firmware/libcommon/source/ringbuffer.c

/* Ring buffer
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307, USA
 */
#include "ringbuffer.h"
#include "trace.h"
#include "utils.h"

/* WARNING: Since console output is internally using this ringbuffer to implement
 * buffered writes, we cannot use any TRACE_*() or printf() style functions here,
 * as it would create infinite recursion! */

void rbuf_reset(volatile ringbuf * rb)
{
	unsigned long state;

	local_irq_save(state);
	rb->ird = 0;
	rb->iwr = 0;
	local_irq_restore(state);
}

uint8_t rbuf_read(volatile ringbuf * rb)
{
	unsigned long state;
	uint8_t val;

	local_irq_save(state);
	val = rb->buf[rb->ird];
	rb->ird = (rb->ird + 1) % RING_BUFLEN;
	local_irq_restore(state);

	return val;
}

uint8_t rbuf_peek(volatile ringbuf * rb)
{
	return rb->buf[rb->ird];
}

bool rbuf_is_empty(volatile ringbuf * rb)
{
	return rb->ird == rb->iwr;
}

static bool __rbuf_is_full(volatile ringbuf * rb)
{
	return rb->ird == (rb->iwr + 1) % RING_BUFLEN;
}

bool rbuf_is_full(volatile ringbuf * rb)
{
	unsigned long state;
	bool rc;

	local_irq_save(state);
	rc = rb->ird == (rb->iwr + 1) % RING_BUFLEN;
	local_irq_restore(state);

	return rc;
}

int rbuf_write(volatile ringbuf * rb, uint8_t item)
{
	unsigned long state;

	local_irq_save(state);
	if (!__rbuf_is_full(rb)) {
		rb->buf[rb->iwr] = item;
		rb->iwr = (rb->iwr + 1) % RING_BUFLEN;
		local_irq_restore(state);
		return 0;
	} else {
		local_irq_restore(state);
		return -1;
	}
}