TCC: Difference between revisions

16/64-bit support, instructions up to MMX are supported.

 

need to recompile TCC without PE support, if you want to use this tutorial on Windows. You can

skip this step if you aren't using Windows.

 

==Building TCC with ELF support==

1. Download [http://download.savannah.gnu.org/releases/tinycc/tcc-0.9.26.tar.bz2 TCC sources] and [http://download.savannah.gnu.org/releases/tinycc/tcc-0.9.26-win32-bin.zip 32-bit TCC] and (if you have a 64-bit OS) [http://download.savannah.gnu.org/releases/tinycc/tcc-0.9.26-win64-bin.zip 64-bit TCC].

 

4. Open Notepad or another text editor, and enter this:

 

@echo off

 

 

:finished

 

5. Save to tcc-0.9.26 with any name you want, but the extension MUST be .bat. If you use notepad, you will have to change the type from "Text Documents" to "All Files".

6. Run the script, make sure everything compiled correctly (note that there may be warnings about assignments from incompatible pointer types and bound checking not supporting malloc in a certain environment, but these are okay), and inside win32-elf you should have a working ELF compiler. You should also have win32 and win64 for 32-bit and 64-bit PE compilers, and a 64-bit ELF compiler in win64-elf. Note: The 64-bit compilers won't be compiled on a non-64 bit OS.

If there are errors compiling TCC, just change the "@echo off" to "@echo on" and run the script again to see where things went wrong.

 

==A small kernel example==

 

===start32.asm===

; Tutorial: A small kernel with Fasm & TCC

; By Tommy.

jmp @b

 

 

===kernel.c===

/* Tutorial: A small kernel with Fasm & TCC

* By Tommy.

}

 

 

==Compiling and linking==

Assemble start32.asm with:

fasm start32.asm

 

Compile kernel.c with:

tcc -c kernel.c

 

Then link the whole thing with:

tcc -nostdlib -Wl,-Ttext,0x100000 start32.o kernel.o -o kernel-i386.elf

 

If you would prefer it in binary form, for example, if you're using your own bootloader that doesn't support ELF, link it with this:

tcc -nostdlib -Wl,-Ttext,0x100000 -Wl,--oformat,binary -static start32.o kernel.o -o kernel-i386.bin

 

That's all!

==Inline Assembly==

TCC supports inline GAS syntax assembly like GCC:

__asm__ __volatile__("hlt");

You can use this to your benefit for many things, such as debugging in Bochs:

#define breakpoint() __asm__ __volatile__("xchg %bx, %bx");

 

}

}

Then adding this to your bochsrc.bxrc file in a text editor:

port_e9_hack: enabled=1

magic_break: enabled=1

And from boch's install location, executing bochsdbg.exe instead of bochs.exe.

 

So if you use structs to store your GDT entries or GDTR, beware, you will encounter issues loading your GDT if you don't specify the packing of structures correctly.

When creating structures, use something like this:

// We use the attribute 'packed' to tell TCC not to change any of the alignment in the structure.

struct some_struct {

// This last attribute can be kept, it won't interfere with the compilation or output, so it may be

// useful to retain compatilbity with GCC, as long as the above attributes don't interfere with GCC.

Instead of this:

// We use the attribute 'packed' to tell GCC not to change any of the alignment in the structure.

struct some_struct {

unsigned char b;

} __attribute__((packed));