TITLE MADD MULTIPLE PRECISION ADDITION AND SUBTRACTION ROUTINES
	SUBTTL V1 UWO 16-NOV-70
	ENTRY MADD,MSUB
	EXTERN MSHIFT,MNORM
MSUB:	Z
	MOVNS @1(16)	;NEGATE 2ND ARGUMENT
	SKIPA
MADD:	Z
	MOVEM 17,STORE+17	;SAVE
	MOVEI 17,STORE		;THE
	BLT 17,STORE+16		;AC'S
	MOVE 1,(16)	;AC1=ADDR OF FIRST CHARACTERISTIC WORD
	MOVE 2,1(16)	;AC2=ADDR OF SECOND CHARACTERISTIC WORD
	MOVE 0,@2(16)	;AC0=PRECISION
	CAILE 0,200
	JRST EROUT
	SKIPN 0,1(1)
	JRST ZERO   ; WORD1 IS 0
	SKIPN 0,1(2)
	JRST ZERO1   ;  WORD 2 IS 0
	MOVEI 3,TEMP1
	ADD 3,0
	HRLZ 4,1
	HRRI 4,TEMP1
	BLT 4,(3)
	MOVEI 3,TEMP2
	ADD 3,0
	HRLZ 4,2
	HRRI 4,TEMP2
	BLT 4,(3)
	HRRZI 1,TEMP1
	HRRZI 2,TEMP2
	MOVE 3,3(16)	;AC3=CHAR WORD OF RESULT, ADDR.
	MOVE 13,(1)	;AC13=FIRST CHARACTERISTIC WORD
	MOVE 14,(2)	;AC14=SECOND CHARACTERISTIC WORD
	SETZ 6,
	JUMPG 13,.+3
	MOVN 13,13	;AC13=ABSOLUTE VALUE OF FIRST CHARACTERISTIC
	AOJ 6,		;AC6=ONE MEANS FIRST CHAR NEGATED
	JUMPG 14,.+3
	MOVN 14,14	;AC14=ABSOLUTE VALUE OF SECOND CHARACTERISTIC
	SOJ 6,		;AC6 MINUS ONE MEANS SECOND CHAR NEGATED
	CAMN 13,14	;IF NOT EQUAL MUST SHIFT THE SMALLER NO.
	JRST CHKSN
	SUB 13,14
	MOVE 15,13	;IF THE DIFFERENCE BETWN THE ABSOLUTE
	JUMPG 15,.+2	;VALUES OF THE CHARACTERISTICS IS SO LARGE
	MOVN 15,15	;THAT THE SMALLER NO. IS SHIFTED OUT COMPLETELY
	MOVE 14,0	;THEN TAKE AN ERROR RETURN TO THE
	IMULI 14,43	;CALLING PROGRAM
	SUB 14,15
	JUMPG 14,CONT
	MOVM	13, (1)
	MOVM	14, (2)
	CAMG	13, 14
	JRST	ZERO
	JRST	ZERO1
EROUT:	HRLZI 17,STORE
	BLT 17,17	;RESTORE THE AC'S       AND ERROR EXIT.
	JRA 16,4(16)
CONT:	JUMPL 13,.+4
	MOVNM 13,SHIFT+3;SHIFT+3 IS NO. OF BITS AND DIRECTION
	MOVEM 2,SHIFT+1
	JRST SHIFT
	MOVEM 13,SHIFT+3;AND SHIFT+1 IS ADDR OF SMALLER CHARACTERISTIC
	MOVEM 1,SHIFT+1
SHIFT:	JSA 16,MSHIFT
	EXP 0,0,0
CHKSN:	MOVE 16,0	;IF SIGNS DIFF NEGATE SMALLER NO. AND ADD
	MOVE 10,1
	MOVE 11,2
COMP:	AOJ 10,0	;AC10=FIRST FRAC WORD FIRST NO. ,  ADDR
	AOJ 11,0	;AC11=ADDR FIRST FRAC, SEC NO
	MOVE 12,(10)	;AC12=FIRST FRAC WORD FIRST NO.
	CAMN 12,(11)	;TESTING FOR SMALLER ABS FRACTION
	SOJG 16,COMP
	CAML 12,(11)
	JRST .+4
	MOVE 13,1
	MOVE 14,2
	JRST .+3
	MOVE 13,2	;AC13=ADDR OF CHAR WORD OF SMALLER FRACT
	MOVE 14,1	;AC14=ADDR OF CHAR WORD OF LARGER FRACT
	MOVE 16,(14)	;SET CHAR OF RESULT TO THAT OF LARGER NO.
	MOVEM 16,(3)
	CAIN 6,0	;IF SIGNS THE SAME, GO TO KADD
	JRST KADD
	MOVE 15,3	;AC15=ADDR OF N+1 WORD OF RESULT
	ADD 15,0
	ADD 14,0	;AC14=ADDR OF N+1 WORD OF LARGER FRACT
	ADD 13,0	;AC13=ADDR OF N+1 WORD OF SMALLER FRACT
	MOVE 16,0	;AC16=COUNTER
	MOVN 10,(13)	;TAKE 2'S COMPLEMENT OF N+1 WORD
	SETZ 17,0	;AC17 WILL CONTAIN ANY CARRIES
	JRST .+2
XXX:	SETCM 10,(13)	;TAKE ONE'S COMPLEMENT REST OF FRACT
	ADD 10,(14)
	ADD 10,17
	TLZN 10,400000  ;STORE A POS RESULT, BUT IF POS, OVERFLOW
	JRST .+3
	SETZ 17,0
	JRST .+2
	MOVEI 17,1
	MOVEM 10,(15)
	SOJ 15,0
	SOJ 13,0
	SOJ 14,0
	SOJG 16,XXX
	MOVEM 3,NORM+1
	JRST NORM
KADD:	MOVE 10,0
	ADD 10,1	;AC10=ADDR OF NTH WORD, FIRST OPERAND
	MOVE 11,0
	ADD 11,2	;AC11=ADDR OF NTH WORD, SECOND OPERAND
	SETZ 17,0	;AC17 WILL BE USED FOR CARRIES INTO NEXT
	MOVE 12,0	;SEQUENTIAL ADD. AC12=A COUNTER FOR LOOPING
	MOVE 13,3	;AC13=ADDR OF CHARACTERISTIC WORD OF RESULT
	ADD 13,0	;AC13=ADDR OF NTH WORD OF RESULT
GO:	JFCL 17,.+1	;CLEAR ALL FLAGS
	MOVE 14,(10)
	ADD 14,(11)	;ADD THE 2 WORDS INDICATED PLUS
	ADD 14,17	;ANY CARRY FROM PREVIOUS OPERATION
	TLZ 14,400000	;MAKE SURE SIGN BIT=0
	MOVEM 14,(13)	;STORE IN RESULT+INDEX
	JOV .+3		;TEST FOR OVERFLOW
	SETZ 17,0	;IF NO OVERFLOW SET AC17=0
	JRST .+2
	MOVEI 17,1	;IF OVERFLOW SET AC17=1
	SOJ 10,0 	;DECREMENT AC'S SO THAT THEY WILL NOW 
	SOJ 11,0	;POINT TO THE (N-1)TH WORD OF FRACTIONAL
	SOJ 13,0	;PART OF BOTH OPERANDS AND THE RESULT
	SOJG 12,GO	;LOOP UNTIL ALL FRACTIONAL WORDS ADDED
	JUMPE 17,NOVER	;IF THERE WAS A CARRY OUT OF THE FINAL
	MOVE 17,(3)	;OPERATION, 1 MUST BE ADDED TO THE
	JUMPG 17,.+3	;CHARACTERISTIC OF THE RESULT AND THE
	SOJ 17,0	;WHOLE FRACTION SHIFTED RIGHT 1 BIT
	JRST .+2
	AOJ 17,0
	MOVEM 17,(3)
	MOVEM 3,OVFLOW+1
OVFLOW:	JSA 16,MSHIFT
	EXP 0,0,-1
	MOVE 17,1(3)
	TLO 17,200000
	MOVEM 17,1(3)
	JRST NORM+3
NOVER:	MOVEM 3,NORM+1	;MAKE RESULT ACCESSIBLE TO NORMALIZE ROUTINE
NORM:	JSA 16,MNORM
	EXP 0,0
	MOVEM 2,ZIP+1
ZIP:	JSA 16,MNORM
	EXP 0,0
	MOVEM 2,ZIP1+1
ZIP1:	JSA 16,MNORM
	EXP 0,0
OUT:	HRLZI 17,STORE
	BLT 17,17	;RESTORE THE AC'S
	JRA 16,5(16)	;RETURN TO CALLING SEQUENCE
STORE:	BLOCK 20
TEMP1:	BLOCK 201
TEMP2:	BLOCK 201
ZERO1:	MOVS 4,1
	JRST .+2
ZERO:	MOVS 4,2
	MOVE 5,3(16)
	ADD 5,0
	HRRM 5,BLOX
	HRR 4,3(16)
BLOX:	BLT 4,.
	JRST OUT
	END