;license:MIT
;(c) 2019 by 4am
;
; common code used by all prelaunchers
;
; you should include this file with a '!source' directive, not assemble it directly

         !source "src/constants.a"   ; no code in these
         !source "src/macros.a"

         ldx   #0                    ; wipe zero page
         txa
-        sta   $00,x
         inx
         bne   -

         lda   #$65                  ; Initialize 'random' seed. These are
         sta   RNDSEED               ; arbitrary values. Some games like Pooyan
         lda   #$02                  ; require these to be non-zero. Ask me
         sta   RNDSEED+1             ; how long that one took to debug.

         +READ_ROM_NO_WRITE

         jsr   ROM_IN0               ; Initialize machine like a cold boot.
         jsr   ROM_PR0               ; Many games assume a 'clean slate' and
         jsr   ROM_NORMAL            ; rely on zero page values set by these
         sta   STOREOFF              ; ROM routines,
         sta   READMAINMEM           ; e.g. Wavy Navy just prints out text via
         sta   WRITEMAINMEM          ; $FDED and expects it to work. Having it
         sta   CLR80VID              ; print all null characters is amusing, in
         sta   PRIMARYCHARSET        ; a quiet way, but not really helpful.
         jsr   ROM_TEXT
         jsr   ROM_HOME

         bit   CLEARKBD
         sei