Initial commit.

atari/ops0.src

@@ -0,0 +1,160 @@
+	PAGE
+	SBTTL "--- 0-OPS ---"
+
+	; -----
+	; RTRUE
+	; -----
+
+	; SIMULATE A "RETURN 1"
+
+ZRTRUE:	LDX	#1
+
+ZRT0:	LDA	#0
+
+ZRT1:	STX	ARG1+LO		; GIVE TO
+	STA	ARG1+HI		; [ARG1]
+	JMP	ZRET		; AND DO THE RETURN
+
+	; ------
+	; RFALSE
+	; ------
+
+	; SIMULATE A "RETURN 0"
+
+ZRFALS:	LDX	#0
+	BEQ	ZRT0
+
+	; ------
+	; PRINTI
+	; ------
+
+	; PRINT Z-STRING FOLLOWING THE OPCODE
+
+ZPRI:	LDA	ZPCH		; MOVE [ZPC] INTO [MPC]
+	STA	MPCH
+	LDA	ZPCM
+	STA	MPCM
+	LDA	ZPCL
+	STA	MPCL
+
+	LDA	#0
+	STA	MPCFLG		; [MPC] NO LONGER VALID
+
+	JSR	PZSTR		; PRINT THE Z-STRING AT [MPC]
+
+	LDX	#5		; COPY STATE OF [MPC]
+PRIL:	LDA	MPC,X		; INTO [ZPC]
+	STA	ZPC,X
+	DEX
+	BPL	PRIL
+	RTS
+
+ 	; ------
+	; PRINTR
+	; ------
+
+	; DO A "PRINTI," FOLLOWED BY "CRLF" AND "RTRUE"
+
+ZPRR:	JSR	ZPRI
+	JSR	ZCRLF
+	JMP	ZRTRUE
+
+	; ------
+	; RSTACK
+	; ------
+
+	; "RETURN" WITH VALUE ON STACK
+
+ZRSTAK:	JSR	POPVAL		; GET VALUE INTO [X/A]
+	JMP	ZRT1		; AND GIVE IT TO "RETURN"
+
+	; ------
+	; VERIFY
+	; ------
+
+	; VERIFY GAME CODE ON DISK
+
+ZVER:	JSR	VERNUM 		; DISPLAY VERSION NUMBER, GET SIDE 1
+
+	LDX	#3
+	LDA	#0
+ZVR:	STA	J+LO,X		; CLEAR [J], [K]
+	STA	MPC,X		; [MPC] AND [MPCFLG]
+	DEX
+	BPL	ZVR
+
+	LDA	#64		; POINT [MPC] TO Z-ADDRESS $00040
+	STA	MPCL		; 1ST 64 BYTES AREN'T CHECKED
+
+	LDA	#K+HI		; PATCH THE "GETBYT" ROUTINE
+	STA	PATCH		; TO USE [K+HI]=0 INSTEAD OF [ZPURE]
+
+	LDA	ZBEGIN+ZENDLD	; GET LAST BYTE OF ENDLOAD
+	STA	I+HI		; FIRST MSB
+	LDA	ZBEGIN+ZENDLD+1
+	STA	I+LO		; THEN LSB
+
+	; CHECKSUM THE PRELOAD (SIDE 1)
+
+VSUM:	JSR	GETBYT		; GET A Z-BYTE INTO [A]
+	CLC
+	ADC	J+LO		; ADD IT TO SUM
+	STA	J+LO		; IN [J]
+	BCC	VSUM0
+	INC 	J+HI
+
+VSUM0:	LDA	MPCL		; END OF Z-CODE YET?
+	CMP	I+LO		; CHECK LSB
+	BNE	VSUM
+
+	LDA	MPCM		; AND MIDDLE BYTE
+	CMP	I+HI		; (HIGH BIT NEEDN'T BE CHECKED)
+	BNE	VSUM
+
+	; CHECKSUM "PURE" CODE (SIDE 2)
+
+	JSR	SIDE2		; PROMPT FOR SIDE 2
+
+	LDA	ZBEGIN+ZLENTH	; GET MSB
+	STA	I+HI		; AND
+	LDA	ZBEGIN+ZLENTH+1	; LSB OF Z-CODE LENGTH IN BYTES
+	ASL	A		; MULTIPLY BY
+	STA	I+LO		; TWO
+	ROL	I+HI		; TO GET # BYTES
+	ROL	K+LO		; IN GAME
+
+VSUM2:	JSR	GETBYT		; GET A Z-BYTE INTO [A]
+	CLC
+	ADC	J+LO		; ADD IT TO SUM
+	STA	J+LO		; IN [J]
+	BCC	VSUM3
+	INC 	J+HI
+
+VSUM3:	LDA	MPCL		; END OF Z-CODE YET?
+	CMP	I+LO		; CHECK LSB
+	BNE	VSUM2
+
+	LDA	MPCM		; MIDDLE BYTE
+	CMP	I+HI
+	BNE	VSUM2
+
+	LDA	MPCH		; AND HIGH BIT
+	CMP	K+LO
+	BNE	VSUM2
+
+	LDA	#ZPURE		; UNPATCH "GETBYT"
+	STA	PATCH
+
+	LDA	ZBEGIN+ZCHKSM+1	; GET LSB OF CHECKSUM
+	CMP	J+LO		; DOES IT MATCH?
+	BNE	BADVER		; NO, PREDICATE FAILS
+
+	LDA	ZBEGIN+ZCHKSM	; ELSE CHECK MSB
+	CMP	J+HI		; LOOK GOOD?
+	BNE	BADVER		; IF MATCHED,
+	JMP	PREDS		; GAME IS OKAY
+
+BADVER:	JMP	PREDF
+
+	END
+