bios_disk.S revision 1.20.6.1
1 /* $NetBSD: bios_disk.S,v 1.20.6.1 2011/06/23 14:19:16 cherry 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 pusha 67 68 movb %al, %dl # device 69 70 call _C_LABEL(prot_to_real) # enter real mode 71 .code16 72 73 movb $0x0, %ah # subfunction 74 int $0x13 75 setc %bl 76 movb %ah, %bh # save error code 77 78 calll _C_LABEL(real_to_prot) # back to protected mode 79 .code32 80 81 movzwl %bx, %eax # return value in %eax 82 movl %eax, 28(%esp) 83 84 popa 85 ret 86 87 /* 88 * BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory 89 * Call with %ah = 0x2 90 * %al = number of sectors 91 * %ch = cylinder 92 * %cl = sector 93 * %dh = head 94 * %dl = drive (0x80 for hard disk, 0x0 for floppy disk) 95 * %es:%bx = segment:offset of buffer 96 * Return: 97 * %al = 0x0 on success; err code on failure 98 * 99 * biosdisk_read(dev, cyl, head, sect, count, buff_addr); 100 * 101 * Note: On failure, you must reset the disk with biosdisk_reset() before 102 * sending another command. 103 */ 104 ENTRY(biosdisk_read) 105 pusha 106 107 movb 44(%esp), %dh 108 movw 40(%esp), %cx 109 xchgb %ch, %cl # cylinder; the highest 2 bits of cyl is in %cl 110 rorb $2, %cl 111 movb 48(%esp), %al 112 orb %al, %cl 113 incb %cl # sector; sec starts from 1, not 0 114 movb 36(%esp), %dl # device 115 movl 56(%esp), %ebx # buffer address (may be >64k) 116 movb 52(%esp), %al # number of sectors 117 118 call _C_LABEL(prot_to_real) # enter real mode 119 .code16 120 121 push %bx 122 shrl $4, %ebx # max segment 123 mov %ds, %si 124 add %si, %bx 125 mov %bx, %es # %es:%bx now valid buffer address 126 pop %bx 127 and $0xf, %bx # and min offset - to avoid overrun 128 129 movb $0x2, %ah # subfunction 130 int $0x13 131 setc %al # error code is in %ah 132 133 calll _C_LABEL(real_to_prot) # back to protected mode 134 .code32 135 136 movl %eax, 28(%esp) 137 138 popa 139 ret 140 141 /* 142 * biosdisk_getinfo(int dev): return a word that represents the 143 * max number of sectors, heads and cylinders for this device 144 */ 145 ENTRY(biosdisk_getinfo) 146 push %es 147 pusha 148 149 movb %al, %dl # diskinfo(drive #) 150 151 call _C_LABEL(prot_to_real) # enter real mode 152 .code16 153 154 push %dx # save drive # 155 movb $0x08, %ah # ask for disk info 156 int $0x13 157 pop %bx # restore drive # 158 jnc ok 159 160 testb $0x80, %bl # is it a hard disk? 161 jnz ok 162 163 /* 164 * Urk. Call failed. It is not supported for floppies by old BIOS's. 165 * Guess it's a 15-sector floppy. Initialize all the registers for 166 * documentation, although we only need head and sector counts. 167 */ 168 xorw %ax, %ax # set status to success 169 # movb %ah, %bh # %bh = 0 170 # movb $2, %bl # %bl bits 0-3 = drive type, 2 = 1.2M 171 movb $79, %ch # max track 172 movb $15, %cl # max sector 173 movb $1, %dh # max head 174 # movb $1, %dl # # floppy drives installed 175 # es:di = parameter table 176 # carry = 0 177 178 ok: 179 calll _C_LABEL(real_to_prot) # back to protected mode 180 .code32 181 182 /* form a longword representing all this gunk */ 183 shrl $8, %eax # clear unnecessary bits 184 shll $24, %eax 185 shll $16, %ecx # do the same for %ecx 186 shrl $8, %ecx 187 movb %dh, %cl # max head 188 orl %ecx, %eax # return value in %eax 189 movl %eax, 28(%esp) 190 191 popa 192 pop %es 193 ret 194 195 /* 196 * int biosdisk_int13ext(int dev): 197 * check for availibility of int13 extensions. 198 */ 199 ENTRY(biosdisk_int13ext) 200 pusha 201 202 movb %al, %dl # drive # 203 movw $0x55aa, %bx 204 205 call _C_LABEL(prot_to_real) # enter real mode 206 .code16 207 208 movb $0x41, %ah # ask for disk info 209 int $0x13 210 setnc %dl 211 212 calll _C_LABEL(real_to_prot) # switch back 213 .code32 214 215 movzbl %dl, %eax # return value in %eax 216 217 cmpw $0xaa55, %bx 218 sete %dl 219 andb %dl, %al 220 221 andb %cl, %al 222 movl %eax, 28(%esp) 223 224 popa 225 ret 226 227 /* 228 * BIOS call "INT 0x13 Function 0x42" to read sectors from disk into memory 229 * Call with %ah = 0x42 230 * %ds:%si = parameter block (data buffer address 231 * must be a real mode physical address). 232 * %dl = drive (0x80 for hard disk, 0x0 for floppy disk) 233 * Return: 234 * %al = 0x0 on success; err code on failure 235 */ 236 ENTRY(biosdisk_extread) 237 pusha 238 239 movl %edx, %esi # parameter block 240 movb %al, %dl # device 241 242 call _C_LABEL(prot_to_real) # enter real mode 243 .code16 244 245 push %ds 246 movl %esi, %eax 247 shrl $4, %eax 248 movw %ds, %bx 249 addw %bx, %ax 250 movw %ax, %ds 251 andw $0xf, %si 252 253 movb $0x42, %ah # subfunction 254 int $0x13 255 setc %bl 256 movb %ah, %bh # save error code 257 pop %ds 258 259 calll _C_LABEL(real_to_prot) # back to protected mode 260 .code32 261 262 movzwl %bx, %eax # return value in %eax 263 movl %eax, 28(%esp) 264 265 popa 266 ret 267 268 ENTRY(biosdisk_getextinfo) 269 pusha 270 271 movl %edx, %esi # parameter block 272 movb %al, %dl # device 273 274 call _C_LABEL(prot_to_real) # enter real mode 275 .code16 276 277 push %ds 278 movl %esi, %eax 279 shrl $4, %eax 280 andw $0xf, %si 281 movw %ds, %bx 282 addw %bx, %ax 283 movw %ax, %ds 284 285 movb $0x48, %ah # subfunction 286 int $0x13 287 setc %bl 288 pop %ds 289 290 calll _C_LABEL(real_to_prot) # back to protected mode 291 .code32 292 293 movzbl %bl, %eax # return value in %eax 294 movl %eax, 28(%esp) 295 296 popa 297 ret 298
Indexes created Wed Oct 15 16:09:53 GMT 2025