1 files changed, 131 insertions, 0 deletions
diff --git a/types-ring.h b/types-ring.h
new file mode 100644
index 0000000..c8b5f77
--- /dev/null
+++ b/types-ring.h
@@ -0,0 +1,131 @@
+/* See LICENSE file for copyright and license details. */
+#ifndef TYPES_RING_H
+#define TYPES_RING_H
+
+#include <stdlib.h>
+
+#ifndef GCC_ONLY
+# if defined(__GNUC__) && !defined(__clang__)
+#  define GCC_ONLY(...) __VA_ARGS__
+# else
+#  define GCC_ONLY(...) /* nothing */
+# endif
+#endif
+
+/**
+ * Ring buffer
+ */
+struct ring {
+	/**
+	 * Buffer for the data
+	 */
+	char *restrict buffer;
+
+	/**
+	 * The first set byte in `.buffer`
+	 */
+	size_t start;
+
+	/**
+	 * The last set byte in `.buffer`, plus 1
+	 */
+	size_t end;
+
+	/**
+	 * The size of `.buffer`
+	 */
+	size_t size;
+};
+
+/**
+ * Initialise a ring buffer
+ * 
+ * @param  this  The ring buffer
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+void ring_initialise(struct ring *restrict this);
+
+/**
+ * Marshal a ring buffer
+ * 
+ * @param   this  The ring buffer
+ * @param   buf   Output buffer for the marshalled data,
+ *                `NULL` to only measure how large buffer
+ *                is needed
+ * @return        The number of marshalled bytes
+ */
+GCC_ONLY(__attribute__((__nonnull__(1))))
+size_t ring_marshal(const struct ring *restrict this, void *restrict buf);
+
+/**
+ * Unmarshal a ring buffer
+ * 
+ * @param   this  Output parameter for the ring buffer
+ * @param   buf   Buffer with the marshalled data
+ * @return        The number of unmarshalled bytes, 0 on error
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+size_t ring_unmarshal(struct ring *restrict this, const void *restrict buf);
+
+/**
+ * Append data to a ring buffer
+ * 
+ * @param   this  The ring buffer
+ * @param   data  The new data
+ * @param   n     The number of bytes in `data`
+ * @return        Zero on success, -1 on error
+ */
+GCC_ONLY(__attribute__((__nonnull__(1))))
+int ring_push(struct ring *restrict this, void *restrict data, size_t n);
+
+/**
+ * Get queued data from a ring buffer
+ * 
+ * It can take up to two calls (with `ring_pop` between)
+ * to get all queued data
+ * 
+ * @param   this  The ring buffer
+ * @param   n     Output parameter for the length
+ *                of the returned segment
+ * @return        The beginning of the queued data,
+ *                `NULL` if there is nothing more
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+void *ring_peek(struct ring *restrict this, size_t *restrict n);
+
+/**
+ * Dequeue data from a ring bubber
+ * 
+ * @param  this  The ring buffer
+ * @param  n     The number of bytes to dequeue
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+void ring_pop(struct ring *restrict this, size_t n);
+
+/**
+ * Release resource allocated to a ring buffer
+ * 
+ * @param  this  The ring buffer
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+static inline void
+ring_destroy(struct ring *restrict this)
+{
+	free(this->buffer);
+}
+
+/**
+ * Check whether there is more data waiting
+ * in a ring buffer
+ * 
+ * @param   this  The ring buffer
+ * @return        1 if there is more data, 0 otherwise
+ */
+GCC_ONLY(__attribute__((__nonnull__)))
+static inline int
+ring_have_more(struct ring *restrict this)
+{
+	return !!this->buffer;
+}
+
+#endif