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#include <stand.h>
28#include <libi386.h>
29
30/*
31 * The idea is borrowed from pxe.c and zfsimpl.c. The original buffer
32 * space in pxe.c was 2x 0x2000. Allocating it from BSS will give us needed
33 * memory below 1MB and usable for real mode calls.
34 *
35 * Note the allocations and frees are to be done in reverse order (LIFO).
36 */
37
38#define	BIO_BUFFER_SIZE	0x4000
39static char bio_buffer[BIO_BUFFER_SIZE];
40static char *bio_buffer_end = bio_buffer + BIO_BUFFER_SIZE;
41static char *bio_buffer_ptr = bio_buffer;
42
43void *
44bio_alloc(size_t size)
45{
46	char *ptr;
47
48	ptr = bio_buffer_ptr;
49	if (ptr + size > bio_buffer_end)
50		return (NULL);
51	bio_buffer_ptr += size;
52
53	return (ptr);
54}
55
56void
57bio_free(void *ptr, size_t size)
58{
59
60	if (ptr == NULL)
61		return;
62
63	bio_buffer_ptr -= size;
64	if (bio_buffer_ptr != ptr)
65		panic("bio_alloc()/bio_free() mismatch");
66}
67