Initial commit.

atari/zstring.src

@@ -0,0 +1,437 @@
+	PAGE
+	SBTTL "--- Z-STRING HANDLERS ---"
+
+	; -----------------------
+	; POINT TO ZSTRING IN [I]
+	; -----------------------
+
+SETSTR:	LDA	I+LO		; WORD-ALIGN THE ADDRESS
+	ASL	A
+	STA	MPCL
+	LDA	I+HI
+	ROL	A
+	STA	MPCM
+	LDA	#0
+	STA	MPCFLG		; [MPC] IS CHANGING!
+	ROL	A
+	STA	MPCH
+
+ZSTEX:	RTS
+
+	; -----------------------
+	; PRINT Z-STRING AT [MPC]
+	; -----------------------
+
+PZSTR:	LDX	#0
+	STX	PSET		; ASSUME PERMANENT CHARSET
+	STX	ZFLAG		; CLEAR BYTE FLAG
+	DEX			; = $FF
+	STX	TSET		; NO TEMPSET ACTIVE
+
+PZTOP:	JSR	GETZCH		; GET A Z-CHAR
+	BCS	ZSTEX		; END OF STRING IF CARRY IS SET
+
+	STA	ZCHAR		; ELSE SAVE CHAR HERE
+	TAX			; SET FLAGS
+	BEQ	BLANK		; PRINT SPACE IF CHAR = 0
+
+	CMP	#4		; IS THIS AN F-WORD?
+	BCC	DOFREQ		; APPARENTLY SO
+
+	CMP	#6		; PERHAPS A SHIFT CODE?
+	BCC	NEWSET		; YES, CHANGE CHARSETS
+
+	JSR	GETSET		; ELSE GET CHARSET
+	TAX			; SET FLAGS
+	BNE	SET1		; SKIP IF NOT CHARSET #0
+
+	; PRINT A LOWER-CASE CHAR (CHARSET #0)
+
+	LDA	#$61-6		; ASCII "a" MINUS Z-OFFSET
+
+TOASC:	CLC
+	ADC	ZCHAR		; ADD Z-CHAR INDEX
+
+SHOVE:	JSR	COUT		; SHOW THE CHAR
+	JMP	PZTOP		; AND GRAB NEXT CHAR
+
+	; PRINT AN UPPER-CASE CHAR (CHARSET #1)
+
+SET1:	CMP	#1		; MAKE SURE IT'S SET #1
+	BNE	SET2		; ELSE MUST BE SET #2
+
+	LDA	#$41-6		; ASCII "A" MINUS Z-OFFSET
+	BNE	TOASC		; SAME AS SET #0
+
+	; PRINT FROM CHARSET #2
+
+SET2:	LDA	ZCHAR		; RETRIEVE THE Z-CHAR
+	SEC
+	SBC	#6		; ZERO-ALIGN IT
+	BEQ	DIRECT		; IF ZERO, IT'S A "DIRECT" ASCII
+
+	TAX			; OTHERWISE USE CODE AS AN INDEX
+	LDA	CHRTBL,X	; INTO THE CHARSET TABLE
+	JMP	SHOVE		; AND PRINT THE CHAR
+
+	; DECODE A "DIRECT" ASCII CHAR
+
+DIRECT:	JSR	GETZCH		; FETCH NEXT Z-CHAR
+	ASL	A
+	ASL	A
+	ASL	A
+	ASL	A
+	ASL	A		; SHIFT INTO POSITION
+	STA	ZCHAR		; AND SAVE HERE
+	JSR	GETZCH		; GRAB YET ANOTHER Z-CHAR
+	ORA	ZCHAR		; SUPERIMPOSE THE 2ND BYTE
+	JMP	SHOVE		; AND PRINT THE RESULT
+
+	; PRINT A SPACE
+
+BLANK:	LDA	#SPACE		; ASCII SPACE CHAR
+	BNE	SHOVE
+
+	; CHANGE CHARSET
+
+NEWSET:	SEC			; CONVERT THE SHIFT CODE
+	SBC	#3		; TO 1 OR 2
+	TAY
+	JSR	GETSET		; IS MODE TEMPORARY?
+	BNE	TOPERM		; YES, DO A PERMSHIFT
+	STY	TSET		; ELSE JUST A TEMPSHIFT
+	JMP	PZTOP		; AND CONTINUE
+
+TOPERM:	STY	PSET		; SET PERM CHARSET
+	CMP	PSET		; SAME AS BEFORE?
+	BEQ	PZTOP		; YES, CONTINUE
+	LDA	#0
+	STA	PSET		; ELSE RESET CHARSET
+	BEQ	PZTOP		; BEFORE LOOPING BACK
+
+	; PRINT AN F-WORD
+
+DOFREQ:	SEC
+	SBC	#1		; ZERO-ALIGN THE CODE
+	ASL	A		; AND MULTIPLY TIMES 64
+	ASL	A		; TO OBTAIN THE SEGMENT OFFSET
+	ASL	A		; INTO THE F-WORDS TABLE
+	ASL	A
+	ASL	A
+	ASL	A
+	STA	OFFSET		; SAVE OFFSET FOR LATER
+
+	JSR	GETZCH		; NOW GET THE F-WORD POINTER
+	ASL	A		; WORD-ALIGN IT
+	CLC			; AND
+	ADC	OFFSET		; ADD THE SEGMENT OFFSET
+	TAY			; TO GET THE OFFSET OF THE F-WORD
+	LDA	(FWORDS),Y	; FROM THE START OF THE F-WORDS TABLE
+	STA	I+HI		; SAVE MSB OF F-WORD ADDRESS
+	INY
+	LDA	(FWORDS),Y	; ALSO SAVE LSB
+	STA	I+LO		; Z-ADDRESS OF F-WORD IS IN [I]
+
+	; SAVE THE STATE OF CURRENT Z-STRING
+
+	LDA	MPCH
+	PHA
+	LDA	MPCM
+	PHA
+	LDA	MPCL
+	PHA
+	LDA	PSET
+	PHA
+	LDA	ZFLAG
+	PHA
+	LDA	ZWORD+HI
+	PHA
+	LDA	ZWORD+LO
+	PHA
+
+	JSR	SETSTR		; PRINT THE Z-STRING
+	JSR	PZSTR		; IN [I]
+
+	; RESTORE OLD Z-STRING
+
+	PLA
+	STA	ZWORD+LO
+	PLA
+	STA	ZWORD+HI
+	PLA
+	STA	ZFLAG
+	PLA
+	STA	PSET
+	PLA
+	STA	MPCL
+	PLA
+	STA	MPCM
+	PLA
+	STA	MPCH
+
+	LDX	#$FF
+	STX	TSET		; DISABLE TEMP CHARSET
+	INX			; = 0
+	STX	MPCFLG		; [MPC] HAS CHANGED
+	JMP	PZTOP		; CONTINUE INNOCENTLY
+
+	; ----------------------
+	; RETURN CURRENT CHARSET
+	; ----------------------
+
+GETSET:	LDA	TSET
+	BPL	GS
+	LDA	PSET
+	RTS
+
+GS:	LDY	#$FF
+	STY	TSET
+	RTS
+
+	; -----------------
+	; FETCH NEXT Z-CHAR
+	; -----------------
+
+GETZCH:	LDA	ZFLAG		; WHICH BYTE IS THIS?
+	BPL	GTZ0		; $FF = LAST
+	SEC			; SET CARRY TO INDICATE
+	RTS			; NO MORE CHARS
+
+GTZ0:	BNE	GETZ1		; NOT FIRST CHAR, EITHER
+
+	; GET A Z-WORD INTO [ZWORD], RETURN 1ST CHAR IN TRIPLET
+
+	INC	ZFLAG		; UPDATE CHAR COUNT
+
+	JSR	GETBYT		; GET TRIPLET AT [MPC]
+	STA	ZWORD+HI	; INTO [ZWORD]
+	JSR	GETBYT
+	STA	ZWORD+LO
+
+	LDA	ZWORD+HI
+	LSR	A
+	LSR	A		; SHIFT 1ST CHAR INTO PLACE
+	JMP	GTEXIT		; AND RETURN IT
+
+GETZ1:	SEC
+	SBC	#1
+	BNE	GETZ2		; LAST CHAR IN TRIPLET IF ZERO
+	LDA	#2		; ELSE
+	STA	ZFLAG		; RESET CHAR INDEX
+
+	LDA	ZWORD+LO	; GET BOTTOM HALF OF TRIPLET
+	STA	I+LO		; MOVE HERE FOR SHIFTING
+	LDA	ZWORD+HI	; GET TOP HALF
+
+	ASL	I+LO		; SHIFT THE TOP 3 BITS OF LOWER HALF
+	ROL	A		; INTO THE BOTTOM OF THE TOP HALF
+	ASL	I+LO
+	ROL	A
+	ASL	I+LO
+	ROL	A
+	JMP	GTEXIT
+
+GETZ2:	LDA	#0		; SET FLAG TO INDICATE
+	STA	ZFLAG		; END OF TRIPLET
+
+	LDA	ZWORD+HI	; TEST TOP HALF OF TRIPLET
+	BPL	GETZ3		; CONTINUE IF NOT END OF STRING
+	LDA	#$FF		; ELSE
+	STA	ZFLAG		; INDICATE LAST TRIPLET IN STRING
+
+GETZ3:	LDA	ZWORD+LO	; GET BOTTOM HALF OF TRIPLET
+
+GTEXIT:	AND	#%00011111	; MASK OUT GARBAGE BITS
+	CLC
+	RTS
+
+	; ---------------------------------
+	; CONVERT [IN] TO Z-STRING IN [OUT]
+	; ---------------------------------
+
+CONZST:	LDA	#$05		; FILL OUTPUT BUFFER
+	TAX			; WITH PAD CHARS ($05)
+CZSL:	STA	OUT,X
+	DEX
+	BPL	CZSL
+
+	LDA	#6		; INIT
+	STA	CONCNT		; CHAR COUNT
+
+	LDA	#0		; CLEAR
+	STA	CONIN		; SOURCE AND
+	STA	CONOUT		; OUTPUT INDEXES
+
+CONTOP:	LDX	CONIN		; FETCH SOURCE INDEX
+	INC	CONIN		; AND UPDATE
+	LDA	IN,X		; GRAB AN ASCII CHAR
+	STA	ZCHAR		; SAVE IT HERE
+	BNE	NEXTZ		; CONTINUE IF CHAR WAS NZ
+
+	LDA	#5		; ELSE SHIP OUT
+	BNE	CSHIP		; A PAD CHAR
+
+NEXTZ:	LDA	ZCHAR
+	JSR	SAYSET		; WHICH CHARSET TO USE?
+	BEQ	CSET0		; LOWER-CASE IF ZERO
+
+	CLC			; ELSE DO A TEMP-SHIFT
+	ADC	#3		; 4 = CHARSET 1, 5 = CHARSET 2
+	LDX	CONOUT		; FETCH OUTPUT INDEX
+	STA	OUT,X		; SEND THE SHIFT CHAR
+
+	INC	CONOUT		; UPDATE INDEX
+	DEC	CONCNT		; AND CHAR COUNT
+	BNE	CTEST		; IF OUT OF CHARS
+	JMP	ZCRUSH		; CRUSH 'EM!
+
+CTEST:	LDA	ZCHAR		; TEST CHAR AGAIN
+	JSR	SAYSET
+	CMP	#2
+	BEQ	CSET2		; CHARSET #2
+
+	; HANDLE CHARSET #1 (UPPER CASE ALPHA)
+
+	LDA	ZCHAR
+	SEC
+	SBC	#$41-6		; CONVERT TO Z-CHAR
+	BPL	CSHIP		; AND SEND TO OUTPUT
+
+	; HANDLE CHARSET #0 (LOWER CASE ALPHA)
+
+CSET0:	LDA	ZCHAR
+	SEC
+	SBC	#$61-6		; CONVERT TO Z-CHAR
+
+	; SHIP Z-CHAR TO OUTPUT BUFFER
+
+CSHIP:	LDX	CONOUT		; FETCH OUTPUT INDEX
+	STA	OUT,X
+
+	INC	CONOUT		; UPDATE INDEX
+	DEC	CONCNT		; DONE 6 CHARS YET?
+	BNE	CONTOP		; NO, LOOP BACK
+	JMP	ZCRUSH		; ELSE CRUSH
+
+	; HANDLE CHARSET #2 (MISCELLANEOUS)
+
+CSET2:	LDA	ZCHAR		; GRAB CHAR
+	JSR	CTABLE		; IS IT IN CHARSET #3 TABLE?
+	BNE	CSHIP		; YES, SEND IT TO OUTPUT
+
+	; SEND A "DIRECT" ASCII CHAR
+
+	LDA	#6		; ASCII ALERT!
+	LDX	CONOUT
+	STA	OUT,X
+
+	INC	CONOUT		; UPDATE INDEX
+	DEC	CONCNT		; AND CHAR COUNT
+	BEQ	ZCRUSH		; BUFFER FULL!
+
+	; SEND 1ST HALF OF "DIRECT"
+
+	LDA	ZCHAR
+	LSR	A
+	LSR	A
+	LSR	A
+	LSR	A
+	LSR	A
+	AND	#%00000011	; MASK GARBAGE
+	LDX	CONOUT
+	STA	OUT,X
+
+	INC	CONOUT
+	DEC	CONCNT
+	BEQ	ZCRUSH		; BUFFER FULL!
+
+	; SEND 2ND HALF OF "DIRECT"
+
+	LDA	ZCHAR		; GET CHAR YET AGAIN
+	AND	#%00011111	; MASK JUNK
+	JMP	CSHIP		; AND SHIP IT OUT
+
+	; ---------------------
+	; IS [A] IN CHARSET #3?
+	; ---------------------
+
+	; EXIT: [A] = CHAR CODE IF FOUND, Z-FLAG CLEARED
+	;       Z-FLAG SET IF NOT FOUND
+
+CTABLE:	LDX	#25
+CNL:	CMP	CHRTBL,X
+	BEQ	CNOK
+	DEX
+	BNE	CNL
+	RTS			; Z-FLAG SET IF NO MATCH
+
+CNOK:	TXA			; CHAR CODE IS INDEX
+	CLC
+	ADC	#6		; PLUS 6
+	RTS
+
+	; -----------------------------
+	; RETURN CHARSET OF CHAR IN [A]
+	; -----------------------------
+
+SAYSET:	CMP	#'a'
+	BCC	SAY1
+	CMP	#'z'+1
+	BCS	SAY1
+	LDA	#0		; IT'S CHARSET #0
+	RTS
+
+SAY1:	CMP	#'A'
+	BCC	SAY2
+	CMP	#'Z'+1
+	BCS	SAY2
+	LDA	#1		; IT'S CHARSET #1
+	RTS
+
+SAY2:	LDA	#2		; IT'S CHARSET #2
+	RTS
+
+	; ----------------------
+	; CRUSH Z-CHARS IN [OUT]
+	; ----------------------
+
+ZCRUSH:	LDA	OUT+1		; GET 2ND Z-CHAR
+	ASL	A		; SHIFT BITS INTO POSITION
+	ASL	A
+	ASL	A
+	ASL	A
+	ROL	OUT		; ALONG WITH 1ST Z-CHAR
+	ASL	A
+	ROL	OUT
+	ORA	OUT+2		; SUPERIMPOSE 3RD Z-CHAR
+	STA	OUT+1
+
+	LDA	OUT+4		; GET 5TH Z-CHAR
+	ASL	A		; SHIFT BITS
+	ASL	A
+	ASL	A
+	ASL	A
+	ROL	OUT+3		; ALONG WITH 4TH Z-CHAR
+	ASL	A
+	ROL	OUT+3
+	ORA	OUT+5		; SUPERIMPOSE 6TH Z-CHAR
+	TAX			; SAVE HERE
+	LDA	OUT+3		; GRAB 4TH Z-CHAR
+	ORA	#%10000000	; SET HIGH BIT
+	STA	OUT+2		; MOVE CRUSHED Z-WORD
+	STX	OUT+3		; INTO PLACE
+	RTS
+
+	; -----------------------
+	; CHARSET #2 DECODE TABLE
+	; -----------------------
+
+CHRTBL:	DB	0		; DUMMY BYTE FOR "DIRECT"
+	DB	$0D		; EOL
+	DB	"0123456789.,!?_#"
+	DB	$27		; SINGLE QUOTE
+	DB	$22		; DOUBLE QUOTE
+	DB	"/\-:()"
+
+	END
+