From: Tu Ha <httu@tma.com.vn>
To: linux-assembly@vger.kernel.org
Subject: please help me
Date: 24 Apr 2006 06:11:31 -0400 [thread overview]
Message-ID: <1145873491.3998.17.camel@gaucon> (raw)
Hi,
I am a beginner writing a boot loader. I use gas to write it and got a
weird issue. The following code just try to show out the screen the
symbol "1" ten times
.code16
.section .text
.globl _start
_start:
movw $STACK_SEGMENT, %sp
movw %sp, %ss
movw $STACK_SIZE, %sp
pushw %cs
popw %ds
pushw $SCREEN_SEGMENT
popw %es
jmp show_banner
show_banner:
movb $0x07, %ah #white on black
movb char, %al #show this char
movw $10, %cx #show this char 10 times
movw $0, %di #show at 0,0
run_banner:
movw %ax, %es:(%di)
inc %di
inc %di
loop run_banner
die: jmp die
#.section .data
char: .ascii "1"
.org 510
boot_flag: .word 0xAA55
#constants
.equ STACK_SEGMENT , 0x9000 # Top of conventional memory
.equ STACK_SIZE , 0xffff # 64K - 1 bytes of stack
.equ SCREEN_SEGMENT , 0xb800
However, when running, it shows out a symbol in the extend ascii table
instead of "1" !!!?
It seems I cannot reference to the "char" memory location. Why?
How can I debug the binary?
Any help is appreciated.
Tuha.
next reply other threads:[~2006-04-24 10:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-24 10:11 Tu Ha [this message]
2006-04-24 4:11 ` please help me Frank Kotler
2006-04-24 12:09 ` Tu Ha
[not found] <000101c6734a$573086d0$c41e1ec7@TuThuyHa>
2006-05-09 16:17 ` Frank Kotler
2006-05-10 14:05 ` httu
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