buf.c

一款类linux的操作系统源码

/* 
 *  Roadrunner/pk
 *    Copyright (C) 1989-2001  Cornfed Systems, Inc.
 *
 *  The Roadrunner/pk operating system is free software; you can
 *  redistribute and/or modify it under the terms of the GNU General
 *  Public License, version 2, as published by the Free Software
 *  Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT 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
 *
 *  More information about the Roadrunner/pk operating system of
 *  which this file is a part is available on the World-Wide Web
 *  at: http://www.cornfed.com.
 *
 */

#include <errno.h>
#include <event.h>
#include <stdlib.h>
#include <string.h>
#include <sys/buf.h>
#include <sys/intr.h>
#include <sys/mem.h>

struct bufpool bufpool;

void
bufpool_init(int nbufs)
{
    int i;

    bzero(&bufpool, sizeof(struct bufpool));
    
    //2002年10月09日修改-vm
    //bufpool.base = (char *) kmalloc(nbufs * sizeof(struct buf));
    bufpool.base = (char *) malloc(nbufs * sizeof(struct buf));
    bzero(bufpool.base, nbufs * sizeof(struct buf));

    for (i = 0; i < nbufs; i++)
	buf_push((buf_t) (bufpool.base + (i * sizeof(struct buf))));

    bufpool.total = nbufs;
}

void
buf_clear(buf_t buf)
{
    buf->prev = NULL;
    buf->next = NULL;
    buf->start = NULL;
    buf->len = 0;
    buf->pos = 0;
    buf->blk = NULL;
}

void
buf_push(buf_t buf)
{
    buf_clear(buf);
    buf->next = bufpool.bufs;
    bufpool.bufs = buf;
    bufpool.nbufs++;
}

buf_t
buf_pop()
{
    buf_t buf;

    if (bufpool.bufs == NULL)
	return NULL;

    buf = bufpool.bufs;
    bufpool.bufs = buf->next;
    buf->next = NULL;
    bufpool.nbufs--;

    return buf;
}

buf_t
_balloc()
{
    return buf_pop();
}

buf_t
balloc()
{
    buf_t buf;

    for (;;) {
	disable;
	buf = _balloc();
	enable;
	if (buf != NULL)
	    return buf;
	event_wait(EVENT_BUF);
    }
}

void
_bfree(buf_t buf)
{
    if (buf->blk != NULL) {
	if (buf->blk->refcnt > 1)
	    buf->blk->refcnt--;
	else {
	    blk_clear(buf->blk);
	    blk_push(buf->blk);
	}
    }
    buf_clear(buf);
    buf_push(buf);
}

int
bfree(buf_t buf)
{
    if (buf == NULL)
	return EINVAL;

    disable;
    _bfree(buf);
    enable;

    event_raise(EVENT_BUF);
    return 0;
}

buf_t
_bget(int size)
{
    buf_t buf;
    blk_t blk;

    disable;

    blk = blk_pop();
    if (blk == NULL) {
	enable;
	return NULL;
    }
    buf = _balloc();
    if (buf == NULL) {
	blk_push(blk);
	enable;
	return NULL;
    }
    blk->refcnt = 1;
    buf->blk = blk;
    buf->start = buf->blk->data;

    enable;
    return buf;
}

buf_t
bget(int size)
{
    buf_t buf;

    while ((buf = _bget(size)) == NULL)
	event_wait(EVENT_BUF);
    return buf;
}

int
brel(buf_t buf)
{
    return bfree(buf);
}