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cobol-source/float.mac
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; UPD ID= 1010 on 4/26/83 at 5:22 PM by NIXON
TITLE FLOAT FOR LIBOL
SUBTTL CONVERT COMP TO FLOATING POINT AL BLACKINGTON/CAM/DMN
SEARCH COPYRT
SALL
;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, 1983, 1984 BY DIGITAL EQUIPMENT CORPORATION
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HISEG
.COPYRIGHT ;Put standard copyright statement in REL file
ENTRY FLOT.2 ;2-WORD COMP TO COMP-2
ENTRY FLT.12 ;1-WORD COMP TO COMP-2
ENTRY FLT.22 ;2-WORD COMP TO COMP-2
ENTRY FLT.42 ;4-WORD COMP TO COMP-2
HIPART==377776
TA=13
TB=TA+1
TC=TB+1
PA=16 ;INPUT PARAMETER
PP=17 ;PUSH-DOWN POINTER
SUBTTL CONVERT TWO-WORD COMP TO COMP-1
;CALLING SEQUENCE:
; MOVE PA,<Z AC,ADDRESS OF HIGH-ORDER HALF OF DOUBLE-PRECISION NUMBER>
; PUSHJ PP,FLOT.2
;EXIT WITH FLOATING POINT NUMBER IN ACCUMULATOR SPECIFIED BY
; AC-FIELD OF AC16.
.
FLOT.2: MOVSI TC,(1.0) ;SET SCALING FACTOR
DMOVE TA,0(PA) ;GET BOTH WORDS
JUMPGE TA,FLOT2B ;POSITIVE?
DMOVN TA,TA ;NEGATE IT
FLOT2B: TLZ TB,1B18 ;BE SURE LOW-HALF IS POSITIVE
FLOT2C: TLNE TA,HIPART ;IS VALUE > 2**54?
JRST FLOT2E ;YES
ASHC TA,10 ;NO--SHIFT OVER 8 BITS
ASH TB,-10 ;RESTORE LOW PART
SKIPE TA ;SET EXPONENT IN HIGH-PART UNLESS
TLC TA,266000 ; IT IS ZERO
SKIPE TB ;SET EXPONENT IN LOW PART UNLESS
TLC TB,233000 ;IT IS NEGATIVE
FADR TA,TB ;ADD TWO-HALVES
FMP TA,TC ;MULTIPLY BY SCALING FACTOR
SKIPGE 0(PA) ;WAS INPUT NEGATIVE?
MOVNS TA ;YES--NEGATE RESULT
LDB TB,[POINT 4,PA,12]; GET AC-FIELD
MOVEM TA,0(TB) ;STORE RESULT
POPJ PP,
FLOT2E: ADD TC,[1B8] ;NUMBER > 2**54--INCREASE SCALING FACTOR
ASHC TA,-1 ;REDUCE TA
JRST FLOT2C ;TRY AGAIN
SUBTTL FLT.12 - ONE-WORD COMP TO COMP-2
;CALLING SEQUENCE:
; MOVE 16,<Z AC,OPERAND>
; PUSHJ 17,FLT.12
;EXIT WITH RESULT IN ACCUMULATOR SPECIFIED BY AC-FIELD OF ACCUMULATOR 16.
FLT.12: SETZ TB, ;CLEAR SECOND WORD
SKIPN TA,0(PA) ;GET INPUT
JRST FLOT2R ;ZERO, RETURN
ASHC TA,-10 ;MAKE ROOM FOR EXPONENT
TLC TA,243000 ;SET EXP TO 27+8 DECIMAL
DFAD TA,[EXP 0,0] ;NORMALIZE
FLOT2R: LDB TC,[POINT 4,PA,12] ;GET AC FIELD
DMOVEM TA,0(TC) ;STORE RESULT
POPJ PP,
SUBTTL FLT.22 - TWO-WORD COMP TO COMP-2
;CALLING SEQUENCE:
; MOVE 16,<Z AC,OPERAND>
; PUSHJ 17,FLT.22
;EXIT WITH RESULT IN ACCUMULATOR SPECIFIED BY AC-FIELD OF ACCUMULATOR 16.
FLT.22: DMOVE TA,0(PA) ;GET INPUT
SKIPGE TA ;INPUT NEGATIVE?
FLT22N: DMOVN TA,TA ;YES, MAKE IT POSITIVE
FLT22P: PUSH PP,TC+1 ;NEED 4 AC'S
MOVE TC,TB ;MOVE LOW WORD
SETZB TB,TC+1 ;ZERO SECOND WORD OF EACH PAIR
JUMPE TA,FLT22A ;LEAVE ALONE IF ZERO
ASHC TA,-10 ;MAKE ROOM FOR EXPONENT
TLC TA,306000 ;SET EXPONENT TO 2*<27+8>
DFAD TA,[EXP 0,0] ;NORMALIZE
FLT22A: JUMPE TC,FLT22B ;LEAVE ALONE IF ZERO
ASHC TC,-10 ;MAKE ROOM FOR EXPONENT
TLC TC,243000 ;SET EXPONENT TO 27+8
DFAD TC,[EXP 0,0] ;NORMALIZE
DFAD TA,TC ;ADD AND NORMALIZE
FLT22B: POP PP,TC+1 ;RESTORE AC
SKIPGE 0(PA) ;WAS INPUT NEGATIVE?
DMOVN TA,TA ;YES, NEGATE OUTPUT
JRST FLOT2R ;RETURN
SUBTTL FLT.42 - FOUR-WORD COMP TO COMP-2
;CALLING SEQUENCE:
; MOVE 16,<Z AC,OPERAND>
; PUSHJ 17,FLT.42
;EXIT WITH RESULT IN ACCUMULATOR SPECIFIED BY AC-FIELD OF ACCUMULATOR 16.
FLT.42: DMOVE TA,0(PA) ;GET HIGH PAIR OF INPUT
SKIPN TA ;SEE IF BOTH ZERO
JUMPE TB,[DMOVE TA,2(PA) ;GET LOWER PAIR
JRST FLT22P] ;TREAT AS JUST 2 WORDS
CAIN TA,[-1] ;SEE IF BOTH -1
CAIE TB,[-1]
JRST FLT42A ;NO
DMOVN TA,2(PA) ;YES, GET LOWER PAIR
JRST FLT22N ;TREAT AS JUST 2 WORDS
FLT42A: DMOVE TA,2(PA) ;GET LOWER PAIR OF INPUT
SKIPGE 0(PA) ;INPUT NEGATIVE?
DMOVN TA,TA ;YES, MAKE IT POSITIVE
PUSH PP,TC+1 ;NEED 4 AC'S
MOVE TC,TB ;MOVE LOW WORD
SETZB TB,TC+1 ;ZERO SECOND WORD OF EACH PAIR
JUMPE TA,FLT42B ;LEAVE ALONE IF ZERO
ASHC TA,-10 ;MAKE ROOM FOR EXPONENT
TLC TA,306000 ;SET EXPONENT TO 2*<27+8>
DFAD TA,[EXP 0,0] ;NORMALIZE
FLT42B: JUMPE TC,FLT42C ;LEAVE ALONE IF ZERO
ASHC TC,-10 ;MAKE ROOM FOR EXPONENT
TLC TC,243000 ;SET EXPONENT TO 27+8
DFAD TC,[EXP 0,0] ;NORMALIZE
DFAD TA,TC ;ADD AND NORMALIZE
FLT42C: MOVE TC+1,(PP) ;RESTORE AC
PUSH PP,TA ;STORE RESULT FOR NOW
PUSH PP,TB
DMOVE TA,0(PA) ;GET HIGH PAIR INPUT
SKIPGE TA ;INPUT NEGATIVE?
DMOVN TA,TA ;YES, MAKE IT POSITIVE
MOVE TC,TB ;MOVE LOW WORD
SETZB TB,TC+1 ;ZERO SECOND WORD OF EACH PAIR
JUMPE TA,FLT42D ;LEAVE ALONE IF ZERO
ASH TA,5 ;MAKE ROOM FOR EXPONENT (NEVER GETS TOO BIG)
TLC TA,377000 ;SET EXPONENT TO 4*<27+8>-13
DFAD TA,[EXP 0,0] ;NORMALIZE
FLT42D: JUMPE TC,FLT42E ;LEAVE ALONE IF ZERO
ASHC TC,-10 ;MAKE ROOM FOR EXPONENT
TLC TC,351000 ;SET EXPONENT TO 3*<27+8>
DFAD TC,[EXP 0,0] ;NORMALIZE
DFAD TA,TC ;ADD AND NORMALIZE
FLT42E: POP PP,TC+1 ;RESTORE LOW ORDER PAIR
POP PP,TC
DFAD TA,TC ;FORM COMPLETE NUMBER
POP PP,TC+1 ;FINALLY RESTORE PA
SKIPGE 0(PA) ;WAS INPUT NEGATIVE?
DMOVN TA,TA ;YES, NEGATE OUTPUT
JRST FLOT2R ;RETURN
END