1 files changed, 53 insertions, 0 deletions

diff --git a/common/ring_buffer.h b/common/ring_buffer.h
new file mode 100644
index 000000000..7bdebbcf3
--- /dev/null
+++ b/common/ring_buffer.h
@@ -0,0 +1,53 @@
+#ifndef RING_BUFFER_H
+#define RING_BUFFER_H
+/*--------------------------------------------------------------------
+ * Ring buffer to store scan codes from keyboard
+ *------------------------------------------------------------------*/
+#define RBUF_SIZE 32
+static uint8_t rbuf[RBUF_SIZE];
+static uint8_t rbuf_head = 0;
+static uint8_t rbuf_tail = 0;
+static inline void rbuf_enqueue(uint8_t data)
+{
+    uint8_t sreg = SREG;
+    cli();
+    uint8_t next = (rbuf_head + 1) % RBUF_SIZE;
+    if (next != rbuf_tail) {
+        rbuf[rbuf_head] = data;
+        rbuf_head = next;
+    } else {
+        print("rbuf: full\n");
+    }
+    SREG = sreg;
+}
+static inline uint8_t rbuf_dequeue(void)
+{
+    uint8_t val = 0;
+
+    uint8_t sreg = SREG;
+    cli();
+    if (rbuf_head != rbuf_tail) {
+        val = rbuf[rbuf_tail];
+        rbuf_tail = (rbuf_tail + 1) % RBUF_SIZE;
+    }
+    SREG = sreg;
+
+    return val;
+}
+static inline bool rbuf_has_data(void)
+{
+    uint8_t sreg = SREG;
+    cli();
+    bool has_data = (rbuf_head != rbuf_tail);
+    SREG = sreg;
+    return has_data;
+}
+static inline void rbuf_clear(void)
+{
+    uint8_t sreg = SREG;
+    cli();
+    rbuf_head = rbuf_tail = 0;
+    SREG = sreg;
+}
+
+#endif  /* RING_BUFFER_H */