1 files changed, 59 insertions, 0 deletions
diff --git a/usb-serial-rs485/ringb.c b/usb-serial-rs485/ringb.c
new file mode 100644
index 0000000..245325b
--- /dev/null
+++ b/usb-serial-rs485/ringb.c
@@ -0,0 +1,59 @@
+
+#include "ringb.h"
+void ringb_init(struct ringb *ring, uint8_t *buf, int len)
+{
+	ring->buf_len = len;
+	ring->buf = buf;
+	ring->idx_r = 0;
+	ring->idx_w = 0;
+}
+
+int ringb_get(struct ringb *ring) {
+#if 1
+	int rval;
+	if (ring->idx_r != ring->idx_w) {
+		rval = ring->buf[ring->idx_r];
+		ring->idx_r = (ring->idx_r + 1) % ring->buf_len;
+		return rval;
+	}
+	return -1;
+#else
+	if (((ring->idx_w - ring->idx_r) % ring->buf_len) >= 0) {
+		int rval = ring->buf[ring->idx_r];
+		ring->idx_r = (ring->idx_r + 1) % ring->buf_len;
+		return rval;
+	} else {
+		return -1;
+	}
+#endif
+}
+
+bool ringb_put(struct ringb *ring, uint8_t c) {
+#if 1
+	unsigned int next = (ring->idx_w + 1) % ring->buf_len;
+	if (next != ring->idx_r) {
+		ring->buf[ring->idx_w] = c;
+		ring->idx_w = next;
+		return true;
+	}
+	return false;
+#else
+	if (((ring->idx_w - ring->idx_r) % ring->buf_len) == 0) {
+		return false;
+	}
+	ring->buf[ring->idx_w] = c;
+	ring->idx_w = (ring->idx_w + 1) % ring->buf_len;
+	return true;
+#endif
+	
+}
+
+
+void ringb_flush(struct ringb *ring) {
+	ring->idx_r = 0;
+	ring->idx_w = 0;
+}
+
+int ringb_depth(struct ringb *ring) {
+	return ((unsigned int)(ring->idx_w - ring->idx_r) % ring->buf_len);
+}
+\ No newline at end of file