bios_disk.S revision 1.11
1 /* $NetBSD: bios_disk.S,v 1.11 2003/02/05 21:41:51 dsl 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 128 129 call _C_LABEL(prot_to_real) # enter real mode 130 .code16 131 132 movl 28(%bp), %ebx # buffer address (may be >64k) 133 movl %ebx, %eax 134 shrl $4, %eax # max segment 135 andl $0xf, %ebx # and min offset - to avoid overrun 136 mov %ds, %si 137 add %si, %ax 138 mov %ax, %es # %es:%bx now valid buffer address 139 140 movb $0x2, %ah # subfunction 141 movb 24(%bp), %al # number of sectors 142 int $0x13 143 setc %bl 144 movb %ah, %bh # save error code 145 146 calll _C_LABEL(real_to_prot) # back to protected mode 147 .code32 148 149 xorl %eax, %eax 150 movw %bx, %ax # return value in %ax 151 152 pop %edi 153 pop %esi 154 pop %edx 155 pop %ecx 156 popl %ebx 157 popl %ebp 158 ret 159 160 /* 161 # 162 # get_diskinfo(): return a word that represents the 163 # max number of sectors, heads and cylinders for this device 164 # 165 */ 166 167 ENTRY(get_diskinfo) 168 pushl %ebp 169 movl %esp, %ebp 170 push %es 171 pushl %ebx 172 push %ecx 173 push %edx 174 push %esi 175 push %edi 176 177 movb 8(%ebp), %dl # diskinfo(drive #) 178 179 call _C_LABEL(prot_to_real) # enter real mode 180 .code16 181 182 movb $0x08, %ah # ask for disk info 183 int $0x13 184 jnc ok 185 186 /* 187 * Urk. Call failed. It is not supported for floppies by old BIOS's. 188 * Guess it's a 15-sector floppy. Initialize all the registers for 189 * documentation, although we only need head and sector counts. 190 */ 191 # subb %ah, %ah # %ax = 0 192 # movb %ah, %bh # %bh = 0 193 # movb $2, %bl # %bl bits 0-3 = drive type, 2 = 1.2M 194 movb $79, %ch # max track 195 movb $15, %cl # max sector 196 movb $1, %dh # max head 197 # movb $1, %dl # # floppy drives installed 198 # es:di = parameter table 199 # carry = 0 200 201 ok: 202 calll _C_LABEL(real_to_prot) # back to protected mode 203 .code32 204 205 /* form a longword representing all this gunk */ 206 shll $8, %ecx 207 movb %dh, %cl 208 209 movl %ecx, %eax 210 211 pop %edi 212 pop %esi 213 pop %edx 214 pop %ecx 215 popl %ebx 216 pop %es 217 popl %ebp 218 ret 219 220 /* 221 # int13_extension: check for availibility of int13 extensions. 222 */ 223 224 ENTRY(int13_extension) 225 pushl %ebp 226 movl %esp, %ebp 227 pushl %ebx 228 pushl %ecx 229 pushl %edx 230 pushl %esi 231 pushl %edi 232 233 movb 8(%ebp), %dl # drive # 234 movw $0x55aa, %bx 235 236 call _C_LABEL(prot_to_real) # enter real mode 237 .code16 238 239 movb $0x41, %ah # ask for disk info 240 int $0x13 241 setnc %dl 242 243 calll _C_LABEL(real_to_prot) # switch back 244 .code32 245 246 xorl %eax, %eax 247 movb %dl, %al # return value in %ax 248 249 cmpw $0xaa55, %bx 250 sete %dl 251 andb %dl, %al 252 253 andb %cl, %al 254 255 popl %edi 256 popl %esi 257 popl %edx 258 popl %ecx 259 popl %ebx 260 popl %ebp 261 ret 262 263 /* 264 # BIOS call "INT 0x13 Function 0x42" to read sectors from disk into memory 265 # Call with %ah = 0x42 266 # %ds:%si = parameter block (data buffer address 267 # must be a real mode physical address). 268 # %dl = drive (0x80 for hard disk, 0x0 for floppy disk) 269 # Return: 270 # %al = 0x0 on success; err code on failure 271 */ 272 ENTRY(biosextread) 273 pushl %ebp 274 movl %esp, %ebp 275 pushl %ebx 276 push %ecx 277 push %edx 278 push %esi 279 push %edi 280 281 movb 8(%ebp), %dl # device 282 movl 12(%ebp), %esi # parameter block 283 284 call _C_LABEL(prot_to_real) # enter real mode 285 .code16 286 287 movl %esi, %eax 288 shrl $4, %eax 289 movw %ds, %bx 290 addw %bx, %ax 291 movw %ax, %ds 292 andw $0xf, %si 293 294 movb $0x42, %ah # subfunction 295 int $0x13 296 setc %bl 297 movb %ah, %bh # save error code 298 299 calll _C_LABEL(real_to_prot) # back to protected mode 300 .code32 301 302 xorl %eax, %eax 303 movw %bx, %ax # return value in %ax 304 305 pop %edi 306 pop %esi 307 pop %edx 308 pop %ecx 309 popl %ebx 310 popl %ebp 311 ret 312 313 ENTRY(int13_getextinfo) 314 pushl %ebp 315 movl %esp, %ebp 316 pushl %ebx 317 push %ecx 318 push %edx 319 push %esi 320 push %edi 321 322 movb 8(%ebp), %dl # device 323 movl 12(%ebp), %esi # parameter block 324 movl $0x01a, (%esi) # length (v 1.x) 325 326 call _C_LABEL(prot_to_real) # enter real mode 327 .code16 328 329 movl %esi, %eax 330 shrl $4, %eax 331 andw $0xf, %si 332 movw %ds, %bx 333 addw %bx, %ax 334 movw %ax, %ds 335 336 movb $0x48, %ah # subfunction 337 int $0x13 338 setc %bl 339 340 calll _C_LABEL(real_to_prot) # back to protected mode 341 .code32 342 343 xorl %eax, %eax 344 movb %bl, %al # return value in %ax 345 346 pop %edi 347 pop %esi 348 pop %edx 349 pop %ecx 350 popl %ebx 351 popl %ebp 352 ret 353
Indexes created Wed Oct 22 13:09:56 GMT 2025