Initial commit.

ted/objects.src

@@ -0,0 +1,160 @@
+	PAGE
+	SBTTL "--- OBJECT & PROPERTY HANDLERS ---"
+
+	; ----------------------------------
+	; GET ABSOLUTE ADDRESS OF OBJECT [A]
+	; ----------------------------------
+
+	; EXIT: ADDRESS IN [I]
+
+OBJLOC:	STA	I+LO		; SAVE LSB FOR ADDING
+
+	LDX	#0		; CLEAR MSB
+	STX	I+HI		; FOR SHIFTING
+
+	ASL	A		; MULTIPLY BY 8
+	ROL	I+HI
+	ASL	A
+	ROL	I+HI
+	ASL	A
+	ROL	I+HI
+
+	CLC			; ADD TO ITSELF
+	ADC	I+LO		; TO GET TIMES 9
+	BCC	OBJ1
+	INC	I+HI
+
+OBJ1:	CLC
+	ADC	#53		; NOW ADD 53
+	BCC	OBJ2		; (THE OBJECT TABLE OFFSET)
+	INC	I+HI
+
+OBJ2:	CLC			; NEXT ADD THE ABS ADDR
+	ADC	OBJTAB+LO	; OF THE OBJECT TABLE
+	STA	I+LO
+
+	LDA	I+HI
+	ADC	OBJTAB+HI
+	STA	I+HI
+	RTS
+
+	; -----------------------------
+	; GET ADDRESS OF PROPERTY TABLE
+	; -----------------------------
+
+	; EXIT: [I] HAS ABSOLUTE ADDR OF PROPERTY TABLE
+	;       [Y] HAS OFFSET TO START OF PROP IDS
+
+PROPB:	LDA	ARG1+LO
+	JSR	OBJLOC
+	LDY 	#7
+	LDA	(I),Y		; GET MSB OF P-TABLE ADDRESS
+	CLC
+	ADC	ZCODE		; MAKE IT ABSOLUTE
+	TAX			; AND SAVE HERE
+	INY
+	LDA	(I),Y		; NOW GET LSB
+	STA	I+LO
+	STX	I+HI		; [I] NOW POINTS TO PROP TABLE
+
+	LDY	#0
+	LDA	(I),Y		; GET LENGTH OF SHORT DESC
+	ASL	A		; WORD-ALIGN IT
+	TAY			; EXPECTED HERE
+	INY			; POINT JUST PAST THE DESCRIPTION
+	RTS
+
+	; -------------------
+	; FETCH A PROPERTY ID
+	; -------------------
+
+	; ENTRY: LIKE "PROPB" EXIT
+
+PROPN:	LDA	(I),Y
+	AND	#%00011111	; MASK OUT LENGTH BITS
+	RTS
+
+	; -------------------------------
+	; FETCH # BYTES IN PROPERTY VALUE
+	; -------------------------------
+
+	; ENTRY: LIKE "PROPB" EXIT
+
+PROPL:	LDA	(I),Y
+	LSR	A		; LENGTH IS IN
+	LSR	A		; BITS 7-5
+	LSR	A		; SO SHIFT INTO PLACE
+	LSR	A
+	LSR	A
+	RTS
+
+	; ----------------------
+	; POINT TO NEXT PROPERTY
+	; ----------------------
+
+	; ENTRY: LIKE "PROPB" EXIT
+
+PROPNX:	JSR	PROPL		; GET LENGTH OF CURRENT PROP
+	TAX			; SAVE HERE
+
+PPX:	INY			; LOOP UNTIL
+	DEX			; [Y] POINTS TO
+	BPL	PPX		; START OF NEXT PROP
+	INY			; CORRECT ALIGNMENT
+	RTS
+
+	; ----------------
+	; GET OBJECT FLAGS
+	; ----------------
+
+	; ENTRY: OBJECT # IN [ARG1], FLAG # IN [ARG2]
+	; EXIT: FLAG WORD IN [K], BIT ID IN [J],
+	;       FLAG WORD ADDRESS IN [I]
+
+FLAGSU:	LDA	ARG1+LO
+	JSR	OBJLOC		; GET OBJECT ADDR IN [I]
+
+	LDA	ARG2+LO		; LOOK AT FLAG ID
+	CMP	#$10		; FIRST SET OF FLAGS?
+	BCC	FLS1		; YES, ADDR IN [I] IS CORRECT
+
+	SBC	#16		; ELSE ZERO-ALIGN FLAG INDEX
+	TAX			; SAVE IT HERE
+
+	LDA	I+LO		; ADD 2 TO ADDRESS IN [I]
+	CLC			; TO POINT TO ADDRESS OF
+	ADC	#2		; 2ND FLAG WORD
+	STA	I+LO
+	BCC	FLS0
+	INC	I+HI
+
+FLS0:	TXA			; RESTORE INDEX
+
+FLS1:	STA	K+LO		; SAVE FLAG ID HERE
+
+	LDX	#1		; INIT THE
+	STX	J+LO		; FLAG WORD TO
+	DEX			; $0001
+	STX	J+HI
+
+	LDA	#15		; SUBTRACT THE BIT POSITION
+	SEC			; FROM 15
+	SBC	K+LO		; TO GET THE SHIFT LOOP
+	TAX			; INDEX
+	BEQ	FLS2		; EXIT NOW IF NO SHIFT NEEDED
+
+FLSL:	ASL	J+LO		; SHIFT THE BIT
+	ROL	J+HI		; INTO POSITION
+	DEX
+	BNE	FLSL
+
+FLS2:	LDY	#0		; MOVE THE FLAG WORD
+	LDA	(I),Y		; INTO [J]
+	STA	K+HI		; FIRST THE MSB
+	INY
+	LDA	(I),Y
+	STA	K+LO		; THEN THE LSB
+	RTS
+
+	END
+