1 files changed, 74 insertions, 0 deletions
diff --git a/include/ring.h b/include/ring.h
new file mode 100644
index 0000000..d57f9aa
--- /dev/null
+++ b/include/ring.h
@@ -0,0 +1,74 @@
+#ifndef RING_H
+#define RING_H
+
+struct ring {
+	uint8_t *data;
+	uint_fast8_t mask;
+	volatile uint_fast8_t begin;
+	volatile uint_fast8_t end;
+};
+
+
+static inline
+void ring_init(struct ring *ring, uint8_t *buf, int size)
+{
+	ring->data = buf;
+	ring->mask = (size-1) & 0xff;
+	ring->begin = 0;
+	ring->end = 0;
+}
+
+static inline
+int ring_write_ch(struct ring *ring, uint8_t ch)
+{
+	uint_fast8_t ep = ring->end;
+
+	ring->data[ep] = ch;
+	ep = (ep + 1) & ring->mask;
+
+	if ((ep) != ring->begin) {
+		ring->end = ep;
+		return 1;
+	}
+
+	return -1;
+}
+
+#if 0
+static inline
+int ring_write(struct ring *ring, uint8_t *data, int size)
+{
+	int i;
+
+	for (i = 0; i < size; i++) {
+		if (ring_write_ch(ring, data[i]) < 0)
+			return -i;
+	}
+
+	return i;
+}
+#endif
+
+static inline
+int ring_read_ch(struct ring *ring)
+{
+	int ret = -1;
+	uint_fast8_t bp = ring->begin;
+
+	if (bp != ring->end) {
+		ret = ring->data[bp];
+		ring->begin = (bp + 1) & ring->mask;
+	}
+
+	return ret;
+}
+
+
+static inline
+int_fast8_t ring_is_empty(struct ring *ring)
+{
+	return ring->begin == ring->end;
+}
+
+#endif /* RING_H */
+