ringbuf.c

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/**
* \file
*       Ring Buffer library
*/

#include "ringbuf.h"


/**
* \brief init a RINGBUF object
* \param r pointer to a RINGBUF object
* \param buf pointer to a byte array
* \param size size of buf
* \return 0 if successfull, otherwise failed
*/
I16 ICACHE_FLASH_ATTR RINGBUF_Init(RINGBUF *r, U8* buf, I32 size)
{
    if(r == NULL || buf == NULL || size < 2) return -1;
    
    r->p_o = r->p_r = r->p_w = buf;
    r->fill_cnt = 0;
    r->size = size;
    
    return 0;
}
/**
* \brief put a character into ring buffer
* \param r pointer to a ringbuf object
* \param c character to be put
* \return 0 if successfull, otherwise failed
*/
I16 ICACHE_FLASH_ATTR RINGBUF_Put(RINGBUF *r, U8 c)
{
    if(r->fill_cnt>=r->size)return -1;      // ring buffer is full, this should be atomic operation
    

    r->fill_cnt++;                          // increase filled slots count, this should be atomic operation

    
    *r->p_w++ = c;                          // put character into buffer
    
    if(r->p_w >= r->p_o + r->size)          // rollback if write pointer go pass
        r->p_w = r->p_o;                    // the physical boundary
    
    return 0;
}
/**
* \brief get a character from ring buffer
* \param r pointer to a ringbuf object
* \param c read character
* \return 0 if successfull, otherwise failed
*/
I16 ICACHE_FLASH_ATTR RINGBUF_Get(RINGBUF *r, U8* c)
{
    if(r->fill_cnt<=0)return -1;                // ring buffer is empty, this should be atomic operation
    

    r->fill_cnt--;                              // decrease filled slots count

    
    *c = *r->p_r++;                             // get the character out
    
    if(r->p_r >= r->p_o + r->size)              // rollback if write pointer go pass
        r->p_r = r->p_o;                        // the physical boundary
    
    return 0;
}