106 lines
3.6 KiB
C
106 lines
3.6 KiB
C
/*
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* Copyright (c) 2006-2021, RT-Thread Development Team
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Change Logs:
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* Date Author Notes
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* 2021-08-14 Jackistang add comments for function interface.
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*/
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#ifndef RINGBUFFER_H__
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#define RINGBUFFER_H__
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <rtthread.h>
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/* ring buffer */
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struct rt_ringbuffer
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{
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rt_uint8_t *buffer_ptr;
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/* use the msb of the {read,write}_index as mirror bit. You can see this as
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* if the buffer adds a virtual mirror and the pointers point either to the
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* normal or to the mirrored buffer. If the write_index has the same value
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* with the read_index, but in a different mirror, the buffer is full.
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* While if the write_index and the read_index are the same and within the
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* same mirror, the buffer is empty. The ASCII art of the ringbuffer is:
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*
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* mirror = 0 mirror = 1
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* +---+---+---+---+---+---+---+|+~~~+~~~+~~~+~~~+~~~+~~~+~~~+
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* | 0 | 1 | 2 | 3 | 4 | 5 | 6 ||| 0 | 1 | 2 | 3 | 4 | 5 | 6 | Full
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* +---+---+---+---+---+---+---+|+~~~+~~~+~~~+~~~+~~~+~~~+~~~+
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* read_idx-^ write_idx-^
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*
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* +---+---+---+---+---+---+---+|+~~~+~~~+~~~+~~~+~~~+~~~+~~~+
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* | 0 | 1 | 2 | 3 | 4 | 5 | 6 ||| 0 | 1 | 2 | 3 | 4 | 5 | 6 | Empty
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* +---+---+---+---+---+---+---+|+~~~+~~~+~~~+~~~+~~~+~~~+~~~+
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* read_idx-^ ^-write_idx
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*
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* The tradeoff is we could only use 32KiB of buffer for 16 bit of index.
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* But it should be enough for most of the cases.
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*
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* Ref: http://en.wikipedia.org/wiki/Circular_buffer#Mirroring */
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rt_uint16_t read_mirror : 1;
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rt_uint16_t read_index : 15;
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rt_uint16_t write_mirror : 1;
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rt_uint16_t write_index : 15;
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/* as we use msb of index as mirror bit, the size should be signed and
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* could only be positive. */
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rt_int16_t buffer_size;
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};
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enum rt_ringbuffer_state
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{
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RT_RINGBUFFER_EMPTY,
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RT_RINGBUFFER_FULL,
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/* half full is neither full nor empty */
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RT_RINGBUFFER_HALFFULL,
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};
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/**
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* RingBuffer for DeviceDriver
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*
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* Please note that the ring buffer implementation of RT-Thread
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* has no thread wait or resume feature.
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*/
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void rt_ringbuffer_init(struct rt_ringbuffer *rb, rt_uint8_t *pool, rt_int16_t size);
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void rt_ringbuffer_reset(struct rt_ringbuffer *rb);
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rt_size_t rt_ringbuffer_put(struct rt_ringbuffer *rb, const rt_uint8_t *ptr, rt_uint16_t length);
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rt_size_t rt_ringbuffer_put_force(struct rt_ringbuffer *rb, const rt_uint8_t *ptr, rt_uint16_t length);
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rt_size_t rt_ringbuffer_putchar(struct rt_ringbuffer *rb, const rt_uint8_t ch);
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rt_size_t rt_ringbuffer_putchar_force(struct rt_ringbuffer *rb, const rt_uint8_t ch);
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rt_size_t rt_ringbuffer_get(struct rt_ringbuffer *rb, rt_uint8_t *ptr, rt_uint16_t length);
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rt_size_t rt_ringbuffer_peek(struct rt_ringbuffer *rb, rt_uint8_t **ptr);
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rt_size_t rt_ringbuffer_getchar(struct rt_ringbuffer *rb, rt_uint8_t *ch);
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rt_size_t rt_ringbuffer_data_len(struct rt_ringbuffer *rb);
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#ifdef RT_USING_HEAP
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struct rt_ringbuffer* rt_ringbuffer_create(rt_uint16_t length);
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void rt_ringbuffer_destroy(struct rt_ringbuffer *rb);
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#endif
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/**
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* @brief Get the buffer size of the ring buffer object.
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*
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* @param rb A pointer to the ring buffer object.
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*
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* @return Buffer size.
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*/
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rt_inline rt_uint16_t rt_ringbuffer_get_size(struct rt_ringbuffer *rb)
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{
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RT_ASSERT(rb != RT_NULL);
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return rb->buffer_size;
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}
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/** return the size of empty space in rb */
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#define rt_ringbuffer_space_len(rb) ((rb)->buffer_size - (rt_int16_t)rt_ringbuffer_data_len(rb))
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#ifdef __cplusplus
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}
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#endif
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#endif
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