// 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 "ringbuffer.h"
#include "kernel/x86.h"
#include "lib/logger/log.h"
#include "kernel/spinlock.h"

#define RINGBUFFER_SIZE 10
static int size=RINGBUFFER_SIZE;
static volatile int front=RINGBUFFER_SIZE-1;
static volatile int back=RINGBUFFER_SIZE-1;
static volatile char buf[RINGBUFFER_SIZE];

static spinlock sl=9;

bool ringbuffer_put(char c)
{

    x86_int_disable();
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"put wants lock");
    lock_spin(sl);
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"locked by put");

    if((back-1+size)%size==front)
    {
	lock_release(sl);
	log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"unlocked by put");
	x86_int_enable();
	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(sl);
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"unlocked by put");
    x86_int_enable();
    
    return true;
}

bool ringbuffer_get(char *c)
{
    x86_int_disable();
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"get wants lock");
    lock_spin(sl);
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"locked by get");
    if(front==back)
    {
	lock_release(sl);
	log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"unlocked by get");
	x86_int_enable();
	*c='_';
	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(sl);
    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_FINE,"unlocked by get");
    x86_int_enable();

    return true;
}