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Re: MIPS/Linux assembly issue

To: adnan iqbal <adnan.iqbal@seecs.edu.pk>
Subject: Re: MIPS/Linux assembly issue
From: Wu Zhangjin <wuzhangjin@gmail.com>
Date: Fri, 21 May 2010 20:30:01 +0800
Cc: linux-mips@linux-mips.org
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Organization: DSLab, Lanzhou University, China
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References: <AANLkTikrUGzUykZJwoK3Jq9mEJa6l35jo5DXHae3vbIG@mail.gmail.com>
Reply-to: wuzhangjin@gmail.com
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Hi,

Just found Arnaud have explained the problems, so here give you an
example I have written one year ago:

# File: hello.s -- Say Hello to MIPS Assembly Language Programmer
# Author: falcon <wuzhangjin@gmail.com>, 2009/01/17
# Ref: 
#    [*] http://www.tldp.org/HOWTO/Assembly-HOWTO/mips.html
#    [*] MIPS Assembly Language Programmer's Guide
#    [*] See MIPS Run Linux(second version)
# Compile:
#       $ gcc -o hello hello.s
#       or
#       $ as -o hello.o hello.s
#       $ ld -e main -o hello hello.o

    .text
    .globl main
main:

    .set noreorder
    .cpload $gp       # setup the pointer to global data
    .set reorder
                      # print sth. via sys_write
    li $a0, 1         # print to standard ouput 
    la $a1, stradr    # set the string address
    lw $a2, strlen    # set the string length
    li $v0, 4004      # index of sys_write: 
                      # __NR_write in /usr/include/asm/unistd.h
    syscall           # causes a system call trap.

                      # exit via sys_exit
    move $a0, $0      # exit status as 0
    li $v0, 4001      # index of sys_exit
                      # __NR_exit in /usr/include/asm/unistd.h
    syscall

    .rdata
stradr: .asciiz "hello, world!\n"
strlen: .word . - stradr  # current address - the string address
# end

Regards,
        Wu Zhangjin

On Fri, 2010-05-21 at 16:46 +0500, adnan iqbal wrote:
> Hi all,
> 
> I am trying to compile/link/execute following very simple program in
> debian/MIPS (Tried on Qemu and Octeon). I am getting errors while
> executing the program. gdb also shows a strange behavior showing
> program entrypoint somehere in data segement. Any help getting this
> sorted out shall be appreciated.
> 
> Regards
> Adnan
> 
> Commands used to compile/link
> ----------------------------------------------------
> $ as hello.s -o hello.o
> $ld hello.o -o hello
> $ ./hello
> 
> 
> The code
> ---------------
>       .data
> str:
>         .asciiz "hello world\n"
>         .text
>         .globl __start
> 
> __start:
>         jal f2
>         la $4,str
>         li $2,4
>         syscall
> 
>         ## terminate program via _exit () system call
>         li $2, 10
>         syscall
> f2:
>         add $8,$8,$0
>         jr $31
>      



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