deque: New module

[ccan] / ccan / deque / deque.c

diff --git a/ccan/deque/deque.c b/ccan/deque/deque.c
new file mode 100644 (file)
index 0000000..cb628d3
--- /dev/null
+++ b/ccan/deque/deque.c
@@ -0,0 +1,91 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include "deque.h"
+
+int deq_resize_(struct deq *q, unsigned n)
+{
+       char *t;
+
+       assert(q && n > 0 && n >= q->len);
+
+       if (!(t = malloc(q->esz * n)))
+               return -1;
+
+       if (q->len) {
+               unsigned part1 = q->head + q->len <= q->cap ? q->len : q->cap - q->head;
+               unsigned part2 = q->len - part1;
+               memcpy(t, q->v + q->head * q->esz, q->esz * part1);
+               if (part2)
+                       memcpy(t + q->esz * part1, q->v, q->esz * part2);
+       }
+       if (q->cap)
+               free(q->v);
+
+       q->v    = t;
+       q->head = 0;
+       q->tail = q->len;
+       q->cap  = n;
+
+       return 0;
+}
+
+int deq_op_(struct deq *q, enum deq_op op, unsigned *i)
+{
+       assert(q && i);
+       assert(op == DEQ_PUSH || op == DEQ_POP ||  op == DEQ_SHIFT || op == DEQ_UNSHIFT);
+
+       switch (op) {
+       case DEQ_PUSH:
+       case DEQ_UNSHIFT:
+               if (q->len == q->cap && deq_resize_(q, q->cap == 0 ? q->min : q->cap * 2) == -1)
+                       return -1;
+               break;
+       case DEQ_POP:
+       case DEQ_SHIFT:
+               if (q->cap > q->min) {
+                       if (q->shrink == DEQ_SHRINK_IF_EMPTY && q->len == 1 && deq_resize_(q, q->min) == -1)
+                               return -1;
+                       if (q->shrink == DEQ_SHRINK_AT_20PCT && (q->len - 1) * 5 <= q->cap && deq_resize_(q, q->cap / 2) == -1)
+                               return -1;
+               }
+               if (q->len == 0)
+                       return 0;
+       }
+
+       switch (op) {
+       case DEQ_PUSH:
+               *i = q->tail++;
+               q->tail  %= q->cap;
+               q->len++;
+               break;
+       case DEQ_SHIFT:
+               *i = q->head++;
+               q->head %= q->cap;
+               q->len--;
+               break;
+       case DEQ_POP:
+               q->tail = (q->tail == 0 ? q->cap : q->tail) - 1;
+               *i = q->tail;
+               q->len--;
+               break;
+       case DEQ_UNSHIFT:
+               q->head = (q->head == 0 ? q->cap : q->head) - 1;
+               *i = q->head;
+               q->len++;
+               break;
+       }
+
+       return 1;
+}
+
+void deq_reset_(struct deq *q)
+{
+       assert(q);
+
+       if (q->v)
+               free(q->v);
+
+       q->v = 0;
+       q->head = q->tail = q->len = q->cap = 0;
+}