk); return coalesce(blk);
@ -326,7 +327,7 @@ static void place(struct block *blck, size_t asize) {
set_block_free(blck, remaining_size); set_block_free(blck, remaining_size);
/* Add remaining free block back into list */ /* Add remaining free block back into list */
list_push_front(find_list(remaining_size), &blck->elem); list_push_front(find_list(0, remaining_size), &blck->elem);
} }
else { else {
set_block_used(blck, csize); set_block_used(blck, csize);
@ -335,12 +336,15 @@ static void place(struct block *blck, size_t asize) {
/** /**
* Find free list with blocks of given size * Find free list with blocks of given size
*
* not_empty == 0, find "any" list
* not_empty == 1, find a not empty list
*/ */
static struct list* find_list(size_t n_words) { static struct list* find_list(int not_empty, size_t n_words) {
for (int i = 0; i < NUM_LISTS; i++) { for (int i = 0; i < NUM_LISTS; i++) {
if ((n_words < list_sizes[i]) || (i == (NUM_LISTS - 1))) { if ((n_words < list_sizes[i]) || (i == (NUM_LISTS - 1))) {
if (list_empty(&free_lists[i])) { if (not_empty && list_empty(&free_lists[i])) {
continue; continue;
} }
return &free_lists[i]; return &free_lists[i];
@ -354,7 +358,7 @@ static struct list* find_list(size_t n_words) {
*/ */
static struct block *find_fit(size_t num_words) static struct block *find_fit(size_t num_words)
{ {
struct list* free_list = find_list(num_words); struct list* free_list = find_list(1, num_words);
if (free_list == NULL) { if (free_list == NULL) {
return NULL; return NULL;