bossay_release_out/iot_link/link_misc/link_ring_buffer.c

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/**
 *  DATE                AUTHOR      INSTRUCTION
 *  2019-04-29 10:34  zhangqianfu  The first version  
 *
 */
#include <stdint.h>
#include <stddef.h>
#include <string.h>

#include <link_misc.h>


int ring_buffer_init(tag_ring_buffer_t *ring,unsigned char *buf, int buflen,int offset,int datalen)
{
    int ret = -1;
    if((NULL == ring))
    {
        return ret;
    }
    ring->buf     = buf;
    ring->buflen  = buflen;
    ring->datalen = datalen;
    ring->dataoff = offset;
    ret = 0;
    return ret;
}


int ring_buffer_write(tag_ring_buffer_t *ring,unsigned char *buf, int len)
{
    int ret = -1;
    int cpylen;  //the current time we should move
    int lenleft;  //and how many data still left to move
    int offset;
    unsigned char *src;
    unsigned char *dst;
    if((NULL == ring)||(NULL == buf)||(0 == len))
    {
        return ret;//which means parameters error
    }
    if((ring->datalen == ring->buflen)|| (ring->buflen <= 0))
    {
        ret = 0;
        return  ret;//which means you could copy nothing here
    }
    ret = len > (ring->buflen-ring->datalen)?(ring->buflen-ring->datalen):len;
    //now let us think the method to fill the data,take care of the roll back
    lenleft = ret;
    src = buf;
    if((ring->dataoff+ring->datalen)>ring->buflen) //which means the data has roll back
    {
        offset = (ring->dataoff+ring->datalen)%ring->buflen; //we could move it one time
        cpylen = lenleft;
        dst = ring->buf + offset;
        if(cpylen > 0)
        {
            (void) memcpy(dst,src,cpylen);
            ring->datalen += cpylen;
            lenleft -= cpylen;
        }
    }
    else if((ring->dataoff+ring->datalen + lenleft)>ring->buflen) //which means the data will be roll back
    {
        //which means roll back,we should copy some here to the tail
        offset = ring->dataoff + ring->datalen;
        cpylen = ring->buflen - offset;
        dst = ring->buf + offset;
        (void) memcpy(dst,src,cpylen);
        src += cpylen;
        ring->datalen += cpylen;
        lenleft -= cpylen;
    }
    //here means we could move it by one time
    if(lenleft > 0)
    {
        offset = (ring->dataoff+ring->datalen)%ring->buflen; //we could move it one time
        cpylen = lenleft;
        dst = ring->buf + offset;
        (void) memcpy(dst,src,cpylen);
        ring->datalen += cpylen;
    }
    return ret;
}


int ring_buffer_read(tag_ring_buffer_t *ring,unsigned char *buf, int len)
{
    int ret = -1;
    int cpylen;  //the current time we should move
    int lenleft;  //and how many data still left to move
    int offset;
    unsigned char *src;
    unsigned char *dst;
    if((NULL == ring)||(NULL == buf)||(0 == len))
    {
        return ret;//which means parameters error
    }
    if((ring->datalen == 0) || (ring->buflen <= 0))
    {
        ret = 0;
        return  ret;//which means you could copy nothing here
    }
    ret = len > ring->datalen?ring->datalen:len;
    //now let us think the method to fill the data,take care of the roll back
    lenleft = ret;
    dst = buf;
    if(ring->dataoff >= (ring->buflen - lenleft)) //which means the data has roll back
    {
        offset =ring->dataoff; //we cpy part
        cpylen = ring->buflen - ring->dataoff;
        src = ring->buf + offset;

        if(cpylen > 0)
        {
            (void) memcpy(dst,src,cpylen);
            ring->dataoff = (ring->dataoff + cpylen)%ring->buflen;
            ring->datalen -= cpylen;
            lenleft -= cpylen;
            dst += cpylen;
        }
    }
    //here means we could move it by one time
    if(lenleft > 0)
    {
        offset =ring->dataoff; //we cpy part
        cpylen = lenleft;
        src = ring->buf + offset;
        (void) memcpy(dst,src,cpylen);
        ring->dataoff = ring->dataoff + cpylen;
        ring->datalen -= cpylen;
    }
    return ret;
}


int ring_buffer_datalen(tag_ring_buffer_t *ring)
{
    int ret = -1;
    if(NULL != ring)
    {
        ret = ring->datalen;
    }
    return ret;
}

int ring_buffer_freespace(tag_ring_buffer_t *ring)
{
    int ret = -1;
    if(NULL != ring)
    {
        ret = ring->buflen-ring->datalen;
    }
    return ret;
}

int ring_buffer_reset(tag_ring_buffer_t *ring)
{
    int ret = -1;
    if(NULL != ring)
    {
        ring->datalen = 0;
        ring->dataoff = 0;
        ret = 0;
    }
    return ret;
}

int ring_buffer_deinit(tag_ring_buffer_t *ring)
{
    int ret = -1;
    if(NULL != ring)
    {
        (void) memset(ring,0,sizeof(tag_ring_buffer_t));
        ret = 0;
    }
    return ret;
}