dqueue.c

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/* $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 ([email protected])
 * Copyright 2000-2003 Cytronics & Melware ([email protected])
 *
 * 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;
        }
    }
}