Hello,

I'm trying to make a really simple compiler, and i'm getting there, but i have one problem. The program makes a tree of the program, so i can traverse it and generate program code. But i would like to generate the (binary) object code, so it can actually create .EXE files, which can be run under DOS / windows. I think i can find the hex-codes of the instructions, but how can i make a REAL executable, so i don't have to make an interpreter. I've heard of the PSP, the first 256 bytes of a program, but i don't know how to write that to a file, neither (or what it is, for that matter).

Do you think you could give me some help with this? Thanks in advance.

k stol

DOS supports two types of binaries.

-- Flat binaries ending with .com that are loaded at 0x100h. ( you can find interesting DOS data structures in the PSP!! =) (16-bit)

-- MZ executables, binaries that have an executable header with important inf0z. (16-bit)

DOS programs that use dos4gw are actually a format called "Linear Executable" -- 32 bit, that are linked to a 16-bit loader stub. -- freepascal uses a similar system.

(at the dos prompt, type "type myexe.exe".. the first two letters of the output is the type.)

Windows supports several other executable types such as "PE"

To link to binaries produced by other tools, you will need to output one of the standard executable formats, OMF, ELF, a.out, etc...

Do you think you could give me some help with this? Thanks in advance.

I'll try, but I have great difficulty with that...

om

If you get anywhere with this I will surely need your experience in developing my OS. =)

I'm trying to make a really simple compiler, and i'm getting there, but i have one problem. The program makes a tree of the program, so i can traverse it and generate program code. But i would like to generate the (binary) object code, so it can actually create .EXE files, which can be run under DOS / windows. I think i can find the hex-codes of the instructions, but how can i make a REAL executable, so i don't have to make an interpreter. I've heard of the PSP, the first 256 bytes of a program, but i don't know how to write that to a file, neither (or what it is, for that matter). Do you think you could give me some help with this? Thanks in advance.

There is somewhere on the net a book online called "linkers and loaders". And for the assembler part you can have a look at the sources of nasm.

K Stol wrote

I think i can find the hex-codes of the instructions, but how can i make a REAL executable, so i don't have to make an interpreter.

I don't know how far you are in programming, but creating a real compiler is a difficult thing.
But there are alternatives between a compiler and an interpreter.

Perhaps one of these is a solution for you:

1) You could make a converter to a programming language for wich you do have a complier. Examples for this are p2c, f2c, ...

2) Another interresting solution I found in the program BEC. It creates a pseudo-code and then it attaches the pseudo-code to the interpreter, so you just have one single executable. When you start the executable, you start the interpreter and this reads the pseudo-code from itself, ie. from the same file. But the enduser doesn't have to know about that. ;-)

btw. "pseudo-code" is simply the source code with the commands replaced by single bytes. Comments may be stripped away.