I'm getting an error in the code "illegal character _ at line xxx"

And there isn't one in line xxx.

I suspect that this line number comes from the assembler, and it's a line number based on the code stripped of comments and white space perhaps?

I've noticed that it's sometimes hard to pin down the correct line number for errors before.

I've never used it at all; but I hear that it's a nice code control system.

How does one get going then?

Do you use windows, or linux?

I've made quite a few changes to the actual FourSpriter code. I have made it significantly shorter, and not a small amount faster in execution, using tricks like LDI to copy directly from (HL) to (DE) as opposed to copying into and out of the A register. I removed at least one redundant section of code that was identical with another one - redirecting calls took care of that. There are also places that use bafflingly long code to do something simple. For example:

I was updating fourspriter to use SUBs as opposed to gotos. Probably slower, but a little cleaner on the interface to the user.

Anyway, as it stands the main program:

Calls initialize for the first sprite
which calls a dummy "data" routine (which is really just for asm. The first line is return. It only calls it to make sure it's not peephole optimized out)
Comes back to main
calls coords for the first sprite
comes back to main
calls initialize for the second sprite
which calls the dummy data routine again......

and then it goes wrong. It never comes back from this data routine this second time, even though it should return immediately. In fact, it restarts the main program again. Over and over - and then after a few cycles, crashes.


I confirmed the code does the same thing with 1.23 and 1.22; and I didn't think they had the stack bugs, so it could be something I'm doing wrong, I suppose. I can't really see what could go wrong with "return" being the only statement, though.

The code is a bit complex, and is unfinished; but hopefully you can see where I'm going. It has testing PRINTs in it. Just copy and paste and see if it behaves the same way for you.

ZXB allows you to do stuff that's pretty crazy.

I had a fancy cls routine - that didn't actually clear the screen, just ran a attribute bar over the screen, and then of course you do a CLS from basic afterwards. The effect is the same, but it looks cool.

It wouldn't compile right - the call to the ZX ROM sound routine kept corrupting things. Probably messing with IX and IY registers in naughty ways.

Then it occurred to me.... just compile a beep into the middle. :-)

Look:

Version zxb 1.2.5-r1489

As I promissed, here I am with an adaptation for the Mojon Twins "Fourspriter". Well, in fact I promissed just the opposite (skip this one and post the other sprite routine I'm working in), but I think this one is more suited to a basic enviroment and the other one is just great for a crap game (see my game Colour Clash of the Titans in the CSSCGC 2010 thread within the WoS games forum) but not so good if you plan to do a polished game.

The engine itself comes in assembler, and all you have to do is POKE the right adresses to configure and move your sprites (up to 4). All I have done is adding 3 subroutines to make easier the poking part, and 4 labes so you can call the different subroutines of the engine via gosub.

Here goes the code you have to include in your library folder (I called it fourspriter.bas):

I was thinking that it might be incredibly useful, for inline assembly to be able to set what's on the registers as you hit z80 asm.

And a command to do that, that works in a similar way to a function call, might be a good way to do it and avoid a lot of the overhead of a function call for very small jobs.

How about a register and an unregister command?

Register - takes a variable and puts it in the current registers
unregister - takes registers and puts them into a variable.

So you could do something like:

DIM a as long
register a
asm
LD D,0
end asm
unregister a

To kill off the top byte of a long, if that was your whimsy.

Not sure if other people would find this useful, but I could imagine ways it could be useful.

How about:
dim a as fixed
dim b as uinteger
(do things)
register a
unregister b

to put the decimal part of a into b if you wanted to deal with the integer part and the decimal part separately. You could even shunt it back later...

Anyway, just a crazy thought from me, as per usual :-)

I did wonder if this was a bug or not, since it might be odd to modulus a floating point number.

But mod works perfectly with type FLOAT, so logically it should also work well with type FIXED. Fixed division works, and the compiler seems to know where the code for mod should be - at label _MODF16.

Error: Undefined label '__MODF16'

Here are more general purpose functions for AND, OR and NOT. They work with Byte, Integer or Long types (the function is long, but the cast works upscale).

A binary NOT is tougher - what bits do you invert? If you send me 8, and I invert 32 is that what you wanted?
(of course, you could bAND the result into the last 8 or 16 bits)

These functions are very similar, of course.

Binary AND: