// can handle one buffer for a start.
// later make it reentrant and manage multiple buffers!
// todo: syncing access to buffer.

#define FOOLOS_MODULE_NAME "ringbuffer"
#include "lib/bool/bool.h"
#include "lib/logger/log.h"

static volatile int front;
static volatile int back;
static volatile int size;

#define RINGBUFFER_SIZE 10
static volatile char buf[RINGBUFFER_SIZE];

bool ringbuffer_selftest();

void ringbuffer_init()
{
    size=RINGBUFFER_SIZE;
    front=size-1;
    back=size-1;

//    ringbuffer_selftest();
//    while(1);
}

bool ringbuffer_put(char c)
{
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"put wants lock)");
    lock_spin(3);
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"locked by put)");
    if((back-1+size)%size==front)
    {
	lock_release(3);
	log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"unlocked by put)");
	return false;
    }
    buf[back]=c;
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"put %d %d (%c)", back, front,c);
    back--;
    back+=size;
    back%=size;
    lock_release(3);
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"unlocked by put)");
    
    return true;
}

bool ringbuffer_get(char *c)
{


    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"get wants lock)");
    lock_spin(3);
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"locked by get)");
    if(front==back)
    {
	lock_release(3);
	log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"unlocked by get)");
	return false;
    }

    *c=buf[front];
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"get %d %d (%c)", back, front,*c);

    front--;
    front+=size;
    front%=size;

    lock_release(3);
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"unlocked by get)");

    return true;
}

bool ringbuffer_selftest()
{
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"ringbuffer selftest");
    char c;

    ringbuffer_put('a');
    ringbuffer_put('b');
    ringbuffer_put('c');
    ringbuffer_put('d');
    ringbuffer_put('e');

    ringbuffer_get(&c);
    ringbuffer_get(&c);
    ringbuffer_get(&c);
    ringbuffer_get(&c);
    ringbuffer_get(&c);
    ringbuffer_get(&c);
    ringbuffer_get(&c);

}