Merge pull request #1 from peterferrie/main

a bit faster, explicit memory init

QR.6502

@@ -112,45 +112,33 @@ GETMESSAGE	LDA MESSAGE,Y	; 0
 			STA $FC
 			JSR MULT45		; RESULT IN FE,FD
 			CLC
-			INY				; 1
-			LDA MESSAGE,Y
+			LDA MESSAGE+1,Y
 			ADC $FD
-			STA $FD
-			BCC STOREPAIR			
-			INC $FE			; RESULT IN FE,FD
-STOREPAIR	DEY				; 0
+			STA STORAGE+1,Y	; LO BYTE
 			LDA $FE
+			ADC #0			; RESULT IN FE,FD
 			STA STORAGE,Y	; HI BYTE
 			INY				; 1
-			LDA $FD
-			STA STORAGE,Y	; LO BYTE
 			INY				; 2
 			CPY MESSAGELENGTH
-			BEQ BUILDQR
+			BCC GETMESSAGE
 			BCS BUILDQR
-			JMP GETMESSAGE
 
 
 **************************************************
 * Byte mode = ROR each byte in message 4x, append to mode/length bits.
 **************************************************
-BYTEMODE	LDY #$00
-FINDLENGTH	LDX MESSAGE,Y
-			BEQ FOUNDLENGTH
-			INY
-			JMP FINDLENGTH
+BYTEMODE	LDY #$FF
+FINDLENGTH	INY
+			LDX MESSAGE,Y
+			BNE FINDLENGTH
 FOUNDLENGTH	STY MESSAGELENGTH
-			LDX MESSAGELENGTH
-			DEX
-			LDA MESSAGE,X				; LAST BYTE OF MESSAGE
-			AND #$0F					; LO 4 BITS
-			CLC
-			ROL
-			ROL
-			ROL
-			ROL
-			INX
-			STA STORAGE,X				; 4 BITS AT END OF CONVERTED MESSAGE
+			LDA MESSAGE-1,Y				; LAST BYTE OF MESSAGE
+			ASL					; LO 4 BITS
+			ASL
+			ASL
+			ASL
+			STA STORAGE,Y				; 4 BITS AT END OF CONVERTED MESSAGE
 
 COPYMSG		LDX #$0						; COPY THE MESSAGE TO STORAGE
 COPYBYTE	LDA MESSAGE,X
@@ -163,12 +151,10 @@ COPYBYTE	LDA MESSAGE,X
 			LDY #$04					
 RORMSG		LDX #$0
 			CLC
-			PHP
-RORBYTE		PLP
-			ROR STORAGE,X
+RORBYTE			ROR STORAGE,X
 			INX
-			PHP							; PRESERVES CARRY
-			CPX MESSAGELENGTH			; BECAUSE CPX CLOBBERS IT
+			TXA							; DON'T USE CPX, PRESERVES CARRY
+			EOR MESSAGELENGTH
 			BNE RORBYTE			
 			DEY
 			BNE RORMSG
@@ -183,7 +169,6 @@ BUILDQR
 **************************************************
 
 			LDA MESSAGELENGTH		; NNNNXXXX
-			CLC
 			LDX MODE
 			CPX #$40
 			BEQ LSR4X
@@ -203,32 +188,22 @@ LSR4X		LSR
 			BNE DOALPHAMODE 
 			JMP DOBYTEMODE
 			
-DOALPHAMODE	AND #$1F				; 000NXXXX
+DOALPHAMODE					; 000NXXXX
 
-			CLC
-			ROL						; <- 3X
-			ROL
-			ROL						; NXXXX 000
+			ASL
+			ASL						; <- 3X
+			ASL						; NXXXX 000
 			
-			LDX #$0
-			ORA STORAGE,X	;  3 BITS OF FIRST HI BYTE
+			ORA STORAGE	;  3 BITS OF FIRST HI BYTE
 			INY
 			STA MPINTS,Y
-			INX
 			INY
-			LDA STORAGE,X	; FIRST LO BYTE
-			STA MPINTS,Y	; HOW CONVENIENT. FIRST PAIR OF BYTES ENDS ON AN 8X BOUNDARY.
-			INY				; SET UP NEXT BYTE OF QR
-			
-			* FOR EACH REMAINING PAIR OF BYTES, GET 3 BITS FROM HI, 8 BITS FROM LO 
-			LDA #$08
-			STA BITCOUNTER	; CURRENT BIT OF QR ENCODING CYCLE
-
-			LDA MPINTS,Y	; CURRENT BYTE OF QR DATA 
-
+			LDA STORAGE+1	; FIRST LO BYTE
+			JSR NEXTQRBYTE	; HOW CONVENIENT. FIRST PAIR OF BYTES ENDS ON AN 8X BOUNDARY.
+					; ALSO INITIALIZES BITCOUNTER
 			LDX #$02		; WHICH BYTE OF MESSAGE
 
-NEXTMBYTE	ROL STORAGE,X		; HI BYTE - ROL 5X
+NEXTMBYTE	ASL STORAGE,X		; HI BYTE - ROL 5X
 			ROL STORAGE,X
 			ROL STORAGE,X
 			ROL STORAGE,X
@@ -291,39 +266,31 @@ BIT10		ROL STORAGE,X
 			JSR NEXTQRBYTE
 NEXTHIBYTE	INX
 			CPX MESSAGELENGTH			; up to 114 BYTES OF MESSAGE
-			BEQ PADBYTES
 			BCS PADBYTES
 			JMP NEXTMBYTE				; 3 BITS OF HI BYTE AND 8 OF LO BYTE ROTATED INTO QR BYTESTREAM
 
 
-DOBYTEMODE	AND #$0F					; A=MESSAGELENGTH. 0000XXXX	
-			CLC
-			ROL
-			ROL
-			ROL
-			ROL							; XXXX____
+DOBYTEMODE						; A=MESSAGELENGTH. 0000XXXX	
+			ASL
+			ASL
+			ASL
+			ASL							; XXXX____
 			ORA STORAGE,Y
-			INY
-BYTEMODELOOP	STA MPINTS,Y
-			CPY MESSAGELENGTH
-			BEQ LASTBYTE
-			LDA STORAGE,Y
-			INY
-			JMP BYTEMODELOOP
-
-LASTBYTE 	LDA STORAGE,Y
-			INY
+BYTEMODELOOP		INY
 			STA MPINTS,Y
-			JMP PADLOOP
+			LDA STORAGE,Y
+			CPY MESSAGELENGTH
+			BCC BYTEMODELOOP
+			BEQ BYTEMODELOOP
+			BCS PADLOOP
 
 * pad to 80 bytes with 0s and 11101100 00010001 (#$EC #$11)
 
 PADBYTES	LDX BITCOUNTER		; ALWAYS TERMINATE WITH 4 ZEROES
-PADBYTES2	CLC
+		db $C9			; MASK ASL
+PADBYTES2	ASL
 			DEC BITCOUNTER
-			BMI PADBITS
-			ROL
-			JMP PADBYTES2
+			BPL PADBYTES2
 PADBITS		STA MPINTS,Y		; STORE INCOMPLETE BYTE WITH TRAILING ZEROS
 			CPX #$04			; NEEDS TO BE AT LEAST 4 FOR TERMINATOR
 			BCS PADLOOP
@@ -342,42 +309,42 @@ PADLOOP		INY					; NEXT QR BYTE
 
 
 
-DOECCBYTES	LDX #$0				; OH, THIS GON' BE FUN.
-			LDA #$50
-			STA BYTECOUNTER		; HOW MANY TIMES HAVE WE BEEN HERE BEFORE?
+DOECCBYTES	LDX #$50				; OH, THIS GON' BE FUN.
+							
+			STX BYTECOUNTER		; HOW MANY TIMES HAVE WE BEEN HERE BEFORE?
 COPYBYTES	LDA MPINTS,X		; COPY COMPLETE MESSAGE BYTES TO STORAGE SPACE AT $8000
 			STA STORAGE,X
-			INX
-			CPX #$51			; DONE ALL 80 BYTES			
-			BNE COPYBYTES
-
-			
-ECCSTEP1	LDX #$0				; convert integers in message to exponents	
-								
-MSGTOEXP	LDY MPINTS,X		; convert integers in message to exponents	
+ECCSTEP1
+MSGTOEXP	TAY		; convert integers in message to exponents	
 			LDA INTTOEXP,Y	
 			STA MPEXP,X
-			INX
-			CPX #$51
-			BNE MSGTOEXP		;  MSG EXPONENTS IN MPEXP
+			LDA #0
+			STA SCRATCH,X
+			DEX			; DONE ALL 80 BYTES			
+			BPL COPYBYTES
+			STA XORRESULT+$50
+			STA XORRESULT+$51
+			STA XORRESULT+$52	; SKIPZERO READS OOB
 
+			
 ECCSTEP2	LDX #$0				; Multiply the Generator Polynomial by the Lead EXPONENT of the Message Polynomial
 STEP2LOOP	LDA MPEXP			; mp first exponent 	
 			CLC
 			ADC GENERATOR,X		; ADDED TO each gp exponent				
+			ADC #0		; MOD 255 ON ROLLOVER > FF ADDS CARRY
 			TAY
-			BCC SCRATCHINT		; MOD 255 ON ROLLOVER > FF ADDS CARRY
-			INY
 SCRATCHINT	LDA EXPTOINT,Y		; convert EXPONENTS in RESULT to INTEGERS
 			STA SCRATCH,X		; STORE IN WORK AREA 2
+ECCSTEP3		EOR MPINTS,X		; INTEGER TERMS OF MESSAGE
+			STA XORRESULT,X		; RESULT FEEDS INTO STEP 1
 			INX
 			CPX #$15
 			BNE STEP2LOOP		; INTEGER RESULTS IN SCRATCH
 
-ECCSTEP3	LDX #$0				; XOR the result with the message polynomial (INTEGERS)
-XORBYTE		LDA SCRATCH,X		; INTEGER RESULT OF MULTIPLICATION
-			EOR MPINTS,X		; INTEGER TERMS OF MESSAGE
-STOREXOR	STA XORRESULT,X		; RESULT FEEDS INTO STEP 1
+					; XOR the result with the message polynomial (INTEGERS)			
+
+XORBYTE		LDA MPINTS,X		; INTEGER TERMS OF MESSAGE
+			STA XORRESULT,X		; RESULT FEEDS INTO STEP 1
 			INX
 			CPX #$51		
 			BNE XORBYTE	
@@ -410,23 +377,21 @@ XORTOEXP	STA MPINTS,Y			; RESULT INTEGERS IN MPINTS
 			BNE XORTOEXP		;  RESULT EXPONENTS IN MPEXP
 
 			DEC BYTECOUNTER		; DO ECC MATH UNTIL THERE'S 20 REMAINDERS
-			BEQ ECCDONE
-			JMP ECCSTEP2
+			BNE ECCSTEP2
 
 
 
 ECCDONE 						; XORRESULT CONTAINS 20 ECC BYTES
-			LDX #$1
-			LDY #$50
+			LDX #$15
+			LDY #$64
 BUILDMSG	LDA XORRESULT,X
 			STA STORAGE,Y
-			INX
-			INY
-			CPX #$16
+			DEY
+			DEX
 			BNE BUILDMSG		; STORAGE NOW HAS FULL 100 BYTES OF MESSAGE
 
-RESETBYTE	LDA #$0				; SET UP FOR BYTE/BIT TRACKING
-			STA BYTECOUNTER
+RESETBYTE	;;LDA #$0				; SET UP FOR BYTE/BIT TRACKING
+			;;STA BYTECOUNTER
 RESETBIT	LDA #$8
 			STA BITCOUNTER
 		
@@ -434,9 +399,10 @@ RESETBIT	LDA #$8
 			LDA #$20			; ROW=33 (0-#$20)
 			STA ROW				; COLUMN=33 (0-#$20)
 			STA COLUMN
-NEXTZIG		CLC					; QRLINE=ROW/2
+NEXTZIG							; QRLINE=ROW/2
 			LDA ROW
 			LSR
+			PHP
 			TAX					; LINE NUM OF BLANK QR = ROW/2
 			LDA QRLINESLO,X
 			STA LOBYTE
@@ -456,8 +422,7 @@ LONIBBLE	AND #$0F
 			BNE	ZAG				; OCCUPIED?
 			JSR SETPIXEL 		; GET A BIT FROM THE MESSAGE, AND DEPOSIT INTO THE PIXEL
 ZAG			DEY					; ZIG IS DONE/OCCUPIED, TIME TO ZAG - ONE COLUMN TO THE LEFT
-			LDA ROW				; LOST THE CARRY, SO CHECK THE ROW AGAIN
-			LSR
+			PLP				; RESTORE THE CARRY
 			LDA (LOBYTE),Y		; GET CURRENT QR PIXEL
 			BCC LONIBBLE2
 			AND #$F0
@@ -482,14 +447,12 @@ DIVBY4		LSR					; DIVIDE STARTING COLUMN BY 2
 GOINGUP		LDA ROW
 			BEQ UTURN			; TURN THE CORNER AT ROW 0
 			DEC ROW
-			LDA COLUMN
 			JMP NEXTZIG			; 			
 								
 GOINGDOWN	LDA ROW
 			CMP #$20			; LAST ROW?								
 			BEQ UTURN			; TURN THE CORNER, ROW 32
 			INC ROW				; OTHERWISE, NEXT ROW
-			LDA COLUMN
 			JMP NEXTZIG
 
 UTURN		LDA COLUMN
@@ -500,7 +463,6 @@ CKCOLUMN	CMP #$01			; IS IT #$01? THEN WE'RE DONE HERE.
 			BEQ DODISPLAY
 			DEC COLUMN
 			DEC COLUMN			; TWO COLUMNS OVER FOR NEXT ZIG
-			LDA COLUMN
 			JMP NEXTZIG	
 
 
@@ -550,28 +512,20 @@ NEXTQRBYTE	STA MPINTS,Y		; STORE COMPLETE BYTE
 *** SETPIXEL
 
 SETPIXEL	CMP #$01			; ACC IS GOING TO BE EITHER 01 OR 10
-			BEQ SETLONIBBLE
-
+			PHP
 			JSR GETNEXTBIT		; LOADS TEMP WITH PROPER F OR 0
 								; Y HAS COLUMN OFFSET
 								; (LOBYTE) HAS ROW
-SETHINIBBLE	LDA TEMP
-			AND #$F0
-			STA TEMP
+			EOR (LOBYTE),Y		; MIX BITS
+			PLP
+			BEQ SETLONIBBLE
 
-			LDA (LOBYTE),Y		; GET CURRENT QR PIXEL
-			AND #$0F			; CLEAR HI NIBBLE
+SETHINIBBLE		AND #$F0		; SEPARATE BITS
 			JMP SETNIBBLE					
 
-SETLONIBBLE	JSR GETNEXTBIT		; LOADS TEMP WITH PROPER F OR 0
-			LDA TEMP
-			AND #$0F
-			STA TEMP
+SETLONIBBLE		AND #$0F		; SEPARATE BITS
 
-			LDA (LOBYTE),Y		; GET CURRENT QR PIXEL
-			AND #$F0			; CLEAR LO NIBBLE
-
-SETNIBBLE	EOR TEMP
+SETNIBBLE		EOR (LOBYTE),Y		; MERGE BITS
 			STA (LOBYTE),Y		; REPLACE QR PIXEL.
 			RTS
 *** SETPIXEL
@@ -583,32 +537,28 @@ GETNEXTBIT	LDA BITCOUNTER		; WHERE WERE WE IN THE ROL SHENANIGANS?
 			LDA #$08			; OR ARE WE?
 			STA BITCOUNTER		; IF SO...
 			INC BYTECOUNTER		; NEXT BYTE
-NEXTBIT		LDX BYTECOUNTER		; ARE WE DONE WITH ALL 100 BYTES?
+NEXTBIT		LDA TEMP
+			LDX BYTECOUNTER		; ARE WE DONE WITH ALL 100 BYTES?
 			CPX #$64
-			BEQ MASKDONE
+			BEQ MASKDONE1
 			DEC BITCOUNTER
 			
 
-			CLC
-			ROL STORAGE,X
-			BCC WHITEPIXEL
-BLACKPIXEL	LDA #$00
-			BEQ COLORPIXEL		; BRANCH ALWAYS
+			ASL STORAGE,X
 WHITEPIXEL	LDA #$FF
-COLORPIXEL	STA TEMP
+BLACKPIXEL	ADC #$00
+COLORPIXEL	TAX
 
 DOMASK		; JFC ON A POGO STICK! GOTTA MASK THE BITS!
 			; MASK PATTERN 1: IF (row) mod 2 == 0 THEN FLIP BIT.
 			LDA ROW
 			LSR
+			TXA
 			BCS MASKDONE		; ROW IS ODD, ALL DONE.
 
-			LDA TEMP			; ROW IS EVEN, FLIP THE BIT
-			BNE	FLIPBIT			
-			DEC TEMP			; TEMP IS ZERO, SET TO FF
-			RTS
-FLIPBIT		INC TEMP			; TEMP IS FF, SET TO ZERO
-MASKDONE	RTS			
+			EOR #$FF		; ROW IS EVEN, FLIP THE BIT
+MASKDONE	STA TEMP
+MASKDONE1	RTS			
 *** GETNEXTBIT