This page (revision-22) was last changed on 03-Feb-2023 15:21 by Gromit 

This page was created on 14-Mar-2010 18:17 by Carsten Strotmann

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Version Date Modified Size Author Changes ... Change note
22 03-Feb-2023 15:21 23 KB Gromit to previous
21 01-Feb-2011 12:53 23 KB Gromit to previous | to last

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At line 345 changed one line
does. This may look very complicated, but it isn't. X&7 computes which bit is to be modified (same as X MOD 8, but much faster). This is used as the index for the ARRAY __m1__. ARRAY __ml__ is declared to contain a set of 8 masks. Each mask represents the bit to be modified for that index. Thus, when m1(X&7) is or'ed into the byte pointed to by __pos__, it sets only the bit to be plotted without affecting the other bits of that byte.
does. This may look very complicated, but it isn't. X&7 computes which bit is to be modified (same as X MOD 8, but much faster). This is used as the index for the ARRAY __m1__. ARRAY __m1__ is declared to contain a set of 8 masks. Each mask represents the bit to be modified for that index. Thus, when m1(X&7) is or'ed into the byte pointed to by __pos__, it sets only the bit to be plotted without affecting the other bits of that byte.
At line 351 changed one line
erases point __X,Y__ on the screen. ARRAY __m2__ is declared to contain 8 masks which, when and’ed with the byte pointed to by __pos__, erase a single bit without effecting the other bits of that byte.
erases point __X,Y__ on the screen. ARRAY __m2__ is declared to contain 8 masks which, when and'ed with the byte pointed to by __pos__, erase a single bit without effecting the other bits of that byte.
At line 359 changed one line
If you haven't followed all of this, don't worry. I didn‘t go into any details about bit-wise operations (& and %) to keep the description brief. You can still enjoy the results {assuming you have an Action! cartridge). You can even use these two PROCs (__Init__ and __Plot__) in other programs that you write yourself.
If you haven't followed all of this, don't worry. I didn't go into any details about bit-wise operations (& and %) to keep the description brief. You can still enjoy the results (assuming you have an Action! cartridge). You can even use these two PROCs (__Init__ and __Plot__) in other programs that you write yourself.