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-rw-r--r--collections/double_ended_queue.c154
1 files changed, 78 insertions, 76 deletions
diff --git a/collections/double_ended_queue.c b/collections/double_ended_queue.c
index b555e3a..956e362 100644
--- a/collections/double_ended_queue.c
+++ b/collections/double_ended_queue.c
@@ -17,14 +17,14 @@
/* Double ended queue as a circular buffer
* base is pointer to buffer.
- * beg is where the first element is stored.
- * end is where the last element is stored.
- * limit is the maximum number of elements.
+ * beg: postiton of the first element is stored.
+ * end: position for the next element to be stored.
+ * limit: the maximum number of elements.
*/
struct double_ended_queue {
- void **base, **end, **beg;
- int limit;
+ void **base;
+ int beg, end, limit;
};
deq* deq_new()
@@ -35,7 +35,8 @@ deq* deq_new()
assert(root);
root->limit = START_SIZE;
- root->base = root->end = root->beg = malloc(root->limit * sizeof(void*));
+ root->beg = root->end = 0;
+ root->base = malloc(root->limit * sizeof(void*));
assert(root->base);
return root;
@@ -50,7 +51,8 @@ int n;
assert(root);
root->limit = n;
- root->base = root->end = root->beg = malloc(root->limit * sizeof(void*));
+ root->beg = root->end = 0;
+ root->base = malloc(root->limit * sizeof(void*));
assert(root->base);
return root;
@@ -59,15 +61,13 @@ int n;
int deq_size(root)
deq *root;
{
- if (!root) {
+ if (!root)
return -1;
- }
- if (root->beg <= root->end) {
+ if (root->beg <= root->end)
return (root->end - root->beg);
- }
- return (root->base + root->limit - root->beg) + (root->end - root->base);
+ return (root->limit - root->beg) + (root->end);
}
void deq_resize(root)
@@ -79,26 +79,25 @@ deq *root;
tmp = malloc(root->limit * 2 * sizeof(void*));
assert(root->base);
- if (root->beg > root->end) {
+ if (root->beg <= root->end) {
+ tmp = memcpy(tmp, root->base + root->beg,
+ deq_size(root) * sizeof(void*));
+ } else {
/*copy beg<->limit*/
- size = (root->base + (root->limit*sizeof(void*)) - root->beg);
- tmp = memcpy(tmp, root->beg, size * sizeof(void*);
+ size = root->limit - root->beg;
+ tmp = memcpy(tmp, root->base + root->beg, size * sizeof(void*));
assert(tmp);
/*copy base<->end*/
- tmp = memcpy(tmp + size, root->beg,
- (root->end - root->base)* sizeof(void*));
+ tmp = memcpy(tmp + size, root->base,
+ root->end * sizeof(void*));
assert(tmp);
- } else {
- size = deq_size(root);
- tmp = memcpy(tmp, root->beg, size*sizeof(void*));
}
root->limit *= 2;
free(root->base);
- root->base = root->beg = tmp;
- root->end = root->base + size;
+ root->base = tmp;
}
void* deq_index(root, index)
@@ -107,16 +106,15 @@ int index;
{
void **tmp;
- if (!root) {
+ if (!root || index > root->limit
+ || (index >= root->end && index < root->beg))
return NULL;
- }
- tmp = root->base + ((root->beg + index - root->base) % root->limit);
- if (tmp > root->end) {
+ index = (root->beg + index) % root->limit;
+ if (index >= root->end)
return NULL;
- }
- return *tmp;
+ return root->base[index];
}
void deq_push_back(root, item)
@@ -125,17 +123,17 @@ void *item;
{
void **tmp;
- if (!root) {
+ if (!root)
return;
- }
- tmp = (root->base + (root->end - root->base) % root->limit);
- if (tmp == root->beg) {
+ if (root->end >= root->limit)
deq_resize(root);
- tmp = (root->base + (root->end - root->base) % root->limit);
- }
- *(root->end = tmp) = item;
+ root->base[root->end++] = item;
+ root->end %= root->limit;
+
+ if (root->end == root->beg)
+ root->end = root->limit;
}
void deq_push_front(root, item)
@@ -144,29 +142,32 @@ void *item;
{
void **tmp;
- if (!root) {
+ if (!root)
return;
- }
- tmp = (root->base + ((root->beg - 1) - root->base) % root->limit);
- if (tmp == root->beg) {
+ if (root->end >= root->limit)
deq_resize(root);
- tmp = (root->base + ((root->beg - 1) - root->base) % root->limit);
- }
- *(root->beg = tmp) = item;
+ --root->beg;
+ root->beg %= root->limit;
+
+ root->base[root->beg] = item;
+
+ if (root->end == root->beg)
+ root->end = root->limit;
}
void* deq_pop_front(root)
deq *root;
{
void* tmp;
- if (!root || root->beg == root->end) {
+ if (!root || root->beg == root->end)
return NULL;
- }
- tmp = *(root->beg++);
- root->beg = (root->base + (root->beg - root->base) % root->limit);
+ tmp = root->base[root->beg];
+
+ ++root->beg;
+ root->beg %= root->limit;
return tmp;
}
@@ -174,15 +175,13 @@ deq *root;
void* deq_pop_back(root)
deq *root;
{
- void* tmp;
- if (!root || root->end == root->beg) {
+ if (!root || root->end == root->beg)
return NULL;
- }
- tmp = *(root->end--);
- root->end = (root->base + (root->end - root->base) % root->limit);
+ --root->end;
+ root->end %= root->limit;
- return tmp;
+ return root->base[root->end];
}
void deq_free(root)
@@ -190,8 +189,6 @@ deq *root;
{
free(root->base);
root->base = NULL;
- root->end = NULL;
- root->beg = NULL;
free(root);
}
@@ -216,9 +213,9 @@ deq *root;
{
void **tmp;
- fprintf(stderr, "VEC[b: %p, p: %p, n:%p]:\n\t ",
+ fprintf(stderr, "VEC[b: %p, beg: %d, end:%d]:\n\t ",
root->base, root->beg, root->end);
- for (tmp = root->beg; tmp < root->end; tmp++){
+ for (tmp = root->base; tmp < root->base + root->limit; tmp++){
fprintf(stderr, "[%p]", *tmp);
}
fprintf(stderr, "\n");
@@ -230,13 +227,16 @@ deq *root;
deq *copy;
copy = deq_with_capacity(root->limit);
+ assert(copy->base);
- copy->base = memcpy(copy->base, root->beg,
- deq_size(root) * sizeof(void*));
+ copy->base = memcpy(copy->base, root->base,
+ root->limit * sizeof(void*));
assert(copy->base);
- copy->beg = copy->base;
- copy->end = copy->base + deq_size(root);
+ copy->beg = root->beg;
+ copy->end = root->end;
+
+ return copy;
}
void deq_swap(root, i, j)
@@ -246,48 +246,50 @@ int i, j;
int len;
void *tmp;
- if (!root) {
+ if (!root)
return;
- }
len = deq_size(root);
- if (i >= len || j >= len) {
+ if (i >= len || j >= len)
return;
- }
- tmp = root->end[i];
- root->end[j] = root->end[i];
- root->end[i] = tmp;
+ i += root->beg;
+ i %= root->limit;
+
+ j += root->beg;
+ j %= root->limit;
+
+ tmp = root->base[i];
+ root->base[i] = root->base[j];
+ root->base[j] = tmp;
}
+/*Note: Does not currently reduce memory footprint*/
void deq_truncate(root, size)
deq *root;
int size;
{
- if ((!root) || size > deq_size(root)) {
+ if (!root || size > deq_size(root))
return;
- }
- root->end = root->beg + size;
+ root->end = (root->beg + size) % root->limit;
}
void* deq_front(root)
deq *root;
{
- if (!root) {
+ if (!root)
return NULL;
- }
- return *root->beg;
+ return root->base[root->beg];
}
void* deq_back(root)
deq *root;
{
- if (!root) {
+ if (!root)
return NULL;
- }
- return *root->end;
+ return root->base[(root->end - 1) % root->limit];
}
generated by cgit v1.1 at 2025-01-08 20:19:23 +0000