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/*
* Copyright (c) 2006-2021, RT-Thread Development Team
*
* SPDX-License-Identifier: Apache-2.0
*
* Change Logs:
* Date Author Notes
* 2021-08-14 Jackistang add comments for function interface.
*/
#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_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);
#ifdef RT_USING_HEAP
struct rt_ringbuffer* rt_ringbuffer_create(rt_uint16_t length);
void rt_ringbuffer_destroy(struct rt_ringbuffer *rb);
#endif
/**
* @brief Get the buffer size of the ring buffer object.
*
* @param rb A pointer to the ring buffer object.
*
* @return Buffer size.
*/
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
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