lib/os/ring_buffer.c - third_party/github/zephyrproject-rtos/zephyr - Git at Google

 /* ring_buffer.c: Simple ring buffer API */

 /*
  * Copyright (c) 2015 Intel Corporation
  *
  * SPDX-License-Identifier: Apache-2.0
  */

 #include <sys/ring_buffer.h>
 #include <string.h>

 /* LCOV_EXCL_START */
 /* The weak function used to allow overwriting it in the test and trigger
  * rewinding earlier.
  */
 uint32_t __weak ring_buf_get_rewind_threshold(void)
 {
 	return RING_BUFFER_MAX_SIZE;
 }
 /* LCOV_EXCL_STOP */

 /**
  * Internal data structure for a buffer header.
  *
  * We want all of this to fit in a single uint32_t. Every item stored in the
  * ring buffer will be one of these headers plus any extra data supplied
  */
 struct ring_element {
 	uint32_t  type   :16; /**< Application-specific */
 	uint32_t  length :8;  /**< length in 32-bit chunks */
 	uint32_t  value  :8;  /**< Room for small integral values */
 };

 static uint32_t mod(struct ring_buf *buf, uint32_t val)
 {
 	return likely(buf->mask) ? val & buf->mask : val % buf->size;
 }

 static uint32_t get_rewind_value(uint32_t buf_size, uint32_t threshold)
 {
 	return buf_size * (threshold / buf_size);
 }

 int ring_buf_is_empty(struct ring_buf *buf)
 {
 	uint32_t tail = buf->tail;
 	uint32_t head = buf->head;

 	if (tail < head) {
 		tail += get_rewind_value(buf->size,
 					 ring_buf_get_rewind_threshold());
 	}

 	return (head == tail);
 }

 uint32_t ring_buf_size_get(struct ring_buf *buf)
 {
 	uint32_t tail = buf->tail;
 	uint32_t head = buf->head;

 	if (tail < head) {
 		tail += get_rewind_value(buf->size,
 					 ring_buf_get_rewind_threshold());
 	}

 	return tail - head;
 }

 uint32_t ring_buf_space_get(struct ring_buf *buf)
 {
 	return buf->size - ring_buf_size_get(buf);
 }

 int ring_buf_item_put(struct ring_buf *buf, uint16_t type, uint8_t value,
 		      uint32_t *data, uint8_t size32)
 {
 	uint32_t i, space, index, rc;
 	uint32_t threshold = ring_buf_get_rewind_threshold();
 	uint32_t rew;

 	space = ring_buf_space_get(buf);
 	if (space >= (size32 + 1)) {
 		struct ring_element *header =
 		    (struct ring_element *)&buf->buf.buf32[mod(buf, buf->tail)];

 		header->type = type;
 		header->length = size32;
 		header->value = value;

 		if (likely(buf->mask)) {
 			for (i = 0U; i < size32; ++i) {
 				index = (i + buf->tail + 1) & buf->mask;
 				buf->buf.buf32[index] = data[i];
 			}
 		} else {
 			for (i = 0U; i < size32; ++i) {
 				index = (i + buf->tail + 1) % buf->size;
 				buf->buf.buf32[index] = data[i];
 			}
 		}

 		/* Check if indexes shall be rewound. */
 		if (buf->tail > threshold) {
 			rew = get_rewind_value(buf->size, threshold);
 		} else {
 			rew = 0;
 		}

 		buf->tail = buf->tail + (size32 + 1 - rew);
 		rc = 0U;
 	} else {
 		buf->misc.item_mode.dropped_put_count++;
 		rc = -EMSGSIZE;
 	}

 	return rc;
 }

 int ring_buf_item_get(struct ring_buf *buf, uint16_t *type, uint8_t *value,
 		      uint32_t *data, uint8_t *size32)
 {
 	struct ring_element *header;
 	uint32_t i, index;
 	uint32_t tail = buf->tail;
 	uint32_t rew;

 	/* Tail is always ahead, if it is not, it's only because it got rewound. */
 	if (tail < buf->head) {
 		/* Locally undo rewind to get tail aligned with head. */
 		rew = get_rewind_value(buf->size,
 				       ring_buf_get_rewind_threshold());
 		tail += rew;
 	} else if (ring_buf_is_empty(buf)) {
 		return -EAGAIN;
 	} else {
 		rew = 0;
 	}

 	header = (struct ring_element *) &buf->buf.buf32[mod(buf, buf->head)];

 	if (data && (header->length > *size32)) {
 		*size32 = header->length;
 		return -EMSGSIZE;
 	}

 	*size32 = header->length;
 	*type = header->type;
 	*value = header->value;

 	if (data) {
 		if (likely(buf->mask)) {
 			for (i = 0U; i < header->length; ++i) {
 				index = (i + buf->head + 1) & buf->mask;
 				data[i] = buf->buf.buf32[index];
 			}
 		} else {
 			for (i = 0U; i < header->length; ++i) {
 				index = (i + buf->head + 1) % buf->size;
 				data[i] = buf->buf.buf32[index];
 			}
 		}
 	}

 	/* Include potential rewinding */
 	buf->head = buf->head + header->length + 1 - rew;

 	return 0;
 }

 /** @brief Wraps index if it exceeds the limit.
  *
  * @param val  Value
  * @param max  Max.
  *
  * @return value % max.
  */
 static inline uint32_t wrap(uint32_t val, uint32_t max)
 {
 	return val >= max ? (val - max) : val;
 }

 uint32_t ring_buf_put_claim(struct ring_buf *buf, uint8_t **data, uint32_t size)
 {
 	uint32_t space, trail_size, allocated, tmp_trail_mod;

 	tmp_trail_mod = mod(buf, buf->misc.byte_mode.tmp_tail);
 	space = (buf->head + buf->size) - buf->misc.byte_mode.tmp_tail;
 	trail_size = buf->size - tmp_trail_mod;

 	/* Limit requested size to available size. */
 	size = MIN(size, space);

 	trail_size = buf->size - (tmp_trail_mod);

 	/* Limit allocated size to trail size. */
 	allocated = MIN(trail_size, size);
 	*data = &buf->buf.buf8[tmp_trail_mod];

 	buf->misc.byte_mode.tmp_tail =
 		buf->misc.byte_mode.tmp_tail + allocated;

 	return allocated;
 }

 int ring_buf_put_finish(struct ring_buf *buf, uint32_t size)
 {
 	uint32_t rew;
 	uint32_t threshold = ring_buf_get_rewind_threshold();

 	if ((buf->tail + size) > (buf->head + buf->size)) {
 		return -EINVAL;
 	}

 	/* Check if indexes shall be rewind. */
 	if (buf->tail > threshold) {
 		rew = get_rewind_value(buf->size, threshold);
 	} else {
 		rew = 0;
 	}

 	buf->tail += (size - rew);
 	buf->misc.byte_mode.tmp_tail = buf->tail;

 	return 0;
 }

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

 	do {
 		partial_size = ring_buf_put_claim(buf, &dst, size);
 		memcpy(dst, data, partial_size);
 		total_size += partial_size;
 		size -= partial_size;
 		data += partial_size;
 	} while (size && partial_size);

 	err = ring_buf_put_finish(buf, total_size);
 	__ASSERT_NO_MSG(err == 0);

 	return total_size;
 }

 uint32_t ring_buf_get_claim(struct ring_buf *buf, uint8_t **data, uint32_t size)
 {
 	uint32_t space, granted_size, trail_size, tmp_head_mod;
 	uint32_t tail = buf->tail;

 	/* Tail is always ahead, if it is not, it's only because it got rewinded. */
 	if (tail < buf->misc.byte_mode.tmp_head) {
 		/* Locally, increment it to pre-rewind value */
 		tail += get_rewind_value(buf->size,
 					 ring_buf_get_rewind_threshold());
 	}

 	tmp_head_mod = mod(buf, buf->misc.byte_mode.tmp_head);
 	space = tail - buf->misc.byte_mode.tmp_head;
 	trail_size = buf->size - tmp_head_mod;

 	/* Limit requested size to available size. */
 	granted_size = MIN(size, space);

 	/* Limit allocated size to trail size. */
 	granted_size = MIN(trail_size, granted_size);

 	*data = &buf->buf.buf8[tmp_head_mod];
 	buf->misc.byte_mode.tmp_head += granted_size;

 	return granted_size;
 }

 int ring_buf_get_finish(struct ring_buf *buf, uint32_t size)
 {
 	uint32_t tail = buf->tail;
 	uint32_t rew;

 	/* Tail is always ahead, if it is not, it's only because it got rewinded. */
 	if (tail < buf->misc.byte_mode.tmp_head) {
 		/* tail was rewinded. Locally, increment it to pre-rewind value */
 		rew = get_rewind_value(buf->size,
 				       ring_buf_get_rewind_threshold());
 		tail += rew;
 	} else {
 		rew = 0;
 	}

 	if ((buf->head + size) > tail) {
 		return -EINVAL;
 	}

 	/* Include potential rewinding. */
 	buf->head += (size - rew);
 	buf->misc.byte_mode.tmp_head = buf->head;

 	return 0;
 }

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

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

 	err = ring_buf_get_finish(buf, total_size);
 	__ASSERT_NO_MSG(err == 0);

 	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;
 }
	/* ring_buffer.c: Simple ring buffer API */

	/*
	* Copyright (c) 2015 Intel Corporation
	*
	* SPDX-License-Identifier: Apache-2.0
	*/

	#include <sys/ring_buffer.h>
	#include <string.h>

	/* LCOV_EXCL_START */
	/* The weak function used to allow overwriting it in the test and trigger
	* rewinding earlier.
	*/
	uint32_t __weak ring_buf_get_rewind_threshold(void)
	{
	return RING_BUFFER_MAX_SIZE;
	}
	/* LCOV_EXCL_STOP */

	/**
	* Internal data structure for a buffer header.
	*
	* We want all of this to fit in a single uint32_t. Every item stored in the
	* ring buffer will be one of these headers plus any extra data supplied
	*/
	struct ring_element {
	uint32_t type :16; /*< Application-specific /
	uint32_t length :8; /*< length in 32-bit chunks /
	uint32_t value :8; /*< Room for small integral values /
	};

	static uint32_t mod(struct ring_buf *buf, uint32_t val)
	{
	return likely(buf->mask) ? val & buf->mask : val % buf->size;
	}

	static uint32_t get_rewind_value(uint32_t buf_size, uint32_t threshold)
	{
	return buf_size * (threshold / buf_size);
	}

	int ring_buf_is_empty(struct ring_buf *buf)
	{
	uint32_t tail = buf->tail;
	uint32_t head = buf->head;

	if (tail < head) {
	tail += get_rewind_value(buf->size,
	ring_buf_get_rewind_threshold());
	}

	return (head == tail);
	}

	uint32_t ring_buf_size_get(struct ring_buf *buf)
	{
	uint32_t tail = buf->tail;
	uint32_t head = buf->head;

	if (tail < head) {
	tail += get_rewind_value(buf->size,
	ring_buf_get_rewind_threshold());
	}

	return tail - head;
	}

	uint32_t ring_buf_space_get(struct ring_buf *buf)
	{
	return buf->size - ring_buf_size_get(buf);
	}

	int ring_buf_item_put(struct ring_buf *buf, uint16_t type, uint8_t value,
	uint32_t *data, uint8_t size32)
	{
	uint32_t i, space, index, rc;
	uint32_t threshold = ring_buf_get_rewind_threshold();
	uint32_t rew;

	space = ring_buf_space_get(buf);
	if (space >= (size32 + 1)) {
	struct ring_element *header =
	(struct ring_element *)&buf->buf.buf32[mod(buf, buf->tail)];

	header->type = type;
	header->length = size32;
	header->value = value;

	if (likely(buf->mask)) {
	for (i = 0U; i < size32; ++i) {
	index = (i + buf->tail + 1) & buf->mask;
	buf->buf.buf32[index] = data[i];
	}
	} else {
	for (i = 0U; i < size32; ++i) {
	index = (i + buf->tail + 1) % buf->size;
	buf->buf.buf32[index] = data[i];
	}
	}

	/* Check if indexes shall be rewound. */
	if (buf->tail > threshold) {
	rew = get_rewind_value(buf->size, threshold);
	} else {
	rew = 0;
	}

	buf->tail = buf->tail + (size32 + 1 - rew);
	rc = 0U;
	} else {
	buf->misc.item_mode.dropped_put_count++;
	rc = -EMSGSIZE;
	}

	return rc;
	}

	int ring_buf_item_get(struct ring_buf buf, uint16_t type, uint8_t *value,
	uint32_t data, uint8_t size32)
	{
	struct ring_element *header;
	uint32_t i, index;
	uint32_t tail = buf->tail;
	uint32_t rew;

	/* Tail is always ahead, if it is not, it's only because it got rewound. */
	if (tail < buf->head) {
	/* Locally undo rewind to get tail aligned with head. */
	rew = get_rewind_value(buf->size,
	ring_buf_get_rewind_threshold());
	tail += rew;
	} else if (ring_buf_is_empty(buf)) {
	return -EAGAIN;
	} else {
	rew = 0;
	}

	header = (struct ring_element *) &buf->buf.buf32[mod(buf, buf->head)];

	if (data && (header->length > *size32)) {
	*size32 = header->length;
	return -EMSGSIZE;
	}

	*size32 = header->length;
	*type = header->type;
	*value = header->value;

	if (data) {
	if (likely(buf->mask)) {
	for (i = 0U; i < header->length; ++i) {
	index = (i + buf->head + 1) & buf->mask;
	data[i] = buf->buf.buf32[index];
	}
	} else {
	for (i = 0U; i < header->length; ++i) {
	index = (i + buf->head + 1) % buf->size;
	data[i] = buf->buf.buf32[index];
	}
	}
	}

	/* Include potential rewinding */
	buf->head = buf->head + header->length + 1 - rew;

	return 0;
	}

	/** @brief Wraps index if it exceeds the limit.
	*
	* @param val Value
	* @param max Max.
	*
	* @return value % max.
	*/
	static inline uint32_t wrap(uint32_t val, uint32_t max)
	{
	return val >= max ? (val - max) : val;
	}

	uint32_t ring_buf_put_claim(struct ring_buf buf, uint8_t *data, uint32_t size)
	{
	uint32_t space, trail_size, allocated, tmp_trail_mod;

	tmp_trail_mod = mod(buf, buf->misc.byte_mode.tmp_tail);
	space = (buf->head + buf->size) - buf->misc.byte_mode.tmp_tail;
	trail_size = buf->size - tmp_trail_mod;

	/* Limit requested size to available size. */
	size = MIN(size, space);

	trail_size = buf->size - (tmp_trail_mod);

	/* Limit allocated size to trail size. */
	allocated = MIN(trail_size, size);
	*data = &buf->buf.buf8[tmp_trail_mod];

	buf->misc.byte_mode.tmp_tail =
	buf->misc.byte_mode.tmp_tail + allocated;

	return allocated;
	}

	int ring_buf_put_finish(struct ring_buf *buf, uint32_t size)
	{
	uint32_t rew;
	uint32_t threshold = ring_buf_get_rewind_threshold();

	if ((buf->tail + size) > (buf->head + buf->size)) {
	return -EINVAL;
	}

	/* Check if indexes shall be rewind. */
	if (buf->tail > threshold) {
	rew = get_rewind_value(buf->size, threshold);
	} else {
	rew = 0;
	}

	buf->tail += (size - rew);
	buf->misc.byte_mode.tmp_tail = buf->tail;

	return 0;
	}

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

	do {
	partial_size = ring_buf_put_claim(buf, &dst, size);
	memcpy(dst, data, partial_size);
	total_size += partial_size;
	size -= partial_size;
	data += partial_size;
	} while (size && partial_size);

	err = ring_buf_put_finish(buf, total_size);
	__ASSERT_NO_MSG(err == 0);

	return total_size;
	}

	uint32_t ring_buf_get_claim(struct ring_buf buf, uint8_t *data, uint32_t size)
	{
	uint32_t space, granted_size, trail_size, tmp_head_mod;
	uint32_t tail = buf->tail;

	/* Tail is always ahead, if it is not, it's only because it got rewinded. */
	if (tail < buf->misc.byte_mode.tmp_head) {
	/* Locally, increment it to pre-rewind value */
	tail += get_rewind_value(buf->size,
	ring_buf_get_rewind_threshold());
	}

	tmp_head_mod = mod(buf, buf->misc.byte_mode.tmp_head);
	space = tail - buf->misc.byte_mode.tmp_head;
	trail_size = buf->size - tmp_head_mod;

	/* Limit requested size to available size. */
	granted_size = MIN(size, space);

	/* Limit allocated size to trail size. */
	granted_size = MIN(trail_size, granted_size);

	*data = &buf->buf.buf8[tmp_head_mod];
	buf->misc.byte_mode.tmp_head += granted_size;

	return granted_size;
	}

	int ring_buf_get_finish(struct ring_buf *buf, uint32_t size)
	{
	uint32_t tail = buf->tail;
	uint32_t rew;

	/* Tail is always ahead, if it is not, it's only because it got rewinded. */
	if (tail < buf->misc.byte_mode.tmp_head) {
	/* tail was rewinded. Locally, increment it to pre-rewind value */
	rew = get_rewind_value(buf->size,
	ring_buf_get_rewind_threshold());
	tail += rew;
	} else {
	rew = 0;
	}

	if ((buf->head + size) > tail) {
	return -EINVAL;
	}

	/* Include potential rewinding. */
	buf->head += (size - rew);
	buf->misc.byte_mode.tmp_head = buf->head;

	return 0;
	}

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

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

	err = ring_buf_get_finish(buf, total_size);
	__ASSERT_NO_MSG(err == 0);

	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;
	}