napisal rec.asm

ass1/rec.asm

@@ -0,0 +1,136 @@
+rec			START	0
+			JSUB	stackinit
+
+mainloop	JSUB	readnum
+			COMP	#0		.if 0 halt
+			JEQ		halt
+			JSUB	fac
+			JSUB	printnum
+			J		mainloop
+
+readnum		STL		readret
+			LDA		#0
+			STA		currentnum
+readchar	RD		devFA
+			COMP	#10		.stop reading if newline
+			JEQ		endread
+			COMP	#48		.stop reading if 0
+			JEQ		endread
+			SUB		#48
+			STA		temp
+			LDA		currentnum
+			MUL		#10
+			ADD		temp
+			STA		currentnum
+			J		readchar
+endread		LDA		currentnum
+			LDL		readret
+			RSUB
+
+ending		LDA		temp
+			JSUB	printnum
+			J		mainloop
+
+printnum	STL		printret
+			STA		num
+			LDA		#0
+			STA		digitcnt
+divloop		LDA		num
+			COMP	#0
+			JEQ		checkzero
+			DIV		#10
+			STA		quotient
+			MUL		#10
+			STA		saveA
+			LDA		num
+			SUB		saveA
+			ADD		#48		.convert to ascii number
+			STA		@stkptr
+			JSUB	push
+			LDA		digitcnt
+			ADD		#1
+			STA		digitcnt
+			LDA		quotient
+			STA		num
+			J		divloop
+checkzero	LDA		digitcnt
+			COMP	#0
+			JGT		printloop
+			LDA		#48
+			WD		devAA
+			LDL		printret
+			RSUB
+printloop	LDA		digitcnt
+			COMP	#0
+			JEQ		printdone
+			LDB		stkptr
+			COMPR	X, B	.stop print if stack empty
+			JEQ		printdone
+			JSUB	pop
+			WD		devAA
+			LDA		digitcnt
+			SUB		#1
+			STA		digitcnt
+			J		printloop
+printdone	LDL		printret
+			LDA		#0x0A	.print newline
+			WD		devAA	
+			RSUB	
+
+halt		J		halt
+
+fac			COMP	#1		.base case
+			JGT		facrecur
+			LDA		#1
+			RSUB
+
+							.only works for < 10 (24 bit registers)
+facrecur	JSUB	push	.recursive case
+			SUB		#1
+			JSUB	fac
+			STA		temp
+			STL		lastJ	.save jump register
+			LDB		stkptr
+			COMPR	X, B	.exit if stack empty
+			JEQ		ending
+			JSUB	pop
+			MUL		temp
+			LDL		lastJ
+			RSUB			
+
+push		STA		temp
+			STA		@stkptr
+			LDA		stkptr
+			ADD 	#3
+			STA		stkptr
+			LDA		temp
+			RSUB
+
+pop			STA		temp
+			LDA		stkptr
+			SUB		#3
+			STA		stkptr
+			LDA		@stkptr
+			RSUB
+
+stackinit	STA		temp
+			LDA		#stack
+			STA		stkptr
+			LDX		stkptr
+			LDA		temp
+			RSUB
+
+stkptr		RESW	1
+temp		RESW	1
+lastJ		RESW	1
+printret	RESW	1
+readret		RESW	1
+currentnum	RESW	1
+num			RESW	1
+quotient	RESW	1
+saveA		RESW	1
+digitcnt	RESW	1
+stack		RESW	50
+devFA		BYTE	X'FA'
+devAA		BYTE	X'AA'
+			END		rec