C
C
C  Copyright (C) 2000, 2001 Silicon Graphics, Inc.  All Rights Reserved.
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C


      SUBROUTINE VXDCTI(FPN,DEST,ISB,NUM,IER,INC)
C
C     The VXDCTI subroutine converts Cray 64-bit single-precision
C     floating-point numbers to VAX D_format single-precision
C     floating-point numbers.  Numbers that produce an underflow when
C     converted to VAX format are converted to 32 binary zeros.  Numbers
C     that are in overflow on the CRAY are converted to a "reserved"
C     floating-point representation with the sign bit set if negative.
C     Numbers that are valid on the CRAY but overflow on the VAX are
C     converted to the most positive possible number or most negative
C     possible number, depending on the sign.
C
C     Presently, you must supply a parameter which, in the future,
C     will contain a nonzero value if any numbers converted produced
C     an overflow.  No such indication will be given for underflow.
C
      REAL    FPN(1)              ! Variable or array of any length and
C                                 ! type real, containing Cray 64-bit,
C                                 ! single-precision, floating-point
C                                 ! numbers to convert.
C
      INTEGER DEST(1)             ! Variable or array of type real to
C                                 ! contain the converted values.
C
      INTEGER ISB                 ! Byte number at which to begin
C                                 ! storing the converted results.  Type
C                                 ! integer variable, expression, or
C                                 ! constant.  Bytes are numbered from
C                                 ! 1, beginning at the leftmost byte
C                                 ! position of DEST.
C
      INTEGER NUM                 ! Number of Cray floating-point
C                                 ! numbers to convert.  Type integer
C                                 ! variable, expression, or constant.
C
      INTEGER IER                 ! Overflow indicator of type integer.
C                                 ! Value is 0 if all Cray values
C                                 ! convert to VAX values without
C                                 ! overflow.  Value is nonzero if one
C                                 ! or more Cray values overflowed in
C                                 ! the conversion.
C
      INTEGER INC                 ! Memory increment for fetching the
C                                 ! number to be converted.  Optional
C                                 ! parameter of type integer variable,
C                                 ! expression, or constant.  Default
C                                 ! value is 1.

      INTEGER ITEMP(64), JTEMP(32)

CDIR$ VFUNCTION VD64O
      INTEGER   VD64O

      IF (NUMARG() .EQ.5) THEN
        JNC = 1
      ELSE IF (NUMARG() .EQ. 6) THEN
        JNC = INC
      ELSE
        CALL ABORT('VAX conversion routine called with incorrect number 
     +of arguments')
      ENDIF

      IF (NUM .LT. 0) THEN
        CALL ABORT('Invalid input to VAX conversion routine')
      ENDIF

      NUMC = NUM
      JSB  = ISB
      J    = 1
      IER  = 0

      IF (NUM .EQ. 0) RETURN

   40 CONTINUE

      NUMP = MIN0(NUMC,64)

CDIR$ SHORTLOOP
      DO 80 I = 1, NUMP
        ITEMP(I) = VD64O(DBLE(FPN(J)))
        J        = J + JNC
   80 CONTINUE

      CALL VXMOVE00(ITEMP,1,NUMP*8,DEST,JSB)

      JSB  = JSB + 8*NUMP
      NUMC = NUMC - NUMP
      IF (NUMC .GT. 0) GO TO 40

      RETURN
CDIR$ ID "@(#) libu/vms/vxdcti.f	92.0	10/08/98 14:57:41"
      END
