dosstart.s

grub4dos-0.4.4-2008- 08-src.zip

//	.word	Exit_Done - nxtdev	# 2  Build BPB
//	.word	Exit_UC - nxtdev	# 3  IOCtl in
//	.word	Exit_Done - nxtdev	# 4  Input
//	.word	Exit_Busy - nxtdev	# 5  Non-destructive input
//	.word	Exit_Done - nxtdev	# 6  Input status
//	.word	Exit_Done - nxtdev	# 7  Input flush
//	.word	Exit_Done - nxtdev	# 8  Output
//	.word	Exit_Done - nxtdev	# 9  Output with verify
//	.word	Exit_Done - nxtdev	#0Ah Output status
//	.word	Exit_Done - nxtdev	#0Bh Output flush
//	.word	Exit_UC - nxtdev	#0Ch IOCtl out
//	.word	Exit_Done - nxtdev	#0Dh Device open (3.0+)
//	.word	Exit_Done - nxtdev	#0Eh Device close (3.0+)
//	.word	Exit_UC - nxtdev	#0Fh Removable media (3.0+)
//	.word	Exit_UC - nxtdev	#10h Output till busy (3.0+)
//	.word	Exit_UC - nxtdev	#11h (Unused)
//	.word	Exit_UC - nxtdev	#12h (Unused)
//	.word	Exit_UC - nxtdev	#13h Generic IOCTL (3.2:B, 3.3+:B/C)
//	.word	Exit_UC - nxtdev	#14h (Unused)
//	.word	Exit_UC - nxtdev	#15h (Unused)
//	.word	Exit_UC - nxtdev	#16h (Unused)
//	.word	Exit_UC - nxtdev	#17h Get logical device (3.2+)
//	.word	Exit_UC - nxtdev	#18h Set logical device (3.2+)
//	.word	Exit_UC - nxtdev	#19h IOCTL query (5.0+)

interrupt:
	pushfw
	cli
	cld
	pushaw
	pushw	%ds			#Save segment registers
	pushw	%es

	movw	%cs, %ax		#Make DS point to us
	movw	%ax, %ds

	lesw	ReqHeader - nxtdev, %bx	#Get ptr to request header in ES:BX
	movb	%es:2(%bx), %al		#Get command

//	cmpb	$0x19, %al		#Check if within range
//	ja      Exit_UC                 # no: set unknown command bit and exit
//	shlb	$1, %al			# yes: make word index
//	xorb	%ah, %ah
//	movw	%ax, %di		#Place it in index register
//	jmp	*(cmdtab - nxtdev)(%di)	# and jump to apropriate routine
	testb	%al, %al
	jz	Init
//Exit_Busy:
//	orw	$0x0200, %es:3(%bx)
//	jmp	Exit_Done
//Exit_UC:
	orw	$0x8103, %es:3(%bx)	#Set ERROR, DONE and UNKNOWN COMMAND
exit:
	popw	%es			#Restore segment registers
	popw	%ds
	popaw
	popfw
	lret				#Return to caller

Init:
#if 0
	/* Display CS and the original value at break address. */
	movw	%cs, %bp
	call	display_word

	movw	$0x0e0d, %ax
	int	$0x10
	movw	$0x0e0a, %ax
	int	$0x10

	lesw	ReqHeader - nxtdev, %bx	#Get ptr to request header in ES:BX
	movl	%es:14(%bx), %esi		#Set zero break address
	movl	%esi, %ebp
	shrl	$16, %ebp
	call	display_word
	movl	%esi, %ebp
	call	display_word

	movw	$0x0e0d, %ax
	int	$0x10
	movw	$0x0e0a, %ax
	int	$0x10

#endif

#if 0
	/* Show commandline (including driver name) */
	movb	$3, %ah			#Read cursor position
	xorb	%bh, %bh		# for video page 0
	int	$0x10			#(BIOS) (Returned in dx)
	lesw	ReqHeader - nxtdev, %bx	#Get ptr to request header in ES:BX
	lesw	%es:18(%bx), %bp	#Get pointer to commandline in ES:BP
	movw	%bp, %di		#Get pointer in ES:DI too
	movb	$0x0A, %al		#Terminating character of commandline
	movw	$2048, %cx		#Search max 2048 bytes
	cld
	repnz scasb			#Search for it
	movw	%di, %cx		#Get pointer to end of string
	subw	%bp, %cx		#Calculate length
	movw	$0x1301, %ax		#Write string in teletype mode
	movw	$2, %bx			# with attribute green
	int	$0x10			#(BIOS)
#endif

#if 1
	/* DS=CS */
	lesw	ReqHeader - nxtdev, %bx	#Get ptr to request header in ES:BX
	ldsw	%es:18(%bx), %si	#Get pointer to commandline in DS:SI

	movw	$0x0080, %di		#Command line will be moved to here
					#as if it is in a PSP
	movw	%cs, %ax
	addw	$((start - nxtdev) >> 4), %ax
	movw	%ax, %es

	cld
	xorw	%ax, %ax
	stosb				#store 0 at offset 0x0080, this is an
					#indicator for device driver than EXE

	/* DS:SI points to driver name */
	movw	$0xfff, %cx		/* move at most 4095 bytes */

	/* first, skip all blank characters. */

1:
	lodsb
	cmpb	$0x20, %al		/* 0x20 is space bar */
	je	1b
	cmpb	$0x09, %al		/* 0x09 is TAB */
	je	1b
	decw	%si

	/* secondly, skip the name of the driver. */

1:
	lodsb
	cmpb	$0x20, %al		/* 0x20 is space bar */
	ja	1b

	/* finally, copy the rest of the command line. */

1:
	cmpb	$0x0A, %al		/* 0x0A is LF */
	jne	2f
	movb	$0x0D, %al		/* 0x0D is CR */
2:
	cmpb	$0x0D, %al		/* 0x0D is CR */
	je	3f

	cmpb	$0x09, %al		/* 0x09 is the TAB key. */
	jne	2f
	movb	$0x20, %al
2:
	stosb
	lodsb
	loop	1b
3:
	movb	$0x00, %al		/* Ends in a NULL */
	stosb				/* the last char stored is NULL */

#endif

	movw	%cs, %ax
	movw	%ax, %ds
	lesw	ReqHeader - nxtdev, %bx	#Get ptr to request header back

	orw	$0x810C, %es:3(%bx)	#Set ERROR and DONE bits
					#          and OTHER ERROR code
	movb	$0, %es:13(%bx)		#Clear UNITS byte for CHAR device
	andw	$0x7FFF, attr - nxtdev	#Clear CHAR bit in device attrib eord

	xorw	%ax, %ax
	xchgw	%ax, %es:14(%bx)	#Set zero break address

	/* MS-DOS will initialize the break address as XXXX:0000. */

	testw	%ax, %ax		#Is it MS-DOS 5.0+ ?
	movw	%cs, %ax
	xchgw	%ax, %es:16(%bx)	#Set break address segment
	jnz	1f			#no, do not check the end address.

	/* yes, check the memory available for this device driver. */

	movw	%cs, %bx		#the driver start segment
	cmpw	%bx, %ax		#Is the end address too low?
	jbe	1f			#yes, do not check the end address.
	cmpw	$0xe000, %ax		#Is the end address too high?
	jae	1f			#yes, do not check the end address.

	/* check if we have 64K room available at the end of the driver image.
	 * This 64K space will be used for backup the HMA. Exit here if no
	 * enough memory. And 12K room for VCPI page_info, and additional
	 * 1K room for restoring EBDA from (nearly)bottom to (nearly)top of
	 * the conventional memory.
	 */

	movw	%cs, %bx		#the driver start segment

	addw	$((exe_sectors * 0x20) + 0x1000 + 0x0300 + 0x0040), %bx
					#0x1000 paragraphs = 64K (HMA_backup)
					#0x0300 paragraphs = 12K (page_info)
					#0x0040 paragraphs = 1K (EBDA)

	jc	2f			#load too high, failure
	cmpw	%bx, %ax
	jnb	1f			#check passed, continue
2:
	/* print error message. */
	movb	$3, %ah				#Read cursor position
	xorb	%bh, %bh			# for video page 0
	int	$0x10				#(BIOS) (Returned in dx)
	movw	$0x1301, %ax			#Write string in teletype mode
	movb	$3, %bl				# with attribute cyan
	movw	$(nomem_end - nomem), %cx	# length of string
	movw	$(nomem - nxtdev), %bp		# start of string
	pushw	%cs				# in es:bp
	popw	%es
	int	$0x10				#(BIOS)

	jmp     exit
1:
	//jmp	2b

#if 1

	/* Because our stack will be changed, we must backup all registers. */

	movw	%cs, %ax
	//movw	%ax, %ds		# DS=CS

//	/* DS=CS=device driver start. Adjust the exit address. */
//	movw	%ax, (device_driver_exit_cs - nxtdev)

	addw	$((start - nxtdev) >> 4), %ax
	movw	%ax, %es	/* ES:0000 now points to START */

	cld

	xorw	%di, %di
	stosl			/* EAX */
	movl	%ebx, %eax
	stosl			/* EBX */
	movl	%ecx, %eax
	stosl			/* ECX */
	movl	%edx, %eax
	stosl			/* EDX */
	movl	%edi, %eax
	stosl			/* EDI */
	movl	%esp, %eax
	stosl			/* ESP */
	movl	%ebp, %eax
	stosl			/* EBP */
	movw	%ss, %ax
	stosw			/* SS */
	movw	%fs, %ax
	stosw			/* FS */
	movw	%gs, %ax
	stosw			/* GS */

	pushfl
	popl	%eax
	stosl			/* EFLAGS */

	movl	%esi, %eax
	stosl			/* ESI */

	/* modify the stack */
	cli
	movw	%es, %ax	/* ES:0000 now points to START */
	movw	%ax, %ds
	movw	%ax, %ss
	movw	$ABS_START(dos_stack), %sp

	/* far jump to _dos_start1. */

	/* Note: DS=ES=CS tells _dos_start we are from device driver. */

	pushw	%es
	pushw	$ABS_START(_dos_start1)
	lret

	/* if need be, we could come back here from _dos_start1. */

device_driver_exit:

//	/* far jump to load CS */
//
//	.byte	0xEA		/* opcode for ljmp */
//	.word	(device_driver_exit1 - nxtdev)
//				/* offset for destination */
//device_driver_exit_cs:
//	.word	0		/* filled with driver CS */
//
//device_driver_exit1:
	cli
	cld
	movw	%cs, %ax
	movw	%ax, %ds
	movw	$(start - nxtdev), %si
	lodsl			/* EAX */
	lodsl			/* EBX */
	xchgl	%eax, %ebx
	lodsl			/* ECX */
	xchgl	%eax, %ecx
	lodsl			/* EDX */
	xchgl	%eax, %edx
	lodsl			/* EDI */
	xchgl	%eax, %edi
	lodsl			/* ESP */
	xchgl	%eax, %esp
	lodsl			/* EBP */
	xchgl	%eax, %ebp
	lodsw			/* SS */
	movw	%ax, %ss
	lodsw			/* FS */
	movw	%ax, %fs
	lodsw			/* GS */
	movw	%ax, %gs

	/* SS:SP has been restored, so it is safe to use stack. */

	lodsl			/* EFLAGS */
	pushl	%eax
	popfl

	/* direction flag here is UPWARD as we saved it before. */

	/* Another note: the direction flag does not matter, because
	 * this is the last LODS instruction executed before we exit.
	 */

	lodsl			/* ESI */
	xchgl	%eax, %esi

	jmp	exit

#endif

#if 0
display_word:
	/* routine for display hex value of BP */
	xorw	%bx, %bx
	movw	%bp, %ax
	shrw	$12, %ax
	cmpb	$9, %al
	jbe	1f
	addb	$7, %al
1:
	addb	$0x30, %al
	movb	$0x0e, %ah
	int	$0x10

	movw	%bp, %ax
	shrw	$8, %ax
	andb	$0x0f, %al
	cmpb	$9, %al
	jbe	1f
	addb	$7, %al
1:
	addb	$0x30, %al
	movb	$0x0e, %ah
	int	$0x10

	movw	%bp, %ax
	shrw	$4, %ax
	andb	$0x0f, %al
	cmpb	$9, %al
	jbe	1f
	addb	$7, %al
1:
	addb	$0x30, %al
	movb	$0x0e, %ah
	int	$0x10

	movw	%bp, %ax
	andb	$0x0f, %al
	cmpb	$9, %al
	jbe	1f
	addb	$7, %al
1:
	addb	$0x30, %al
	movb	$0x0e, %ah
	int	$0x10
	ret
#endif

nomem:
	.ascii	"\r\nError: No enough memory to run GRUB.EXE with the DEVICE command in CONFIG.SYS\r\n"
nomem_end:

#-----------------------------------------------------------------------------
#		DOS device driver structure ends here
#-----------------------------------------------------------------------------

#undef ENTRY
#define __ASSEMBLY__
#define __KERNEL__
#define __BIG_KERNEL__
#define SVGA_MODE NORMAL_VGA
	
/* stolen from linux-2.6.13.1/arch/i386/boot/bootsect.S */

/*
 *	bootsect.S		Copyright (C) 1991, 1992 Linus Torvalds
 *
 *	modified by Drew Eckhardt
 *	modified by Bruce Evans (bde)
 *	modified by Chris Noe (May 1999) (as86 -> gas)
 *	gutted by H. Peter Anvin (Jan 2003)
 *
 * BIG FAT NOTE: We're in real mode using 64k segments.  Therefore segment
 * addresses must be multiplied by 16 to obtain their respective linear
 * addresses. To avoid confusion, linear addresses are written using leading
 * hex while segment addresses are written as segment:offset.
 *
 */

#include <asm/boot.h>

SETUPSECTS	= 4			/* default nr of setup-sectors */
BOOTSEG		= 0x07C0		/* original address of boot-sector */
INITSEG		= DEF_INITSEG		/* we move boot here - out of the way */
SETUPSEG	= DEF_SETUPSEG		/* setup starts here */
SYSSEG		= DEF_SYSSEG		/* system loaded at 0x10000 (65536) */
SYSSIZE		= DEF_SYSSIZE		/* system size: # of 16-byte clicks */
					/* to be loaded */
ROOT_DEV	= 0 			/* ROOT_DEV is now written by "build" */
SWAP_DEV	= 0			/* SWAP_DEV is now written by "build" */

#ifndef SVGA_MODE
#define SVGA_MODE ASK_VGA
#endif

#ifndef RAMDISK
#define RAMDISK 0
#endif

#ifndef ROOT_RDONLY
#define ROOT_RDONLY 1
#endif

//.code16
//.text

//.global _start
//_start: