1/*-
2 * Copyright 2018 Toomas Soome <tsoome@me.com>
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 */
25
26#include <sys/cdefs.h>
27__FBSDID("$FreeBSD: stable/11/stand/i386/libi386/bio.c 346476 2019-04-21 03:36:05Z kevans $");
28
29#include <stand.h>
30#include "libi386.h"
31
32/*
33 * The idea is borrowed from pxe.c and zfsimpl.c. The original buffer
34 * space in pxe.c was 2x 0x2000. Allocating it from BSS will give us needed
35 * memory below 1MB and usable for real mode calls.
36 *
37 * Note the allocations and frees are to be done in reverse order (LIFO).
38 */
39
40static char bio_buffer[BIO_BUFFER_SIZE];
41static char *bio_buffer_end = bio_buffer + BIO_BUFFER_SIZE;
42static char *bio_buffer_ptr = bio_buffer;
43
44void *
45bio_alloc(size_t size)
46{
47	char *ptr;
48
49	ptr = bio_buffer_ptr;
50	if (ptr + size > bio_buffer_end)
51		return (NULL);
52	bio_buffer_ptr += size;
53
54	return (ptr);
55}
56
57void
58bio_free(void *ptr, size_t size)
59{
60
61	if (ptr == NULL)
62		return;
63
64	bio_buffer_ptr -= size;
65	if (bio_buffer_ptr != ptr)
66		panic("bio_alloc()/bio_free() mismatch\n");
67}
68