Condensing Spell List in Battle

I'd be curious to see yours, just to compare -- I learn more from seeing everyone else's coding than I do just by coding myself, half the time.

untested, hasn't been assembled:

Code:

phx

ldy #$04      ; full list index.  start at 1st Magic slot.
tyx           ; index of next spot to write in shortened list.  start at 1st
              ;  Magic slot.

mainLoop:
LDA ($F2),Y
CMP #$FF
BEQ checkNextSpell   ; branch if current entry null

stx $f0
cpy $f0       ; does full list index == output index?  yes, i use
              ;  this variable in a single place, because no other
              ;  easy way to compare X and Y. :/
beq noCopy    ; skip copying if so, but still advance

clc
rep #$20

copyLoop:
lda ($F2),Y   ; read two spell menu bytes from original position
phy
txy
sta ($F2),Y   ; save to new position
ply
iny
iny
inx
inx
bcs done      ; exit loop if we've iterated twice.  this
              ;  way lets us avoid using decrementor.
sec
bra copyLoop  ; otherwise, iterate that second time
done:

sep #$20

bra alreadyInced

noCopy:
inx
inx
inx
inx           ; advance index of next place to write in shortened list

checkNextSpell:
iny
iny
iny
iny           ; advance full list index
alreadyInced:

cpy #$D8      ; have we processed end of Magic list?
bcc mainLoop  ; loop if not

; now blank out unused remainder of shortened list

txy
blankLoop:
cpy #$D8         ; have we reached Lore Land yet?
bcs nothingLeft  ; branch if so

LDA #$FF
STA ($F2),Y   ; this blanks out a spell
LDA #$00
STA ($F4),Y   ; and zeroes out the MP cost
iny
iny
iny
iny

bra blankLoop
nothingLeft:

plx

one strong point is i'm able to mostly keep the second index in a register.  but i do resort to using $F0 briefly to avoid stack jackassery.  that could pose problems if i wanted to use the variable for bounds or other parameters in a unified version.

for the zeroing+FF'ing of spell data, it'd be a little smaller (and maybe faster) to have a "TDC ... DEC", with the ($F4) write first.