Re: [ql-users] coulours on SMSQ

[Malcolm Lear]

Dave Westbury wrote:

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I sent a corrected piece of code using two 16 bit 64k lookup tables
as follows.

a0 points to RG table and a1 to B.

m33RGB    move.w    (a4)+,d2     get B0
         move.w    (a4)+,d3     get RG
         move.w    (a0,d3.w),d3 use lookup table to sort RG
         move.w    (a1,d2.w),d2 also sort B
         or.w      d2,d3        combine RGB
m33done   move.w    d3,d6        left pixel done, now do right
         swap      d6
         ...                    inline repeat of above for right pixel
         move.l    d6,(a3)+     two pixels to window save area

BORG in         BBBBBBBBOOOOOOOO   RRRRRRRRGGGGGGGG
               76543210           7654321076543210
After Lookup    0000000000BBBBB0   GGGGGRRRRR00000G
                         76543    7654376543     2
After OR        GGGGGRRRRRBBBBBG
               7654376543765432

Using just G2 it would be quicker to do:

m33RGB    move.l    (a4)+,d3     get BORG
          roxr.b    #3,d3        get G7-3, G2 to eXtend flag
          rol.w     #5,d3        get R7-3
          rol.l     #5,d3        get B7-3
          roxl.w    #1,d3        get G2 from eXtend flag

Comparison of clocks (if I have got them correct) for 68040:

move (An)+,Dn       2 (x 2)
move d8(An,Xn),Dn   9 (x 2)
or   Dn,Dn          2 (x 1)  total 24

move (An)+,Dn       2 (x 1)
roxr/l #n,Dn        6 (x 2)
rol    #n,Dn        4 (x 2)  total 22

and it wouldn't require 128K of tables :-)

Regards,
Dave.

A very neat solution. Lookup tables are a last resort.

Cheers
Malcolm

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