2011/7/20 Sébastien Doutreligne <sebastien.doutreli...@gmail.com>:
> I am involved in programming computer without any operating system on top. I
> practised intel assembly in qemu and try to run an assembly program on the
> yeeloong laptop. I use a gnu toolchain mipsel build from embedian.
>
> Here is the code:
>>
>> .text
>> .globl __start
>> __start:
>> li $8, 5
>> li $9, 5
>
> I use a linker script as such:
>>
>> SECTIONS
>> {
>> . = 0xffffffff80000000;
>> .text : { * (.text); }
>> }
>
> The makefile is as simple:
>
>> CROSS=mipsel-linux-gnu-
>> CC=${CROSS}gcc
>> OBJCOPY=${CROSS}objcopy
>> LDFLAGS=-mips3 -T test.lds -Wall -nostdlib
>>
>> test.elf: test.s test.c
>> ${CC} $(LDFLAGS) $^ -o $@
>
> Once compiled, I copy it in a tftp server directory. In the pmon's prompt, I
> set an IP address then load the program from the server.
>
> Using pmon's r command, I can't see any change in registers (t0 to t7 set to
> 00000000). So is my program really executed? Do I need any kind of
> initialization?
In order to learn MIPS Assembly, why not try it in Linux system
directly? In Linux, you can use gdb to check what you want easily.
Try the following simply example:
# File: hello.s -- Say Hello to MIPS Assembly Language Programmer
# Author: falcon <wuzhang...@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
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