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12fafb2d5a
2. Clean up the .S files to use /* */ style comments. This is a totally cosmetic change, not one byte of the resulting boot code changes. But at least it is installed with correct owners and in the right places, and gets recompiled correctly when things change!
333 lines
6.8 KiB
ArmAsm
333 lines
6.8 KiB
ArmAsm
/*
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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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* from: Mach, Revision 2.2 92/04/04 11:34:26 rpd
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* $Id: bios.S,v 1.2 1993/10/16 19:11:30 rgrimes Exp $
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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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.file "bios.s"
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#include "asm.h"
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.text
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/*
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* biosread(dev, cyl, head, sec, nsec, offset)
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* Read "nsec" sectors from disk to offset "offset" in boot segment
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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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ENTRY(biosread)
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push %ebp
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mov %esp, %ebp
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push %ebx
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push %ecx
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push %edx
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push %es
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movb 0x10(%ebp), %dh
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movw 0x0c(%ebp), %cx
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/* cylinder; the highest 2 bits of cyl is in %cl */
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xchgb %ch, %cl
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rorb $2, %cl
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movb 0x14(%ebp), %al
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orb %al, %cl
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incb %cl /* sector; sec starts from 1, not 0 */
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movb 0x8(%ebp), %dl /* device */
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movl 0x1c(%ebp), %ebx /* offset */
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/* prot_to_real will set %es to BOOTSEG */
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call EXT(prot_to_real) /* enter real mode */
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movb $0x2, %ah /* subfunction */
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addr32
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movb 0x18(%ebp), %al /* number of sectors */
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sti
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int $0x13
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cli
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/* save return value (actually movw %ax, %bx) */
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mov %eax, %ebx
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data32
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call EXT(real_to_prot) /* back to protected mode */
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xor %eax, %eax
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movb %bh, %al /* return value in %ax */
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pop %es
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pop %edx
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pop %ecx
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pop %ebx
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pop %ebp
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ret
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/*
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* putc(ch)
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* BIOS call "INT 10H Function 0Eh" to write character to console
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* Call with %ah = 0x0e
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* %al = character
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* %bh = page
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* %bl = foreground color ( graphics modes)
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*/
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ENTRY(putc)
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push %ebp
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mov %esp, %ebp
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push %ebx
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push %ecx
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movb 0x8(%ebp), %cl
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call EXT(prot_to_real)
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data32
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mov $0x1, %ebx /* %bh=0, %bl=1 (blue) */
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movb $0xe, %ah
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movb %cl, %al
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sti
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int $0x10 /* display a byte */
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cli
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data32
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call EXT(real_to_prot)
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pop %ecx
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pop %ebx
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pop %ebp
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ret
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/*
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* getc()
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* BIOS call "INT 16H Function 00H" to read character from keyboard
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* Call with %ah = 0x0
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* Return: %ah = keyboard scan code
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* %al = ASCII character
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*/
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ENTRY(getc)
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push %ebp
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mov %esp, %ebp
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push %ebx /* save %ebx */
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call EXT(prot_to_real)
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movb $0x0, %ah
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sti
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int $0x16
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cli
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movb %al, %bl /* real_to_prot uses %eax */
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data32
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call EXT(real_to_prot)
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xor %eax, %eax
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movb %bl, %al
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pop %ebx
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pop %ebp
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ret
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/*
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* ischar()
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* if there is a character pending, return it; otherwise return 0
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* BIOS call "INT 16H Function 01H" to check whether a character is pending
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* Call with %ah = 0x1
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* Return:
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* If key waiting to be input:
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* %ah = keyboard scan code
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* %al = ASCII character
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* Zero flag = clear
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* else
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* Zero flag = set
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*/
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ENTRY(ischar)
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push %ebp
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mov %esp, %ebp
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push %ebx
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call EXT(prot_to_real) /* enter real mode */
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xor %ebx, %ebx
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movb $0x1, %ah
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sti
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int $0x16
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cli
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data32
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jz nochar
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movb %al, %bl
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nochar:
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data32
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call EXT(real_to_prot)
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xor %eax, %eax
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movb %bl, %al
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pop %ebx
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pop %ebp
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ret
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/*
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*
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* get_diskinfo(): return a word that represents the
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* max number of sectors and heads and drives for this device
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*
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*/
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ENTRY(get_diskinfo)
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push %ebp
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mov %esp, %ebp
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push %es
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push %ebx
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push %ecx
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push %edx
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movb 0x8(%ebp), %dl /* diskinfo(drive #) */
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call EXT(prot_to_real) /* enter real mode */
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movb $0x8, %ah /* ask for disk info */
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sti
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int $0x13
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cli
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jnc ok
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/*
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* Urk. Call failed. It is not supported for floppies by old BIOS's.
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* Guess it's a 15-sector floppy. Initialize all the registers for
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* documentation, although we only need head and sector counts.
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*/
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subb %ah, %ah /* %ax = 0 */
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movb %al, %al
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movb %ah, %bh /* %bh = 0 */
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movb $2, %bl /* %bl bits 0-3 = drive type,
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bit 2 = 1.2M */
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movb $79, %ch /* max track */
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movb $15, %cl /* max sector */
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movb $1, %dh /* max head */
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movb $1, %dl /* # floppy drives installed */
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/* es:di = parameter table */
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/* carry = 0 */
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ok:
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data32
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call EXT(real_to_prot) /* back to protected mode */
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xor %eax, %eax
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/* form a longword representing all this gunk */
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movb %dh, %ah /* max head */
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andb $0x3f, %cl /* mask of cylinder gunk */
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movb %cl, %al /* max sector (and # sectors) */
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pop %edx
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pop %ecx
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pop %ebx
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pop %es
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pop %ebp
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ret
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/*
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*
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* memsize(i) : return the memory size in KB. i == 0 for conventional memory,
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* i == 1 for extended memory
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* BIOS call "INT 12H" to get conventional memory size
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* BIOS call "INT 15H, AH=88H" to get extended memory size
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* Both have the return value in AX.
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*
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*/
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ENTRY(memsize)
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push %ebp
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mov %esp, %ebp
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push %ebx
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mov 8(%ebp), %ebx
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call EXT(prot_to_real) /* enter real mode */
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cmpb $0x1, %bl
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data32
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je xext
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sti
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int $0x12
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cli
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data32
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jmp xdone
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xext: movb $0x88, %ah
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sti
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int $0x15
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cli
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xdone:
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mov %eax, %ebx
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data32
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call EXT(real_to_prot)
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mov %ebx, %eax
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pop %ebx
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pop %ebp
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ret
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