/*      $NetBSD: queue.c,v 1.5 2011/08/31 16:24:57 plunky Exp $ */

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1999 James Howard and Dag-Erling Smørgrav
 * All rights reserved.
 * Copyright (c) 2020 Kyle Evans <kevans@FreeBSD.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * A really poor man's queue.  It does only what it has to and gets out of
 * Dodge.  It is used in place of <sys/queue.h> to get a better performance.
 */

#include <sys/param.h>
#include <sys/queue.h>

#include <stdlib.h>
#include <string.h>

#include "grep.h"

typedef struct str              qentry_t;

static long long                filled;
static qentry_t                 *qend, *qpool;

/*
 * qnext is the next entry to populate.  qlist is where the list actually
 * starts, for the purposes of printing.
 */
static qentry_t         *qlist, *qnext;

void
initqueue(void)
{

        qlist = qnext = qpool = grep_calloc(Bflag, sizeof(*qpool));
        qend = qpool + (Bflag - 1);
}

static qentry_t *
advqueue(qentry_t *itemp)
{

        if (itemp == qend)
                return (qpool);
        return (itemp + 1);
}

/*
 * Enqueue another line; return true if we've dequeued a line as a result
 */
bool
enqueue(struct str *x)
{
        qentry_t *item;
        bool rotated;

        item = qnext;
        qnext = advqueue(qnext);
        rotated = false;

        if (filled < Bflag) {
                filled++;
        } else if (filled == Bflag) {
                /* We had already filled up coming in; just rotate. */
                qlist = advqueue(qlist);
                rotated = true;
                free(item->dat);
        }
        /* len + 1 for NUL-terminator */
        item->dat = grep_malloc(sizeof(char) * x->len + 1);
        item->len = x->len;
        item->line_no = x->line_no;
        item->boff = x->boff;
        item->off = x->off;
        memcpy(item->dat, x->dat, x->len);
        item->dat[x->len] = '\0';
        item->file = x->file;

        return (rotated);
}

void
printqueue(void)
{
        qentry_t *item;

        item = qlist;
        do {
                /* Buffer must have ended early. */
                if (item->dat == NULL)
                        break;

                grep_printline(item, '-');
                free(item->dat);
                item->dat = NULL;
                item = advqueue(item);
        } while (item != qlist);

        qlist = qnext = qpool;
        filled = 0;
}

void
clearqueue(void)
{
        qentry_t *item;

        item = qlist;
        do {
                free(item->dat);
                item->dat = NULL;
                item = advqueue(item);
        } while (item != qlist);

        qlist = qnext = qpool;
        filled = 0;
}