(
	100r animated logo splash screen
	by Andrew Alderwick, 2021
	based on artwork by Hundred Rabbits
)

( devices )

|00 @System     [ &vector $2 &wst      $1 &rst    $1 &pad   $4 &r      $2 &g      $2 &b    $2 &debug  $1 &halt $1 ]
|20 @Screen     [ &vector $2 &width    $2 &height $2 &pad   $2 &x      $2 &y      $2 &addr $2 &pixel  $1 &sprite $1 ]
|c0 @DateTime   [ &year   $2 &month    $1 &day    $1 &hour  $1 &minute $1 &second $1 &dotw $1 &doty   $2 &isdst $1 ]

( variables )

|0000

( program )

|0100 @Reset ( -> )
	( seed prng (must be nonzero) )
	#00 .DateTime/second DEI
	#00 .DateTime/minute DEI #60 SFT2 EOR2
	#00 .DateTime/hour   DEI #c0 SFT2 EOR2 ;prng/x STA2
	#00 .DateTime/hour   DEI #04 SFT2
	#00 .DateTime/day    DEI #10 SFT2 EOR2
	#00 .DateTime/month  DEI #60 SFT2 EOR2
	    .DateTime/year  DEI2 #a0 SFT2 EOR2 ;prng/y STA2
	;prng/x LDA2 ;prng/y LDA2 EOR2

	;rabbits STH2 #0f05 &loop-x
		#0f05 &loop-y
			ROTk SWP STH2kr STA2 POP
			INC2r INC2r
			INC
			GTHk ,&loop-y JCN
			POP2
		INC
		GTHk ,&loop-x JCN
		POP2 POP2r
	( fall through )

@repeat
	;init-occupancy JSR2
	#00 ;precalc-frame STA
	;precalculate-vector .Screen/vector DEO2
	BRK

@init-occupancy ( -- )
	#1400 &loop-y
		#1400 &loop-x
			ROTk #00 ;set-occupied JSR2 POP
			INC
			GTHk ,&loop-x JCN
			POP2
		INC
		GTHk ,&loop-y JCN
		POP2
	;rabbits
	DUP2 #00c8 ADD2 SWP2 &loop-rabbits
		LDA2k #01 ;set-occupied JSR2
		INC2 INC2
		GTH2k ,&loop-rabbits JCN
		POP2 POP2
	JMP2r

@precalculate-vector ( -> )
	,precalculate JSR BRK

@precalculate ( -- )
	;rabbits #00c8 OVR ,precalc-frame LDR MUL2 ADD2 ( first rabbit address )
	DUP2 #00c8 ADD2 SWP2 &loop-rabbits
		DUP2 ,move-rabbit JSR
		INC2 INC2
		GTH2k ,&loop-rabbits JCN
		POP2 POP2
	,precalc-frame LDR INC DUP ,precalc-frame STR
		#05 EQU JMP JMP2r
	;display-init JSR2
	;display .Screen/vector DEO2
	JMP2r

@precalc-frame $1

@set-occupied ( x y value -- )
	STH
	#00 SWP #0014 MUL2 ( x yoffset* / value )
	ROT #00 SWP ADD2 ( offset* / value )
	;occupied ADD2 STH2 STAr
	JMP2r

@move-rabbit ( addr* -- )
	STH2k LDA2 ( x y / addr* )
	DUP2 #00 ,set-occupied JSR
	;&possible-moves ( x y possible* / addr* )
	OVR2 #01   SUB  ,&check-move JSR ( up )
	OVR2 INC   INC  ,&check-move JSR ( down )
	OVR2 #0100 SUB2 ,&check-move JSR ( left )
	OVR2 #0100 ADD2 ,&check-move JSR ( right )
	;&possible-moves SUB2 ( x y num-possible-times-2* / addr* )
	DUP ,&can-move JCN
	POP2
	&write ( x y / addr* )
	DUP2 #01 ,set-occupied JSR
	STH2r #00c8 ADD2 STA2
	JMP2r

	&can-move ( x y num-possible-times-2* / addr* )
	NIP2 ( num-possible-times-2* / addr* )
	,prng JSR SWP2 DIV2k MUL2 SUB2 #fe AND ( chosen-move* / addr* )
	;&possible-moves ADD2 LDA2
	,&write JMP

	&check-move ( possible* new-x new-y -- possible'* )
	DUP2 ,get-occupied JSR ,&blocked JCN
	OVR2r LIT2r 00c8 SUB2r ( possible* new-x new-y / previous-frame-addr* )
		&check-history-loop
		;rabbits INC2 STH2kr GTH2 ,&history-okay JCN
		DUP2 STH2kr LDA2 EQU2 ,&history-clash JCN
		LIT2r 00c8 SUB2r
		,&check-history-loop JMP
	&history-okay
	POP2r
	OVR2 STA2 INC2 INC2
	JMP2r
	&history-clash ( possible* new-x new-y / previous-frame-addr* )
	POP2r
	&blocked ( possible* new-x new-y )
	POP2
	JMP2r

	&possible-moves $10

@get-occupied ( x y -- value )
	#00 SWP #0014 MUL2 ( x yoffset* )
	ROT #00 SWP ADD2 ( offset* )
	;occupied ADD2 LDA
	JMP2r

@prng ( -- number* )
	LIT2 &x $2
	DUP2 #50 SFT2 EOR2
	DUP2 #03 SFT2 EOR2
	LIT2 &y $2 DUP2 ,&x STR2
	DUP2 #01 SFT2 EOR2 EOR2
	,&y STR2k POP
	JMP2r

@display-init ( -- )
	.Screen/width  DEI2 #01 SFT2 #0050 SUB2 ;display-rabbit/xoffset STA2
	.Screen/height DEI2 #01 SFT2 #0050 SUB2 ;display-rabbit/yoffset STA2
	;rabbit-sprite .Screen/addr DEO2
	JMP2r

@display-rabbit ( color n counter -- )
	OVR LTHk ,&finish JCN
	SUB ( color n timeline )
	DUP #63 GTH ,&start JCN
	#17 DIVk STHk MUL SUB ( color n stage-timeline / frame )
	DUP #07 GTH ,&static JCN
	( rabbit is in-between two frames )
	#08 OVR SUB ,&from-weight STR
	,&to-weight STR ( color n / frame )
	#00 SWP #10 SFT2 ;rabbits ADD2 #00c8 #00 STHr MUL2 ADD2 ( color from-addr* )
	LDA2k STH2 #00c8 ADD2 LDA2
	&draw ( color to-x to-y / from-x from-y )
	STHr ,&mix JSR LIT2 &yoffset $2 ADD2 .Screen/y DEO2
	STHr ,&mix JSR LIT2 &xoffset $2 ADD2 .Screen/x DEO2
	.Screen/sprite DEO
	JMP2r

	&mix ( to-z from-z -- mixed* )
	    #00 SWP LIT2 00 &from-weight 00 MUL2 ( to-n from-mixed* )
	ROT #00 SWP LIT2 00 &to-weight   00 MUL2 ADD2
	JMP2r

	&finish ( color n counter n )
	POP
	LITr ff ,&static JMP
	&start ( color n counter )
	LITr 04
	&static ( color n counter / frame )
	INCr
	POP
	#00 SWP #10 SFT2 ;rabbits ADD2 #00c8 #00 STHr MUL2 ADD2
	LDA2 STH2k
	,&draw JMP

@display-counter $1

@display ( -> )
	,display-counter LDR #01 SUB DUP ,display-counter STR
	DUP #f0 LTH ,&skip-palette JCN
	#ff OVR SUB #00
		DUP2 .System/r DEO2
		DUP2 .System/g DEO2
		     .System/b DEO2
	&skip-palette
	INCk #0000 &clear-loop
		ROTk ;display-rabbit JSR2
		INC
		DUP #64 LTH ,&clear-loop JCN
		POP2 POP
	#0500 &draw-loop
		ROTk ;display-rabbit JSR2
		INC
		DUP #64 LTH ,&draw-loop JCN
	POP2
	,&no-finish JCN
	;sunset .Screen/vector DEO2
	&no-finish
	BRK

@sunset ( -> )
	;display-counter LDA #02 SUB DUP ;display-counter STA
	DUP #1f GTH ,&skip-palette JCN
	DUP #01 SFT #00
		DUP2 .System/r DEO2
		DUP2 .System/g DEO2
		     .System/b DEO2
	#6400 &draw-loop
		#05 OVR #00 ;display-rabbit JSR2
		INC
		GTHk ,&draw-loop JCN
		POP2
	&skip-palette
	,&no-finish JCN
	;repeat JMP2
	&no-finish
	BRK

@rabbit-sprite 003c 7e7e 7e7e 3c00

@occupied $190

@rabbits