4cade/src/glue.launch.a

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;license:MIT
;(c) 2018-9 by 4am
;
; Functions to launch games and self-running demos
;
; Public functions
; - GetGameDisplayName
; - GetGameDisplayNameInActionSlideshow
; - PlayGame
; - Launch
;
; Public variables:
; - gGameToLaunch - 0-based index into gGamesListStore
;
GetGameDisplayName
; in: A/Y points to game filename
; out: C clear if game exists in gGamesListStore, and
; A/Y points to game display name (but see hack notes below)
; X = game index, or #$FF if the game doesn't really exist but
; we want to return a successful result anyway (really, read the
; hack notes, they're important)
; C set if game does not exist (this can happen because slideshows
; list games that require a joystick, but the games list parser
; filters out joystick-only games if the machine doesn't have a
; joystick)
ldx #$60
+HIDE_NEXT_2_BYTES
GetGameDisplayNameInActionSlideshow
ldx #$EA
stx @maybeExit
+STAY @key
+STAY @slideshowKey
jsr okvs_get
!word gGamesListStore
@key !word $FDFD ; SMC
bcc @exit
; Hack to allow self-running demos that don't correspond to a game
; filename. If the name ends in a '.', accept it unconditionally.
; The filename is its own display name. Launching this fake game
; will of course fail, so don't do that.
+LDAY @key
+STAY PARAM
ldy #0
lda (PARAM),y
tay
lda (PARAM),y
cmp #"."
beq @forceGoodResult
sec
@maybeExit
!byte $00 ; SMC
; if the key is still not found, AND the caller said to try this, then try
; getting the value of the current record from gSlideshowStore
; (some games have multiple action screenshots, in which case the filename of
; the action screenshot is not the game name, but the value is)
jsr okvs_get
!word gSlideshowStore
@slideshowKey
!word $FDFD ; SMC
+STAY @key3
jsr okvs_get
!word gGamesListStore
@key3 !word $FDFD ; SMC
; note that the game might still not be found (C will be set by okvs_get),
; which can happen if the game can't be played due to memory or joystick
; requirements
rts
@forceGoodResult
+LDAY @key
ldx #$FF
clc
@exit rts
PlayGame
gGameToLaunch=*+1
ldx #$FF ; SMC
+LDADDR gGamesListStore
jsr okvs_nth
; A/Y = address of game filename
+STAY SAVE
+STAY @pfile ; assume we're loading a game-specific prelaunch file
jsr Home ; clear screen (clobbers $106, must do now before loading prelaunch code)
lda #$20 ; clear both hi-res pages
sta @clear+2 ; (in case game loader shows them, we don't want
ldx #$40 ; to flash previous bits of the launcher UI)
ldy #$00
tya
@clear sta $FD00,y ; SMC
iny
bne @clear
inc @clear+2
dex
bne @clear
bit gCheatsEnabled ; are cheats enabled?
bpl @noCheats
ldx gGameToLaunch
ldy gCheatsAvailable,x ; are there any cheats for this game?
bne @Cheats
@noCheats
+LDADDR kStandardPrelaunch ; no game-specific prelaunch file, so
+STAY @pfile ; load standard prelaunch file instead
@Cheats
jsr LoadFile ; if cheats are enabled and this game has a prelaunch
!word kPrelaunchDirectory ; file that will set up the cheats, load that, otherwise
@pfile !word $FDFD ; load the standard prelaunch file
!word $0106
ldx #1 ; construct path to game's startup file
sec ; which is always /X/game/game
!byte $2c
-- pha
clc
php
ldy #0
lda (SAVE), y
tay
iny
sty MAX
ldy #0
lda #'X'
sta ProDOS_prefix+1
lda #'/'
- inx
sta ProDOS_prefix, x
iny
lda (SAVE), y
cpy MAX
bne -
txa
plp
bcs --
stx ProDOS_prefix
jsr LoadFile ; load the game startup file
!word kRootDirectory
!word ProDOS_prefix
!word 0 ; use file's default address
pla
sta ProDOS_prefix ; set 'root' directory to the path part
; of the game startup file we just loaded
; so games can load other files without
; knowing which directory they're in
; execution falls through here
Launch
jsr SwitchToBank2
jmp LaunchInternal