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fcnvff.c

/*
 * Linux/PA-RISC Project (http://www.parisc-linux.org/)
 *
 * Floating-point emulation code
 *  Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
 *
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2, or (at your option)
 *    any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
/*
 * BEGIN_DESC
 *
 *  File:
 *    @(#)  pa/spmath/fcnvff.c            $Revision: 1.1 $
 *
 *  Purpose:
 *    Single Floating-point to Double Floating-point
 *    Double Floating-point to Single Floating-point
 *
 *  External Interfaces:
 *    dbl_to_sgl_fcnvff(srcptr,nullptr,dstptr,status)
 *    sgl_to_dbl_fcnvff(srcptr,nullptr,dstptr,status)
 *
 *  Internal Interfaces:
 *
 *  Theory:
 *    <<please update with a overview of the operation of this file>>
 *
 * END_DESC
*/


#include "float.h"
#include "sgl_float.h"
#include "dbl_float.h"
#include "cnv_float.h"

/*
 *  Single Floating-point to Double Floating-point 
 */
/*ARGSUSED*/
int
sgl_to_dbl_fcnvff(
          sgl_floating_point *srcptr,
          unsigned int *nullptr,
          dbl_floating_point *dstptr,
          unsigned int *status)
{
      register unsigned int src, resultp1, resultp2;
      register int src_exponent;

      src = *srcptr;
      src_exponent = Sgl_exponent(src);
      Dbl_allp1(resultp1) = Sgl_all(src);  /* set sign of result */
      /* 
       * Test for NaN or infinity
       */
      if (src_exponent == SGL_INFINITY_EXPONENT) {
            /*
             * determine if NaN or infinity
             */
            if (Sgl_iszero_mantissa(src)) {
                  /*
                   * is infinity; want to return double infinity
                   */
                  Dbl_setinfinity_exponentmantissa(resultp1,resultp2);
                  Dbl_copytoptr(resultp1,resultp2,dstptr);
                  return(NOEXCEPTION);
            }
            else {
                  /* 
                   * is NaN; signaling or quiet?
                   */
                  if (Sgl_isone_signaling(src)) {
                        /* trap if INVALIDTRAP enabled */
                        if (Is_invalidtrap_enabled())
                              return(INVALIDEXCEPTION);
                        /* make NaN quiet */
                        else {
                              Set_invalidflag();
                              Sgl_set_quiet(src);
                        }
                  }
                  /* 
                   * NaN is quiet, return as double NaN 
                   */
                  Dbl_setinfinity_exponent(resultp1);
                  Sgl_to_dbl_mantissa(src,resultp1,resultp2);
                  Dbl_copytoptr(resultp1,resultp2,dstptr);
                  return(NOEXCEPTION);
            }
      }
      /* 
       * Test for zero or denormalized
       */
      if (src_exponent == 0) {
            /*
             * determine if zero or denormalized
             */
            if (Sgl_isnotzero_mantissa(src)) {
                  /*
                   * is denormalized; want to normalize
                   */
                  Sgl_clear_signexponent(src);
                  Sgl_leftshiftby1(src);
                  Sgl_normalize(src,src_exponent);
                  Sgl_to_dbl_exponent(src_exponent,resultp1);
                  Sgl_to_dbl_mantissa(src,resultp1,resultp2);
            }
            else {
                  Dbl_setzero_exponentmantissa(resultp1,resultp2);
            }
            Dbl_copytoptr(resultp1,resultp2,dstptr);
            return(NOEXCEPTION);
      }
      /*
       * No special cases, just complete the conversion
       */
      Sgl_to_dbl_exponent(src_exponent, resultp1);
      Sgl_to_dbl_mantissa(Sgl_mantissa(src), resultp1,resultp2);
      Dbl_copytoptr(resultp1,resultp2,dstptr);
      return(NOEXCEPTION);
}

/*
 *  Double Floating-point to Single Floating-point 
 */
/*ARGSUSED*/
int
dbl_to_sgl_fcnvff(
                dbl_floating_point *srcptr,
                unsigned int *nullptr,
                sgl_floating_point *dstptr,
                unsigned int *status)
{
        register unsigned int srcp1, srcp2, result;
        register int src_exponent, dest_exponent, dest_mantissa;
        register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE;
      register boolean lsb_odd = FALSE;
      boolean is_tiny;

      Dbl_copyfromptr(srcptr,srcp1,srcp2);
        src_exponent = Dbl_exponent(srcp1);
      Sgl_all(result) = Dbl_allp1(srcp1);  /* set sign of result */
        /* 
         * Test for NaN or infinity
         */
        if (src_exponent == DBL_INFINITY_EXPONENT) {
                /*
                 * determine if NaN or infinity
                 */
                if (Dbl_iszero_mantissa(srcp1,srcp2)) {
                        /*
                         * is infinity; want to return single infinity
                         */
                        Sgl_setinfinity_exponentmantissa(result);
                        *dstptr = result;
                        return(NOEXCEPTION);
                }
                /* 
                 * is NaN; signaling or quiet?
                 */
                if (Dbl_isone_signaling(srcp1)) {
                        /* trap if INVALIDTRAP enabled */
                        if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
                        else {
                        Set_invalidflag();
                              /* make NaN quiet */
                              Dbl_set_quiet(srcp1);
                  }
                }
                /* 
                 * NaN is quiet, return as single NaN 
                 */
                Sgl_setinfinity_exponent(result);
            Sgl_set_mantissa(result,Dallp1(srcp1)<<3 | Dallp2(srcp2)>>29);
            if (Sgl_iszero_mantissa(result)) Sgl_set_quiet(result);
                *dstptr = result;
                return(NOEXCEPTION);
        }
        /*
         * Generate result
         */
        Dbl_to_sgl_exponent(src_exponent,dest_exponent);
      if (dest_exponent > 0) {
            Dbl_to_sgl_mantissa(srcp1,srcp2,dest_mantissa,inexact,guardbit, 
            stickybit,lsb_odd);
      }
      else {
            if (Dbl_iszero_exponentmantissa(srcp1,srcp2)){
                  Sgl_setzero_exponentmantissa(result);
                  *dstptr = result;
                  return(NOEXCEPTION);
            }
                if (Is_underflowtrap_enabled()) {
                  Dbl_to_sgl_mantissa(srcp1,srcp2,dest_mantissa,inexact,
                  guardbit,stickybit,lsb_odd);
                }
            else {
                  /* compute result, determine inexact info,
                   * and set Underflowflag if appropriate
                   */
                  Dbl_to_sgl_denormalized(srcp1,srcp2,dest_exponent,
                  dest_mantissa,inexact,guardbit,stickybit,lsb_odd,
                  is_tiny);
            }
      }
        /* 
         * Now round result if not exact
         */
        if (inexact) {
                switch (Rounding_mode()) {
                        case ROUNDPLUS: 
                                if (Sgl_iszero_sign(result)) dest_mantissa++;
                                break;
                        case ROUNDMINUS: 
                                if (Sgl_isone_sign(result)) dest_mantissa++;
                                break;
                        case ROUNDNEAREST:
                                if (guardbit) {
                                   if (stickybit || lsb_odd) dest_mantissa++;
                                   }
                }
        }
        Sgl_set_exponentmantissa(result,dest_mantissa);

        /*
         * check for mantissa overflow after rounding
         */
        if ((dest_exponent>0 || Is_underflowtrap_enabled()) && 
          Sgl_isone_hidden(result)) dest_exponent++;

        /* 
         * Test for overflow
         */
        if (dest_exponent >= SGL_INFINITY_EXPONENT) {
                /* trap if OVERFLOWTRAP enabled */
                if (Is_overflowtrap_enabled()) {
                        /* 
                         * Check for gross overflow
                         */
                        if (dest_exponent >= SGL_INFINITY_EXPONENT+SGL_WRAP) 
                              return(UNIMPLEMENTEDEXCEPTION);
                        
                        /*
                         * Adjust bias of result
                         */
                  Sgl_setwrapped_exponent(result,dest_exponent,ovfl);
                  *dstptr = result;
                  if (inexact) 
                      if (Is_inexacttrap_enabled())
                        return(OVERFLOWEXCEPTION|INEXACTEXCEPTION);
                      else Set_inexactflag();
                        return(OVERFLOWEXCEPTION);
                }
                Set_overflowflag();
            inexact = TRUE;
            /* set result to infinity or largest number */
            Sgl_setoverflow(result);
        }
        /* 
         * Test for underflow
         */
        else if (dest_exponent <= 0) {
                /* trap if UNDERFLOWTRAP enabled */
                if (Is_underflowtrap_enabled()) {
                        /* 
                         * Check for gross underflow
                         */
                        if (dest_exponent <= -(SGL_WRAP))
                              return(UNIMPLEMENTEDEXCEPTION);
                        /*
                         * Adjust bias of result
                         */
                  Sgl_setwrapped_exponent(result,dest_exponent,unfl);
                  *dstptr = result;
                  if (inexact) 
                      if (Is_inexacttrap_enabled())
                        return(UNDERFLOWEXCEPTION|INEXACTEXCEPTION);
                      else Set_inexactflag();
                        return(UNDERFLOWEXCEPTION);
                }
                 /* 
                  * result is denormalized or signed zero
                  */
               if (inexact && is_tiny) Set_underflowflag();

        }
      else Sgl_set_exponent(result,dest_exponent);
      *dstptr = result;
        /* 
         * Trap if inexact trap is enabled
         */
        if (inexact)
            if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
            else Set_inexactflag();
        return(NOEXCEPTION);
}

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