Tidy up ringbuf and make tests

include/ucore/ringbuf.h

@@ -0,0 +1,98 @@
+#ifndef UC_RINGBUG_H_
+#define UC_RINGBUG_H_
+#include <stdint.h>
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct UCRingBuf UCRingBuf;
+struct UCRingBuf {
+    char *base;
+    uint32_t sz;
+    uint32_t read_idx;
+    uint32_t write_idx;
+};
+
+/**
+ * Creates a new ringbuffer of at least @sz length.
+ * The length will be rounded up to the neares page size
+ *
+ * The ringbuffer is implementd by mapping the same physical memory
+ * twice into virtual memory adjacent to eachother, avoiding
+ * a splitting up read/writes when the ringbuffer wraps around.
+ *
+ * This means accessing rb.base[rb.len] up to rb.base[rb.len * 2 - 1]
+ * is accessing the same memory as rb.base[0] up to rb.base[rb.len -1]
+ *
+ * @param rb UCRingBuf to initialize
+ * @param sz minimum length of the ring buffer
+ * @returns 0 on success
+ */
+int uc_ringbuf_init(UCRingBuf *rb, uint32_t sz);
+
+/** Free resources used by the ring buffer.
+ *
+ * @return 0 on success
+ */
+int uc_ringbuf_destroy(UCRingBuf *rb);
+
+/**
+ * Write data to the ringbuffer. The number of bytes to write must fit
+ * in the free space of the ringbuffer
+ *
+ * @param rb UCRingBuf to write to.
+ * @param data data to write
+ * @param sz number of bytes to write from data
+ * @return 0 on success
+ */
+int uc_ringbuf_write(UCRingBuf *rb, const void *restrict data, uint32_t sz);
+
+/** Read data from the ringbuffer
+ *
+ * @param rb UCRingBuf to write to.
+ * @param data buffer to copy data into
+ * @param sz number of bytes to read, must not exceed available data
+ *            in the buffer
+ * @return 0 on success
+ */
+int uc_ringbuf_read(UCRingBuf *rb, void *restrict data, uint32_t sz);
+
+
+/** Inspect how much free space is available for writing to the ring buffer
+ *
+ * @param rb UCRingBuf to inspect
+ * @returns number of free bytes
+ */
+uint32_t uc_ringbuf_available(const UCRingBuf *rb);
+
+/**
+ * Length of available data in the ringbuffer
+ *
+ * @param rb UCRingBuf get length of
+ *
+ * @return length of data available to read
+ */
+static inline uint32_t uc_ringbuf_len(const UCRingBuf *rb)
+{
+    return rb->write_idx - rb->read_idx;
+}
+
+/**
+ *  Get a pointer to the first unread byte
+ *  Caller is responsible for reading no more than the available
+ *  data
+ *
+ * @param rb UCRingBuf to peek into
+ *
+ * @returns pointer to first unread byte
+*/
+static inline void *uc_ringbuf_peek(const UCRingBuf *rb)
+{
+    return &rb->base[rb->read_idx];
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif