bbstart.s revision 1.8
1 /* $NetBSD: bbstart.s,v 1.8 2001/03/02 16:43:26 mhitch Exp $ */ 2 3 /*- 4 * Copyright (c) 1996 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Ignatios Souvatzis. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include <machine/asm.h> 40 #include "aout2bb.h" 41 42 #define LVOAllocMem -0x0c6 43 #define LVODoIO -0x1c8 44 #define LVOCacheClearU -0x27c 45 46 #define IOcmd 28 47 #define IOerr 31 48 #define IOlen 36 49 #define IObuf 40 50 #define IOoff 44 51 52 #define Cmd_Rd 2 53 54 .text 55 Lzero: .asciz "DOS" | "DOS type" 56 /* 57 * We put the relocator version here, for aout2bb, which replaces 58 * it with the bootblock checksum. 59 */ 60 Chksum: .long RELVER_RELATIVE_BYTES_FORWARD 61 Filesz: .long 8192 | dummy 62 63 /* 64 * Entry point from Kickstart. 65 * A1 points to an IOrequest, A6 points to ExecBase, we have a stack. 66 * _must_ be at offset 12. 67 */ 68 ENTRY_NOPROFILE(start) 69 #ifdef AUTOLOAD 70 jra Lautoload 71 #else 72 jra Lrelocate 73 #endif 74 75 Lreltab: 76 .word 0 | aout2bb puts the reloc table address here 77 78 #ifdef AUTOLOAD 79 /* 80 * autoload 81 */ 82 Lautoload: 83 movl %a6,%sp@- |SysBase 84 movl %a1,%sp@- |IORequest 85 86 movl #AUTOLOAD,%d0 |Howmuch 87 movl %d0,%a1@(IOlen) | for the actual read... 88 movl #0x10001,%d1 |MEMF_CLEAR|MEMF_PUBLIC 89 jsr %a6@(LVOAllocMem) 90 movl %sp@+,%a1 |IORequest 91 movl %sp@+,%a6 |SysBase 92 orl %d0,%d0 93 jne Lgotmem 94 movql #1,%d0 95 rts 96 97 Lgotmem: 98 movl %d0,%sp@- |Address 99 movl %a1@(IOoff),%sp@- |Old offset 100 movl %a1,%sp@- 101 movl %a6,%sp@- 102 103 /* we've set IOlen above */ 104 movl %d0,%a1@(IObuf) 105 movw #Cmd_Rd,%a1@(IOcmd) 106 jsr %a6@(LVODoIO) 107 108 movl %sp@+,%a6 109 movl %sp@+,%a1 110 movl %sp@+,%a1@(IOoff) 111 112 tstb %a1@(IOerr) 113 jne Lioerr 114 addl #Lrelocate-Lzero,%sp@ 115 116 movl %a6,%sp@- 117 jsr %a6@(LVOCacheClearU) 118 movl %sp@+,%a6 119 rts 120 Lioerr: 121 movql #1,%d0 122 addql #4,%sp 123 rts 124 #endif 125 126 /* 127 * Relocate ourselves, at the same time clearing the relocation table 128 * (in case it overlaps with BSS). 129 * 130 * Register usage: 131 * A2: points into the reloc table, located at our end. 132 * A0: pointer to the longword to relocate. 133 * D0: word offset of longword to relocate 134 * D1: points to our start. 135 * 136 * Table has relative byte offsets, if a byte offset is zero, it is 137 * followed by an absolute word offset. If this is zero, too, table 138 * end is reached. 139 */ 140 141 Lrelocate: 142 lea %pc@(Lzero),%a0 143 movl %a0,%d1 144 movw %pc@(Lreltab),%a2 145 addl %d1,%a2 146 jra Loopend 147 148 Loopw: 149 clrw %a2@+ 150 movl %d1,%a0 | for a variant with relative words, erase this line 151 Loopb: 152 addl %d0,%a0 153 addl %d1,%a0@ 154 Loopend: 155 movq #0,%d0 156 movb %a2@,%d0 157 clrb %a2@+ | bfclr %a2@+{0:8} is still two shorts 158 tstb %d0 | we could save one short by using casb %d0,d0,%a2@+ 159 jne Loopb 160 161 movw %a2@,%d0 162 jne Loopw 163 164 Lendtab: 165 movl %a6,%sp@- 166 jsr %a6@(LVOCacheClearU) 167 movl %sp@+,%a6 168 169 /* We are relocated. Now it is safe to initialize _SysBase: */ 170 171 movl %a6,_C_LABEL(SysBase) 172 173 movl %a1,%sp@- 174 bsr _C_LABEL(pain) 175 176 Lerr: 177 movq #1,%d0 178 rts 179 180 .comm _C_LABEL(SysBase),4 181
Indexes created Wed Oct 29 12:09:47 GMT 2025