kernel/arch/parisc/math-emu/fcnvff.c

   1 /*
   2  * Linux/PA-RISC Project (http://www.parisc-linux.org/)
   3  *
   4  * Floating-point emulation code
   5  *  Copyright (C) 2001 Hewlett-Packard (Paul Bame) <bame@debian.org>
   6  *
   7  *    This program is free software; you can redistribute it and/or modify
   8  *    it under the terms of the GNU General Public License as published by
   9  *    the Free Software Foundation; either version 2, or (at your option)
  10  *    any later version.
  11  *
  12  *    This program is distributed in the hope that it will be useful,
  13  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *    GNU General Public License for more details.
  16  *
  17  *    You should have received a copy of the GNU General Public License
  18  *    along with this program; if not, write to the Free Software
  19  *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21 /*
  22  * BEGIN_DESC
  23  *
  24  *  File:
  25  *      @(#)    pa/spmath/fcnvff.c              $Revision: 1.1 $
  26  *
  27  *  Purpose:
  28  *      Single Floating-point to Double Floating-point
  29  *      Double Floating-point to Single Floating-point
  30  *
  31  *  External Interfaces:
  32  *      dbl_to_sgl_fcnvff(srcptr,nullptr,dstptr,status)
  33  *      sgl_to_dbl_fcnvff(srcptr,nullptr,dstptr,status)
  34  *
  35  *  Internal Interfaces:
  36  *
  37  *  Theory:
  38  *      <<please update with a overview of the operation of this file>>
  39  *
  40  * END_DESC
  41 */
  42
  43
  44 #include "float.h"
  45 #include "sgl_float.h"
  46 #include "dbl_float.h"
  47 #include "cnv_float.h"
  48
  49 /*
  50  *  Single Floating-point to Double Floating-point
  51  */
  52 /*ARGSUSED*/
  53 int
  54 sgl_to_dbl_fcnvff(
  55             sgl_floating_point *srcptr,
  56             unsigned int *nullptr,
  57             dbl_floating_point *dstptr,
  58             unsigned int *status)
  59 {
  60         register unsigned int src, resultp1, resultp2;
  61         register int src_exponent;
  62
  63         src = *srcptr;
  64         src_exponent = Sgl_exponent(src);
  65         Dbl_allp1(resultp1) = Sgl_all(src);  /* set sign of result */
  66         /*
  67          * Test for NaN or infinity
  68          */
  69         if (src_exponent == SGL_INFINITY_EXPONENT) {
  70                 /*
  71                  * determine if NaN or infinity
  72                  */
  73                 if (Sgl_iszero_mantissa(src)) {
  74                         /*
  75                          * is infinity; want to return double infinity
  76                          */
  77                         Dbl_setinfinity_exponentmantissa(resultp1,resultp2);
  78                         Dbl_copytoptr(resultp1,resultp2,dstptr);
  79                         return(NOEXCEPTION);
  80                 }
  81                 else {
  82                         /*
  83                          * is NaN; signaling or quiet?
  84                          */
  85                         if (Sgl_isone_signaling(src)) {
  86                                 /* trap if INVALIDTRAP enabled */
  87                                 if (Is_invalidtrap_enabled())
  88                                         return(INVALIDEXCEPTION);
  89                                 /* make NaN quiet */
  90                                 else {
  91                                         Set_invalidflag();
  92                                         Sgl_set_quiet(src);
  93                                 }
  94                         }
  95                         /*
  96                          * NaN is quiet, return as double NaN
  97                          */
  98                         Dbl_setinfinity_exponent(resultp1);
  99                         Sgl_to_dbl_mantissa(src,resultp1,resultp2);
 100                         Dbl_copytoptr(resultp1,resultp2,dstptr);
 101                         return(NOEXCEPTION);
 102                 }
 103         }
 104         /*
 105          * Test for zero or denormalized
 106          */
 107         if (src_exponent == 0) {
 108                 /*
 109                  * determine if zero or denormalized
 110                  */
 111                 if (Sgl_isnotzero_mantissa(src)) {
 112                         /*
 113                          * is denormalized; want to normalize
 114                          */
 115                         Sgl_clear_signexponent(src);
 116                         Sgl_leftshiftby1(src);
 117                         Sgl_normalize(src,src_exponent);
 118                         Sgl_to_dbl_exponent(src_exponent,resultp1);
 119                         Sgl_to_dbl_mantissa(src,resultp1,resultp2);
 120                 }
 121                 else {
 122                         Dbl_setzero_exponentmantissa(resultp1,resultp2);
 123                 }
 124                 Dbl_copytoptr(resultp1,resultp2,dstptr);
 125                 return(NOEXCEPTION);
 126         }
 127         /*
 128          * No special cases, just complete the conversion
 129          */
 130         Sgl_to_dbl_exponent(src_exponent, resultp1);
 131         Sgl_to_dbl_mantissa(Sgl_mantissa(src), resultp1,resultp2);
 132         Dbl_copytoptr(resultp1,resultp2,dstptr);
 133         return(NOEXCEPTION);
 134 }
 135
 136 /*
 137  *  Double Floating-point to Single Floating-point
 138  */
 139 /*ARGSUSED*/
 140 int
 141 dbl_to_sgl_fcnvff(
 142                     dbl_floating_point *srcptr,
 143                     unsigned int *nullptr,
 144                     sgl_floating_point *dstptr,
 145                     unsigned int *status)
 146 {
 147         register unsigned int srcp1, srcp2, result;
 148         register int src_exponent, dest_exponent, dest_mantissa;
 149         register boolean inexact = FALSE, guardbit = FALSE, stickybit = FALSE;
 150         register boolean lsb_odd = FALSE;
 151         boolean is_tiny;
 152
 153         Dbl_copyfromptr(srcptr,srcp1,srcp2);
 154         src_exponent = Dbl_exponent(srcp1);
 155         Sgl_all(result) = Dbl_allp1(srcp1);  /* set sign of result */
 156         /*
 157          * Test for NaN or infinity
 158          */
 159         if (src_exponent == DBL_INFINITY_EXPONENT) {
 160                 /*
 161                  * determine if NaN or infinity
 162                  */
 163                 if (Dbl_iszero_mantissa(srcp1,srcp2)) {
 164                         /*
 165                          * is infinity; want to return single infinity
 166                          */
 167                         Sgl_setinfinity_exponentmantissa(result);
 168                         *dstptr = result;
 169                         return(NOEXCEPTION);
 170                 }
 171                 /*
 172                  * is NaN; signaling or quiet?
 173                  */
 174                 if (Dbl_isone_signaling(srcp1)) {
 175                         /* trap if INVALIDTRAP enabled */
 176                         if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
 177                         else {
 178                                 Set_invalidflag();
 179                                 /* make NaN quiet */
 180                                 Dbl_set_quiet(srcp1);
 181                         }
 182                 }
 183                 /*
 184                  * NaN is quiet, return as single NaN
 185                  */
 186                 Sgl_setinfinity_exponent(result);
 187                 Sgl_set_mantissa(result,Dallp1(srcp1)<<3 | Dallp2(srcp2)>>29);
 188                 if (Sgl_iszero_mantissa(result)) Sgl_set_quiet(result);
 189                 *dstptr = result;
 190                 return(NOEXCEPTION);
 191         }
 192         /*
 193          * Generate result
 194          */
 195         Dbl_to_sgl_exponent(src_exponent,dest_exponent);
 196         if (dest_exponent > 0) {
 197                 Dbl_to_sgl_mantissa(srcp1,srcp2,dest_mantissa,inexact,guardbit,
 198                 stickybit,lsb_odd);
 199         }
 200         else {
 201                 if (Dbl_iszero_exponentmantissa(srcp1,srcp2)){
 202                         Sgl_setzero_exponentmantissa(result);
 203                         *dstptr = result;
 204                         return(NOEXCEPTION);
 205                 }
 206                 if (Is_underflowtrap_enabled()) {
 207                         Dbl_to_sgl_mantissa(srcp1,srcp2,dest_mantissa,inexact,
 208                         guardbit,stickybit,lsb_odd);
 209                 }
 210                 else {
 211                         /* compute result, determine inexact info,
 212                          * and set Underflowflag if appropriate
 213                          */
 214                         Dbl_to_sgl_denormalized(srcp1,srcp2,dest_exponent,
 215                         dest_mantissa,inexact,guardbit,stickybit,lsb_odd,
 216                         is_tiny);
 217                 }
 218         }
 219         /*
 220          * Now round result if not exact
 221          */
 222         if (inexact) {
 223                 switch (Rounding_mode()) {
 224                         case ROUNDPLUS:
 225                                 if (Sgl_iszero_sign(result)) dest_mantissa++;
 226                                 break;
 227                         case ROUNDMINUS:
 228                                 if (Sgl_isone_sign(result)) dest_mantissa++;
 229                                 break;
 230                         case ROUNDNEAREST:
 231                                 if (guardbit) {
 232                                    if (stickybit || lsb_odd) dest_mantissa++;
 233                                    }
 234                 }
 235         }
 236         Sgl_set_exponentmantissa(result,dest_mantissa);
 237
 238         /*
 239          * check for mantissa overflow after rounding
 240          */
 241         if ((dest_exponent>0 || Is_underflowtrap_enabled()) &&
 242             Sgl_isone_hidden(result)) dest_exponent++;
 243
 244         /*
 245          * Test for overflow
 246          */
 247         if (dest_exponent >= SGL_INFINITY_EXPONENT) {
 248                 /* trap if OVERFLOWTRAP enabled */
 249                 if (Is_overflowtrap_enabled()) {
 250                         /*
 251                          * Check for gross overflow
 252                          */
 253                         if (dest_exponent >= SGL_INFINITY_EXPONENT+SGL_WRAP)
 254                                 return(UNIMPLEMENTEDEXCEPTION);
 255
 256                         /*
 257                          * Adjust bias of result
 258                          */
 259                         Sgl_setwrapped_exponent(result,dest_exponent,ovfl);
 260                         *dstptr = result;
 261                         if (inexact)
 262                             if (Is_inexacttrap_enabled())
 263                                 return(OVERFLOWEXCEPTION|INEXACTEXCEPTION);
 264                             else Set_inexactflag();
 265                         return(OVERFLOWEXCEPTION);
 266                 }
 267                 Set_overflowflag();
 268                 inexact = TRUE;
 269                 /* set result to infinity or largest number */
 270                 Sgl_setoverflow(result);
 271         }
 272         /*
 273          * Test for underflow
 274          */
 275         else if (dest_exponent <= 0) {
 276                 /* trap if UNDERFLOWTRAP enabled */
 277                 if (Is_underflowtrap_enabled()) {
 278                         /*
 279                          * Check for gross underflow
 280                          */
 281                         if (dest_exponent <= -(SGL_WRAP))
 282                                 return(UNIMPLEMENTEDEXCEPTION);
 283                         /*
 284                          * Adjust bias of result
 285                          */
 286                         Sgl_setwrapped_exponent(result,dest_exponent,unfl);
 287                         *dstptr = result;
 288                         if (inexact)
 289                             if (Is_inexacttrap_enabled())
 290                                 return(UNDERFLOWEXCEPTION|INEXACTEXCEPTION);
 291                             else Set_inexactflag();
 292                         return(UNDERFLOWEXCEPTION);
 293                 }
 294                  /*
 295                   * result is denormalized or signed zero
 296                   */
 297                if (inexact && is_tiny) Set_underflowflag();
 298
 299         }
 300         else Sgl_set_exponent(result,dest_exponent);
 301         *dstptr = result;
 302         /*
 303          * Trap if inexact trap is enabled
 304          */
 305         if (inexact)
 306                 if (Is_inexacttrap_enabled()) return(INEXACTEXCEPTION);
 307                 else Set_inexactflag();
 308         return(NOEXCEPTION);
 309 }