*bump* So how's this going, David? Are you still working on honing your ASM? I've seen you on IRC a few times.

I have a new question:


Code:


I heard that I can shorten this to make it only 1 call. I'd also know how to make this able for press RIGHT and UP at the same time for example.

Oh and thanks calcdude, he told me this.

I was very happy to code most of that alone But I need help to polish it and make it even better.

When multiple keys are pressed, the key value (the number in A after in (A),1) is basically all of them AND'd together. It works like this:

For the arrow group, DOWN is $FE. That's %11111110. RIGHT is $FB, or %11111011. If both of them are pressed at the same time, the value in A would be %11111110 AND %11111011, or %11111010. So to check if one of the keys are pressed, you use BIT to see if that particular bit is reset or not.

So here's some code:


Code:


No need to keep doing LD A,$FE \ OUT (1),A since the key port's already set to $FE.

That alone didn't work so I did this:


Code:


I got what you did, but I still can't press multiple keys, but yeah a hell of an optimization in the code

So how can I press multiple keys?

[/code] bit 2,a
cp $FE [/code] Is not correct. The bit opcode sets or resets the zero flag. The cp $FE afterwards wipes out the result of the bit operation. Just remove all the cp's.

I tried this and none of the keys work:


Code:


I also tried adding another 'nop' but with no success.

Notice that each of your calls is going to wipe out the accumulator (a); you need to do something about that.

If you mean saving the value of 'a' everytime I call a CheckMove label I tried this with no luck too:


Code:


I don't get what calls you're referring to, is it the other calls like iPutSprite and such that ruin a so I have to save it?

Um, what the heck are you doing there? You know there's push af and pop af, right? No need to move to de every time. I was saying that in CheckMoveLeft and CheckMoveRight, you modify the value of the accumulator.

Yeah I only found out about af now... :$


Code:


I got this, but not working perfectly yet, the multi key pressing only works sometimes and when I press <DOWN> it goes left *sometimes*, going left doesn't always work, and it's *very* weird.

Oddly enough, I don't see anything wrong with that code. Can anyone else spot something that I've missed? David, did you happen to find the problem in the meantime?

Wouldn't the compiler notify you of your mistake?

*Assembler, and only mistakes that are obvious opcode mistakes such as misspelled opcodes or invalid operands. It won't detect if you do something incorrectly but with individually-valid opcodes.

The assembler told me nothing, here's what I did:


Code:


Because Deep Though said this here:



I sort of get it because of the table I can see here. The lowest value is stored in the lower bit (0).

The order is $FE, $FD, $FE, $F7. So 0,1,2,3, Down, Left,Right, Up.

<EDIT>

Code:


I have new code, I need to decrease the y position of the sprite by 1 if the pixel below it is white to give a gravity effect. I'm using iGetSprite and have something wrong because there is no gravity at all.

What am I doing wrong?

Thanks in advance.

You mean iGetPixel; there's no iGetSprite. That doesn't work because after you inc l you pop hl again.

Cemetech should really have scrollbars when code is too big :/


Code:


This is my current code, the problem with it is the sprite is going through the line I draw, so gravity is not really working.

No, you should really Pastebin code that is too big. Giant blocks of code take up tons of space in the database, and I like being miserly about database space to limit the rate of growth of the DB so that Cemetech stays sustainable for the long term.

Ah ok Kerm

All of my current code is here.

I tried implementing some stuff I was recommended by other ASM coders over at Omnimaga, but the ball still doesn't stop in the lines.

You didn't listen to me. I told you that you were popping hl after modifying it, so all you needed to do was move the pop hl to right before call z,SetGravity.

If I do that, then I won't be testing 'and hl' the right way I think.
<EDIT> The z flag is set, popping won't reset it actually I think</EDIT>

http://pastebin.com/LqNhsVWq

Here it is, my current code, the sprite goes wild.