40 column routines (split from: Two Days to the Race)

[DarwinNE]

Hi Mike,
many thanks for the useful hints!

... pulling this off just 3 days after the "Hello World" of the Italian language (so to speak ) is quite an achievement.

The C code of the game is generated with a tool I wrote, called AWS2C:

https://github.com/DarwinNE/aws2c

Everything is done to have very simple I/O entry points and to be as portable as possible: it's not very difficult to hook specific routines.

You seriously should reconsider the arrangement of the characters in the text screen though. As I've spotted in your alpha, you use a row-wise arrangement

I see you noticed it

To say the truth, I was looking at your code and I haven't understood the scrolling routine, so nice and tidy, for a few days
I realized yesterday it would have been much easier to arrange the screen with a column-wise organization.
Currently, as you saw, the scrolling mechanism is a /real/ mess

It's one of the reasons why I haven't shown the code, yet

There're two ideas that I found non trivial. The first one is to set the chargen and the video memory both at $1000, then fill the video memory with characters that make the chargen read only starting from $1100. The second is that it is much better to have the screen oriented in a column-wise arrangement.

[Mike]

There're two ideas that I found non trivial. The first one is to set the chargen and the video memory both at $1000, then fill the video memory with characters that make the chargen read only starting from $1100. The second is that it is much better to have the screen oriented in a column-wise arrangement.

Add to this the duplicated nibbles in the font definition, so it's not necessary to shift left 4 times to get the upper nibble (just mask out the correct half), and you're nearly there.

BTW someone tried to play the game?

I'll try to take the time for this on this weekend.

From a quick start up I've however already found out, that you'll also need to handle NTSC correctly. Currently, on NTSC the display window is shown off center - something which is (besides the column-wise char arrangement) also correctly handled by my "On"-routine by putting the correct values into the horizontal/vertical position registers of the VIC chip, which *are* different for PAL/NTSC:

This also takes care, that PAL and NTSC VIC chips need different values for some registers. The values are obtained by adding/subtracting offsets from the default values of the VIC registers in the KERNAL ROM at $EDE4, so the screen remains centered on both TV systems.

Cheers,

Michael

[DarwinNE]

Add to this the duplicated nibbles in the font definition, so it's not necessary to shift left 4 times to get the upper nibble (just mask out the correct half), and you're nearly there.

Thanks for the hint! I noticed that the nybbles were repeated but I must've forgot it, I will review the code for finding other inefficiencies.

From a quick start up I've however already found out, that you'll also need to handle NTSC correctly. Currently, on NTSC the display window is shown off center - something which is (besides the column-wise char arrangement) also correctly handled by my "On"-routine by putting the correct values into the horizontal/vertical position registers of the VIC chip, which *are* different for PAL/NTSC:

That's true. I will correct this soon.

[DarwinNE]

Hi, Mile

Even if it is far from being presentable, if you want to have a look at the 40 column driver, here is the file on which I'm working on:

https://github.com/DarwinNE/aws2c/blob/ ... vic40col.s

And here's the corresponding C header:

https://github.com/DarwinNE/aws2c/blob/ ... vic40col.h

This way, you will not have to disassemble the code to see its horrors

Those files are part of aws2c, the project on which I am working since a few months ago and that allows to generate C code for text adventure games.
I only need there a pretty simplistic driver. Once I get something stable, I'm planning to create a separate GitHub project specifically dedicated to the 40 column driver, as it seems that there's enough interest.

Sorry for the current state of the scroll routine and I haven't reviewed the code throughly yet. Of course, I'm open to suggestions, they're always welcome.

The code includes the corrected initialization routine you suggested, but I haven't reviewed yet the _putc40ch routine.

[DarwinNE]

Hi to all,
I put together a small example here:

https://github.com/DarwinNE/aws2c/tree/ ... t_VIC_40ch

It's not very difficult to use the 40-column console driver. The example file is as follows:

Code: Select all

#include "vic40col.h"

#define BUFSIZE 38

int main(void)
{
    char buffer[BUFSIZE];
    initGraphic();
    negative();
    puts40ch("Please enter your name: \n");
    positive();
    puts40ch("> ");
    gets40ch(buffer, BUFSIZE-1);
    puts40ch("Hello ");
    puts40ch(buffer);
    puts40ch("\n\n");
    cgetc40ch();
    normalText();
    return 0;
}

The actual driver is in vic40col.s. Feel free to use it and modify it as you want.
I put more information about how to compile and run it in the directory on GitHub.
The colour is fixed at compile time in vic40col.s.
I haven't written routines to change the cursor position from C, but in the asm file you can do it by changing currLine and currCol and then calling _puts40ch.