srt0.S revision 1.3
1 /* $NetBSD: srt0.S,v 1.3 2004/06/13 20:50:14 abs 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 57 ENTRY(_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 77 Lhimem: 78 .word HIMEM 79 80
Indexes created Mon Oct 13 21:09:55 GMT 2025