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/* ring_buffer.h: Simple ring buffer API */
/*
* Copyright (c) 2015 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
/** @file */
#ifndef ZEPHYR_INCLUDE_SYS_RING_BUFFER_H_
#define ZEPHYR_INCLUDE_SYS_RING_BUFFER_H_
#include <kernel.h>
#include <sys/util.h>
#include <errno.h>
#include <string.h>
#ifdef __cplusplus
extern "C" {
#endif
#define SIZE32_OF(x) (sizeof((x))/sizeof(u32_t))
/**
* @brief A structure to represent a ring buffer
*/
struct ring_buf {
u32_t head; /**< Index in buf for the head element */
u32_t tail; /**< Index in buf for the tail element */
union ring_buf_misc {
struct ring_buf_misc_item_mode {
u32_t dropped_put_count; /**< Running tally of the
* number of failed put
* attempts.
*/
} item_mode;
struct ring_buf_misc_byte_mode {
u32_t tmp_tail;
u32_t tmp_head;
} byte_mode;
} misc;
u32_t size; /**< Size of buf in 32-bit chunks */
union ring_buf_buffer {
u32_t *buf32; /**< Memory region for stored entries */
u8_t *buf8;
} buf;
u32_t mask; /**< Modulo mask if size is a power of 2 */
};
/**
* @defgroup ring_buffer_apis Ring Buffer APIs
* @ingroup kernel_apis
* @{
*/
/**
* @brief Statically define and initialize a high performance ring buffer.
*
* This macro establishes a ring buffer whose size must be a power of 2;
* that is, the ring buffer contains 2^pow 32-bit words, where @a pow is
* the specified ring buffer size exponent. A high performance ring buffer
* doesn't require the use of modulo arithmetic operations to maintain itself.
*
* The ring buffer can be accessed outside the module where it is defined
* using:
*
* @code extern struct ring_buf <name>; @endcode
*
* @param name Name of the ring buffer.
* @param pow Ring buffer size exponent.
*/
#define RING_BUF_ITEM_DECLARE_POW2(name, pow) \
static u32_t _ring_buffer_data_##name[BIT(pow)]; \
struct ring_buf name = { \
.size = (BIT(pow)), \
.mask = (BIT(pow)) - 1, \
.buf = { .buf32 = _ring_buffer_data_##name } \
}
/** @deprecated Renamed to RING_BUF_ITEM_DECLARE_POW2. */
#define SYS_RING_BUF_DECLARE_POW2(name, pow) \
__DEPRECATED_MACRO RING_BUF_ITEM_DECLARE_POW2(name, pow)
/**
* @brief Statically define and initialize a standard ring buffer.
*
* This macro establishes a ring buffer of an arbitrary size. A standard
* ring buffer uses modulo arithmetic operations to maintain itself.
*
* The ring buffer can be accessed outside the module where it is defined
* using:
*
* @code extern struct ring_buf <name>; @endcode
*
* @param name Name of the ring buffer.
* @param size32 Size of ring buffer (in 32-bit words).
*/
#define RING_BUF_ITEM_DECLARE_SIZE(name, size32) \
static u32_t _ring_buffer_data_##name[size32]; \
struct ring_buf name = { \
.size = size32, \
.buf = { .buf32 = _ring_buffer_data_##name} \
}
/** @deprecated Renamed to RING_BUF_ITEM_DECLARE_SIZE. */
#define SYS_RING_BUF_DECLARE_SIZE(name, size32) \
__DEPRECATED_MACRO RING_BUF_ITEM_DECLARE_SIZE(name, size32)
/**
* @brief Statically define and initialize a ring buffer for byte data.
*
* This macro establishes a ring buffer of an arbitrary size.
*
* The ring buffer can be accessed outside the module where it is defined
* using:
*
* @code extern struct ring_buf <name>; @endcode
*
* @param name Name of the ring buffer.
* @param size8 Size of ring buffer (in bytes).
*/
#define RING_BUF_DECLARE(name, size8) \
static u8_t _ring_buffer_data_##name[size8]; \
struct ring_buf name = { \
.size = size8, \
.buf = { .buf8 = _ring_buffer_data_##name} \
}
/**
* @brief Initialize a ring buffer.
*
* This routine initializes a ring buffer, prior to its first use. It is only
* used for ring buffers not defined using RING_BUF_DECLARE,
* RING_BUF_ITEM_DECLARE_POW2 or RING_BUF_ITEM_DECLARE_SIZE.
*
* Setting @a size to a power of 2 establishes a high performance ring buffer
* that doesn't require the use of modulo arithmetic operations to maintain
* itself.
*
* @param buf Address of ring buffer.
* @param size Ring buffer size (in 32-bit words or bytes).
* @param data Ring buffer data area (u32_t data[size] or u8_t data[size] for
* bytes mode).
*/
static inline void ring_buf_init(struct ring_buf *buf, u32_t size, void *data)
{
memset(buf, 0, sizeof(struct ring_buf));
buf->size = size;
buf->buf.buf32 = (u32_t *)data;
if (is_power_of_two(size)) {
buf->mask = size - 1;
} else {
buf->mask = 0U;
}
}
/** @brief Determine free space based on ring buffer parameters.
*
* @note Function for internal use.
*
* @param size Ring buffer size.
* @param head Ring buffer head.
* @param tail Ring buffer tail.
*
* @return Ring buffer free space (in 32-bit words or bytes).
*/
static inline u32_t z_ring_buf_custom_space_get(u32_t size, u32_t head,
u32_t tail)
{
if (tail < head) {
return head - tail - 1;
}
/* buf->tail > buf->head */
return (size - tail) + head - 1;
}
/**
* @brief Determine if a ring buffer is empty.
*
* @param buf Address of ring buffer.
*
* @return 1 if the ring buffer is empty, or 0 if not.
*/
static inline int ring_buf_is_empty(struct ring_buf *buf)
{
return (buf->head == buf->tail);
}
/**
* @brief Reset ring buffer state.
*
* @param buf Address of ring buffer.
*/
static inline void ring_buf_reset(struct ring_buf *buf)
{
buf->head = 0;
buf->tail = 0;
memset(&buf->misc, 0, sizeof(buf->misc));
}
/**
* @brief Determine free space in a ring buffer.
*
* @param buf Address of ring buffer.
*
* @return Ring buffer free space (in 32-bit words or bytes).
*/
static inline u32_t ring_buf_space_get(struct ring_buf *buf)
{
return z_ring_buf_custom_space_get(buf->size, buf->head, buf->tail);
}
/**
* @brief Return ring buffer capacity.
*
* @param buf Address of ring buffer.
*
* @return Ring buffer capacity (in 32-bit words or bytes).
*/
static inline u32_t ring_buf_capacity_get(struct ring_buf *buf)
{
/* One element is used to distinguish between empty and full state. */
return buf->size - 1;
}
/**
* @brief Write a data item to a ring buffer.
*
* This routine writes a data item to ring buffer @a buf. The data item
* is an array of 32-bit words (from zero to 1020 bytes in length),
* coupled with a 16-bit type identifier and an 8-bit integer value.
*
* @warning
* Use cases involving multiple writers to the ring buffer must prevent
* concurrent write operations, either by preventing all writers from
* being preempted or by using a mutex to govern writes to the ring buffer.
*
* @param buf Address of ring buffer.
* @param type Data item's type identifier (application specific).
* @param value Data item's integer value (application specific).
* @param data Address of data item.
* @param size32 Data item size (number of 32-bit words).
*
* @retval 0 Data item was written.
* @retval -EMSGSIZE Ring buffer has insufficient free space.
*/
int ring_buf_item_put(struct ring_buf *buf, u16_t type, u8_t value,
u32_t *data, u8_t size32);
/**
* @brief Read a data item from a ring buffer.
*
* This routine reads a data item from ring buffer @a buf. The data item
* is an array of 32-bit words (up to 1020 bytes in length),
* coupled with a 16-bit type identifier and an 8-bit integer value.
*
* @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.
*
* @param buf Address of ring buffer.
* @param type Area to store the data item's type identifier.
* @param value Area to store the data item's integer value.
* @param data Area to store the data item.
* @param size32 Size of the data item storage area (number of 32-bit chunks).
*
* @retval 0 Data item was fetched; @a size32 now contains the number of
* 32-bit words read into data area @a data.
* @retval -EAGAIN Ring buffer is empty.
* @retval -EMSGSIZE Data area @a data is too small; @a size32 now contains
* the number of 32-bit words needed.
*/
int ring_buf_item_get(struct ring_buf *buf, u16_t *type, u8_t *value,
u32_t *data, u8_t *size32);
/**
* @brief Allocate buffer for writing data to a ring buffer.
*
* With this routine, memory copying can be reduced since internal ring buffer
* can be used directly by the user. Once data is written to allocated area
* number of bytes written can be confirmed (see @ref ring_buf_put_finish).
*
* @warning
* Use cases involving multiple writers to the ring buffer must prevent
* concurrent write operations, either by preventing all writers from
* being preempted or by using a mutex to govern writes to the ring buffer.
*
* @warning
* Ring buffer instance should not mix byte access and item access
* (calls prefixed with ring_buf_item_).
*
* @param[in] buf Address of ring buffer.
* @param[out] data Pointer to the address. It is set to a location within
* ring buffer.
* @param[in] size Requested allocation size (in bytes).
*
* @return Size of allocated buffer which can be smaller than requested if
* there is not enough free space or buffer wraps.
*/
u32_t ring_buf_put_claim(struct ring_buf *buf, u8_t **data, u32_t size);
/**
* @brief Indicate number of bytes written to allocated buffers.
*
* @warning
* Use cases involving multiple writers to the ring buffer must prevent
* concurrent write operations, either by preventing all writers from
* being preempted or by using a mutex to govern writes to the ring buffer.
*
* @warning
* Ring buffer instance should not mix byte access and item access
* (calls prefixed with ring_buf_item_).
*
* @param buf Address of ring buffer.
* @param size Number of valid bytes in the allocated buffers.
*
* @retval 0 Successful operation.
* @retval -EINVAL Provided @a size exceeds free space in the ring buffer.
*/
int ring_buf_put_finish(struct ring_buf *buf, u32_t size);
/**
* @brief Write (copy) data to a ring buffer.
*
* This routine writes data to a ring buffer @a buf.
*
* @warning
* Use cases involving multiple writers to the ring buffer must prevent
* concurrent write operations, either by preventing all writers from
* being preempted or by using a mutex to govern writes to the ring buffer.
*
* @warning
* Ring buffer instance should not mix byte access and item access
* (calls prefixed with ring_buf_item_).
*
* @param buf Address of ring buffer.
* @param data Address of data.
* @param size Data size (in bytes).
*
* @retval Number of bytes written.
*/
u32_t ring_buf_put(struct ring_buf *buf, const u8_t *data, u32_t size);
/**
* @brief Get address of a valid data in a ring buffer.
*
* With this routine, memory copying can be reduced since internal ring buffer
* can be used directly by the user. Once data is processed it can be freed
* using @ref ring_buf_get_finish.
*
* @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 access
* (calls prefixed with ring_buf_item_).
*
* @param[in] buf Address of ring buffer.
* @param[out] data Pointer to the address. It is set to a location within
* ring buffer.
* @param[in] size Requested size (in bytes).
*
* @return Number of valid bytes in the provided buffer which can be smaller
* than requested if there is not enough free space or buffer wraps.
*/
u32_t ring_buf_get_claim(struct ring_buf *buf, u8_t **data, u32_t size);
/**
* @brief Indicate number of bytes read from claimed buffer.
*
* @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_).
*
* @param buf Address of ring buffer.
* @param size Number of bytes that can be freed.
*
* @retval 0 Successful operation.
* @retval -EINVAL Provided @a size exceeds valid bytes in the ring buffer.
*/
int ring_buf_get_finish(struct ring_buf *buf, u32_t size);
/**
* @brief Read data from a ring buffer.
*
* This routine reads data from a ring buffer @a buf.
*
* @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_).
*
* @param buf Address of ring buffer.
* @param data Address of the output buffer.
* @param size Data size (in bytes).
*
* @retval Number of bytes written to the output buffer.
*/
u32_t ring_buf_get(struct ring_buf *buf, u8_t *data, u32_t size);
/**
* @}
*/
#ifdef __cplusplus
}
#endif
#endif /* ZEPHYR_INCLUDE_SYS_RING_BUFFER_H_ */