sys: ring_buffer: ring_buf_peek() and ring_buf_size_get() (0ca511a4) · Commits · Wenxi XU / zephyr

include/sys/ring_buffer.h

+40 −0

Original line number	Diff line number	Diff line
		@@ -215,6 +215,18 @@ static inline uint32_t ring_buf_capacity_get(struct ring_buf *buf)
		return buf->size;
		}

		/**
		* @brief Determine used space in a ring buffer.
		*
		* @param buf Address of ring buffer.
		*
		* @return Ring buffer space used (in 32-bit words or bytes).
		*/
		static inline uint32_t ring_buf_size_get(struct ring_buf *buf)
		{
		return buf->tail - buf->head;
		}

		/**
		* @brief Write a data item to a ring buffer.
		*
		@@ -406,6 +418,34 @@ int ring_buf_get_finish(struct ring_buf *buf, uint32_t size);
		*/
		uint32_t ring_buf_get(struct ring_buf buf, uint8_t data, uint32_t size);

		/**
		* @brief Peek at data from a ring buffer.
		*
		* This routine reads data from a ring buffer @a buf without removal.
		*
		* @warning
		* Use cases involving multiple reads of the ring buffer must prevent
		* concurrent read operations, either by preventing all readers from
		* being preempted or by using a mutex to govern reads to the ring buffer.
		*
		* @warning
		* Ring buffer instance should not mix byte access and item mode
		* (calls prefixed with ring_buf_item_).
		*
		* @warning
		* Multiple calls to peek will result in the same data being 'peeked'
		* multiple times. To remove data, use either @ref ring_buf_get or
		* @ref ring_buf_get_claim followed by @ref ring_buf_get_finish with a
		* non-zero `size`.
		*
		* @param buf Address of ring buffer.
		* @param data Address of the output buffer. Cannot be NULL.
		* @param size Data size (in bytes).
		*
		* @retval Number of bytes written to the output buffer.
		*/
		uint32_t ring_buf_peek(struct ring_buf buf, uint8_t data, uint32_t size);

		/**
		* @}
		*/

lib/os/ring_buffer.c

+25 −0

Original line number	Diff line number	Diff line
		@@ -284,3 +284,28 @@ uint32_t ring_buf_get(struct ring_buf buf, uint8_t data, uint32_t size)

		return total_size;
		}

		uint32_t ring_buf_peek(struct ring_buf buf, uint8_t data, uint32_t size)
		{
		uint8_t *src;
		uint32_t partial_size;
		uint32_t total_size = 0U;
		int err;

		size = MIN(size, ring_buf_size_get(buf));

		do {
		partial_size = ring_buf_get_claim(buf, &src, size);
		__ASSERT_NO_MSG(data != NULL);
		memcpy(data, src, partial_size);
		data += partial_size;
		total_size += partial_size;
		size -= partial_size;
		} while (size && partial_size);

		/* effectively unclaim total_size bytes */
		err = ring_buf_get_finish(buf, 0);
		__ASSERT_NO_MSG(err == 0);

		return total_size;
		}

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