WebSVN – HelenOS – Diff – /SPARTAN/trunk/arch/ia32/boot/boot.S



 
.code16
_start_0x7c00:
	xorw %ax,%ax		# reset, %al will be used below
	movw %ax,%dx		# fd0, %dh and %dl will be used below
	movw %dx,%ds
 
	movw %dx,%ss		# initialize stack
	movw $stack,%sp
 
	int $0x13		# reset floppy
	jc stop_trying
 
	movw %dx,%ds
	movw %dx,%ss
	movw $0x7c00,%sp
	movw $0xffe0,%si	# after next increment, %si will become 0x0000
	movw %si,%es
	movw $0x8000,%bx	# at %es:%bx

	addw $0x20,%si
	movw %si,%es
 
	movw logical_sector,%ax
	divb sectors
 
	movb %ah,%cl
	incb %cl			# sector
 
	movb %al,%ch
	shrb $1,%ch			# track
 
	movb %al,%dh
	andb $1,%dh			# head
 
	movw $0x0201,%ax
	int $0x13

CH=4
echo_mark:
	push %bp
	movw %sp,%bp
	pusha
 
	movb $0xe,%ah
	movb $7,%bl
	int $0x10
 
	popa
	pop %bp
	ret
 
# current logical sector from the beginning of the disk

Rev 18	Rev 125
Line 48...	Line 48...
48		48
49	.code16	49	.code16
50	_start_0x7c00:	50	_start_0x7c00:
51	xorw %ax,%ax # reset, %al will be used below	51	xorw %ax,%ax # reset, %al will be used below
52	movw %ax,%dx # fd0, %dh and %dl will be used below	52	movw %ax,%dx # fd0, %dh and %dl will be used below
53	movw %dx,%ds	53	movw %dx,%ds
54		54
55	movw %dx,%ss # initialize stack	55	movw %dx,%ss # initialize stack
56	movw $stack,%sp	56	movw $stack,%sp
57		57
58	int $0x13 # reset floppy	58	int $0x13 # reset floppy
59	jc stop_trying	59	jc stop_trying
60		60
61	movw %dx,%ds	61	movw %dx,%ds
62	movw %dx,%ss	62	movw %dx,%ss
63	movw $0x7c00,%sp	63	movw $0x7c00,%sp
64	movw $0xffe0,%si # after next increment, %si will become 0x0000	64	movw $0xffe0,%si # after next increment, %si will become 0x0000
65	movw %si,%es	65	movw %si,%es
66	movw $0x8000,%bx # at %es:%bx	66	movw $0x8000,%bx # at %es:%bx
Line 90...	Line 90...
90	addw $0x20,%si	90	addw $0x20,%si
91	movw %si,%es	91	movw %si,%es
92		92
93	movw logical_sector,%ax	93	movw logical_sector,%ax
94	divb sectors	94	divb sectors
95		95
96	movb %ah,%cl	96	movb %ah,%cl
97	incb %cl # sector	97	incb %cl # sector
98		98
99	movb %al,%ch	99	movb %al,%ch
100	shrb $1,%ch # track	100	shrb $1,%ch # track
101		101
102	movb %al,%dh	102	movb %al,%dh
103	andb $1,%dh # head	103	andb $1,%dh # head
104		104
105	movw $0x0201,%ax	105	movw $0x0201,%ax
106	int $0x13	106	int $0x13
Line 124...	Line 124...
124	CH=4	124	CH=4
125	echo_mark:	125	echo_mark:
126	push %bp	126	push %bp
127	movw %sp,%bp	127	movw %sp,%bp
128	pusha	128	pusha
129		129
130	movb $0xe,%ah	130	movb $0xe,%ah
131	movb $7,%bl	131	movb $7,%bl
132	int $0x10	132	int $0x10
133		133
134	popa	134	popa
135	pop %bp	135	pop %bp
136	ret	136	ret
137		137
138	# current logical sector from the beginning of the disk	138	# current logical sector from the beginning of the disk

Subversion Repositories HelenOS

(root)/SPARTAN/trunk/arch/ia32/boot/boot.S – Rev 18 → 125