1 /*-
2 * Copyright 2018 Toomas Soome <[email protected]>
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("$FreeBSD$");
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
40 static char bio_buffer[BIO_BUFFER_SIZE];
41 static char *bio_buffer_end = bio_buffer + BIO_BUFFER_SIZE;
42 static char *bio_buffer_ptr = bio_buffer;
43
44 void *
bio_alloc(size_t size)45 bio_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
57 void
bio_free(void * ptr,size_t size)58 bio_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