/*- * Copyright (c) 2007-2008 *      Bill Paul <wpaul@windriver.com>.  All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright *    notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright *    notice, this list of conditions and the following disclaimer in the *    documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software *    must display the following acknowledgement: *      This product includes software developed by Bill Paul. * 4. Neither the name of the author nor the names of any co-contributors *    may be used to endorse or promote products derived from this software *    without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED.  IN NO EVENT SHALL Bill Paul OR THE VOICES IN HIS HEAD * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF * THE POSSIBILITY OF SUCH DAMAGE. */#define _ASM#include "data.h"#include "disk.h"#define _SEG(x)          (((x) & 0xF0000) >> 4)#define _OFF(x)          ((x) & 0xFFFF)	.code16	.set PRT_OFF,		DOSPARTOFF              # Partition table/* Information about the 4th entry in the partition table. */	.set PRT4_START,	0x7DEE	.set PRT4_FLAGS,	0x7DEE	.set PRT4_STARTHD,	0x7DEF	.set PRT4_STARTSEC,	0x7DF0	.set PRT4_STARTCYL,	0x7DF1	.set PRT4_TYPE,		0x7DF2	.set PRT4_ENDHD,	0x7DF3	.set PRT4_ENDSEC,	0x7DF4	.set PRT4_ENDCYL,	0x7DF5	.set PRT4_START,	0x7DF6	.set PRT4_SIZE,		0x7DFA/* * Bootstrap code. * This code resides at sector 0 on a disk and is loaded by the BIOS * to 0x7c00 during bootstrap. Once we're running, we use the BIOS * to load an additional group of sectors (up to 32) from the disk * to 0x7e00, which is where the real memory dumper code will live. * As soon as the code is loaded, we branch to 0x7e00 to launch it. * When we're called, the BIOS will pass us the boot disk number * (0x0 for floppies/USB, 0x80 for hard disk) in %dl. We save this * value and insure it's still present in %dl when we invoke the * memory dump code. * * Everything here runs in real mode. We don't switch to protected * mode until we hit the startup code in the memory dumper. */	.globl	boot	.textboot:	cli	/* Clear segment registers */	ljmp	$0, $setcssetcs:	xor	%ax, %ax	mov	%ax, %ds	mov	%ax, %ss	/* Set up a temporary stack. */	mov	$boot, %sp	cld	mov	PRT4_STARTSEC, %al	/* Save the BIOS disk number */	mov	%dl, bios_disk	mov	$str1, %si	call	printf	/* Reset the drive */	mov	$INT13_RESET, %ah	mov	bios_disk, %dl	int	$DISK_INT	jc	stop	/* Check disk status */	mov	$INT13_STSCHK, %ah	mov	bios_disk, %dl	int	$DISK_INT	jc	stop	cmp	$0x0, %al	jne	stop	/* Check for extended INT13 services. */	mov	$EXT_SIG, %bx	mov	$INT13_EXTCHK, %ah	mov	bios_disk, %dl	int	$DISK_INT	jc	use_chs        cmp     $BOOT_SIG, %bx	jne	use_chs	mov	bios_disk, %dl	testb	$0x80, %dl	jz	use_chs		/*	 * Try loading the scraper code into RAM. We look at the	 * partition table entry for partition 4 in the master	 * boot record (i.e. us) and use its 'absolute starting sector	 * offset' as the location on the disk from which we will	 * read the scraper. If the scraper.bin image has been	 * written directly to a disk starting at sector 0, the entire	 * partition table will be empty, and the offset for partition	 * 4 will be zero. In effect, no offset will be applied.	 * However, if the partition table has been edited such that	 * partition 4 exists, we assume that the scraper.bin image	 * has been written there instead, and we use the start of	 * partition 4 as the start offset.	 */	/* Try using packet mode */	mov	$packet, %si	call	printf	mov	PRT4_START, %eax	inc	%eax		/* skip over the boot sector */	mov	%eax, pkt_soff1        mov	$pkt, %si        mov	$INT13_EXTRD, %ah	mov	bios_disk, %dl        int     $DISK_INT	jc	use_chs	jmp	startup	/* Try using CHS mode */use_chs:	mov	$chs, %si	call	printf	xor	%ax, %ax	mov	%ax, %es	mov	$SCRAPER_BASE, %bx	mov	$INT13_RD, %ah	mov	$DISK_SCRAPER_SIZE, %al	mov	PRT4_STARTCYL, %ch	mov	PRT4_STARTSEC, %cl	mov	PRT4_STARTHD, %dh	cmp	$0x0, %ch	jne	read	cmp	$0x0, %cl	jne	read	cmp	$0x0, %dh	jne	read	add	$1, %clread:	add	$1, %cl	mov	bios_disk, %dl	int	$DISK_INT	jc	stopstartup:	mov	$str2, %si	call	printf	mov	bios_disk, %dl	/*         * Do a long jump here instead of a jump. This prevents the	 * assembler from possibly calculating a relative offset which,	 * with the Cygwin and MinGW assembler, always seems to be	 * calculated wrong.	 */	ljmp	$0, $SCRAPER_BASEstop:	mov	$fail, %si	call	printfhalt:	hlt	jmp	halt	/*	 * Stripped down printf implementation.	 */printf:	lodsb	testb	%al, %al	jnz	putc	retputc:	movb	$0xE, %ah	movw	$0x7, %bx	int	$0x10	jmp	printfstr1:	.asciz	"Bootstrap loaded... "str2:	.asciz	"starting.\r\n"chs:	.asciz	"trying c/h/s mode... "packet:	.asciz	"trying packet mode... "fail:	.asciz	"epic fail!\r\n"bios_disk:	.word	0x00pkt:	.byte	0x10			/* structure size (16 bytes) */	.byte	0x00			/* Must be 0 */	.byte	DISK_SCRAPER_SIZE	/* 16 sectors */		.byte	0x00			/* Must also be 0 */	.word	_OFF(SCRAPER_BASE)	/* Destination buffer offset */	.word	_SEG(SCRAPER_BASE)	/* Destination buffer segment */pkt_soff1:	.long	0x00000000		/* Sector offset */pkt_soff2:	.long	0x00000000		/* Sector offset */	/* Fake partition table */	.org	PRT_OFF, 0x00partbl:	.fill	0x40,0x1,0x0		/* Partition table */	.word	BOOT_SIG		/* Magic number */