How do i run assembly (.s) files on VSCode in Linux subsystem - c

Question

I have just got into ARM programming. Learned a few basics but am having issues with running code. I use VSCode on Linux Subsystem as my IDE.
I have nothing installed on my computer and i would like to run ARM code. I have read online something about "qemu" and "kernel" and stuff, but am not sure what they mean. It would be great if someone provides a detailed walkthrough for such a problem. I do not have a raspberry pi.
For example, how do i run the following division.s file on VSCode?
.global _start
_start:
MOV R1, #X
MOV R2, #Y
MOV R3, #Z
CMP R1, R2 # is x>y ?
BGT _tryx
CMP R2, R3 # is y>z ?
BGT _isy
MOV R4, R3
B _exit
_isy:
MOV R4, R2
B _exit
_tryx:
CMP R1, R3 # is x>z ?
BGT _isx
MOV R4, R3
B _exit
_isx:
MOV R4, R1
_exit:
MOV R0, R4
MOV R7, #1
SWI 0
.data
.equ X, 3
.equ Y, 5
.equ Z, 4
Are there any extensions i need to install? Is there anything i need to download? I have used gcc to compile C code. Can it be used here too?
Thx in advance! :D

Answer 1

Your question is rather a broad one. This being said, a slightly modified version of your program can be executed in WSL using the following procedure:
sudo apt-get install qemu-user
sudo mkdir -p /opt/arm/10
wget 'https://developer.arm.com/-/media/Files/downloads/gnu-a/10.2-2020.11/binrel/gcc-arm-10.2-2020.11-x86_64-arm-none-linux-gnueabihf.tar.xz?revision=d0b90559-3960-4e4b-9297-7ddbc3e52783&la=en&hash=985078B758BC782BC338DB947347107FBCF8EF6B' -O gcc-arm-10.2-2020.11-x86_64-arm-none-linux-gnueabihf.tar.xz
sudo tar Jxf gcc-arm-10.2-2020.11-x86_64-arm-none-linux-gnueabihf.tar.xz -C /opt/arm/10
/tmp/division.s:
# count how often we can take Y from X
.global main
main:
MOV R1, #X
MOV R2, #Y
MOV R3, #0 # Q
_loop:
CMP R1, R2
BLT _exit
SUB R1, R2
ADD R3, #1
B _loop
_exit:
MOV R0, R3
MOV R7, #1
SWI 0
.data
.equ X, 23
.equ Y, 4
Compiling:
/opt/arm/10/gcc-arm-10.2-2020.11-x86_64-arm-none-linux-gnueabihf/bin/arm-none-linux-gnueabihf-gcc -static -o /tmp/division /tmp/division.s
Executing - WSL:
qemu-arm /tmp/division
echo $?
5
Which is the expected result, since 23 div 4 is 5.
Executing - Windows 10:
C:\>c:\Windows\System32\bash -c "qemu-arm /tmp/division; echo $?"
5
C:\>
Or:
C:\>c:\Windows\System32\bash -c "qemu-arm /tmp/division"
C:\>echo %ERRORLEVEL%
5
Note that division.s may have been compiled in Windows 10 as well by downloading/installing gcc-arm-10.2-2020.11-mingw-w64-i686-arm-none-linux-gnueabihf.tar.xz instead of gcc-arm-10.2-2020.11-x86_64-arm-none-linux-gnueabihf.tar.xz - your choice.
I let it to you than to go into the details of using the information above for running your program from vscode, you question being a bit too broad IMHO.
Update: division.s was compiled statically on purpose for avoiding having to specify the locations for any non-needed dynamic libraries.
Compiling it without using the -static option, and executing it would result in the following error message to be displayed:
qemu-arm division
/lib/ld-linux-armhf.so.3: No such file or directory
It can be avoided by telling qemu-arm where to look for required dynamic libraries, /lib/ld-linux-armhf.so.3 in this case:
qemu-arm -L /opt/arm/10/gcc-arm-10.2-2020.11-x86_64-arm-none-linux-gnueabihf/arm-none-linux-gnueabihf/libc division
echo $?
5

Answer 2

That looks like a Linux program. And I guess you have an 64-bit x86 computer.
You want QEMU, specifically the executable qemu-arm which emulates an ARM processor running Linux on another Linux compatible system. In Debian derived Linux distributions it is in the package qemu-arm.
And on ebian derived Linux distributions for a compiler you can install the gcc-arm-linux-gnueabihf package for compiling for ARMv7 and ARMv8 with hardware floating point (Debian port name armhf), or gcc-arm-linux-gnueabi for some older ARMs with no hardware floating point Debian port name armel).
If you wish to install libraries, you need add the architecture to dpkg's list, for example:
dpkg --add-architecture armhf