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/*

    		 Crown Copyright (c) 1997

    This TenDRA(r) Computer Program is subject to Copyright

    owned by the United Kingdom Secretary of State for Defence

    acting through the Defence Evaluation and Research Agency

    (DERA).  It is made available to Recipients with a

    royalty-free licence for its use, reproduction, transfer

    to other parties and amendment for any purpose not excluding

    product development provided that any such use et cetera

    shall be deemed to be acceptance of the following conditions:-

        (1) Its Recipients shall ensure that this Notice is

        reproduced upon any copies or amended versions of it;

        (2) Any amended version of it shall be clearly marked to

        show both the nature of and the organisation responsible

        for the relevant amendment or amendments;

        (3) Its onward transfer from a recipient to another

        party shall be deemed to be that party's acceptance of

        these conditions;

        (4) DERA gives no warranty or assurance as to its

        quality or suitability for any purpose and DERA accepts

        no liability whatsoever in relation to any use to which

        it may be put.

*/

/**********************************************************************

$Author: release $

$Date: 1998/01/17 15:55:47 $

$Revision: 1.1.1.1 $

$Log: f64.c,v $

 * Revision 1.1.1.1  1998/01/17  15:55:47  release

 * First version to be checked into rolling release.

 *

 * Revision 1.1  1995/04/06  10:44:05  currie

 * Initial revision

 *

***********************************************************************/

#include "config.h"

#include "common_types.h"

#include "flpttypes.h"

#include "messages_c.h"

#include "flpt.h"

#include "basicread.h"

#include "expmacs.h"

#include "exp.h"

#include "f64.h"

/* PROCEDURES */

flt64 flt_to_f64

    PROTO_N ( (fp, sg, ov) )

    PROTO_T ( flpt fp X int sg X int * ov )

{

  flt * f = &flptnos[fp];

  flt64 res;

  int i = f->exp;

  *ov = 0;

  if (f->sign == 0 || i<0) {

    res.big = 0;

    res.small = 0;

  }

  else {

    res.big = 0;

    res.small = f->mant[i];

    if (i>0)

      res.small += (unsigned int)(f->mant[i-1] << 16);

    if (i>1)

      res.big = (int)f->mant[i-2];

    if (i>2)

      res.big += (int)(f->mant[i-3] << 16);

    if (i>3 || (sg && res.big < 0))

      *ov = 1;

  };

  if (f->sign == -1)  {

    res.small = ~res.small;

    res.big = ~res.big;

    if (res.small == 0xffffffff) {

      ++res.big;

    };

    ++res.small;

  };

  return res;

}

flpt f64_to_flt

    PROTO_N ( (a, sg) )

    PROTO_T ( flt64 a X int sg )

{

  flpt r = new_flpt();

  flt * res = &flptnos[r];

  flt_zero(res);

  if (a.big == 0 && a.small == 0)  {

    return r;

  };

  if (sg && a.big < 0) {

    a.small = ~a.small;

    a.big = ~a.big;

    if (a.small == 0xffffffff) {

      ++a.big;

    };

    ++a.small;

    res->sign = -1;

  }

  else

    res->sign = 1;

  if (a.big == 0) {

    if ((a.small & 0xffff0000) == 0) {

      res->exp = 0;

      res->mant[0] = (unsigned short)(a.small & 0xffff);

    }

    else {

      res->exp = 1;

      res->mant[0] = (unsigned short)((a.small & 0xffff0000) >> 16);

      res->mant[1] = (unsigned short)(a.small & 0xffff);

    };

  }

  else {

    if ((a.big & (int)0xffff0000) == 0) {

      res->exp = 2;

      res->mant[0] = (unsigned short)(a.big & 0xffff);

      res->mant[1] = (unsigned short)((a.small & 0xffff0000) >> 16);

      res->mant[2] = (unsigned short)(a.small & 0xffff);

    }

    else {

      res->exp = 3;

      res->mant[0] = (unsigned short)(((unsigned int)a.big >> 16) & 0xffff);

      res->mant[1] = (unsigned short)(a.big & 0xffff);

      res->mant[2] = (unsigned short)((a.small & 0xffff0000) >> 16);

      res->mant[3] = (unsigned short)(a.small & 0xffff);

    };

  };

  return r;

}

int f64_to_flpt

    PROTO_N ( (a, sg, pr, sz) )

    PROTO_T ( flt64 a X int sg X int * pr X int sz )

{

  int t = (int)a.small;

  *pr = 0;

  if (sg && (t >> 31) == a.big)

    return t;

  if (!sg && a.big == 0 && ((a.small & 0x80000000) == 0 || sz <= 32))

    return t;

  *pr = 1;

  return  f64_to_flt(a, sg);

}

flt64 int_to_f64

    PROTO_N ( (i, sg) )

    PROTO_T ( int i X int sg )

{

  flt64 res;

  res.small = (unsigned int)i;

  if (sg && i < 0)

    res.big = -1;

  else

    res.big = 0;

  return res;

}

flt64 exp_to_f64

    PROTO_N ( (e) )

    PROTO_T ( exp e )

{

  int ov;

  if (isbigval(e))

    return flt_to_f64(no(e), is_signed(sh(e)), &ov);

  return int_to_f64(no(e), is_signed(sh(e)));

}