source: rtos_arduino/trunk/arduino_lib/libraries/Ciao/src/lib/ringbuf.c@ 175

/**
* \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
*/
int16_t RINGBUF_Init(RINGBUF *r, uint8_t* buf, int32_t 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
*/
int16_t RINGBUF_Put(RINGBUF *r, uint8_t 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
*/
int16_t RINGBUF_Get(RINGBUF *r, uint8_t* 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;
}