arch/parisc/math-emu/fcnvxf.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/fcnvxf.c              $Revision: 1.1 $
  26  *
  27  *  Purpose:
  28  *      Single Fixed-point to Single Floating-point
  29  *      Single Fixed-point to Double Floating-point
  30  *      Double Fixed-point to Single Floating-point
  31  *      Double Fixed-point to Double Floating-point
  32  *
  33  *  External Interfaces:
  34  *      dbl_to_dbl_fcnvxf(srcptr,nullptr,dstptr,status)
  35  *      dbl_to_sgl_fcnvxf(srcptr,nullptr,dstptr,status)
  36  *      sgl_to_dbl_fcnvxf(srcptr,nullptr,dstptr,status)
  37  *      sgl_to_sgl_fcnvxf(srcptr,nullptr,dstptr,status)
  38  *
  39  *  Internal Interfaces:
  40  *
  41  *  Theory:
  42  *      <<please update with a overview of the operation of this file>>
  43  *
  44  * END_DESC
  45 */
  46
  47
  48 #include "float.h"
  49 #include "sgl_float.h"
  50 #include "dbl_float.h"
  51 #include "cnv_float.h"
  52
  53 /*
  54  *  Convert single fixed-point to single floating-point format
  55  */
  56
  57 int
  58 sgl_to_sgl_fcnvxf(
  59                     int *srcptr,
  60                     unsigned int *nullptr,
  61                     sgl_floating_point *dstptr,
  62                     unsigned int *status)
  63 {
  64         register int src, dst_exponent;
  65         register unsigned int result = 0;
  66
  67         src = *srcptr;
  68         /*
  69          * set sign bit of result and get magnitude of source
  70          */
  71         if (src < 0) {
  72                 Sgl_setone_sign(result);
  73                 Int_negate(src);
  74         }
  75         else {
  76                 Sgl_setzero_sign(result);
  77                 /* Check for zero */
  78                 if (src == 0) {
  79                         Sgl_setzero(result);
  80                         *dstptr = result;
  81                         return(NOEXCEPTION);
  82                 }
  83         }
  84         /*
  85          * Generate exponent and normalized mantissa
  86          */
  87         dst_exponent = 16;    /* initialize for normalization */
  88         /*
  89          * Check word for most significant bit set.  Returns
  90          * a value in dst_exponent indicating the bit position,
  91          * between -1 and 30.
  92          */
  93         Find_ms_one_bit(src,dst_exponent);
  94         /*  left justify source, with msb at bit position 1  */
  95         if (dst_exponent >= 0) src <<= dst_exponent;
  96         else src = 1 << 30;
  97         Sgl_set_mantissa(result, src >> (SGL_EXP_LENGTH-1));
  98         Sgl_set_exponent(result, 30+SGL_BIAS - dst_exponent);
  99
 100         /* check for inexact */
 101         if (Int_isinexact_to_sgl(src)) {
 102                 switch (Rounding_mode()) {
 103                         case ROUNDPLUS:
 104                                 if (Sgl_iszero_sign(result))
 105                                         Sgl_increment(result);
 106                                 break;
 107                         case ROUNDMINUS:
 108                                 if (Sgl_isone_sign(result))
 109                                         Sgl_increment(result);
 110                                 break;
 111                         case ROUNDNEAREST:
 112                                 Sgl_roundnearest_from_int(src,result);
 113                 }
 114                 if (Is_inexacttrap_enabled()) {
 115                         *dstptr = result;
 116                         return(INEXACTEXCEPTION);
 117                 }
 118                 else Set_inexactflag();
 119         }
 120         *dstptr = result;
 121         return(NOEXCEPTION);
 122 }
 123
 124 /*
 125  *  Single Fixed-point to Double Floating-point
 126  */
 127
 128 int
 129 sgl_to_dbl_fcnvxf(
 130                     int *srcptr,
 131                     unsigned int *nullptr,
 132                     dbl_floating_point *dstptr,
 133                     unsigned int *status)
 134 {
 135         register int src, dst_exponent;
 136         register unsigned int resultp1 = 0, resultp2 = 0;
 137
 138         src = *srcptr;
 139         /*
 140          * set sign bit of result and get magnitude of source
 141          */
 142         if (src < 0) {
 143                 Dbl_setone_sign(resultp1);
 144                 Int_negate(src);
 145         }
 146         else {
 147                 Dbl_setzero_sign(resultp1);
 148                 /* Check for zero */
 149                 if (src == 0) {
 150                         Dbl_setzero(resultp1,resultp2);
 151                         Dbl_copytoptr(resultp1,resultp2,dstptr);
 152                         return(NOEXCEPTION);
 153                 }
 154         }
 155         /*
 156          * Generate exponent and normalized mantissa
 157          */
 158         dst_exponent = 16;    /* initialize for normalization */
 159         /*
 160          * Check word for most significant bit set.  Returns
 161          * a value in dst_exponent indicating the bit position,
 162          * between -1 and 30.
 163          */
 164         Find_ms_one_bit(src,dst_exponent);
 165         /*  left justify source, with msb at bit position 1  */
 166         if (dst_exponent >= 0) src <<= dst_exponent;
 167         else src = 1 << 30;
 168         Dbl_set_mantissap1(resultp1, src >> DBL_EXP_LENGTH - 1);
 169         Dbl_set_mantissap2(resultp2, src << (33-DBL_EXP_LENGTH));
 170         Dbl_set_exponent(resultp1, (30+DBL_BIAS) - dst_exponent);
 171         Dbl_copytoptr(resultp1,resultp2,dstptr);
 172         return(NOEXCEPTION);
 173 }
 174
 175 /*
 176  *  Double Fixed-point to Single Floating-point
 177  */
 178
 179 int
 180 dbl_to_sgl_fcnvxf(
 181                         dbl_integer *srcptr,
 182                         unsigned int *nullptr,
 183                         sgl_floating_point *dstptr,
 184                         unsigned int *status)
 185 {
 186         int dst_exponent, srcp1;
 187         unsigned int result = 0, srcp2;
 188
 189         Dint_copyfromptr(srcptr,srcp1,srcp2);
 190         /*
 191          * set sign bit of result and get magnitude of source
 192          */
 193         if (srcp1 < 0) {
 194                 Sgl_setone_sign(result);
 195                 Dint_negate(srcp1,srcp2);
 196         }
 197         else {
 198                 Sgl_setzero_sign(result);
 199                 /* Check for zero */
 200                 if (srcp1 == 0 && srcp2 == 0) {
 201                         Sgl_setzero(result);
 202                         *dstptr = result;
 203                         return(NOEXCEPTION);
 204                 }
 205         }
 206         /*
 207          * Generate exponent and normalized mantissa
 208          */
 209         dst_exponent = 16;    /* initialize for normalization */
 210         if (srcp1 == 0) {
 211                 /*
 212                  * Check word for most significant bit set.  Returns
 213                  * a value in dst_exponent indicating the bit position,
 214                  * between -1 and 30.
 215                  */
 216                 Find_ms_one_bit(srcp2,dst_exponent);
 217                 /*  left justify source, with msb at bit position 1  */
 218                 if (dst_exponent >= 0) {
 219                         srcp1 = srcp2 << dst_exponent;
 220                         srcp2 = 0;
 221                 }
 222                 else {
 223                         srcp1 = srcp2 >> 1;
 224                         srcp2 <<= 31;
 225                 }
 226                 /*
 227                  *  since msb set is in second word, need to
 228                  *  adjust bit position count
 229                  */
 230                 dst_exponent += 32;
 231         }
 232         else {
 233                 /*
 234                  * Check word for most significant bit set.  Returns
 235                  * a value in dst_exponent indicating the bit position,
 236                  * between -1 and 30.
 237                  *
 238                  */
 239                 Find_ms_one_bit(srcp1,dst_exponent);
 240                 /*  left justify source, with msb at bit position 1  */
 241                 if (dst_exponent > 0) {
 242                         Variable_shift_double(srcp1,srcp2,(32-dst_exponent),
 243                          srcp1);
 244                         srcp2 <<= dst_exponent;
 245                 }
 246                 /*
 247                  * If dst_exponent = 0, we don't need to shift anything.
 248                  * If dst_exponent = -1, src = - 2**63 so we won't need to
 249                  * shift srcp2.
 250                  */
 251                 else srcp1 >>= -(dst_exponent);
 252         }
 253         Sgl_set_mantissa(result, srcp1 >> SGL_EXP_LENGTH - 1);
 254         Sgl_set_exponent(result, (62+SGL_BIAS) - dst_exponent);
 255
 256         /* check for inexact */
 257         if (Dint_isinexact_to_sgl(srcp1,srcp2)) {
 258                 switch (Rounding_mode()) {
 259                         case ROUNDPLUS:
 260                                 if (Sgl_iszero_sign(result))
 261                                         Sgl_increment(result);
 262                                 break;
 263                         case ROUNDMINUS:
 264                                 if (Sgl_isone_sign(result))
 265                                         Sgl_increment(result);
 266                                 break;
 267                         case ROUNDNEAREST:
 268                                 Sgl_roundnearest_from_dint(srcp1,srcp2,result);
 269                 }
 270                 if (Is_inexacttrap_enabled()) {
 271                         *dstptr = result;
 272                         return(INEXACTEXCEPTION);
 273                 }
 274                 else Set_inexactflag();
 275         }
 276         *dstptr = result;
 277         return(NOEXCEPTION);
 278 }
 279
 280 /*
 281  *  Double Fixed-point to Double Floating-point
 282  */
 283
 284 int
 285 dbl_to_dbl_fcnvxf(
 286                     dbl_integer *srcptr,
 287                     unsigned int *nullptr,
 288                     dbl_floating_point *dstptr,
 289                     unsigned int *status)
 290 {
 291         register int srcp1, dst_exponent;
 292         register unsigned int srcp2, resultp1 = 0, resultp2 = 0;
 293
 294         Dint_copyfromptr(srcptr,srcp1,srcp2);
 295         /*
 296          * set sign bit of result and get magnitude of source
 297          */
 298         if (srcp1 < 0) {
 299                 Dbl_setone_sign(resultp1);
 300                 Dint_negate(srcp1,srcp2);
 301         }
 302         else {
 303                 Dbl_setzero_sign(resultp1);
 304                 /* Check for zero */
 305                 if (srcp1 == 0 && srcp2 ==0) {
 306                         Dbl_setzero(resultp1,resultp2);
 307                         Dbl_copytoptr(resultp1,resultp2,dstptr);
 308                         return(NOEXCEPTION);
 309                 }
 310         }
 311         /*
 312          * Generate exponent and normalized mantissa
 313          */
 314         dst_exponent = 16;    /* initialize for normalization */
 315         if (srcp1 == 0) {
 316                 /*
 317                  * Check word for most significant bit set.  Returns
 318                  * a value in dst_exponent indicating the bit position,
 319                  * between -1 and 30.
 320                  */
 321                 Find_ms_one_bit(srcp2,dst_exponent);
 322                 /*  left justify source, with msb at bit position 1  */
 323                 if (dst_exponent >= 0) {
 324                         srcp1 = srcp2 << dst_exponent;
 325                         srcp2 = 0;
 326                 }
 327                 else {
 328                         srcp1 = srcp2 >> 1;
 329                         srcp2 <<= 31;
 330                 }
 331                 /*
 332                  *  since msb set is in second word, need to
 333                  *  adjust bit position count
 334                  */
 335                 dst_exponent += 32;
 336         }
 337         else {
 338                 /*
 339                  * Check word for most significant bit set.  Returns
 340                  * a value in dst_exponent indicating the bit position,
 341                  * between -1 and 30.
 342                  */
 343                 Find_ms_one_bit(srcp1,dst_exponent);
 344                 /*  left justify source, with msb at bit position 1  */
 345                 if (dst_exponent > 0) {
 346                         Variable_shift_double(srcp1,srcp2,(32-dst_exponent),
 347                          srcp1);
 348                         srcp2 <<= dst_exponent;
 349                 }
 350                 /*
 351                  * If dst_exponent = 0, we don't need to shift anything.
 352                  * If dst_exponent = -1, src = - 2**63 so we won't need to
 353                  * shift srcp2.
 354                  */
 355                 else srcp1 >>= -(dst_exponent);
 356         }
 357         Dbl_set_mantissap1(resultp1, srcp1 >> (DBL_EXP_LENGTH-1));
 358         Shiftdouble(srcp1,srcp2,DBL_EXP_LENGTH-1,resultp2);
 359         Dbl_set_exponent(resultp1, (62+DBL_BIAS) - dst_exponent);
 360
 361         /* check for inexact */
 362         if (Dint_isinexact_to_dbl(srcp2)) {
 363                 switch (Rounding_mode()) {
 364                         case ROUNDPLUS:
 365                                 if (Dbl_iszero_sign(resultp1)) {
 366                                         Dbl_increment(resultp1,resultp2);
 367                                 }
 368                                 break;
 369                         case ROUNDMINUS:
 370                                 if (Dbl_isone_sign(resultp1)) {
 371                                         Dbl_increment(resultp1,resultp2);
 372                                 }
 373                                 break;
 374                         case ROUNDNEAREST:
 375                                 Dbl_roundnearest_from_dint(srcp2,resultp1,
 376                                 resultp2);
 377                 }
 378                 if (Is_inexacttrap_enabled()) {
 379                         Dbl_copytoptr(resultp1,resultp2,dstptr);
 380                         return(INEXACTEXCEPTION);
 381                 }
 382                 else Set_inexactflag();
 383         }
 384         Dbl_copytoptr(resultp1,resultp2,dstptr);
 385         return(NOEXCEPTION);
 386 }