SBC6303 YM2151 VGM PLAYER

SBC63-VGM-PLAY.ASM

;
; YM2151 Play for SBC6303 
;
	ORG	$0100
;
; LILBUG INTERNAL ROUTINE
PDATA1	EQU	$F80C
LIL_MAIN EQU	$F952
;
MUSIC	EQU	$3000
OPN_IO	EQU	$C000
;
START	EQU	*
	LDS	#STACK
	STS	SP	
;
	LDX	#MESG
	JSR	PDATA1
	BSR	MAIN
;
	JMP	LIL_MAIN	;PGM END
;
MAIN	EQU	*
	LDX	#MUSIC
LOOP	EQU	*
	LDAA	0,X
	CMPA	#$54
	BEQ	PLAY
	CMPA	#$61
	BEQ	WAIT11
	CMPA	#$62
	BEQ	WAIT22
	CMPA	#$63
	BEQ	WAIT33
	CMPA	#$64
	BEQ	WAIT33
	CMPA	#$66
	BEQ	END_RTN
;
	CMPA	#$70
	BEQ	WAIT4
	BGT	CHK_WAIT
NEXT	EQU	*
	INX
	BRA	LOOP
;
END_RTN	EQU	*
	RTS
;
WAIT11	EQU	*
	JMP	WAIT1
WAIT33 EQU	*
	JMP	WAIT3
WAIT22 EQU	*
	JMP	WAIT2
;
PLAY	EQU	*
	INX
	LDAA	0,X
	PSHA
	INX
	LDAB	0,X
;
WRITEOPN EQU *
	LDAA	OPN_IO+1
	ROLA
	BCS	WRITEOPN
;
	PULA
	STAA	OPN_IO
	NOP			;DUMMY
	NOP			;DUMMY
	STAB	OPN_IO+1
	JMP	NEXT
;
CHK_WAIT EQU	*
	CMPA	#$80
	BLT	NEXT
;
WAIT4	EQU	*
	ANDA	$0F
	INCA
	STAA	WAIT_T+1
	LDAA	#0
	STAA	WAIT_T
	JSR	WAIT
	JMP	NEXT
;
WAIT1 	EQU	*
	INX
	LDAA	0,X
	STAA	WAIT_T+1
	INX
	LDAA	0,X
	STAA	WAIT_T
	BSR	WAIT
	JMP	NEXT
;
WAIT2	EQU	*
	STS	SP
	LDS	#735
	STS	WAIT_T
	LDS	SP
	BSR	WAIT
	JMP	NEXT
;
WAIT3	EQU	*
	STS	SP
	LDS	#882
	STS	WAIT_T
	LDS	SP
	BSR	WAIT
	JMP	NEXT
;
;
WAIT	EQU	*
	STX	X_BUF
	LDX	WAIT_T
;
WAIT_LOOP	EQU	*
	BSR	WAIT1MS
	DEX
	BEQ	WAIT_END
	BRA	WAIT_LOOP
;
WAIT_END  EQU	*
	LDX	X_BUF
	RTS
;
WAIT1MS	EQU	*
	LDAA	#1
WAIT1MS_LOOP 	EQU  *
	DECA
	NOP	;DUMMY
	NOP	;DUMMY
	NOP	;DUMMY
	BNE	WAIT1MS_LOOP
	RTS
; MESSAGE
MESG	FCB	$0D,$0C
	FCC	"** YM2151 PLAY for SBC6303 **"
	FCB	$0D,$0C,4
; RAM
SP	RMB	2	; STACK POINTER STORE
X_BUF	RMB	2	; IX BUFF
WAIT_T	RMB	2
; STACK
        RMB    46
STACK   RMB    1         ;STACK POINTER