mirror of https://github.com/a2-4am/4cade.git
274 lines
9.1 KiB
Plaintext
274 lines
9.1 KiB
Plaintext
;license:MIT
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;(c) 2018-9 by 4am
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;
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; Functions to launch games and self-running demos
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;
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; Public functions
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; - AnyGameSelected
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; - GetGameToLaunch
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; - FindGame
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; - PlayGame
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; - Launch
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; - Joystick
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; - LoadXSingle
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; - LoadStandardPrelaunch
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;
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; Public variables:
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; - gGameToLaunch - 0-based index into gSearchStore (word)
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;
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gGameToLaunch
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!word $FFFF
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gLastMegaAttractGame
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!word $FFFF
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;------------------------------------------------------------------------------
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; AnyGameSelected
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; get index of game that is currently selected in the UI (if any)
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;
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; in: none
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; out: A/Y = gGameToLaunch (word)
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; C clear if gGameToLaunch is not #$FFFF
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; C set if gGameToLaunch is #$FFFF
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; X preserved
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;------------------------------------------------------------------------------
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AnyGameSelected
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+LD16 gGameToLaunch
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+CMP16_NE $FFFF, ForceGoodResult
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rts ; CMP sets carry when equal
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;------------------------------------------------------------------------------
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; GetGameToLaunch
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; get filename of game that is currently selected in the UI (if any)
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;
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; in: gGameToLaunch = index into gSearchStore (word) or #$FFFF if no game selected
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; gSearchStore populated
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; out: C clear if a game is selected, and
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; A/Y points to game filename
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; C set if no game is selected
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;------------------------------------------------------------------------------
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GetGameToLaunch
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jsr AnyGameSelected
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bcs _gameToLaunchExit
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+ST16 WINDEX
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+LDADDR gSearchStore
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jsr okvs_nth
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ForceGoodResult
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clc
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_gameToLaunchExit
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rts
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;------------------------------------------------------------------------------
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; FindGame
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; check if an arbitrary game exists, for some definition of 'exists', while
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; in the middle of a slideshow
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;
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; in: A/Y points to a key in gSlideshowStore
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; out: C clear if game exists and is playable on current machine, and
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; (SAVE) -> game display name, and
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; (gLastMegaAttractGame) -> game filename
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; C set otherwise
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; clobbers $FF, PTR
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; all registers clobbered
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;------------------------------------------------------------------------------
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FindGame
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+ST16 gLastMegaAttractGame
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jsr okvs_next_field ; (PTR) -> OKVS value (filename or empty string)
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; Y=0
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lda (PTR), y
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beq +
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+LD16 PTR
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+ST16 gLastMegaAttractGame
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+ jsr okvs_next_field_PTR_is_already_set ; (PTR) -> game display name
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+LD16 PTR ; A/Y -> game display name
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+ST16 SAVE ; (SAVE) -> game display name
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jsr okvs_next_field ; (PTR) -> game requirements bitfield
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; Y=0
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; check if game requires joystick
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lda (PTR), y
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sta $FF
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bpl @check128K
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lda MachineStatus
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and #HAS_JOYSTICK
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beq @failedCheck ; machine doesn't have joystick but game requires it
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@check128K
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; check if game requires 128K
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bit $FF
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bvc @passedAllChecks
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lda MachineStatus
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and #HAS_128K
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beq @failedCheck ; machine doesn't have 128K but game requires it
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@passedAllChecks
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clc
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rts
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@failedCheck
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sec
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rts
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;------------------------------------------------------------------------------
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; PlayGame
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;
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; in: gGameToLaunch != #$FFFF
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; out: exits via the game, but also backs up the stack, which may get
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; restored in |Reenter|... what I'm saying is that we might actually
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; 'return' from this after the user is done playing the game, which is
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; a neat trick
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;------------------------------------------------------------------------------
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PlayGame
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jsr GetGameToLaunch
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; A/Y = address of game filename in gSearchIndex
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PlayGameInAY
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+ST16 SAVE
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+ST16 @pfile
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+ST16 xfile
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jsr okvs_next_field
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jsr okvs_next_field_PTR_is_already_set
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; (PTR) -> length-prefixed game info bitfield
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; Y = 0
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iny ; Y = 1
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lda (PTR), y ; A = game info bitfield
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and #IS_SINGLE_LOAD
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php
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jsr ClearScreens ; avoid seeing code load into the HGR page
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; (clobbers $106, must do now before loading prelaunch code)
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jsr LoadIndexedFile ; load prelaunch index file
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- !word gSearchCache ; clobber gSearchCache which we no longer need
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!word kPrelaunchIndexRecord
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jsr okvs_find ; find this game's prelaunch index record
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!word -
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@pfile !word $FDFD ; SMC
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+ST16 @prelaunchIndexRecordPtr
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jsr LoadIndexedFile ; load this game's prelaunch code into $0106
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!word $0106
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@prelaunchIndexRecordPtr
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!word $FDFD ; SMC
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plp
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beq @loadFromSubdirectory
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jsr LoadXSingle_NameIsAlreadySet
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jmp Launch
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@loadFromSubdirectory
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; we start by placing the subdirectory name at gPathname+kGameDirectoryLen
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; to leave room for the GameDirectory name as the parent
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lda #kGameDirectoryLen
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sta gPathname
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+LD16 SAVE
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jsr AddToPath
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; attach the separator
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inc gPathname
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lda #'/'
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sta gPathname+1,x
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; then we save the length of the resulting string without the count byte
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dex
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txa
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pha
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; then attach the game name
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+LD16 SAVE
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jsr AddToPath
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; don't look while I do this
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; we "place" a string at gPathname+kGameDirectoryLen
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; whose length is the subdirectory name and game name
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; then we load it
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; the load sets the path to the GameDirectory
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; and then finds the subdirectory name and game name right after it
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; and attaches it to the path by overwriting the count byte
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;;sec ; carry set by AddToPath
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lda gPathname
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sbc #kGameDirectoryLen
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sta gPathname+kGameDirectoryLen
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jsr LoadFile ; load the game startup file
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!word kGameDirectory
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!word gPathname+kGameDirectoryLen
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!word 0 ; use file's default address
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pla
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sta ProDOS_prefix ; set 'root' directory to the path part
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; of the game startup file we just loaded
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; so games can load other files without
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; knowing which directory they're in
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; execution falls through here
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Launch
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jsr SwitchToBank2
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lda #$BD
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sta launchpatch
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jsr saveslot ; set proper slot information
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lda #$9D
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sta launchpatch
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jmp LaunchInternal
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;------------------------------------------------------------------------------
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; LoadXSingle/LoadXSingle_NameIsAlreadySet/LoadXFile
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; load an indexed file via an extended index record that also contains starting
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; address information
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;
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; in: A/Y points to game filename (must be listed in xsingle OKVS)
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; out: all flags & registers clobbered
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;------------------------------------------------------------------------------
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LoadXSingle ; entry point used by demos to load additional resources
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+ST16 xfile
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LoadXSingle_NameIsAlreadySet ; entry point used by PlayGame
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jsr LoadIndexedFile ; load xsingle index file (contains pointers to game binaries)
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- !word gSearchCache ; clobber search cache which we no longer need
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!word kXSingleRecord
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LoadXFile ; entry point used by attract mode to load self-running demo
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jsr okvs_find ; find this game's extended index record
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!word -
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xfile !word $FDFD ; SMC
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+ST16 @xsingleIndexRecordPtr
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jsr okvs_next_field
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ldy #5
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lda (PTR), y ; get game load address (stored immediately after index record)
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sta @xsingleAddr
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iny
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lda (PTR), y
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sta @xsingleAddr+1
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jsr LoadIndexedFile ; load this game binary
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@xsingleAddr
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!word $FDFD ; SMC
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@xsingleIndexRecordPtr
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!word $FDFD ; SMC
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rts
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;------------------------------------------------------------------------------
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; Joystick
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; launch joystick calibration program
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;
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; in: none
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; out: exits via Launch
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;------------------------------------------------------------------------------
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Joystick
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jsr LoadStandardPrelaunch
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jsr LoadIndexedFile
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!word $800
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!word kJoystickRecord
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jmp Launch
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LoadStandardPrelaunch
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jsr LoadIndexedFile ; load standard prelaunch code at $0106
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!word $0106
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!word kStandardPrelaunchRecord
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rts
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