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324 lines
7.1 KiB
ArmAsm
324 lines
7.1 KiB
ArmAsm
/*
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* Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992
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*
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* Mach Operating System
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* Copyright (c) 1992, 1991 Carnegie Mellon University
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* All Rights Reserved.
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*
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* Permission to use, copy, modify and distribute this software and its
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* documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
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* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie Mellon
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* the rights to redistribute these changes.
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*/
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/*
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* HISTORY
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* $Log: start.s,v $
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* Revision 2.2 92/04/04 11:36:29 rpd
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* Fix Intel Copyright as per B. Davies authorization.
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* [92/04/03 rvb]
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* Need to zero dh on hd path; at least for an adaptec card.
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* [92/01/14 rvb]
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*
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* From 2.5 boot:
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* Flush digit printing.
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* Fuse floppy and hd boot by using Int 21 to tell
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* boot type (slightly dubious since Int 21 is DOS
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* not BIOS)
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* [92/03/30 mg32]
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*
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* Revision 2.2 91/04/02 14:42:04 mbj
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* Fix the BIG boot bug. We had missed a necessary data
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* before a xor that was clearing a register used later
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* as an index register.
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* [91/03/01 rvb]
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* Remember floppy type for swapgeneric
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* Add Intel copyright
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* [90/02/09 rvb]
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*
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*/
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/*
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Copyright 1988, 1989, 1990, 1991, 1992
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by Intel Corporation, Santa Clara, California.
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All Rights Reserved
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Permission to use, copy, modify, and distribute this software and
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its documentation for any purpose and without fee is hereby
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granted, provided that the above copyright notice appears in all
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copies and that both the copyright notice and this permission notice
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appear in supporting documentation, and that the name of Intel
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not be used in advertising or publicity pertaining to distribution
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of the software without specific, written prior permission.
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INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
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INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS,
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IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
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CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
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NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
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WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "asm.h"
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.file "start.s"
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BOOTSEG = 0x9000 # boot will be loaded at 640k-64k
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BOOTSTACK = 0xe000 # boot stack
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SIGNATURE = 0xaa55
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LOADSZ = 14 # size of unix boot
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PARTSTART = 0x1be # starting address of partition table
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NUMPART = 4 # number of partitions in partition table
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PARTSZ = 16 # each partition table entry is 16 bytes
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BSDPART = 0xA5 # value of boot_ind, means bootable partition
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BOOTABLE = 0x80 # value of boot_ind, means bootable partition
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.text
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ENTRY(boot1)
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# boot1 is loaded at 0x0:0x7c00
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# ljmp to the next instruction to set up %cs
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data32
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ljmp $0x7c0, $start
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start:
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# set up %ds
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mov %cs, %ax
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mov %ax, %ds
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# set up %ss and %esp
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data32
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mov $BOOTSEG, %eax
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mov %ax, %ss
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data32
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mov $BOOTSTACK, %esp
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/*** set up %es, (where we will load boot2 to) ***/
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mov %ax, %es
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#ifdef DEBUG
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data32
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mov $one, %esi
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data32
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call message
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#endif
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# get the boot drive id
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movb $0x33, %ah
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movb $0x05, %al
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int $0x21
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cmpb $0x80, %dl
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data32
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jge hd
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fd:
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# reset the disk system
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#ifdef DEBUG
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data32
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mov $two, %esi
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data32
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call message
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#endif
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movb $0x0, %ah
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int $0x13
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data32
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mov $0x0001, %ecx # cyl 0, sector 1
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data32
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#ifdef DEBUG
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data32
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mov $three, %esi
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data32
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call message
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#endif
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jmp load
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hd: /**** load sector 0 into the BOOTSEG ****/
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#ifdef DEBUG
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data32
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mov $four, %esi
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data32
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call message
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#endif
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data32
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mov $0x0201, %eax
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xor %ebx, %ebx # %bx = 0
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data32
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mov $0x0001, %ecx
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#ifdef DEBUG
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data32
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mov $five, %esi
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data32
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call message
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#endif
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data32
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andl $0xff, %edx
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/*mov $0x0080, %edx*/
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int $0x13
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data32
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jb read_error
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/***# find the bootable partition *****/
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data32
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mov $PARTSTART, %ebx
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data32
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mov $NUMPART, %ecx
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again:
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addr16
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movb %es:4(%ebx), %al
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cmpb $BSDPART, %al
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data32
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je found
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data32
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add $PARTSZ, %ebx
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data32
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loop again
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data32
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mov $enoboot, %esi
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data32
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jmp err_stop
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/*
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# BIOS call "INT 0x13 Function 0x2" to read sectors from disk into memory
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# Call with %ah = 0x2
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# %al = number of sectors
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# %ch = cylinder
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# %cl = sector
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# %dh = head
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# %dl = drive (0x80 for hard disk, 0x0 for floppy disk)
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# %es:%bx = segment:offset of buffer
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# Return:
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# %al = 0x0 on success; err code on failure
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*/
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found:
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addr16
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movb %es:1(%ebx), %dh /* head */
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addr16
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xor %ecx, %ecx
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addr16
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movw %es:2(%ebx), %ecx /*sect,cyl (+ 2 bytes junk in top word )*/
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load:
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movb $0x2, %ah /* function 2 */
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movb $LOADSZ, %al /* number of blocks */
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xor %ebx, %ebx /* %bx = 0, put it at 0 in the BOOTSEG */
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int $0x13
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data32
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jb read_error
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# ljmp to the second stage boot loader (boot2).
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# After ljmp, %cs is BOOTSEG and boot1 (512 bytes) will be used
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# as an internal buffer "intbuf".
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#ifdef DEBUG
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data32
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mov $six, %esi
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data32
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call message
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#endif
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data32
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ljmp $BOOTSEG, $EXT(boot2)
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#
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# read_error
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#
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read_error:
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data32
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mov $eread, %esi
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err_stop:
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data32
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call message
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data32
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jmp stop
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#
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# message: write the error message in %ds:%esi to console
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#
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message:
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# Use BIOS "int 10H Function 0Eh" to write character in teletype mode
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# %ah = 0xe %al = character
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# %bh = page %bl = foreground color (graphics modes)
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data32
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push %eax
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data32
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push %ebx
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data32
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mov $0x0001, %ebx
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cld
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nextb:
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lodsb # load a byte into %al
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cmpb $0x0, %al
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data32
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je done
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movb $0xe, %ah
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int $0x10 # display a byte
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data32
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jmp nextb
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done:
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data32
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pop %ebx
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data32
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pop %eax
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data32
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ret
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stop: hlt
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data32
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jmp stop # halt doesnt actually halt forever
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/* error messages */
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#ifdef DEBUG
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one: String "1\r\n\0"
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two: String "2\r\n\0"
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three: String "3\r\n\0"
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four: String "4\r\n\0"
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five: String "5\r\n\0"
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six: String "6\r\n\0"
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seven: String "7\r\n\0"
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#endif DEBUG
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eread: String "Read error\r\n\0"
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enoboot: String "No bootable partition\r\n\0"
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endofcode:
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/* throw in a partition in case we are block0 as well */
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/* flag,head,sec,cyl,typ,ehead,esect,ecyl,start,len */
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. = EXT(boot1) + PARTSTART
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.byte 0x0,0,0,0,0,0,0,0
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.long 0,0
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.byte 0x0,0,0,0,0,0,0,0
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.long 0,0
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.byte 0x0,0,0,0,0,0,0,0
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.long 0,0
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.byte BOOTABLE,0,1,0,BSDPART,255,255,255
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.long 0,50000
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/* the last 2 bytes in the sector 0 contain the signature */
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. = EXT(boot1) + 0x1fe
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.value SIGNATURE
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ENTRY(disklabel)
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. = EXT(boot1) + 0x400
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