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PDP-10 Archives
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decuslib20-01
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decus/20-0009/random.mac
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TITLE RANDOM NUMBER GENERATOR
;CALLED BY CALL RANDOM(R), WHERE R IS RETURNED, -1.0<R>1.0
; OR BY A=RANDOM(R), EQUIVALENT TO CALL RANDOM(R), A = R
;Calling convention changed by Paul T. Robinson, Wesleyan Univ.
;for DECUS conversion to DEC-20 library.
ENTRY RANDOM
RANDOM: MOVEM 01, SAVAC1
MOVE 00, VAR
MUL 00, CONST
ASHC 00, 5
MOVEM 00, SIGN ;SAVE FOR SIGN BIT
SETZ 00,
ASHC 00, -5
MOVEM 01, VAR
ASHC 00, 40
TLC 00, 200000 ;FLOAT
MOVE 01, SIGN ;GET A SIGN BIT
TRNE 01, 1
MOVNS 00
FADR 00, NORM ;NORMALIZE
MOVEM 00, @0(16)
popj 17,
VAR: OCT 5343277245
CONST: OCT 5343277245
NORM: OCT 200000000000
SIGN: BLOCK 1
SAVAC1: BLOCK 1
END