;license:MIT
;(c) 2017-2021 by qkumba/4am/John Brooks

!cpu 6502
!to "build/FX.INDEXED/FIZZLE",plain
*=$6000

         !source "src/fx/macros.a"

         +OVERCOPY_TO_0 start, end
         ;$FF clobbered
         ;X=0
         ;Y=0
         jmp   loop

start
!pseudopc 0 {
         ;X=0
         ;Y=0
loop     txa
loop1    eor   #$1B                  ; LFSR form 0x1B00 with period 8191
wait     dex
         bne   wait
         tax
loop2    txa
         ora   #$20
         sta   <dst+2
         eor   #$60
         sta   <src+2
         jsr   src
         txa
         lsr
         tax
         tya
         ror
         tay
         bcc   loop2
         bne   loop
         bit   $C000
         bmi   exit
         txa
         bne   loop1
src      lda   $FD00, y              ; SMC high byte
dst      sta   $FD00, y              ; SMC high byte
exit     rts
}
end