[MSX-C] Q&A official thread

If you want to print the content of what buf or buf2 is pointing to you should dereference it first, using *:

printf("%d %d", (int)(*buf), (int)(*buf2);

And remember that arrays in C start counting at zero so buf2 should than point to &xi[0] to get the '1' value.

Actually there is no need for a new pointer at all, since xi itself can also be treated as a TINY* type.

Nice, now it works, here goes the code:

#include<stdio.h>

TINY xi[2]={1,2};

saveFile() {
	FILE *fp;
	fp=fopen("file.dat","wb");
	fwrite(xi,sizeof(char),sizeof(xi),fp); 
	fclose(fp);
}

readFile() {
	FILE *fp;
	TINY xo[2];
	fp=fopen("file.dat","rb");
	fread(xo,sizeof(char),sizeof(xi),fp);
	printf("%d",(int)xo[1]);
	fclose(fp);
}

main() {
	saveFile();
	readFile();
}

This works exactly as COPY Basic commands. Another working code. Thanks for your help

Should malloc be used?

Ok, here's how you compile a program by parts using MSX-C:

1) Move into their own files the function(s) that you want to move out of your program.

You need two files:

- A .h file that contains only the function declaration, plus any #includes that this function needs.
- A .c file that #includes the corresponding .h file, followed by the actual code of the function.

2) Your main program #includes the .h of the external function (or functions).

3) Create a new batch file that will compile and assemble without linking:

(note: I called this script LINK.BAT, but it doesn't actually do any linking. I should have called it ASSEMBLE.BAT or something like that)

- Make a copy of the MSXC.BAT script and call it LINK.BAT
- Edit LINK.BAT and remove the linker command (L80) and anything that removes the .REL files. We need those REL files!
- If you want, remove also the line that removes the .MAC files. That's the assembler code for the function.

4) Assemble all the .c files that compose your program

(Again, I should have called this script ASSEMBLE.BAT instead of LINK.BAT)

At this point you will have a couple of .REL files. That's the assembled code for each part of your program in relocatable object format (this means that it's assembled code that can be linked on any memory address). You'll also have the assembler source code in a .MAC file corresponding to each .C file:

5) Link all the relocatable files

In this example I did it manually, but you can put this in your own script (this time it's appropriate to call it LINK.BAT) to avoid having to type all this every single time:

- CK.REL is the C kernel
- MAIN.REL and HELLO.REL are your program relocatables. Link them always after CK
- MLIB.REL is the MSX-C Library
- CLIB.REL is MSX-C's standard library
- CRUN.REL is the C runtime (I think it sets up internal variables, prepares command line parameters, etc)
- CEND.REL is just an almost empty .REL file that marks the end of MSX-C programs
- MAIN/N/Y/E defines the name of the .COM file. If you want to call the final program "FINAL.COM" then change this to FINAL/N/Y/E
- :XMAIN tells the linker that it has to start execution in the main() function

6) Now you have compiled and linked a program that was actually stored in several .C/.H files:

The advantages of this method are:

- You can have a program composed of many files, instead of having a single big file that your text editor won't handle well
- Faster compilation times. You only need to compile the parts that have changed.
- Reusability. You can reuse parts of your program easily by just copying the files that contain the functions you want to reuse.

Thanks Javi this is a very good aproach. If you split code into several parte you will gain compilation split. You can put standar and tested routines to handle graphic,files, sound...in precompiled programa in order to reuse them anywere. I am really surprised by MSX-C flexibility...Let's go for a very general question.

Question: Somebody knows the sintaxis to insert asm code into a C program?

Once more, thanks