bios_disk.S revision 1.15
1 /* $NetBSD: bios_disk.S,v 1.15 2005/06/22 15:29:48 junyoung 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 /* 59 * BIOS call "INT 0x13 Function 0x0" to reset the disk subsystem 60 * Call with %ah = 0x0 61 * %dl = drive (0x80 for hard disk, 0x0 for floppy disk) 62 * Return: 63 * %al = 0x0 on success; err code on failure 64 */ 65 ENTRY(biosdiskreset) 66 pushl %ebp 67 movl %esp, %ebp 68 pushl %ebx 69 push %edx 70 push %edi 71 72 movb 8(%ebp), %dl # device 73 74 call _C_LABEL(prot_to_real) # enter real mode 75 .code16 76 77 movb $0x0, %ah # subfunction 78 int $0x13 79 setc %bl 80 movb %ah, %bh # save error code 81 82 calll _C_LABEL(real_to_prot) # back to protected mode 83 .code32 84 85 xorl %eax, %eax 86 movw %bx, %ax # return value in %ax 87 88 pop %edi 89 pop %edx 90 popl %ebx 91 popl %ebp 92 ret 93 94 /* 95 * BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory 96 * Call with %ah = 0x2 97 * %al = number of sectors 98 * %ch = cylinder 99 * %cl = sector 100 * %dh = head 101 * %dl = drive (0x80 for hard disk, 0x0 for floppy disk) 102 * %es:%bx = segment:offset of buffer 103 * Return: 104 * %al = 0x0 on success; err code on failure 105 * 106 * biosread( dev, cyl, head, sect, count, buff_addr ); 107 * 108 * Note: On failure, you must reset the disk with biosdiskreset() before 109 * sending another command. 110 */ 111 ENTRY(biosread) 112 pushl %ebp 113 movl %esp, %ebp 114 pushl %ebx 115 push %ecx 116 push %edx 117 push %esi 118 push %edi 119 120 movb 16(%ebp), %dh 121 movw 12(%ebp), %cx 122 xchgb %ch, %cl # cylinder; the highest 2 bits of cyl is in %cl 123 rorb $2, %cl 124 movb 20(%ebp), %al 125 orb %al, %cl 126 incb %cl # sector; sec starts from 1, not 0 127 movb 8(%ebp), %dl # device 128 movl 28(%ebp), %ebx # buffer address (may be >64k) 129 movb 24(%ebp), %al # number of sectors 130 131 call _C_LABEL(prot_to_real) # enter real mode 132 .code16 133 134 push %bx 135 shrl $4, %ebx # max segment 136 mov %ds, %si 137 add %si, %bx 138 mov %bx, %es # %es:%bx now valid buffer address 139 pop %bx 140 and $0xf, %bx # and min offset - to avoid overrun 141 142 movb $0x2, %ah # subfunction 143 int $0x13 144 setc %al # error code is in %ah 145 146 calll _C_LABEL(real_to_prot) # back to protected mode 147 .code32 148 149 andl $0xffff, %eax 150 151 pop %edi 152 pop %esi 153 pop %edx 154 pop %ecx 155 popl %ebx 156 popl %ebp 157 ret 158 159 /* 160 * 161 * get_diskinfo(): return a word that represents the 162 * max number of sectors, heads and cylinders for this device 163 * 164 */ 165 ENTRY(get_diskinfo) 166 pushl %ebp 167 movl %esp, %ebp 168 push %es 169 pushl %ebx 170 push %ecx 171 push %edx 172 push %esi 173 push %edi 174 175 movb 8(%ebp), %dl # diskinfo(drive #) 176 177 call _C_LABEL(prot_to_real) # enter real mode 178 .code16 179 180 movb $0x08, %ah # ask for disk info 181 int $0x13 182 jnc ok 183 184 /* 185 * Urk. Call failed. It is not supported for floppies by old BIOS's. 186 * Guess it's a 15-sector floppy. Initialize all the registers for 187 * documentation, although we only need head and sector counts. 188 */ 189 # subb %ah, %ah # %ax = 0 190 # movb %ah, %bh # %bh = 0 191 # movb $2, %bl # %bl bits 0-3 = drive type, 2 = 1.2M 192 movb $79, %ch # max track 193 movb $15, %cl # max sector 194 movb $1, %dh # max head 195 # movb $1, %dl # # floppy drives installed 196 # es:di = parameter table 197 # carry = 0 198 199 ok: 200 calll _C_LABEL(real_to_prot) # back to protected mode 201 .code32 202 203 /* form a longword representing all this gunk */ 204 shll $8, %ecx 205 movb %dh, %cl 206 207 movl %ecx, %eax 208 209 pop %edi 210 pop %esi 211 pop %edx 212 pop %ecx 213 popl %ebx 214 pop %es 215 popl %ebp 216 ret 217 218 /* 219 * int13_extension: check for availibility of int13 extensions. 220 */ 221 ENTRY(int13_extension) 222 pushl %ebp 223 movl %esp, %ebp 224 pushl %ebx 225 pushl %ecx 226 pushl %edx 227 pushl %esi 228 pushl %edi 229 230 movb 8(%ebp), %dl # drive # 231 movw $0x55aa, %bx 232 233 call _C_LABEL(prot_to_real) # enter real mode 234 .code16 235 236 movb $0x41, %ah # ask for disk info 237 int $0x13 238 setnc %dl 239 240 calll _C_LABEL(real_to_prot) # switch back 241 .code32 242 243 xorl %eax, %eax 244 movb %dl, %al # return value in %ax 245 246 cmpw $0xaa55, %bx 247 sete %dl 248 andb %dl, %al 249 250 andb %cl, %al 251 252 popl %edi 253 popl %esi 254 popl %edx 255 popl %ecx 256 popl %ebx 257 popl %ebp 258 ret 259 260 /* 261 * BIOS call "INT 0x13 Function 0x42" to read sectors from disk into memory 262 * Call with %ah = 0x42 263 * %ds:%si = parameter block (data buffer address 264 * must be a real mode physical address). 265 * %dl = drive (0x80 for hard disk, 0x0 for floppy disk) 266 * Return: 267 * %al = 0x0 on success; err code on failure 268 */ 269 ENTRY(biosextread) 270 pushl %ebp 271 movl %esp, %ebp 272 pushl %ebx 273 push %ecx 274 push %edx 275 push %esi 276 push %edi 277 278 movb 8(%ebp), %dl # device 279 movl 12(%ebp), %esi # parameter block 280 281 call _C_LABEL(prot_to_real) # enter real mode 282 .code16 283 284 movl %esi, %eax 285 shrl $4, %eax 286 movw %ds, %bx 287 addw %bx, %ax 288 movw %ax, %ds 289 andw $0xf, %si 290 291 movb $0x42, %ah # subfunction 292 int $0x13 293 setc %bl 294 movb %ah, %bh # save error code 295 296 calll _C_LABEL(real_to_prot) # back to protected mode 297 .code32 298 299 xorl %eax, %eax 300 movw %bx, %ax # return value in %ax 301 302 pop %edi 303 pop %esi 304 pop %edx 305 pop %ecx 306 popl %ebx 307 popl %ebp 308 ret 309 310 ENTRY(int13_getextinfo) 311 pushl %ebp 312 movl %esp, %ebp 313 pushl %ebx 314 push %ecx 315 push %edx 316 push %esi 317 push %edi 318 319 movb 8(%ebp), %dl # device 320 movl 12(%ebp), %esi # parameter block 321 322 call _C_LABEL(prot_to_real) # enter real mode 323 .code16 324 325 movl %esi, %eax 326 shrl $4, %eax 327 andw $0xf, %si 328 movw %ds, %bx 329 addw %bx, %ax 330 movw %ax, %ds 331 332 movb $0x48, %ah # subfunction 333 int $0x13 334 setc %bl 335 336 calll _C_LABEL(real_to_prot) # back to protected mode 337 .code32 338 339 xorl %eax, %eax 340 movb %bl, %al # return value in %ax 341 342 pop %edi 343 pop %esi 344 pop %edx 345 pop %ecx 346 popl %ebx 347 popl %ebp 348 ret 349
Indexes created Wed Oct 15 16:09:53 GMT 2025