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-rw-r--r--circleq.c105
1 files changed, 105 insertions, 0 deletions
diff --git a/circleq.c b/circleq.c
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--- /dev/null
+++ b/circleq.c
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+#include <sys/queue.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <err.h>
+
+/*
+ * circleq macro usage examples by Peter Werner <peterw@ifost.org.au>
+ *
+ * please see http://www.ifost.org.au/~peterw/queue.html for more info
+ */
+
+/*
+ * our struct definition, with the circleq element to be referenced by f_link
+ */
+
+struct foo {
+ int f_a;
+ char f_b;
+ CIRCLEQ_ENTRY(foo) f_link;
+};
+
+/*
+ * the head of our circleq of struct foo's (see the manpage for more info)
+ */
+CIRCLEQ_HEAD(cqhead, foo) cq;
+
+struct foo *alloc_foo(int a, char b);
+
+int
+main(void)
+{
+ struct foo *fp, *other;
+ struct cqhead *cqp;
+
+ CIRCLEQ_INIT(&cq);
+ cqp = &cq;
+
+ /*
+ * insert the elements, note the use of the f_link item
+ */
+ fp = alloc_foo(1, 'a');
+ CIRCLEQ_INSERT_HEAD(cqp, fp, f_link);
+
+ fp = alloc_foo(2, 'b');
+ CIRCLEQ_INSERT_TAIL(cqp, fp, f_link);
+
+ /*
+ * put this one after the head of the queue
+ */
+ fp = alloc_foo(3, 'c');
+ CIRCLEQ_INSERT_AFTER(cqp, CIRCLEQ_FIRST(cqp), fp, f_link);
+
+ /*
+ * put this one in front of the one we just inserted
+ */
+ other = alloc_foo(4, 'd');
+ CIRCLEQ_INSERT_BEFORE(cqp, fp, other, f_link);
+
+
+ /*
+ * loop through the list
+ */
+ CIRCLEQ_FOREACH(fp, cqp, f_link)
+ printf("%d %c\n", fp->f_a, fp->f_b);
+
+ /*
+ * loop through the other way, note the use of cqhead
+ */
+ printf("backwards!\n");
+ CIRCLEQ_FOREACH_REVERSE(fp, cqp, f_link)
+ printf("%d %c\n", fp->f_a, fp->f_b);
+
+ /*
+ * free up our list
+ */
+ for (fp = CIRCLEQ_FIRST(cqp); fp != CIRCLEQ_END(cqp); fp = other) {
+ other = CIRCLEQ_NEXT(fp, f_link);
+ CIRCLEQ_REMOVE(cqp, fp, f_link);
+ free(fp);
+ }
+
+ /*
+ * make sure
+ */
+ if (CIRCLEQ_EMPTY(cqp))
+ printf("List is empty!\n");
+ else
+ printf("List not empty!\n");
+
+ return(0);
+}
+
+struct foo *
+alloc_foo(int a, char b)
+{
+ struct foo *tmp;
+
+ tmp = (struct foo *)malloc(sizeof(struct foo));
+ if (tmp == NULL)
+ err(1, "malloc");
+
+ tmp->f_a = a;
+ tmp->f_b = b;
+ return(tmp);
+}