Hi..
moving on from dotflags, to a new effect involving bitmap scaling, i've come across a bug i simply can't explain.
i've done some scaling with 4 blitter copies with masks and shifting, after that have a tempbuffer where every 2nd word contains my final image. so i read a long word from tempbuffer, and write a word to Drawbuffer. effectively copying everu 2nd word to the drawbuffer
This work
move.l TempBuffer,A5
move.l DrawBuffer,A6
REPT 64
movem.l (A5)+,D0-D4
Movem.w D0-D4,(A6)
Movem.w D0-D4,10(A6)
Movem.w D0-D4,2560(A6)
Movem.w D0-D4,2570(A6)
Add.w #40,A6
ENDR
But this dont:
REPT 32
move.l TempBuffer,A5
move.l DrawBuffer,A6
movem.l (A5)+,D0-D7/A0-A1
Movem.w D0-D4,(A6)
Movem.w D0-D4,10(A6)
Movem.w D0-D4,2560(A6)
Movem.w D0-D4,2570(A6)
Movem.w D5-D7/A0-A1,40(A6)
Movem.w D5-D7/A0-A1,50(A6)
Movem.w D5-D7/A0-A1,2600(A6)
Movem.w D5-D7/A0-A1,2610(A6)
Add.l #80,A6
ENDR
the really strange thing is, that number 2 method does what i expect if i comment out this line "Movem.w D0-D4,2560(A6)"
then everything else works as it should. but if this single line is included, the Drawbuffer get mangled with missing bitplanes and what not.
it does not pass vblank, as everything is neatly under one frame. and it does not write into some unwanted memory (checked that to).
another fun fact. if i repeat the code 16 times (REPT 16), but if i repeat it 17 times, the bug starts to show??..
any pointers would be helpfull, maybe it's a winuae bug :D (not likely)
regards
