bbstart.s revision 1.1.1.1
1 /* 2 * $NetBSD: bbstart.s,v 1.1.1.1 1996/11/29 23:36:29 is Exp $ 3 * 4 * Copyright (c) 1996 Ignatios Souvatzis 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. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by Ignatios Souvatzis 18 * for the NetBSD project. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 * 33 */ 34 35 #include "aout2bb/aout2bb.h" 36 37 #define LVOAllocMem -0x0c6 38 #define LVODoIO -0x1c8 39 #define LVOCacheClearU -0x27c 40 41 #define IOcmd 28 42 #define IOerr 31 43 #define IOlen 36 44 #define IObuf 40 45 #define IOoff 44 46 47 #define Cmd_Rd 2 48 49 .globl _configure 50 .globl _pain 51 52 .text 53 Lzero: .asciz "DOS" | "DOS type" 54 /* 55 * We put the relocator version here, for aout2bb, which replaces 56 * it with the bootblock checksum. 57 */ 58 Chksum: .long RELVER_RELATIVE_BYTES_FORWARD 59 Filesz: .long 8192 | dummy 60 61 /* 62 * Entry point from Kickstart. 63 * A1 points to an IOrequest, A6 points to ExecBase, we have a stack. 64 * _must_ be at offset 12. 65 */ 66 .globl _start 67 _start: 68 #ifdef AUTOLOAD 69 jra Lautoload 70 #else 71 jra Lrelocate 72 #endif 73 74 Lreltab: 75 .word 0 | aout2bb puts the reloc table address here 76 77 #ifdef AUTOLOAD 78 /* 79 * autoload 80 */ 81 Lautoload: 82 movl a6,sp@- |SysBase 83 movl a1,sp@- |IORequest 84 85 movl #AUTOLOAD,d0 |Howmuch 86 movl d0,a1@(IOlen) | for the actual read... 87 movl #0x10001,d1 |MEMF_CLEAR|MEMF_PUBLIC 88 jsr a6@(LVOAllocMem) 89 movl sp@+,a1 |IORequest 90 movl sp@+,a6 |SysBase 91 orl d0,d0 92 jne Lgotmem 93 movql #1,d0 94 rts 95 96 Lgotmem: 97 movl d0,sp@- |Address 98 movl a1@(IOoff),sp@- |Old offset 99 movl a1,sp@- 100 movl a6,sp@- 101 102 /* we've set IOlen above */ 103 movl d0,a1@(IObuf) 104 movw #Cmd_Rd,a1@(IOcmd) 105 jsr a6@(LVODoIO) 106 107 movl sp@+,a6 108 movl sp@+,a1 109 movl sp@+,a1@(IOoff) 110 111 tstb a1@(IOerr) 112 jne Lioerr 113 addl #Lrelocate-Lzero,sp@ 114 115 movl a6,sp@- 116 jsr a6@(LVOCacheClearU) 117 movl sp@+,a6 118 rts 119 Lioerr: 120 movql #1,d0 121 addql #4,sp 122 rts 123 #endif 124 125 /* 126 * Relocate ourselves, at the same time clearing the relocation table 127 * (in case it overlaps with BSS). 128 * 129 * Register usage: 130 * A2: points into the reloc table, located at our end. 131 * A0: pointer to the longword to relocate. 132 * D0: word offset of longword to relocate 133 * D1: points to our start. 134 * 135 * Table has relative byte offsets, if a byte offset is zero, it is 136 * followed by an absolute word offset. If this is zero, too, table 137 * end is reached. 138 */ 139 140 Lrelocate: 141 lea pc@(Lzero),a0 142 movl a0,d1 143 movw pc@(Lreltab),a2 144 addl d1,a2 145 jra Loopend 146 147 Loopw: 148 clrw a2@+ 149 movl d1,a0 | for a variant with relative words, erase this line 150 Loopb: 151 addl d0,a0 152 addl d1,a0@ 153 Loopend: 154 movq #0,d0 155 movb a2@,d0 156 clrb a2@+ | bfclr a2@+{0:8} is still two shorts 157 tstb d0 | we could save one short by using casb d0,d0,a2@+ 158 jne Loopb 159 160 movw a2@,d0 161 jne Loopw 162 163 Lendtab: 164 movl a6,sp@- 165 jsr a6@(LVOCacheClearU) 166 movl sp@+,a6 167 168 /* We are relocated. Now it is safe to initialize _SysBase: */ 169 170 movl a6,_SysBase 171 172 movl a1,sp@- 173 bsr _configure 174 addql #4,sp 175 tstl d0 176 jne Lerr 177 178 bsr _pain 179 180 Lerr: 181 movq #1,d0 182 rts 183 184 .comm _SysBase,4 185
Indexes created Thu Oct 30 03:10:01 GMT 2025