ca65 V2.17 - Git 582aa41
Main file   : decimal_to_hex.ca65
Current file: decimal_to_hex.ca65

000000r 1               ;
000000r 1               ; ACORN System 1 Applications: Decimal To Hexadecimal
000000r 1               ;
000000r 1               ; From the Acorn System 1 User's Manual
000000r 1               ;
000000r 1               ; (Chris Oddy January 2022)
000000r 1               ;
000000r 1               ; entry point $0200
000000r 1               ;
000000r 1               		.setcpu			"6502"
000000r 1               		.listbytes		unlimited
000000r 1               ;
000000r 1               D		:=		$10
000000r 1               DECL	:=		$20
000000r 1               DECH	:=		$21
000000r 1               DECVH	:=		$22
000000r 1               DISPLAY	:=		$FE0C		; scan the display
000000r 1               QHEXTD1	:=		$FE64		; quad hex to display 1
000000r 1               HEXTD	:=		$FE7A		; hex to display
000000r 1               QDATFET	:=		$FE88		; quad data fetch
000000r 1               RESTART	:=		$FF04		; Monitor reentry point
000000r 1               ;
000000r 1               		.org			$0200
000200  1               ;
000200  1  98           DECHEX:	tya					; clear A
000201  1  85 20        		sta		DECL		; clear No
000203  1  85 21        		sta		DECH
000205  1  A2 20        		ldx		#DECL
000207  1  85 22        AGAIN:	sta		DECVH		; fetch the first digit
000209  1  20 7A FE     		jsr		HEXTD
00020C  1  20 0C FE     		jsr		DISPLAY
00020F  1  90 F6        		bcc		AGAIN
000211  1  20 88 FE     		jsr		QDATFET		; and then the last four digits
000214  1  F8           		sed					; decimal mode
000215  1  84 10        		sty		D			; clear left display
000217  1  A6 21        		ldx		DECH		; X & Y as double accumulator
000219  1  98           		tya
00021A  1  85 21        		sta		DECH
00021C  1  A4 20        		ldy		DECL
00021E  1  85 20        		sta		DECL
000220  1  38           NEXT:	sec					; do a decimal subtract, double byte
000221  1  98           ALSO:	tya
000222  1  E9 01        		sbc		#$01
000224  1  A8           		tay
000225  1  8A           		txa
000226  1  E9 00        		sbc		#$00
000228  1  AA           		tax
000229  1  B0 04        		bcs		NODEC
00022B  1  C6 22        		dec		DECVH		; last of the decimal subtract, to do 5 digits
00022D  1  30 09        		bmi		RESLT		; if minus then finished
00022F  1  E6 20        NODEC:	inc		DECL		; double hex increment
000231  1  D0 ED        		bne		NEXT
000233  1  E6 21        		inc		DECH
000235  1  38           		sec					; create branch always, but don't bother to set the carry twice
000236  1  B0 E9        		bcs		ALSO
000238  1  A2 20        RESLT:	ldx		#$20
00023A  1  20 64 FE     		jsr		QHEXTD1		; display result
00023D  1  4C 04 FF     		jmp		RESTART
00023D  1