1 files changed, 88 insertions, 0 deletions
diff --git a/components/drivers/include/ipc/ringbuffer.h b/components/drivers/include/ipc/ringbuffer.h
new file mode 100644
index 0000000000..4cfab6d69c
--- /dev/null
+++ b/components/drivers/include/ipc/ringbuffer.h
@@ -0,0 +1,88 @@
+#ifndef RINGBUFFER_H__
+#define RINGBUFFER_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <rtthread.h>
+
+/* ring buffer */
+struct rt_ringbuffer
+{
+    rt_uint8_t *buffer_ptr;
+    /* use the msb of the {read,write}_index as mirror bit. You can see this as
+     * if the buffer adds a virtual mirror and the pointers point either to the
+     * normal or to the mirrored buffer. If the write_index has the same value
+     * with the read_index, but in a different mirror, the buffer is full.
+     * While if the write_index and the read_index are the same and within the
+     * same mirror, the buffer is empty. The ASCII art of the ringbuffer is:
+     *
+     *          mirror = 0                    mirror = 1
+     * +---+---+---+---+---+---+---+|+~~~+~~~+~~~+~~~+~~~+~~~+~~~+
+     * | 0 | 1 | 2 | 3 | 4 | 5 | 6 ||| 0 | 1 | 2 | 3 | 4 | 5 | 6 | Full
+     * +---+---+---+---+---+---+---+|+~~~+~~~+~~~+~~~+~~~+~~~+~~~+
+     *  read_idx-^                   write_idx-^
+     *
+     * +---+---+---+---+---+---+---+|+~~~+~~~+~~~+~~~+~~~+~~~+~~~+
+     * | 0 | 1 | 2 | 3 | 4 | 5 | 6 ||| 0 | 1 | 2 | 3 | 4 | 5 | 6 | Empty
+     * +---+---+---+---+---+---+---+|+~~~+~~~+~~~+~~~+~~~+~~~+~~~+
+     * read_idx-^ ^-write_idx
+     *
+     * The tradeoff is we could only use 32KiB of buffer for 16 bit of index.
+     * But it should be enough for most of the cases.
+     *
+     * Ref: http://en.wikipedia.org/wiki/Circular_buffer#Mirroring */
+    rt_uint16_t read_mirror : 1;
+    rt_uint16_t read_index : 15;
+    rt_uint16_t write_mirror : 1;
+    rt_uint16_t write_index : 15;
+    /* as we use msb of index as mirror bit, the size should be signed and
+     * could only be positive. */
+    rt_int16_t buffer_size;
+};
+
+enum rt_ringbuffer_state
+{
+    RT_RINGBUFFER_EMPTY,
+    RT_RINGBUFFER_FULL,
+    /* half full is neither full nor empty */
+    RT_RINGBUFFER_HALFFULL,
+};
+
+/**
+ * RingBuffer for DeviceDriver
+ *
+ * Please note that the ring buffer implementation of RT-Thread
+ * has no thread wait or resume feature.
+ */
+void rt_ringbuffer_init(struct rt_ringbuffer *rb, rt_uint8_t *pool, rt_int16_t size);
+void rt_ringbuffer_reset(struct rt_ringbuffer *rb);
+rt_size_t rt_ringbuffer_put(struct rt_ringbuffer *rb, const rt_uint8_t *ptr, rt_uint16_t length);
+rt_size_t rt_ringbuffer_put_force(struct rt_ringbuffer *rb, const rt_uint8_t *ptr, rt_uint16_t length);
+rt_size_t rt_ringbuffer_putchar(struct rt_ringbuffer *rb, const rt_uint8_t ch);
+rt_size_t rt_ringbuffer_putchar_force(struct rt_ringbuffer *rb, const rt_uint8_t ch);
+rt_size_t rt_ringbuffer_get(struct rt_ringbuffer *rb, rt_uint8_t *ptr, rt_uint16_t length);
+rt_size_t rt_ringbuffer_getchar(struct rt_ringbuffer *rb, rt_uint8_t *ch);
+rt_size_t rt_ringbuffer_data_len(struct rt_ringbuffer *rb);
+
+#ifdef RT_USING_HEAP
+struct rt_ringbuffer* rt_ringbuffer_create(rt_uint16_t length);
+void rt_ringbuffer_destroy(struct rt_ringbuffer *rb);
+#endif
+
+rt_inline rt_uint16_t rt_ringbuffer_get_size(struct rt_ringbuffer *rb)
+{
+    RT_ASSERT(rb != RT_NULL);
+    return rb->buffer_size;
+}
+
+/** return the size of empty space in rb */
+#define rt_ringbuffer_space_len(rb) ((rb)->buffer_size - rt_ringbuffer_data_len(rb))
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif