bios_disk.S revision 1.8
1 /* $NetBSD: bios_disk.S,v 1.8 2000/05/21 16:59:28 perry 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 movb %ah, %bh # save error code 101 102 data32 103 call _C_LABEL(real_to_prot) # back to protected mode 104 105 xorl %eax, %eax 106 movw %bx, %ax # return value in %ax 107 108 pop %edi 109 pop %esi 110 pop %edx 111 pop %ecx 112 popl %ebx 113 popl %ebp 114 ret 115 116 /* 117 # 118 # get_diskinfo(): return a word that represents the 119 # max number of sectors, heads and cylinders for this device 120 # 121 */ 122 123 ENTRY(get_diskinfo) 124 pushl %ebp 125 movl %esp, %ebp 126 push %es 127 pushl %ebx 128 push %ecx 129 push %edx 130 push %esi 131 push %edi 132 133 movb 8(%ebp), %dl # diskinfo(drive #) 134 135 call _C_LABEL(prot_to_real) # enter real mode 136 137 movb $0x08, %ah # ask for disk info 138 int $0x13 139 jnc ok 140 141 /* 142 * Urk. Call failed. It is not supported for floppies by old BIOS's. 143 * Guess it's a 15-sector floppy. Initialize all the registers for 144 * documentation, although we only need head and sector counts. 145 */ 146 # subb %ah, %ah # %ax = 0 147 # movb %ah, %bh # %bh = 0 148 # movb $2, %bl # %bl bits 0-3 = drive type, 2 = 1.2M 149 movb $79, %ch # max track 150 movb $15, %cl # max sector 151 movb $1, %dh # max head 152 # movb $1, %dl # # floppy drives installed 153 # es:di = parameter table 154 # carry = 0 155 156 ok: 157 data32 158 call _C_LABEL(real_to_prot) # back to protected mode 159 160 /* form a longword representing all this gunk */ 161 shll $8, %ecx 162 movb %dh, %cl 163 164 movl %ecx, %eax 165 166 pop %edi 167 pop %esi 168 pop %edx 169 pop %ecx 170 popl %ebx 171 pop %es 172 popl %ebp 173 ret 174 175 /* 176 # int13_extension: check for availibility of int13 extensions. 177 */ 178 179 ENTRY(int13_extension) 180 pushl %ebp 181 movl %esp, %ebp 182 pushl %ebx 183 pushl %ecx 184 pushl %edx 185 pushl %esi 186 pushl %edi 187 188 movb 8(%ebp), %dl # drive # 189 movw $0x55aa, %bx 190 191 call _C_LABEL(prot_to_real) # enter real mode 192 193 movb $0x41, %ah # ask for disk info 194 int $0x13 195 setnc %dl 196 197 data32 198 CALL _C_LABEL(real_to_prot) # switch back 199 200 xorl %eax, %eax 201 movb %dl, %al # return value in %ax 202 203 cmpw $0xaa55, %bx 204 sete %dl 205 andb %dl, %al 206 207 andb %cl, %al 208 209 popl %edi 210 popl %esi 211 popl %edx 212 popl %ecx 213 popl %ebx 214 popl %ebp 215 ret 216 217 /* 218 # BIOS call "INT 0x13 Function 0x42" to read sectors from disk into memory 219 # Call with %ah = 0x42 220 # %ds:%si = parameter block 221 # %dl = drive (0x80 for hard disk, 0x0 for floppy disk) 222 # Return: 223 # %al = 0x0 on success; err code on failure 224 */ 225 ENTRY(biosextread) 226 pushl %ebp 227 movl %esp, %ebp 228 pushl %ebx 229 push %ecx 230 push %edx 231 push %esi 232 push %edi 233 234 movb 8(%ebp), %dl # device 235 movl 12(%ebp), %esi # parameter block 236 237 call _C_LABEL(prot_to_real) # enter real mode 238 239 movb $0x42, %ah # subfunction 240 int $0x13 241 setc %bl 242 movb %ah, %bh # save error code 243 244 data32 245 call _C_LABEL(real_to_prot) # back to protected mode 246 247 xorl %eax, %eax 248 movw %bx, %ax # return value in %ax 249 250 pop %edi 251 pop %esi 252 pop %edx 253 pop %ecx 254 popl %ebx 255 popl %ebp 256 ret 257 258 ENTRY(int13_getextinfo) 259 pushl %ebp 260 movl %esp, %ebp 261 pushl %ebx 262 push %ecx 263 push %edx 264 push %esi 265 push %edi 266 267 movb 8(%ebp), %dl # device 268 movl 12(%ebp), %esi # parameter block 269 movl $0x01a, (%esi) # length (v 1.x) 270 271 call _C_LABEL(prot_to_real) # enter real mode 272 273 movb $0x48, %ah # subfunction 274 int $0x13 275 setc %bl 276 277 data32 278 call _C_LABEL(real_to_prot) # back to protected mode 279 280 xorl %eax, %eax 281 movb %bl, %al # return value in %ax 282 283 pop %edi 284 pop %esi 285 pop %edx 286 pop %ecx 287 popl %ebx 288 popl %ebp 289 ret 290
Indexes created Wed Oct 15 16:09:53 GMT 2025