Pascal: Difference between revisions

Just like when Doing a kernel in C++, Pascal compilers mangle functions name to make them convey more information (such as arguments and return types). That means if you just write

 

unit KernelMain;

 

 

end.

 

You may end up with "THREADVARLIST_P$KERNEL_MAIN" rather than just "kernel_main" as a function name. If you're using FreePascal, the tool <tt>objdump</tt> can show you the symbol table of the .o file generated by the compiler, which will give you the "real" name of the function.

Alternatively, you could use compiler extra statements to enforce a "public name" to your function:

 

unit KernelMain;

 

 

end.

 

Finally, simply declaring a program like you would when writing Pascal code for any normal platform will create a main routine named PASCALMAIN.

 

program Kernel;

 

{Your kernel here.}

end.

 

Note, too, that C and PASCAL doesn't share the same calling convention. Most notably, arguments in PASCAL are pushed from left to right while C push them from right to left. If this gets you in trouble, you can use cdecl modifier to force the compiler considering that your PASCAL procedure works like a C function (that should mainly be useful to interface pascal code with C code). Moreover, in PASCAL, the callee function is responsible from [[Stack#Stack example on the X86 architecture|stack cleaning]], while this is typically the job of the caller in C/C++ environment.

 

== Pascal BareBones ==

Credit flies to De Deyn Kim for the freepascal, public domain version of BareBones.

 

 

=== stub.asm ===

;/////////////////////////////////////////////////////////

;// //

KERNEL_STACK:

resb KERNEL_STACKSIZE

 

=== kernel.pas ===

{

/////////////////////////////////////////////////////////

 

end.

 

=== console.pas ===

{

/////////////////////////////////////////////////////////

 

end.

 

=== multiboot.pas ===

unit multiboot;

 

 

end.

 

=== system.pas ===

unit system;

 

 

end.

 

=== Linker script ===