[A83] Re: lcd mem as ram
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[A83] Re: lcd mem as ram
At 18:26 2002-01-04, you wrote:
>Wasn't x-incrementing vertical and y-incrementing horizontal? The TIOS
>expects the lcd driver in x-increment mode, but the standard TIOS gbufcpy
>routine switches to y-increment as that makes reading the contents of the
>screen buffer easier. Joe's FastCopy routine uses x-incrementing and uses
>the necessary additions (to get the proper screen buffer data) as delays
>between two writes.
Yeah, sorry, x-incrementing is vertical and y horizontal. I mixed them up,
took it from memory and didn't check the pdf. (I fiddled a lot with the lcd
driver a few years ago when I programmed for the 83) I cheerfully assumed
it was logical as you are used too :)
But you do not have to rearrange the graph buffer to switch direction. just
read every 12th byte of the graphbuffer the first round, decrease your
pointer so it points to the second byte the next round, and read every 12th
byte again, and so on for 12 rounds, and you will have your graph buffer
arranged in the exact same way as you are used to. (and can use the same
sprite routines)
The necessary delay between writes to the driver is long enough so this
jump-around reading creates no overhead at all.
The lcd update routine I posted on this list a few weeks ago used this
tech. (written by me sometime 1998 I think)
It though had a bit too short delays, but that is easily fixed.
hmm.. just realized this might be what you meant with "necessary
additions", and not having other sprite routines as I first thought :)
///Olle
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