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fcnvfu.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/fcnvfu.c            $Revision: 1.1 $
 *
 *  Purpose:
 *    Floating-point to Unsigned Fixed-point Converts
 *
 *  External Interfaces:
 *    dbl_to_dbl_fcnvfu(srcptr,nullptr,dstptr,status)
 *    dbl_to_sgl_fcnvfu(srcptr,nullptr,dstptr,status)
 *    sgl_to_dbl_fcnvfu(srcptr,nullptr,dstptr,status)
 *    sgl_to_sgl_fcnvfu(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"

/************************************************************************
 *  Floating-point to Unsigned Fixed-point Converts               *
 ************************************************************************/

/*
 *  Single Floating-point to Single Unsigned Fixed 
 */
/*ARGSUSED*/
int
sgl_to_sgl_fcnvfu(
                  sgl_floating_point *srcptr,
                  unsigned int *nullptr,
                  unsigned int *dstptr,
                  unsigned int *status)
{
      register unsigned int src, result;
      register int src_exponent;
      register boolean inexact = FALSE;

      src = *srcptr;
      src_exponent = Sgl_exponent(src) - SGL_BIAS;

      /* 
       * Test for overflow
       */
      if (src_exponent > SGL_FX_MAX_EXP + 1) {
            if (Sgl_isone_sign(src)) {
                  result = 0;
            } else {
                  result = 0xffffffff;
            }
            if (Is_invalidtrap_enabled()) {
                  return(INVALIDEXCEPTION);
            }
            Set_invalidflag();
            *dstptr = result;
            return(NOEXCEPTION);
      }
      /*
       * Generate result
       */
      if (src_exponent >= 0) {
            /* 
             * Check sign.
             * If negative, trap unimplemented.
             */
            if (Sgl_isone_sign(src)) {
                  result = 0;
                  if (Is_invalidtrap_enabled()) {
                        return(INVALIDEXCEPTION);
                  }
                  Set_invalidflag();
                  *dstptr = result;
                  return(NOEXCEPTION);
            }
            Sgl_clear_signexponent_set_hidden(src);
            Suint_from_sgl_mantissa(src,src_exponent,result);

            /* check for inexact */
            if (Sgl_isinexact_to_unsigned(src,src_exponent)) {
                  inexact = TRUE;
                  /*  round result  */
                  switch (Rounding_mode()) {
                  case ROUNDPLUS:
                        result++;
                        break;
                  case ROUNDMINUS: /* never negative */
                        break;
                  case ROUNDNEAREST:
                        if (Sgl_isone_roundbit(src,src_exponent) &&
                            (Sgl_isone_stickybit(src,src_exponent) ||
                             (result & 1))) {
                              result++;
                        }
                        break;
                  }
            }
      } else {
            result = 0;

            /* check for inexact */
            if (Sgl_isnotzero_exponentmantissa(src)) {
                  inexact = TRUE;
                  /*  round result  */
                  switch (Rounding_mode()) {
                  case ROUNDPLUS:
                        if (Sgl_iszero_sign(src)) {
                              result++;
                        }
                        break;
                  case ROUNDMINUS:
                        if (Sgl_isone_sign(src)) {
                              result = 0;
                              if (Is_invalidtrap_enabled()) {
                                    return(INVALIDEXCEPTION);
                              }
                              Set_invalidflag();
                              inexact = FALSE;
                        }
                        break;
                  case ROUNDNEAREST:
                        if (src_exponent == -1 &&
                            Sgl_isnotzero_mantissa(src)) {
                              if (Sgl_isone_sign(src)) {
                                    result = 0;
                                    if (Is_invalidtrap_enabled()) {
                                          return(INVALIDEXCEPTION);
                                    }
                                    Set_invalidflag();
                                    inexact = FALSE;
                              }
                                    else result++;
                        }
                        break;
                  }
            }
      }
      *dstptr = result;
      if (inexact) {
            if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
            else Set_inexactflag();
      }
      return(NOEXCEPTION);
}

/*
 *  Single Floating-point to Double Unsigned Fixed 
 */
/*ARGSUSED*/
int
sgl_to_dbl_fcnvfu(
                sgl_floating_point *srcptr,
                unsigned int *nullptr,
                dbl_unsigned *dstptr,
                unsigned int *status)
{
      register int src_exponent;
      register unsigned int src, resultp1, resultp2;
      register boolean inexact = FALSE;

      src = *srcptr;
      src_exponent = Sgl_exponent(src) - SGL_BIAS;

      /* 
       * Test for overflow
       */
      if (src_exponent > DBL_FX_MAX_EXP + 1) {
            if (Sgl_isone_sign(src)) {
                  resultp1 = resultp2 = 0;
            } else {
                  resultp1 = resultp2 = 0xffffffff;
            }
            if (Is_invalidtrap_enabled()) {
                  return(INVALIDEXCEPTION);
            }
            Set_invalidflag();
            Duint_copytoptr(resultp1,resultp2,dstptr);
            return(NOEXCEPTION);
      }
      /*
       * Generate result
       */
      if (src_exponent >= 0) {
            /* 
             * Check sign.
             * If negative, trap unimplemented.
             */
            if (Sgl_isone_sign(src)) {
                  resultp1 = resultp2 = 0;
                  if (Is_invalidtrap_enabled()) {
                        return(INVALIDEXCEPTION);
                  }
                  Set_invalidflag();
                  Duint_copytoptr(resultp1,resultp2,dstptr);
                  return(NOEXCEPTION);
            }
            Sgl_clear_signexponent_set_hidden(src);
            Duint_from_sgl_mantissa(src,src_exponent,resultp1,resultp2);

            /* check for inexact */
            if (Sgl_isinexact_to_unsigned(src,src_exponent)) {
                  inexact = TRUE;
                  /*  round result  */
                  switch (Rounding_mode()) {
                  case ROUNDPLUS:
                        Duint_increment(resultp1,resultp2);
                        break;
                  case ROUNDMINUS: /* never negative */
                        break;
                  case ROUNDNEAREST:
                        if (Sgl_isone_roundbit(src,src_exponent) &&
                            (Sgl_isone_stickybit(src,src_exponent) || 
                             Duint_isone_lowp2(resultp2))) {
                              Duint_increment(resultp1,resultp2);
                        }
                        break;
                  }
            }
      } else {
            Duint_setzero(resultp1,resultp2);

            /* check for inexact */
            if (Sgl_isnotzero_exponentmantissa(src)) {
                  inexact = TRUE;
                  /*  round result  */
                  switch (Rounding_mode()) {
                  case ROUNDPLUS:
                        if (Sgl_iszero_sign(src)) {
                              Duint_increment(resultp1,resultp2);
                        }
                        break;
                  case ROUNDMINUS:
                        if (Sgl_isone_sign(src)) {
                              resultp1 = resultp2 = 0;
                              if (Is_invalidtrap_enabled()) {
                                    return(INVALIDEXCEPTION);
                              }
                              Set_invalidflag();
                              inexact = FALSE;
                        }
                        break;
                  case ROUNDNEAREST:
                        if (src_exponent == -1 &&
                            Sgl_isnotzero_mantissa(src)) {
                              if (Sgl_isone_sign(src)) {
                                    resultp1 = 0;
                                    resultp2 = 0;
                                    if (Is_invalidtrap_enabled()) {
                                          return(INVALIDEXCEPTION);
                                    }
                                    Set_invalidflag();
                                    inexact = FALSE;
                              }
                              else Duint_increment(resultp1,resultp2);
                        }
                  }
            }
      }
      Duint_copytoptr(resultp1,resultp2,dstptr);
      if (inexact) {
            if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
            else Set_inexactflag();
      }
      return(NOEXCEPTION);
}

/*
 *  Double Floating-point to Single Unsigned Fixed 
 */
/*ARGSUSED*/
int
dbl_to_sgl_fcnvfu (dbl_floating_point * srcptr, unsigned int *nullptr,
               unsigned int *dstptr, unsigned int *status)
{
      register unsigned int srcp1, srcp2, result;
      register int src_exponent;
      register boolean inexact = FALSE;

      Dbl_copyfromptr(srcptr,srcp1,srcp2);
      src_exponent = Dbl_exponent(srcp1) - DBL_BIAS;

      /* 
       * Test for overflow
       */
      if (src_exponent > SGL_FX_MAX_EXP + 1) {
            if (Dbl_isone_sign(srcp1)) {
                  result = 0;
            } else {
                  result = 0xffffffff;
            }
            if (Is_invalidtrap_enabled()) {
                  return(INVALIDEXCEPTION);
            }
            Set_invalidflag();
            *dstptr = result;
            return(NOEXCEPTION);
      }
      /*
       * Generate result
       */
      if (src_exponent >= 0) {
            /* 
             * Check sign.
             * If negative, trap unimplemented.
             */
            if (Dbl_isone_sign(srcp1)) {
                  result = 0;
                  if (Is_invalidtrap_enabled()) {
                        return(INVALIDEXCEPTION);
                  }
                  Set_invalidflag();
                  *dstptr = result;
                  return(NOEXCEPTION);
            }
            Dbl_clear_signexponent_set_hidden(srcp1);
            Suint_from_dbl_mantissa(srcp1,srcp2,src_exponent,result);

            /* check for inexact */
            if (Dbl_isinexact_to_unsigned(srcp1,srcp2,src_exponent)) {
                  inexact = TRUE;
                  /*  round result  */
                  switch (Rounding_mode()) {
                  case ROUNDPLUS:
                       result++;
                       break;
                  case ROUNDMINUS: /* never negative */
                       break;
                  case ROUNDNEAREST:
                       if(Dbl_isone_roundbit(srcp1,srcp2,src_exponent) &&
                        (Dbl_isone_stickybit(srcp1,srcp2,src_exponent)||
                         result&1))
                           result++;
                       break;
                  }
                  /* check for overflow */
                  if (result == 0) {
                        result = 0xffffffff;
                        if (Is_invalidtrap_enabled()) {
                              return(INVALIDEXCEPTION);
                        }
                        Set_invalidflag();
                        *dstptr = result;
                        return(NOEXCEPTION);
                  }
            }
      } else {
            result = 0;

            /* check for inexact */
            if (Dbl_isnotzero_exponentmantissa(srcp1,srcp2)) {
                  inexact = TRUE;
                  /*  round result  */
                  switch (Rounding_mode()) {
                  case ROUNDPLUS:
                        if (Dbl_iszero_sign(srcp1)) result++;
                        break;
                  case ROUNDMINUS:
                        if (Dbl_isone_sign(srcp1)) {
                              result = 0;
                              if (Is_invalidtrap_enabled()) {
                                    return(INVALIDEXCEPTION);
                              }
                              Set_invalidflag();
                              inexact = FALSE;
                        }
                        break;
                  case ROUNDNEAREST:
                        if (src_exponent == -1 &&
                            Dbl_isnotzero_mantissa(srcp1,srcp2))
                              if (Dbl_isone_sign(srcp1)) {
                                    result = 0;
                                    if (Is_invalidtrap_enabled()) {
                                          return(INVALIDEXCEPTION);
                                    }
                                    Set_invalidflag();
                                    inexact = FALSE;
                              }
                              else result++;
                  }
            }
      }
      *dstptr = result;
      if (inexact) {
            if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
            else Set_inexactflag();
      }
      return(NOEXCEPTION);
}

/*
 *  Double Floating-point to Double Unsigned Fixed 
 */
/*ARGSUSED*/
int
dbl_to_dbl_fcnvfu (dbl_floating_point * srcptr, unsigned int *nullptr,
               dbl_unsigned * dstptr, unsigned int *status)
{
      register int src_exponent;
      register unsigned int srcp1, srcp2, resultp1, resultp2;
      register boolean inexact = FALSE;

      Dbl_copyfromptr(srcptr,srcp1,srcp2);
      src_exponent = Dbl_exponent(srcp1) - DBL_BIAS;

      /* 
       * Test for overflow
       */
      if (src_exponent > DBL_FX_MAX_EXP + 1) {
            if (Dbl_isone_sign(srcp1)) {
                  resultp1 = resultp2 = 0;
            } else {
                  resultp1 = resultp2 = 0xffffffff;
            }
            if (Is_invalidtrap_enabled()) {
                  return(INVALIDEXCEPTION);
            }
            Set_invalidflag();
            Duint_copytoptr(resultp1,resultp2,dstptr);
            return(NOEXCEPTION);
      }
 
      /*
       * Generate result
       */
      if (src_exponent >= 0) {
            /* 
             * Check sign.
             * If negative, trap unimplemented.
             */
            if (Dbl_isone_sign(srcp1)) {
                  resultp1 = resultp2 = 0;
                  if (Is_invalidtrap_enabled()) {
                        return(INVALIDEXCEPTION);
                  }
                  Set_invalidflag();
                  Duint_copytoptr(resultp1,resultp2,dstptr);
                  return(NOEXCEPTION);
            }
            Dbl_clear_signexponent_set_hidden(srcp1);
            Duint_from_dbl_mantissa(srcp1,srcp2,src_exponent,resultp1,
              resultp2);

            /* check for inexact */
            if (Dbl_isinexact_to_unsigned(srcp1,srcp2,src_exponent)) {
                  inexact = TRUE;
                  /*  round result  */
                  switch (Rounding_mode()) {
                  case ROUNDPLUS:
                        Duint_increment(resultp1,resultp2);
                        break;
                  case ROUNDMINUS: /* never negative */
                        break;
                  case ROUNDNEAREST:
                        if(Dbl_isone_roundbit(srcp1,srcp2,src_exponent))
                          if(Dbl_isone_stickybit(srcp1,srcp2,src_exponent) || 
                             Duint_isone_lowp2(resultp2))
                              Duint_increment(resultp1,resultp2);
                  } 
            }
      } else {
            Duint_setzero(resultp1,resultp2);

            /* check for inexact */
            if (Dbl_isnotzero_exponentmantissa(srcp1,srcp2)) {
                  inexact = TRUE;
                  /*  round result  */
                  switch (Rounding_mode()) {
                  case ROUNDPLUS:
                        if (Dbl_iszero_sign(srcp1)) {
                              Duint_increment(resultp1,resultp2);
                        }
                        break;
                  case ROUNDMINUS:
                        if (Dbl_isone_sign(srcp1)) {
                              resultp1 = resultp2 = 0;
                              if (Is_invalidtrap_enabled()) {
                                    return(INVALIDEXCEPTION);
                              }
                              Set_invalidflag();
                              inexact = FALSE;
                        }
                        break;
                  case ROUNDNEAREST:
                        if (src_exponent == -1 &&
                            Dbl_isnotzero_mantissa(srcp1,srcp2))
                              if (Dbl_iszero_sign(srcp1)) {
                                    Duint_increment(resultp1,resultp2);
                              } else {
                                    resultp1 = 0;
                                    resultp2 = 0;
                                    if (Is_invalidtrap_enabled()) {
                                          return(INVALIDEXCEPTION);
                                    }
                                    Set_invalidflag();
                                    inexact = FALSE;
                              }
                  }
            }
      }
      Duint_copytoptr(resultp1,resultp2,dstptr);
      if (inexact) {
            if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
            else Set_inexactflag();
      }
      return(NOEXCEPTION);
}


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