Quote:
Originally Posted by Asman
@Leffmann, StingRay - thanks a lot.
Is there any difference between
Code:
wait_vb_1
.1 btst #0,(_custom+vposr+1)
beq .1
.2 btst #0,(_custom+vposr+1)
bne .2
rts
and
Code:
wait_vb_2
.1 btst #0,(_custom+vposr+1)
bne .1
.2 btst #0,(_custom+vposr+1)
beq .2
rts
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First waits for line 0, second waits for line 256. (it can also wait for line 512, 1024 and so on but I think this was about standard video modes
)
Quote:
And second ( stupid  ) question. Is legal to do btst on odd address _custom+vposr+1 ?
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Technically byte read from custom register is "illegal" but has always worked perfectly fine. Everyone did that
Byte writes to custom registers may not work properly with all accelerator models (Blizzard 1260 for example, only to odd or even bytes, if I remember correctly)