bios_disk.S revision 1.19.4.1
1 /* $NetBSD: bios_disk.S,v 1.19.4.1 2011/03/05 20:50:44 rmind 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(biosdisk_reset) 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 movzwl %bx, %eax # return value in %eax 86 87 pop %edi 88 pop %edx 89 popl %ebx 90 popl %ebp 91 ret 92 93 /* 94 * BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory 95 * Call with %ah = 0x2 96 * %al = number of sectors 97 * %ch = cylinder 98 * %cl = sector 99 * %dh = head 100 * %dl = drive (0x80 for hard disk, 0x0 for floppy disk) 101 * %es:%bx = segment:offset of buffer 102 * Return: 103 * %al = 0x0 on success; err code on failure 104 * 105 * biosdisk_read(dev, cyl, head, sect, count, buff_addr); 106 * 107 * Note: On failure, you must reset the disk with biosdisk_reset() before 108 * sending another command. 109 */ 110 ENTRY(biosdisk_read) 111 pushl %ebp 112 movl %esp, %ebp 113 pushl %ebx 114 push %ecx 115 push %edx 116 push %esi 117 push %edi 118 119 movb 16(%ebp), %dh 120 movw 12(%ebp), %cx 121 xchgb %ch, %cl # cylinder; the highest 2 bits of cyl is in %cl 122 rorb $2, %cl 123 movb 20(%ebp), %al 124 orb %al, %cl 125 incb %cl # sector; sec starts from 1, not 0 126 movb 8(%ebp), %dl # device 127 movl 28(%ebp), %ebx # buffer address (may be >64k) 128 movb 24(%ebp), %al # number of sectors 129 130 call _C_LABEL(prot_to_real) # enter real mode 131 .code16 132 133 push %bx 134 shrl $4, %ebx # max segment 135 mov %ds, %si 136 add %si, %bx 137 mov %bx, %es # %es:%bx now valid buffer address 138 pop %bx 139 and $0xf, %bx # and min offset - to avoid overrun 140 141 movb $0x2, %ah # subfunction 142 int $0x13 143 setc %al # error code is in %ah 144 145 calll _C_LABEL(real_to_prot) # back to protected mode 146 .code32 147 148 movzwl %ax, %eax # return value in %eax 149 150 pop %edi 151 pop %esi 152 pop %edx 153 pop %ecx 154 popl %ebx 155 popl %ebp 156 ret 157 158 /* 159 * biosdisk_getinfo(int dev): return a word that represents the 160 * max number of sectors, heads and cylinders for this device 161 */ 162 ENTRY(biosdisk_getinfo) 163 pushl %ebp 164 movl %esp, %ebp 165 push %es 166 pushl %ebx 167 push %ecx 168 push %edx 169 push %esi 170 push %edi 171 172 movb 8(%ebp), %dl # diskinfo(drive #) 173 174 call _C_LABEL(prot_to_real) # enter real mode 175 .code16 176 177 push %dx # save drive # 178 movb $0x08, %ah # ask for disk info 179 int $0x13 180 pop %bx # restore drive # 181 jnc ok 182 183 testb $0x80, %bl # is it a hard disk? 184 jnz 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 xorw %ax, %ax # set status to success 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 shrl $8, %eax # clear unnecessary bits 207 shll $24, %eax 208 shll $16, %ecx # do the same for %ecx 209 shrl $8, %ecx 210 movb %dh, %cl # max head 211 orl %ecx, %eax # return value in %eax 212 213 pop %edi 214 pop %esi 215 pop %edx 216 pop %ecx 217 popl %ebx 218 pop %es 219 popl %ebp 220 ret 221 222 /* 223 * int biosdisk_int13ext(int dev): 224 * check for availibility of int13 extensions. 225 */ 226 ENTRY(biosdisk_int13ext) 227 pushl %ebp 228 movl %esp, %ebp 229 pushl %ebx 230 pushl %ecx 231 pushl %edx 232 pushl %esi 233 pushl %edi 234 235 movb 8(%ebp), %dl # drive # 236 movw $0x55aa, %bx 237 238 call _C_LABEL(prot_to_real) # enter real mode 239 .code16 240 241 movb $0x41, %ah # ask for disk info 242 int $0x13 243 setnc %dl 244 245 calll _C_LABEL(real_to_prot) # switch back 246 .code32 247 248 movzbl %dl, %eax # return value in %eax 249 250 cmpw $0xaa55, %bx 251 sete %dl 252 andb %dl, %al 253 254 andb %cl, %al 255 256 popl %edi 257 popl %esi 258 popl %edx 259 popl %ecx 260 popl %ebx 261 popl %ebp 262 ret 263 264 /* 265 * BIOS call "INT 0x13 Function 0x42" to read sectors from disk into memory 266 * Call with %ah = 0x42 267 * %ds:%si = parameter block (data buffer address 268 * must be a real mode physical address). 269 * %dl = drive (0x80 for hard disk, 0x0 for floppy disk) 270 * Return: 271 * %al = 0x0 on success; err code on failure 272 */ 273 ENTRY(biosdisk_extread) 274 pushl %ebp 275 movl %esp, %ebp 276 pushl %ebx 277 push %ecx 278 push %edx 279 push %esi 280 push %edi 281 282 movb 8(%ebp), %dl # device 283 movl 12(%ebp), %esi # parameter block 284 285 call _C_LABEL(prot_to_real) # enter real mode 286 .code16 287 288 push %ds 289 movl %esi, %eax 290 shrl $4, %eax 291 movw %ds, %bx 292 addw %bx, %ax 293 movw %ax, %ds 294 andw $0xf, %si 295 296 movb $0x42, %ah # subfunction 297 int $0x13 298 setc %bl 299 movb %ah, %bh # save error code 300 pop %ds 301 302 calll _C_LABEL(real_to_prot) # back to protected mode 303 .code32 304 305 movzwl %bx, %eax # return value in %eax 306 307 pop %edi 308 pop %esi 309 pop %edx 310 pop %ecx 311 popl %ebx 312 popl %ebp 313 ret 314 315 ENTRY(biosdisk_getextinfo) 316 pushl %ebp 317 movl %esp, %ebp 318 pushl %ebx 319 push %ecx 320 push %edx 321 push %esi 322 push %edi 323 324 movb 8(%ebp), %dl # device 325 movl 12(%ebp), %esi # parameter block 326 327 call _C_LABEL(prot_to_real) # enter real mode 328 .code16 329 330 push %ds 331 movl %esi, %eax 332 shrl $4, %eax 333 andw $0xf, %si 334 movw %ds, %bx 335 addw %bx, %ax 336 movw %ax, %ds 337 338 movb $0x48, %ah # subfunction 339 int $0x13 340 setc %bl 341 pop %ds 342 343 calll _C_LABEL(real_to_prot) # back to protected mode 344 .code32 345 346 movzbl %bl, %eax # return value in %eax 347 348 pop %edi 349 pop %esi 350 pop %edx 351 pop %ecx 352 popl %ebx 353 popl %ebp 354 ret 355
Indexes created Wed Oct 15 16:09:53 GMT 2025