bios_disk.S revision 1.7
1 /* $NetBSD: bios_disk.S,v 1.7 1999/03/30 22:35:21 fvdl Exp $ */ 2 3 /* 4 * Ported to boot 386BSD by Julian Elischer (julian (at) tfs.com) Sept 1992 5 * 6 * Mach Operating System 7 * Copyright (c) 1992, 1991 Carnegie Mellon University 8 * All Rights Reserved. 9 * 10 * Permission to use, copy, modify and distribute this software and its 11 * documentation is hereby granted, provided that both the copyright 12 * notice and this permission notice appear in all copies of the 13 * software, derivative works or modified versions, and any portions 14 * thereof, and that both notices appear in supporting documentation. 15 * 16 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 17 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR 18 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 19 * 20 * Carnegie Mellon requests users of this software to return to 21 * 22 * Software Distribution Coordinator or Software.Distribution (at) CS.CMU.EDU 23 * School of Computer Science 24 * Carnegie Mellon University 25 * Pittsburgh PA 15213-3890 26 * 27 * any improvements or extensions that they make and grant Carnegie Mellon 28 * the rights to redistribute these changes. 29 */ 30 31 /* 32 Copyright 1988, 1989, 1990, 1991, 1992 33 by Intel Corporation, Santa Clara, California. 34 35 All Rights Reserved 36 37 Permission to use, copy, modify, and distribute this software and 38 its documentation for any purpose and without fee is hereby 39 granted, provided that the above copyright notice appears in all 40 copies and that both the copyright notice and this permission notice 41 appear in supporting documentation, and that the name of Intel 42 not be used in advertising or publicity pertaining to distribution 43 of the software without specific, written prior permission. 44 45 INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE 46 INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, 47 IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR 48 CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 49 LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT, 50 NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION 51 WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 52 */ 53 54 /* extracted from netbsd:sys/arch/i386/boot/bios.S */ 55 56 #include <machine/asm.h> 57 58 #define addr32 .byte 0x67 59 #define data32 .byte 0x66 60 61 /* 62 # BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory 63 # Call with %ah = 0x2 64 # %al = number of sectors 65 # %ch = cylinder 66 # %cl = sector 67 # %dh = head 68 # %dl = drive (0x80 for hard disk, 0x0 for floppy disk) 69 # %es:%bx = segment:offset of buffer 70 # Return: 71 # %al = 0x0 on success; err code on failure 72 */ 73 ENTRY(biosread) 74 pushl %ebp 75 movl %esp, %ebp 76 pushl %ebx 77 push %ecx 78 push %edx 79 push %esi 80 push %edi 81 82 movb 16(%ebp), %dh 83 movw 12(%ebp), %cx 84 xchgb %ch, %cl # cylinder; the highest 2 bits of cyl is in %cl 85 rorb $2, %cl 86 movb 20(%ebp), %al 87 orb %al, %cl 88 incb %cl # sector; sec starts from 1, not 0 89 movb 8(%ebp), %dl # device 90 movl 28(%ebp), %ebx # offset 91 # prot_to_real will set %es to BOOTSEG 92 93 call _C_LABEL(prot_to_real) # enter real mode 94 95 movb $0x2, %ah # subfunction 96 addr32 97 movb 24(%ebp), %al # number of sectors 98 int $0x13 99 setc %bl 100 101 data32 102 call _C_LABEL(real_to_prot) # back to protected mode 103 104 xorl %eax, %eax 105 movb %bl, %al # return value in %ax 106 107 pop %edi 108 pop %esi 109 pop %edx 110 pop %ecx 111 popl %ebx 112 popl %ebp 113 ret 114 115 /* 116 # 117 # get_diskinfo(): return a word that represents the 118 # max number of sectors, heads and cylinders for this device 119 # 120 */ 121 122 ENTRY(get_diskinfo) 123 pushl %ebp 124 movl %esp, %ebp 125 push %es 126 pushl %ebx 127 push %ecx 128 push %edx 129 push %esi 130 push %edi 131 132 movb 8(%ebp), %dl # diskinfo(drive #) 133 134 call _C_LABEL(prot_to_real) # enter real mode 135 136 movb $0x08, %ah # ask for disk info 137 int $0x13 138 jnc ok 139 140 /* 141 * Urk. Call failed. It is not supported for floppies by old BIOS's. 142 * Guess it's a 15-sector floppy. Initialize all the registers for 143 * documentation, although we only need head and sector counts. 144 */ 145 # subb %ah, %ah # %ax = 0 146 # movb %ah, %bh # %bh = 0 147 # movb $2, %bl # %bl bits 0-3 = drive type, 2 = 1.2M 148 movb $79, %ch # max track 149 movb $15, %cl # max sector 150 movb $1, %dh # max head 151 # movb $1, %dl # # floppy drives installed 152 # es:di = parameter table 153 # carry = 0 154 155 ok: 156 data32 157 call _C_LABEL(real_to_prot) # back to protected mode 158 159 /* form a longword representing all this gunk */ 160 shll $8, %ecx 161 movb %dh, %cl 162 163 movl %ecx, %eax 164 165 pop %edi 166 pop %esi 167 pop %edx 168 pop %ecx 169 popl %ebx 170 pop %es 171 popl %ebp 172 ret 173 174 /* 175 # int13_extension: check for availibility of int13 extensions. 176 */ 177 178 ENTRY(int13_extension) 179 pushl %ebp 180 movl %esp, %ebp 181 pushl %ebx 182 pushl %ecx 183 pushl %edx 184 pushl %esi 185 pushl %edi 186 187 movb 8(%ebp), %dl # drive # 188 movw $0x55aa, %bx 189 190 call _C_LABEL(prot_to_real) # enter real mode 191 192 movb $0x41, %ah # ask for disk info 193 int $0x13 194 setnc %dl 195 196 data32 197 CALL _C_LABEL(real_to_prot) # switch back 198 199 xorl %eax, %eax 200 movb %dl, %al # return value in %ax 201 202 cmpw $0xaa55, %bx 203 sete %dl 204 andb %dl, %al 205 206 andb %cl, %al 207 208 popl %edi 209 popl %esi 210 popl %edx 211 popl %ecx 212 popl %ebx 213 popl %ebp 214 ret 215 216 /* 217 # BIOS call "INT 0x13 Function 0x42" to read sectors from disk into memory 218 # Call with %ah = 0x42 219 # %ds:%si = parameter block 220 # %dl = drive (0x80 for hard disk, 0x0 for floppy disk) 221 # Return: 222 # %al = 0x0 on success; err code on failure 223 */ 224 ENTRY(biosextread) 225 pushl %ebp 226 movl %esp, %ebp 227 pushl %ebx 228 push %ecx 229 push %edx 230 push %esi 231 push %edi 232 233 movb 8(%ebp), %dl # device 234 movl 12(%ebp), %esi # parameter block 235 236 call _C_LABEL(prot_to_real) # enter real mode 237 238 movb $0x42, %ah # subfunction 239 int $0x13 240 setc %bl 241 242 data32 243 call _C_LABEL(real_to_prot) # back to protected mode 244 245 xorl %eax, %eax 246 movb %bl, %al # return value in %ax 247 248 pop %edi 249 pop %esi 250 pop %edx 251 pop %ecx 252 popl %ebx 253 popl %ebp 254 ret 255 256 ENTRY(int13_getextinfo) 257 pushl %ebp 258 movl %esp, %ebp 259 pushl %ebx 260 push %ecx 261 push %edx 262 push %esi 263 push %edi 264 265 movb 8(%ebp), %dl # device 266 movl 12(%ebp), %esi # parameter block 267 movl $0x01a, (%esi) # length (v 1.x) 268 269 call _C_LABEL(prot_to_real) # enter real mode 270 271 movb $0x48, %ah # subfunction 272 int $0x13 273 setc %bl 274 275 data32 276 call _C_LABEL(real_to_prot) # back to protected mode 277 278 xorl %eax, %eax 279 movb %bl, %al # return value in %ax 280 281 pop %edi 282 pop %esi 283 pop %edx 284 pop %ecx 285 popl %ebx 286 popl %ebp 287 ret 288
Indexes created Wed Oct 15 03:09:54 GMT 2025