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; UPD ID= 3549 on 5/14/81 at 1:29 PM by NIXON                           
TITLE	DPADD FOR LIBOL
SUBTTL	DOUBLE-PRECISION INTEGER ADDITION	PETE WILSON/ALB/CAM



;THIS SOFTWARE IS FURNISHED UNDER A LICENSE AND MAY ONLY BE USED
;  OR COPIED IN ACCORDANCE WITH THE TERMS OF SUCH LICENSE.
;
;COPYRIGHT (C) 1974, 1981 BY DIGITAL EQUIPMENT CORPORATION


;V12*****
;	 6-OCT-78	[540] ADD QUAD-WORD ROUNDING FUNCTION

;V10*****
;	5/10/75		/DBT	ADD BIS CODE
;***********

	SEARCH	LBLPRM
	%%LBLP==:%%LBLP
	BIS==:BIS

	HISEG

;CALLING SEQUENCE:
;	MOVE 16,<Z AC,OPERAND B>
;	PUSHJ 17,ADD.12/ADD.21/ADD.22

;ENTER WITH FIRST OPERAND (OPERAND A) IN ACCUMULATOR SPECIFIED BY AC-FIELD OF PARAMETER
;SECOND OPERAND (OPERAND B) IS ACCESSED VIA AC 16 (WHERE THE UUO IS).
; IF DOUBLE-PRECISION:
;	0(16) GETS HIGH-ORDER WORD, 1(16) REFERENCES LOW HALF.
; IF SINGLE-PRECISION:
;	0(16) REFERENCES SINGLE WORD.
;EXIT WITH TWO-WORD RESULT IN AC'S SPECIFIED BY AC-FIELD OF PARAMETER

	ENTRY	ADD.12	;ADD TWO WORDS IN MEMORY TO ONE WORD IN AC 1.
	ENTRY	ADD.21	;ADD ONE WORD IN MEMORY TO TWO WORDS IN AC'S 0 AND 1.
	ENTRY	ADD.22	;ADD TWO WORDS IN MEMORY TO TWO WORDS IN AC'S 0 AND 1.
IFN BIS,<
	ENTRY	ADD.4R	;[540] ADD ONE WORD IN ACC 4 TO 4 WORDS IN ACCS 0-3
>

RS=11		;RESULT AC POINTER
TA=13		;TEMPORARY
TB=14		;TEMPORARY
TC=15		;TEMPORARY
PA=16		;POINTER TO OPERAND B.
PP=17		;PUSH-DOWN POINTER.

IFE	BIS,<

ADD.21:	SKIPL	0(PA)		;ADD SINGLE TO DOUBLE, CHECK SIGN OF LOW B OPERAND.
	TDZA	TC,TC		;MAKE SIGN OF HIGH-ORDER B OPERAND AGREE
	SETO	TC,		;  WITH LOW-ORDER SIGN.
	SOJA	PA,ADDXX		;THEN ADJUST POINTER AND ENTER MAIN LINE.

ADD.12:	LDB	RS,[POINT 4,PA,12]	;GET INPUT AC
	MOVE	TA,0(RS)	;GET OPERAND
	MULI	TA,1		;CREATE DOUBLE-PRECISION
	MOVE	TC,0(PA)	;GET HI-PART OF OTHER OPERAND
	JRST	ADDXX1

ADD.22:	MOVE	TC,0(PA)	;ADD DOUBLE TO DOUBLE, GET HIGH-ORDER B WORD.

ADDXX:	LDB	RS,[POINT 4,PA,12] ;GET OPERAND AC
	MOVE	TA,0(RS)	;GET OPERAND
	MOVE	TB,1(RS)
ADDXX1:	JFCL	17,.+1		;CLEAR ARITHMETIC FLAGS.
	PUSHJ	PP,CHECK	;BE SURE SIGNS AGREE
	ADD	TB,1(PA)	;ADD LOW-ORDER WORDS.
	JCRY1	CARRYS		;IF A CARRY OCCURRED, GO ADJUST HIGH-ORDER WORD.
ADDXX2:	ADD	TA,TC		;ADD TWO HIGH-ORDER WORDS.
	PUSHJ	PP,CHECK	;BE SURE SIGNS AGREE
	MOVEM	TA,0(RS)	;STASH HI-PART
	MOVEM	TB,1(RS)	;STASH LOW PART
	POPJ	PP,		;RETURN

CHECK:	TLNE	TA,1B18		;MAKE SIGN OF LOW-ORDER PART
	TLOA	TB,1B18		;  AGREE WITH SIGN OF
	TLZ	TB,1B18		;  HIGH-ORDER RESULT.
	POPJ	PP,

;COME HERE ON CARRY GENERATED IN ADDITION OF LOW-ORDER WORDS.
CARRYS:	ADDI	TA,1		;ADD CARRY TO HIGH-ORDER HALF.
	PUSHJ	PP,CHECK	;THEN GO CHECK FOR SIGN CHANGE IN HIGH HALF.
	JFCL	17,ADDXX2	;CLEAR OVERFLOW AND GO ADD HIGH-ORDER WORDS.

>	;END OF NON-BIS

IFN	BIS,<

ADD.12:
	LDB	TA,PACFL.##	; GET AC NUMBER
	MOVE	TB,(TA)		;GET LOW ORDER WORD.
	MOVEM	TB,1(TA)	;PUT IT WHERE IT SHOULD BE.
	SETZM	(TA)		;CLEAR HIGH ORDER AC
	SKIPGE	1(TA)		;IS LOW ORDER NEGATIVE
	SETOM	(TA)		;YES - EXTEND SIGN

ADD.22:
	;CHANGE PA INTO A DADD

	TLZ	PA,777000	;JUST TO BE SAFE
	TLO	PA,(DADD)		;PUT IN OP CODE
	XCT	PA		;DO IT
	POPJ	PP,		;DONE

ADD.21:
	MOVE	TA,0(PA)	;GET WORD IN MEMORY
	ASHC	TA,-^D35	;EXTEND SIGN
	HRRI	PA,TA		;WE WILL ADD IN TA
	TLZ	PA,777000	;JUST TO BE SURE
	TLO	PA,(DADD)		;SET OP CODE
	XCT	PA
	POPJ	PP,		;DONE

;[540] HERE TO DO ROUNDING TO QUAD-WORD VALUE

ADD.4R:	ASHC	4,-^D35		;[540] EXTEND SIGN
	JFCL	17,.+1		;[540] CLEAR FLAGS
	DADD	2,4		;[540] ADD IN ROUNDING CONSTANT
	JOV	CARRY4		;[540] OVERFLOW OCCURED
	POPJ	PP,		;[540] NO, ALL DONE

CARRY4:	SKIPL	5,4		;[540] IF IT WAS NEGATIVE USE -1
	MOVEI	5,1		;[540] NO, SO ADD 1
	DADD	0,4		;[540] ADJUST HIGH WORD
	POPJ	PP,		;[540] AND RETURN

>	;END BIS
	END