static uint8_t readBuffer(void){
    uint8_t ret;    
    if(buff_empty){
        return 0;
    }
    ret=buffer[buff_end];
    buff_end++;
    if(buff_end==BUFFER_SIZE){
        buff_end=0;
    }
    if(buff_end==buff_start){
        buff_empty=1;
    }
    return ret;
}

static uint8_t writeToBuffer(uint8_t data){
    if(buff_start==buff_end && !buff_empty){
        /*overrun*/
		printk("<1>%s: Buffer overrun!\n",MOD_NAME);
		return 1;
    }
    buffer[buff_start]=data;
    buff_start++;
    if(buff_start==BUFFER_SIZE){
        buff_start=0;
    }
    buff_empty=0;
	return 0;
}

static ssize_t device_read(struct file *filp, char __user *buffer, size_t length, loff_t *offset){
	uint8_t val;
	if(!buff_empty){
		val = readBuffer();
		DEBUG_OUT("<1>%s: device_read invoked writing: mem[%x]=%02x\n",MOD_NAME,buffer,val);
		if( copy_to_user(buffer,&val,1)<0 ){
			printk("<1>%s: Device read error!\n",MOD_NAME);
			return 0;
		}
		return 1;
	}
	return 0;
}

static ssize_t device_write(struct file *filp, const char __user *buff, size_t len, loff_t *off){
	int ret;	
	DEBUG_OUT("<1>%s: device_write invoked\n",MOD_NAME);
	if(len!=1){
		return -EINVAL;
	}
	ret = copy_from_user(pin_status, buff, len);
	if( ret<0 ){
		printk("<1>%s: Device write error!\n",MOD_NAME);
		return 0;
	}
	up(&read_sema);
	return len;
}

struct file_operations fops = {
	read: device_read,
	write: device_write,
};