bios_disk.S revision 1.5
1 /* $NetBSD: bios_disk.S,v 1.5 1999/03/08 00:09:25 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(): takes a pointer to a biosdisk_ll struct, and fills it in. 118 # 119 */ 120 121 ENTRY(get_diskinfo) 122 pushl %ebp 123 movl %esp, %ebp 124 push %es 125 pushl %ebx 126 push %ecx 127 push %edx 128 push %esi 129 push %edi 130 131 movl 8(%ebp), %esi # diskinfo(drive #) 132 movb (%esi), %dl 133 pushl %esi 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 popl %esi 161 162 movzbl %dh, %eax 163 movl %eax, 8(%esi) # heads 164 movb %cl, %al 165 andb $0x3f, %al 166 movzbl %al, %ebx 167 movl %ebx, 4(%esi) # sectors per track 168 xorl %eax, %eax 169 movb %ch, %al 170 andl $0x0c0, %ecx 171 shll $2, %ecx 172 orl %ecx, %eax 173 movl %eax, 12(%esi) # cylinders 174 175 pop %edi 176 pop %esi 177 pop %edx 178 pop %ecx 179 popl %ebx 180 pop %es 181 popl %ebp 182 ret 183 184 /* 185 # int13_extension: check for availibility of int13 extensions. 186 */ 187 188 ENTRY(int13_extension) 189 pushl %ebp 190 movl %esp, %ebp 191 pushl %ebx 192 pushl %ecx 193 pushl %edx 194 pushl %esi 195 pushl %edi 196 197 movb 8(%ebp), %dl # drive # 198 movw $0x55aa, %bx 199 200 call _C_LABEL(prot_to_real) # enter real mode 201 202 movb $0x41, %ah # ask for disk info 203 int $0x13 204 setnc %dl 205 206 data32 207 CALL _C_LABEL(real_to_prot) # switch back 208 209 xorl %eax, %eax 210 movb %dl, %al # return value in %ax 211 212 cmpw $0xaa55, %bx 213 sete %dl 214 andb %dl, %al 215 216 andb %cl, %al 217 218 popl %edi 219 popl %esi 220 popl %edx 221 popl %ecx 222 popl %ebx 223 popl %ebp 224 ret 225 226 /* 227 # BIOS call "INT 0x13 Function 0x42" to read sectors from disk into memory 228 # Call with %ah = 0x42 229 # %ds:%si = parameter block 230 # %dl = drive (0x80 for hard disk, 0x0 for floppy disk) 231 # Return: 232 # %al = 0x0 on success; err code on failure 233 */ 234 ENTRY(biosextread) 235 pushl %ebp 236 movl %esp, %ebp 237 pushl %ebx 238 push %ecx 239 push %edx 240 push %esi 241 push %edi 242 243 movb 8(%ebp), %dl # device 244 movl 12(%ebp), %esi # parameter block 245 246 call _C_LABEL(prot_to_real) # enter real mode 247 248 movb $0x42, %ah # subfunction 249 int $0x13 250 setc %bl 251 252 data32 253 call _C_LABEL(real_to_prot) # back to protected mode 254 255 xorl %eax, %eax 256 movb %bl, %al # return value in %ax 257 258 pop %edi 259 pop %esi 260 pop %edx 261 pop %ecx 262 popl %ebx 263 popl %ebp 264 ret 265 266 ENTRY(int13_getextinfo) 267 pushl %ebp 268 movl %esp, %ebp 269 pushl %ebx 270 push %ecx 271 push %edx 272 push %esi 273 push %edi 274 275 movb 8(%ebp), %dl # device 276 movl 12(%ebp), %esi # parameter block 277 movl $0x01a, (%esi) # length (v 1.x) 278 279 call _C_LABEL(prot_to_real) # enter real mode 280 281 movb $0x48, %ah # subfunction 282 int $0x13 283 setc %bl 284 285 data32 286 call _C_LABEL(real_to_prot) # back to protected mode 287 288 xorl %eax, %eax 289 movb %bl, %al # return value in %ax 290 291 pop %edi 292 pop %esi 293 pop %edx 294 pop %ecx 295 popl %ebx 296 popl %ebp 297 ret 298
Indexes created Wed Oct 15 07:09:58 GMT 2025