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Commit 50765b70 authored by DocQuantum's avatar DocQuantum
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Implemented coalescing when adding to list

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with 82 additions and 52 deletions
mm.c
+ 82
− 52
View file @ 50765b70
......@@ -111,7 +111,6 @@ static void *extend_heap(size_t words);
static void place(void *bp, size_t asize);
static void *find_fit(size_t asize);
static void printblock(void *bp);
static int mm_coalesce(void *bp);
static void mm_memcpy(void * dest, void * src);
static void add_to_list(void* bp);
static void remove_from_list(void* bp);
......@@ -169,6 +168,7 @@ void *mm_malloc(size_t size)
/* Search the free list for a fit */
if ((bp = find_fit(asize)) != NULL) {
place(bp, asize);
//mm_checkheap(0);
return bp;
}
......@@ -181,6 +181,8 @@ void *mm_malloc(size_t size)
place(bp, asize);
//mm_checkheap(0);
return bp;
}
/* $end mmmalloc */
......@@ -200,15 +202,11 @@ void mm_free(void *bp)
return;
}
// If allocated...
// If allocated, free
if(!GET_ALLOC(HDRP(bp))){
// try to coalesce...
if(mm_coalesce(bp)){
// else free
*HDRP(bp) |= 1;
*FTRP(bp) |= 1;
add_to_list(bp);
}
} else {
fprintf(stderr, "mm_free(): memory not alloced or corrupted");
return;
......@@ -218,42 +216,6 @@ void mm_free(void *bp)
/* $end mmfree */
/**
* mm_coalesce - Coalesce the freespace around a block
*
* Given a block pointer that has been freed, find empty
* blocks near it to be combined into a large free chunk.
*
* Returns 0 on success, 1 on failure
*
*/
static int mm_coalesce(void *bp)
{
return 1;
size_t nextBlock = GET_ALLOC(HDRP(NEXT_BLKP(bp)));
size_t prevBlock = GET_ALLOC(HDRP(PREV_BLKP(bp)));
size_t size = GET_SIZE(HDRP(bp));
if(prevBlock && nextBlock){
size += GET_SIZE(HDRP(PREV_BLKP(bp))) + GET_SIZE(HDRP(NEXT_BLKP(bp)));
PUT(HDRP(PREV_BLKP(bp)), PACK(size, 1));
PUT(FTRP(PREV_BLKP(bp)), PACK(size, 1));
return 0;
} else if(prevBlock && !nextBlock){
size += GET_SIZE(HDRP(PREV_BLKP(bp)));
PUT(HDRP(PREV_BLKP(bp)), PACK(size, 1));
PUT(FTRP(PREV_BLKP(bp)), PACK(size, 1));
return 0;
} else if(!prevBlock && nextBlock){
size += GET_SIZE(HDRP(NEXT_BLKP(bp)));
PUT(HDRP(bp), PACK(size, 1));
PUT(FTRP(bp), PACK(size, 1));
return 0;
}
return 1;
}
/*
* mm_realloc - naive implementation of mm_realloc
*
......@@ -313,7 +275,6 @@ void *mm_realloc(void *ptr, size_t size)
PUT(FTRP(ptr), PACK(size, 0));
PUT(HDRP(NEXT_BLKP(ptr)), PACK(oldSize-size, 1));
PUT(FTRP(NEXT_BLKP(ptr)), PACK(oldSize-size, 1));
mm_coalesce(NEXT_BLKP(ptr));
}
else {
PUT(HDRP(ptr), PACK(oldSize, 0));
......@@ -331,7 +292,6 @@ void *mm_realloc(void *ptr, size_t size)
PUT(FTRP(ptr), PACK(size, 0));
PUT(HDRP(NEXT_BLKP(ptr)), PACK(nextSize-size, 1));
PUT(FTRP(NEXT_BLKP(ptr)), PACK(nextSize-size, 1));
mm_coalesce(NEXT_BLKP(ptr));
}
else {
PUT(HDRP(ptr), PACK(nextSize, 0));
......@@ -437,9 +397,9 @@ void mm_checkheap(int verbose)
}
/**
* add_to_list - Adds free block to list
* add_to_list - Adds free block to list and coalesces
*
* Will try to add block in address order
* Will try to add block in address order, or combine
*/
static void add_to_list(void* bp){
......@@ -462,6 +422,21 @@ static void add_to_list(void* bp){
// case for 1 node in list.
if(free_listp == GET_NEXT_FREE(free_listp)){
//make sure they're not next to eachother
if((char *) NEXT_BLKP(bp) == free_listp){
size_t size = GET_SIZE(HDRP(free_listp)) + GET_SIZE(HDRP(bp));
PUT(HDRP(bp), PACK(size, 1));
PUT(FTRP(bp), PACK(size, 1));
free_listp = bp;
SET_NEXT_FREE(free_listp, free_listp);
SET_PREV_FREE(free_listp, free_listp);
return;
} else if((char *) PREV_BLKP(bp) == free_listp){
size_t size = GET_SIZE(HDRP(PREV_BLKP(bp))) + GET_SIZE(HDRP(bp));
PUT(HDRP(free_listp), PACK(size, 1));
PUT(FTRP(free_listp), PACK(size, 1));
return;
}
// Set head next to new
SET_NEXT_FREE(free_listp, bp);
// Set pre prev as new
......@@ -482,7 +457,33 @@ static void add_to_list(void* bp){
{
if((char *) bp > node){
if((char *) bp < GET_NEXT_FREE(node) || node > GET_NEXT_FREE(node)){
//printf("Adding %p between %p -> %p\n\n", bp, node, GET_NEXT_FREE(node));
if((char *) PREV_BLKP(bp) == node && (char *) NEXT_BLKP(bp) == GET_NEXT_FREE(node)){
size_t size = GET_SIZE(HDRP(node)) + GET_SIZE(HDRP(bp)) + GET_SIZE(HDRP(GET_NEXT_FREE(node)));
PUT(HDRP(node), PACK(size, 1));
PUT(FTRP(node), PACK(size, 1));
remove_from_list(GET_NEXT_FREE(node));
free_listp = node;
return;
} else if((char *) PREV_BLKP(bp) == node && (char *) NEXT_BLKP(bp) != GET_NEXT_FREE(node) && GET_ALLOC(HDRP(NEXT_BLKP(bp)))){
size_t size = GET_SIZE(HDRP(node)) + GET_SIZE(HDRP(bp));
PUT(HDRP(node), PACK(size, 1));
PUT(FTRP(node), PACK(size, 1));
free_listp = node;
return;
} else if((char *) PREV_BLKP(bp) != node && (char *) NEXT_BLKP(bp) == GET_NEXT_FREE(node)){
size_t size = GET_SIZE(HDRP(bp)) + GET_SIZE(HDRP(GET_NEXT_FREE(node)));
PUT(HDRP(bp), PACK(size, 1));
PUT(FTRP(bp), PACK(size, 1));
char * old = GET_NEXT_FREE(node);
// set next to the next of next-next
SET_NEXT_FREE(bp, GET_NEXT_FREE(old));
// set the prev of next-next node to bp
SET_PREV_FREE(GET_NEXT_FREE(old), bp);
SET_PREV_FREE(bp, node);
SET_NEXT_FREE(node, bp);
free_listp = node;
return;
}
/* bp inserted after node */
// Set new next as current next
SET_NEXT_FREE(bp, GET_NEXT_FREE(node));
......@@ -500,7 +501,36 @@ static void add_to_list(void* bp){
}
else if((char *) bp < node){
if((char *) bp > GET_PREV_FREE(node) || node < GET_PREV_FREE(node)){
//printf("Adding %p between %p -> %p\n\n", bp, GET_PREV_FREE(node), node);
if((char *) NEXT_BLKP(bp) == node && (char *) PREV_BLKP(bp) == GET_PREV_FREE(node)){
node = GET_PREV_FREE(node);
size_t size = GET_SIZE(HDRP(node)) + GET_SIZE(HDRP(bp)) + GET_SIZE(HDRP(GET_NEXT_FREE(node)));
PUT(HDRP(node), PACK(size, 1));
PUT(FTRP(node), PACK(size, 1));
remove_from_list(GET_NEXT_FREE(node));
free_listp = node;
return;
} else if((char *) PREV_BLKP(bp) == GET_PREV_FREE(node) && (char *) NEXT_BLKP(bp) != node){
node = GET_PREV_FREE(node);
size_t size = GET_SIZE(HDRP(node)) + GET_SIZE(HDRP(bp));
PUT(HDRP(node), PACK(size, 1));
PUT(FTRP(node), PACK(size, 1));
free_listp = node;
return;
} else if((char *) NEXT_BLKP(bp) == node && (char *) PREV_BLKP(bp) != GET_PREV_FREE(node)){
node = GET_PREV_FREE(node);
size_t size = GET_SIZE(HDRP(bp)) + GET_SIZE(HDRP(GET_NEXT_FREE(node)));
PUT(HDRP(bp), PACK(size, 1));
PUT(FTRP(bp), PACK(size, 1));
char * old = GET_NEXT_FREE(node);
// set next to the next of next-next
SET_NEXT_FREE(bp, GET_NEXT_FREE(old));
// set the prev of next-next node to bp
SET_PREV_FREE(GET_NEXT_FREE(old), bp);
SET_PREV_FREE(bp, node);
SET_NEXT_FREE(node, bp);
free_listp = node;
return;
}
/* bp inserted before node */
// Set new next to node
SET_NEXT_FREE(bp, node);
......@@ -570,8 +600,8 @@ static void *extend_heap(size_t words)
/* Initialize free block and the epilogue header */
PUT(HDRP(bp), PACK(size, 1)); /* free block header */
PUT(FTRP(bp), PACK(size, 1)); /* free block footer */
PUT(HDRP(NEXT_BLKP(bp)), PACK(8, 0)); /* new epilogue header */
add_to_list(bp);
PUT(HDRP(NEXT_BLKP(bp)), PACK(0, 0)); /* new epilogue header */
return bp;
}
/* $end mmextendheap */
......
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