shared: implement a basic ring buffer

1 files changed, 35 insertions, 0 deletions

diff --git a/src/shared/container/ring.c b/src/shared/container/ring.c
new file mode 100644
index 0000000..525fade
--- /dev/null
+++ b/src/shared/container/ring.c
@@ -0,0 +1,35 @@
+#include <shared/container/ring.h>
+#include <stdbool.h>
+// TODO use memcpy
+
+static bool at_end(ring_t *r) {
+	return  r->_head + 1 == r->_tail
+		|| (r->_head + 1 == r->capacity && r->_tail == 0);
+}
+
+size_t ring_size(ring_t *r) {
+	if (r->_head >= r->_tail)
+		return r->_head - r->_tail;
+	else
+		return r->_head + r->capacity - r->_tail;
+}
+
+void ring_put(ring_t *r, void *buf, size_t len) {
+	for (size_t i = 0; i < len; i++)
+		ring_put1b(r, ((uint8_t*)buf)[i]);
+}
+
+void ring_put1b(ring_t *r, uint8_t byte) {
+	if (at_end(r)) return;
+	((uint8_t*)r->buf)[r->_head++] = byte;
+	if (r->_head >= r->capacity) r->_head = 0;
+}
+
+size_t ring_get(ring_t *r, void *buf, size_t len) {
+	for (size_t i = 0; i < len; i++) {
+		if (at_end(r)) return i;
+		((uint8_t*)buf)[i] = ((uint8_t*)r->buf)[r->_tail++];
+		if (r->_tail >= r->capacity) r->_tail = 0;
+	}
+	return len;
+}