4cade/src/prelaunch/head.on.a

;license:MIT
;(c) 2019, 2022 by Frank M., qkumba

!cpu 6502
!to "build/PRELAUNCH.INDEXED/HEAD.ON",plain
*=$106

    !source "src/macros.a"

         +READ_RAM2_WRITE_RAM2
         jsr   EnableAccelerator

         ; clobbers $100, sets LC & page 3 reset vectors
         +NEW_RESET_VECTOR $7000

         lda   #0
         sta   $FFFC
         lda   #$70
         sta   $FFFD      ; LC reset vector fix to $7000

         lda   #$4C
         sta   $203E
         lda   #<callback
         sta   $203F
         lda   #>callback
         sta   $2040
         jmp   $2000      ; decompress

callback
         lda   MachineStatus
         and   #CHEATS_ENABLED
         beq   +
         lda   #$a5
         sta   $1072      ; patch - don't increase lives
         sta   $18B7      ; patch - don't decrease lives
+
         jsr   DisableAccelerator
         +READ_ROM_NO_WRITE

         jmp   $6900

!if * > $1C0 {
  !error "code is too large, ends at ", *
}