Basic light weight teeworlds 0.7 client written in pure assembly. Terminal only (no gui) and no external dependencies. Not even libc.
# debian / ubuntu
sudo apt install nasm make
It requires nasm 2.16 or newer.
make
./teeworlds_asmr "connect 127.0.0.1:8303"- Can connect to teeworlds 0.7 and ddnet 0.7 servers.
- Walk left and right with "a" and "d" keys
- Get basic log output from broadcast/motd and chat
To debug syscalls you can use strace to see args passed to kernel calls and also see the error message the linux kernel gives you back.
strace ./teeworlds_asmr
For full on assembly debugging. You can turn on symbols and step instruction by instruction.
make clean
make debug
gdb ./teeworlds_asmr
(gdb) layout asm
(gdb) set disassembly-flavor intel
(gdb) break _start
(gdb) stepi
After the last stepi just spam enter to "run" the program.
The gdb extension peda is quite helpful. It shows useful details while stepping.
Implement enough client side teeworlds 0.7 protocol to have a headless (without graphics) client that can connect to real teeworlds servers. Written in pure assembly without depending on any external library not even libc.
Thanks to these blog posts and documentations. They helped a lot.
- https://x64.syscall.sh/
- http://ansonliu.com/si485-site/lec/15/lec.html
- https://blog.rchapman.org/posts/Linux_System_Call_Table_for_x86_64/
- https://www.nasm.us/doc/nasmdoc3.html
- http://www.egr.unlv.edu/~ed/assembly64.pdf
- https://wiki.cdot.senecacollege.ca/wiki/X86_64_Register_and_Instruction_Quick_Start
- https://www.felixcloutier.com/x86/
- https://cs.lmu.edu/~ray/notes/nasmtutorial/
- https://web.stanford.edu/class/cs107/resources/x86-64-reference.pdf
- https://cs.brown.edu/courses/cs033/docs/guides/x64_cheatsheet.pdf
- https://www.cs.uaf.edu/2017/fall/cs301/reference/x86_64.html
- https://lwn.net/Articles/604287/