Erik wrote:
> The xxx_Disable constants may be a bit excessive, but I thought it might
> help make some code a little more clear.
I think the problem with to many constants is, that they make it harder to optimize the code. You don't see the actual values anymore. Look at the following (quite usual) simple sequences:
lda #M_Disable
sta ENAM0
sta ENAM1
lda #BL_Disable
sta ENABL
and
lda #VR_NoDelay
sta VDELP0
sta VDELP1
lda #0
sta GRP0
sta GRP1
With using constants, you might not recognize, that you can avoid loading #0 twice.
Optimizing is (unlike other plattforms) an essential factor for the 2600. Constants should be used *very* carefully.
Is suggest only to use enabling (For disabling the TIA uses zero in most cases) constants and only one of them for similar registers (M0,M1,BL: ENABLE) . But even then they might still be to many:
lda #ENABLE
cpy m0Start
bcs .enable
lsr ; this little trick will save you one byte
.enable:
sta ENAM0
As always for true the 2600, you have to make compromises here too.
Have fun!
Thomas
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Thomas Jentzsch | *** Every bit is sacred ! ***
tjentzsch at web dot de |
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