add 'rt_ringbuffer_peak' API

components/drivers/include/ipc/ringbuffer.h

@@ -71,6 +71,7 @@ rt_size_t rt_ringbuffer_put_force(struct rt_ringbuffer *rb, const rt_uint8_t *pt
 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_peak(struct rt_ringbuffer *rb, rt_uint8_t **ptr);
 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);
 

components/drivers/src/ringbuffer.c

@@ -193,6 +193,40 @@ rt_size_t rt_ringbuffer_get(struct rt_ringbuffer *rb,
 }
 RTM_EXPORT(rt_ringbuffer_get);
 
+/**
+ *  peak data from ring buffer
+ */
+rt_size_t rt_ringbuffer_peak(struct rt_ringbuffer *rb, rt_uint8_t **ptr)
+{
+    RT_ASSERT(rb != RT_NULL);
+
+    *ptr = RT_NULL;
+
+    /* whether has enough data  */
+    rt_size_t size = rt_ringbuffer_data_len(rb);
+
+    /* no data */
+    if (size == 0)
+        return 0;
+
+    *ptr = &rb->buffer_ptr[rb->read_index];
+
+    if(rb->buffer_size - rb->read_index > size)
+    {
+        rb->read_index += size;
+        return size;
+    }
+
+    size = rb->buffer_size - rb->read_index;
+
+    /* we are going into the other side of the mirror */
+    rb->read_mirror = ~rb->read_mirror;
+    rb->read_index = 0;
+
+    return size;
+}
+RTM_EXPORT(rt_ringbuffer_peak);
+
 /**
  * put a character into ring buffer
  */