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什么是ring buffer？

news 2026/3/26 17:22:25

1、什么是ring buffer？

环形缓冲区（ring buffer），是一种基于数组的循环队列。其特点是首尾相连，形成一个环状结构。

ring buffer包含两个主要的指针（head、tail）：

head指针：指向队列的第一个有效数据的位置。
tail指针：指向队列的下一个可写入的位置。（当tail指针到达数组的末尾时，它会绕到数组的开头继续写入，从而形成一个环形）

2、代码实现（C语言）

（缺点：下述代码，未实现overwrite，即当缓存区满时，覆盖旧数据）

#include <stdlib.h>
#include <stdbool.h>
#include <stdint.h>typedef struct {uint8_t *buffer;size_t head;size_t tail;size_t size;bool full;
} ringbuffer_t;/*** Initialize&&Free ringbuffer*/
void ringbuffer_init(ringbuffer_t *rb, size_t size){if(rb == NULL || size == 0){return;}rb->buffer = (uint8_t *)malloc(size);if(rb->buffer == NULL){// malloc errorreturn;}rb->head = 0;rb->tail = 0;rb->size = size;rb->full = false;
}void ringbuffer_free(ringbuffer_t *rb){free(rb->buffer);
}/*** Get ringbuffer status*/
bool ringbuffer_is_full(const ringbuffer_t *rb){return rb->full;
}bool ringbuffer_is_empty(const ringbuffer_t *rb){return (!rb->full&&(rb->head == rb->tail));
}size_t ringbuffer_available_data(const ringbuffer_t *rb){if(rb->full){return rb->size;}return (rb->head >= rb->tail) ? (rb->head-rb->tail) : (rb->size-rb->tail+rb->head);
}size_t ringbuffer_available_space(const ringbuffer_t *rb){return rb->size - ringbuffer_available_data(rb);
}/*** Write&&Read ringbuffer*/
void ringbuffer_write(ringbuffer_t *rb, const uint8_t *data, size_t len){if(len > ringbuffer_available_space(rb)) {return;}for(size_t i=0; i<len; i++) {rb->buffer[rb->head] = data[i];rb->head = (rb->head+1) % rb->size;}if(rb->head == rb->tail) {rb->full = true;}
}void ringbuffer_read(ringbuffer_t *rb, uint8_t *data, size_t len){if(len > ringbuffer_available_data(rb)) {return;}for(size_t i=0; i<len; i++) {data[i] = rb->buffer[rb->tail];rb->tail = (rb->tail+1) % rb->size;}rb->full = false;
}

3、测试代码（C语言）

#include <stdio.h>
#include "ringbuffer.c"int main() {ringbuffer_t buffer;ringbuffer_init(&buffer, 10);printf("Available space: %zu\n", ringbuffer_available_space(&buffer));printf("Available data: %zu\n", ringbuffer_available_data(&buffer));//writeuint8_t write_data[] = {1, 2, 3, 4, 5};printf("\nWriting data: ");for(int i = 0; i < 5; i++) {printf("%d ", write_data[i]);}printf("\n");ringbuffer_write(&buffer, write_data, 5);printf("After writing - Available data: %zu, Available space: %zu\n", ringbuffer_available_data(&buffer), ringbuffer_available_space(&buffer));//readuint8_t read_data[5];
    ringbuffer__read(&buffer, read_data, 3);
printf("Read 3 bytes: ");for(int i = 0; i < 3; i++) {printf("%d ", read_data[i]);}printf("\n");

    printf("Final - Available data: %zu, Available space: %zu\n", ringbuffer_available_data(&buffer), ringbuffer_available_space(&buffer));ringbuffer_free(&buffer);return 0;
}

~/workspace$ gcc -o test main.c 
~/workspace$ ./test 
Available space: 10
Available data: 0Writing data: 1 2 3 4 5 
After writing - Available data: 5, Available space: 5
Read 3 bytes: 1 2 3 
Final - Available data: 2, Available space: 8