.TITLE	JADD
	.IDENT	/V1.01/
	.PSECT	CODE,RO
	.NLIST	SYM,TOC
 
; DOUBLE-PRECISION INTEGER ADDITION
;
; 'PROCEDURE' JADD(JSUM,JA,JB);
;
; JSUM:=JA+JB
 
G1570::	CMP	(%3)+,(%2)+	; ADDRESS LO WORDS
	MOV	@%2,%4		; GET JA LOW
	ADD	@%3,%4		; ADD JB LO
	MOV	-(%2),%5	; GET JA HI, W/O AFFECTING CARRY
	ADC	%5		; ADD IN CARRY
	BVS	10$		; TRAP OVERFLOW
	ADD	-(%3),%5	; ELSE ADD IN JB HI
	BVC	100$		; EXIT IF OK
	BR	11$		; BUT TRAP OVERFLOW AGAIN
 
10$:	ADD	-(%3),%5	; COMPLETE SUM IF OVERFLOW ON ADC
11$:	DEC	V		; DEC OVERFLOW COUNTER
	MOV	#785.,FLOERR	; SET UP FLOERRORCODE
100$:	MOV	%5,(%1)+	; STORE HI
	MOV	%4,@%1		; AND LO PART OF RESULT
 
	ADD	#2,@SP		; STANDARD EXIT
	RTS	PC
 
	.PSECT	GLOBAL,OVR,GBL,RW
 
G=.
 
V=G+300.
FLOERR=G+302.
 
	.END