Teco L510 VFD Driver installation

Hello! I'm new to the forum but have used it as a resource for 6 months or so. I have a Teco L510 VFD I'm trying to control via RS-485. I found the driver that someone has so generously created. I've been trying to figure out how to install it for at least a month. After numerous google searches, consulting linuxcnc.org and trying many different things I've finally decided it was time to ask for help! I'm pretty computer literate(code html,css,etc.), but linux is so foreign to me...

From what I gather, in terminal I'm supposed to navigate to the directory that contains the L510_vfd.c file and submakefile, and
"halcompile --install L510_vfd.c" I've done this and a ton of different other things and keep getting errors. Should I be placing the files in a specific directory before compiling? Also, how is the submakefile installed/used? Any help is greatly appreciated.

Here's the errors when I try to install it. Tried looking up the missing file but didn't find anything related to linuxcnc/debian.

g0704@g0704:~/Desktop$ cd l510_vfd-master
g0704@g0704:~/Desktop/l510_vfd-master$ ls
l510_vfd.c README.md Submakefile
g0704@g0704:~/Desktop/l510_vfd-master$ halcompile --install l510_vfd.c
make KBUILD_EXTRA_SYMBOLS=/usr/realtime-3.4-9-rtai-686-pae/modules/linuxcnc/Module.symvers -C /usr/src/linux-headers-3.4-9-rtai-686-pae SUBDIRS=`pwd` CC=gcc V=0 modules
make[1]: Entering directory `/usr/src/linux-headers-3.4-9-rtai-686-pae'
CC [M] /tmp/tmp2JMyA2/l510_vfd.o
/tmp/tmp2JMyA2/l510_vfd.c:29:19: fatal error: stdio.h: No such file or directory
compilation terminated.
make[4]: *** [/tmp/tmp2JMyA2/l510_vfd.o] Error 1
make[3]: *** [_module_/tmp/tmp2JMyA2] Error 2
make[2]: *** [sub-make] Error 2
make[1]: *** [all] Error 2
make[1]: Leaving directory `/usr/src/linux-headers-3.4-9-rtai-686-pae'
make: *** [modules] Error 2

I tried it once before, but tried again so you can see the result.

g0704@g0704:~/Desktop$ sudo halcompile --install l510_vfd.c
[sudo] password for g0704:
make KBUILD_EXTRA_SYMBOLS=/usr/realtime-3.4-9-rtai-686-pae/modules/linuxcnc/Module.symvers -C /usr/src/linux-headers-3.4-9-rtai-686-pae SUBDIRS=`pwd` CC=gcc V=0 modules
make[1]: Entering directory `/usr/src/linux-headers-3.4-9-rtai-686-pae'
CC [M] /tmp/tmpNKgA_5/l510_vfd.o
/tmp/tmpNKgA_5/l510_vfd.c:29:19: fatal error: stdio.h: No such file or directory
compilation terminated.
make[4]: *** [/tmp/tmpNKgA_5/l510_vfd.o] Error 1
make[3]: *** [_module_/tmp/tmpNKgA_5] Error 2
make[2]: *** [sub-make] Error 2
make[1]: *** [all] Error 2
make[1]: Leaving directory `/usr/src/linux-headers-3.4-9-rtai-686-pae'
make: *** [modules] Error 2

Yeah I tried that early on also. The first time I did it installed, but now just says newest version is already installed. Still have the same error. Could the driver be looking for includes in the wrong directory or something like that?

I tried all of their suggestions, no luck though. Thanks, for the suggestions. I'm gonna keep working on it in my spare time, see if I can get it figured out.