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Old 12 November 2018, 10:49   #1
sandruzzo
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A500 cp2 need help

I need to perform nibble rotation as fast as is possible. Can someone help me?

from:

a-b-c-d
e-f-g-h
i-l-m-n
o-p-q-r

to

a-e-i-o
b-f-l-p
c-g-m-q
d-h-n-r

is it possible to do it faster than 68000 with blitter?

Thanks to all
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Old 12 November 2018, 10:53   #2
Samurai_Crow
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Don't we all wish that chunky to planar conversions were blitter accelerated? If it were possible, interleaved bitplanes would be interchangeable with chunky modes quite quickly! Isn't that what you're trying to do?

Edit: I see it is just a typo in the title of your post. That is why I ask.
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Old 12 November 2018, 11:00   #3
sandruzzo
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Quote:
Originally Posted by Samurai_Crow View Post
Don't we all wish that chunky to planar conversions were blitter accelerated? If it were possible, interleaved bitplanes would be interchangeable with chunky modes quite quickly! Isn't that what you're trying to do?

Edit: I see it is just a typo in the title of your post. That is why I ask.
I don't need to perform full cp2, but exchange only nibbles
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Old 12 November 2018, 11:38   #4
britelite
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Quote:
Originally Posted by sandruzzo View Post
is it possible to do it faster than 68000 with blitter?
It's faster with the blitter than with the cpu, for example my OCS c2p is blitter only. You might need to have a scrambled chunky buffer for optimal performance though.

Taking a look at Kalms' cpu+blitter c2p's might be a good place for you to start.
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Old 12 November 2018, 11:40   #5
sandruzzo
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Originally Posted by britelite View Post
It's faster with the blitter than with the cpu, for example my OCS c2p is blitter only. You might need to have a scrambled chunky buffer for optimal performance though.

Taking a look at Kalms' cpu+blitter c2p's might be a good place for you to start.
Thanks. I need only to exchange nibbles, not full c2p: Any helps?
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Old 12 November 2018, 11:43   #6
britelite
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Originally Posted by sandruzzo View Post
Thanks. I need only to exchange nibbles, not full c2p: Any helps?
You could post here how you're currently doing it, and I'll be happy to give some pointers on how to improve it.
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Old 12 November 2018, 11:45   #7
sandruzzo
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You could post here how you're currently doing it, and I'll be happy to give some pointers on how to improve it.
Thanks for your help. I would like to have a good help from you and others, instead doing it again. I need this operation just cos want to test a possible way to do cp2, not for fast reasons, just to test...
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Old 12 November 2018, 14:29   #8
chb
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Quote:
Originally Posted by sandruzzo View Post
I need to perform nibble rotation as fast as is possible. Can someone help me?

from:

a-b-c-d
e-f-g-h
i-l-m-n
o-p-q-r

to

a-e-i-o
b-f-l-p
c-g-m-q
d-h-n-r

is it possible to do it faster than 68000 with blitter?
You can use blitter merge (two blits with shift by 8 left resp. right for one source, mask 0xFF00 and 0x00FF) to get the following intermediate matrix:

a-b-i-l
e-f-o-p
c-d-m-n
g-h-q-r

then shift by 4 left / right, mask 0xF0F0/0x0F0F to get your result. So just the first passes of ordinary blitter c2p. Don't know if it is faster than with the CPU, but I'd think so.
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