AOTM AFOS problems

["Shrek" <matzieq@xxxxxxxxxxxxxx>]

Hello there!

 

I'm working on the AOTM AFOS  now, I decided to rewrite the game almost from the beginning. Now I'm playing with the vertical positioning routine mentioned by Andrew Davie in his tutorial, something like this:

 

SEC
 TXA
 SBC Ufo_Y  
 ADC #12   
 BCC EndOfDrawingUfo

 CLC
 ADC Ufo_Frame_Offset

 

 TAY
 LDA (Ufo_Sprite_Ad),Y
 STA Ufo_Buffer

 

EndOfDrawingUfo 

 

It was supposed to be around 20 cycles. I've inserted three such routines into one scanline, and 20*3 is 60 as far as I know. But when I run it, it seems, that it doesn't fit into the line! So what's wrong?!?

 

I attach the code, and the place where all trouble began is commented "HERE BEGINS THE PROBLEM".

 

Please, help!... I don't know what to do... I begin to feel frustrated!

 

Maciej

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