/* $Id: dqueue.c,v 1.5 2003/04/12 21:40:49 schindler Exp $
 *
 * Driver for Eicon DIVA Server ISDN cards.
 * User Mode IDI Interface
 *
 * Copyright 2000-2003 by Armin Schindler (mac@melware.de)
 * Copyright 2000-2003 Cytronics & Melware (info@melware.de)
 *
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 */

#include "platform.h"
#include "dqueue.h"

int
diva_data_q_init(diva_um_idi_data_queue_t *q,
                 int max_length, int max_segments)
{
        int i;

        q->max_length = max_length;
        q->segments = max_segments;

        for (i = 0; i < q->segments; i++) {
                q->data[i] = NULL;
                q->length[i] = 0;
        }
        q->read = q->write = q->count = q->segment_pending = 0;

        for (i = 0; i < q->segments; i++) {
                if (!(q->data[i] = diva_os_malloc(0, q->max_length))) {
                        diva_data_q_finit(q);
                        return (-1);
                }
        }

        return (0);
}

int diva_data_q_finit(diva_um_idi_data_queue_t *q)
{
        int i;

        for (i = 0; i < q->segments; i++) {
                if (q->data[i]) {
                        diva_os_free(0, q->data[i]);
                }
                q->data[i] = NULL;
                q->length[i] = 0;
        }
        q->read = q->write = q->count = q->segment_pending = 0;

        return (0);
}

int diva_data_q_get_max_length(const diva_um_idi_data_queue_t *q)
{
        return (q->max_length);
}

void *diva_data_q_get_segment4write(diva_um_idi_data_queue_t *q)
{
        if ((!q->segment_pending) && (q->count < q->segments)) {
                q->segment_pending = 1;
                return (q->data[q->write]);
        }

        return NULL;
}

void
diva_data_q_ack_segment4write(diva_um_idi_data_queue_t *q, int length)
{
        if (q->segment_pending) {
                q->length[q->write] = length;
                q->count++;
                q->write++;
                if (q->write >= q->segments) {
                        q->write = 0;
                }
                q->segment_pending = 0;
        }
}

const void *diva_data_q_get_segment4read(const diva_um_idi_data_queue_t *
                                         q)
{
        if (q->count) {
                return (q->data[q->read]);
        }
        return NULL;
}

int diva_data_q_get_segment_length(const diva_um_idi_data_queue_t *q)
{
        return (q->length[q->read]);
}

void diva_data_q_ack_segment4read(diva_um_idi_data_queue_t *q)
{
        if (q->count) {
                q->length[q->read] = 0;
                q->count--;
                q->read++;
                if (q->read >= q->segments) {
                        q->read = 0;
                }
        }
}