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struct kfifo{    uint8_t *buffer;    uint32_t in; // 输入指针    uint32_t out; // 输出指针    uint32_t size; // 缓冲区大小，必须为2的次幂}/*判断n是否为2的幂*/static bool is_power_of_2(unsigned int n){    return (n != 0 && ((n & (n - 1)) == 0));}/*将数字a向上取整为2的次幂*/static uint32_t roundup_power_of_2(uint32_t a){    if (a == 0)        return 0;    uint32_t position = 0;    for (int i = a; i != 0; i >>= 1)        position++;    return (uint32_t)(1 << position);}/*全局变量*/struct kfifo fifo;/*环形缓冲区初始化*/void fifo_init(uint32_t size){    if (!is_power_of_2(size))        size = roundup_power_of_2(_size);    fifo->buffer = (unsigned char *)(malloc(size * sizeof(unsigned char)));    fifo->in = 0;    fifo->out = 0;    fifo->size = size;}/*返回实际写入缓冲区中的数据*/uint32_t put(const uint8_t *data, uint32_t len){    unsigned int l;    /*当前缓冲区空闲空间*/    len = min(len,fifo->size - fifo->in + fifo->out);    /*当前in位置到buffer末尾的长度*/    l = min(len, fifo->size - (fifo->in  & (fifo->size - 1)));    /*首先复制数据到[in，buffer的末尾]*/    memcpy(fifo->buffer + (fifo->in & (fifo->size - 1)), data, l);    /*复制剩余的数据（如果有）到[buffer的起始位置,...]*/    memcpy(fifo->buffer, data + l, len - l);    fifo->in += len; // 直接加，不作模运算。当溢出时，从buffer的开始位置重新开始    return len;}/*返回实际读取的数据长度*/uint32_t get(uint8_t *data, uint32_t len){    unsigned int l;    /*缓冲区中的数据长度: 注意都是无符号数*/    len = min(len, fifo->in - fifo->out);    // 首先从[out,buffer end]读取数据    l = min(len, fifo->size - (fifo->out & (fifo->size - 1)));    memcpy(data, fifo->buffer + (fifo->out & (fifo->size - 1)), l);    // 从[buffer start,...]读取数据    memcpy(data + l, fifo->buffer, len - l);    fifo->out += len; // 直接加，不错模运算。溢出后，从buffer的起始位置重新开始    return len;}版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/vertor11/article/details/53741681