1/*	$NetBSD: srt0.S,v 1.1.4.3 2004/09/21 13:11:35 skrll Exp $	*/
2
3/*-
4 * Copyright (c) 2001 Ben Harris
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote products
16 *    derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 *
29 * Modified by Reinoud Zandijk to get the program high water mark into the
30 * HIMEM variable as normally seen in RISC OS. This is the max address+1 of
31 * the current `WIMPSlot'. It used to be a #define. The HIMEM var needs to be
32 * initialised though so it doesn't get zero'd when the BSS is later cleared.
33 * (see srt1.c)
34 */
35
36/* Minimum desired free memory */
37
38#ifndef BOOT_MIN_AVAIL_MEMORY
39#define BOOT_MIN_AVAIL_MEMORY	10 * 1024 * 1024
40#endif
41
42/* If enough above BOOT_MIN_AVAIL_MEMORY, leave BOOT_LEAVE_MEMORY unused */
43/* Avoids sparkfs failing on memory if we try to read a kernel from it */
44
45#ifndef BOOT_LEAVE_MEMORY
46#define BOOT_LEAVE_MEMORY	5 * 1024 * 1024
47#endif
48
49/*
50 * Both BOOT_LEAVE_MEMORY and BOOT_MIN_AVAIL_MEMORY + BOOT_LEAVE_MEMORY
51 * must fit into an immediate ATM constant - 8 bits with arbitrary rotation
52 */
53
54#include <machine/asm.h>
55#include <riscoscalls.h>
56
57ENTRY(_start)
58#ifdef BOOT_MAXIMISE_MEMORY
59	mvn	r0, #0
60	mvn	r1, #0
61	swi	Wimp_SlotSize
62	add	r0, r0, r2
63#if (BOOT_LEAVE_MEMORY > 0)
64	cmp	r0, #BOOT_MIN_AVAIL_MEMORY + BOOT_LEAVE_MEMORY
65	subhi	r0, r0, #BOOT_LEAVE_MEMORY
66#endif
67	mvn	r1, #0
68	swi	Wimp_SlotSize
69#endif
70	swi	OS_GetEnv
71	ldr	r6, Lhimem
72	str	r1, [r6]
73	mov	sp, r1
74	mov	fp, #0
75	b	__start
76
77Lhimem:
78	.word	HIMEM
79
80