sys/arch/hppa/spmath/sfrem.c

   1 /*      $NetBSD: sfrem.c,v 1.3 2005/12/11 12:17:40 christos Exp $       */
   2
   3 /*      $OpenBSD: sfrem.c,v 1.4 2001/03/29 03:58:19 mickey Exp $        */
   4
   5 /*
   6  * Copyright 1996 1995 by Open Software Foundation, Inc.
   7  *              All Rights Reserved
   8  *
   9  * Permission to use, copy, modify, and distribute this software and
  10  * its documentation for any purpose and without fee is hereby granted,
  11  * provided that the above copyright notice appears in all copies and
  12  * that both the copyright notice and this permission notice appear in
  13  * supporting documentation.
  14  *
  15  * OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
  16  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  17  * FOR A PARTICULAR PURPOSE.
  18  *
  19  * IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
  20  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  21  * LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
  22  * NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
  23  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  24  *
  25  */
  26 /*
  27  * pmk1.1
  28  */
  29 /*
  30  * (c) Copyright 1986 HEWLETT-PACKARD COMPANY
  31  *
  32  * To anyone who acknowledges that this file is provided "AS IS"
  33  * without any express or implied warranty:
  34  *     permission to use, copy, modify, and distribute this file
  35  * for any purpose is hereby granted without fee, provided that
  36  * the above copyright notice and this notice appears in all
  37  * copies, and that the name of Hewlett-Packard Company not be
  38  * used in advertising or publicity pertaining to distribution
  39  * of the software without specific, written prior permission.
  40  * Hewlett-Packard Company makes no representations about the
  41  * suitability of this software for any purpose.
  42  */
  43
  44 #include <sys/cdefs.h>
  45 __KERNEL_RCSID(0, "$NetBSD: sfrem.c,v 1.3 2005/12/11 12:17:40 christos Exp $");
  46
  47 #include "../spmath/float.h"
  48 #include "../spmath/sgl_float.h"
  49
  50 /*
  51  *  Single Precision Floating-point Remainder
  52  */
  53 int
  54 sgl_frem(srcptr1,srcptr2,dstptr,status)
  55
  56 sgl_floating_point *srcptr1, *srcptr2, *dstptr;
  57 unsigned int *status;
  58 {
  59         register unsigned int opnd1, opnd2, result;
  60         register int opnd1_exponent, opnd2_exponent, dest_exponent, stepcount;
  61         register int roundup = false;
  62
  63         opnd1 = *srcptr1;
  64         opnd2 = *srcptr2;
  65         /*
  66          * check first operand for NaN's or infinity
  67          */
  68         if ((opnd1_exponent = Sgl_exponent(opnd1)) == SGL_INFINITY_EXPONENT) {
  69                 if (Sgl_iszero_mantissa(opnd1)) {
  70                         if (Sgl_isnotnan(opnd2)) {
  71                                 /* invalid since first operand is infinity */
  72                                 if (Is_invalidtrap_enabled())
  73                                         return(INVALIDEXCEPTION);
  74                                 Set_invalidflag();
  75                                 Sgl_makequietnan(result);
  76                                 *dstptr = result;
  77                                 return(NOEXCEPTION);
  78                         }
  79                 }
  80                 else {
  81                         /*
  82                          * is NaN; signaling or quiet?
  83                          */
  84                         if (Sgl_isone_signaling(opnd1)) {
  85                                 /* trap if INVALIDTRAP enabled */
  86                                 if (Is_invalidtrap_enabled())
  87                                         return(INVALIDEXCEPTION);
  88                                 /* make NaN quiet */
  89                                 Set_invalidflag();
  90                                 Sgl_set_quiet(opnd1);
  91                         }
  92                         /*
  93                          * is second operand a signaling NaN?
  94                          */
  95                         else if (Sgl_is_signalingnan(opnd2)) {
  96                                 /* trap if INVALIDTRAP enabled */
  97                                 if (Is_invalidtrap_enabled())
  98                                         return(INVALIDEXCEPTION);
  99                                 /* make NaN quiet */
 100                                 Set_invalidflag();
 101                                 Sgl_set_quiet(opnd2);
 102                                 *dstptr = opnd2;
 103                                 return(NOEXCEPTION);
 104                         }
 105                         /*
 106                          * return quiet NaN
 107                          */
 108                         *dstptr = opnd1;
 109                         return(NOEXCEPTION);
 110                 }
 111         }
 112         /*
 113          * check second operand for NaN's or infinity
 114          */
 115         if ((opnd2_exponent = Sgl_exponent(opnd2)) == SGL_INFINITY_EXPONENT) {
 116                 if (Sgl_iszero_mantissa(opnd2)) {
 117                         /*
 118                          * return first operand
 119                          */
 120                         *dstptr = opnd1;
 121                         return(NOEXCEPTION);
 122                 }
 123                 /*
 124                  * is NaN; signaling or quiet?
 125                  */
 126                 if (Sgl_isone_signaling(opnd2)) {
 127                         /* trap if INVALIDTRAP enabled */
 128                         if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
 129                         /* make NaN quiet */
 130                         Set_invalidflag();
 131                         Sgl_set_quiet(opnd2);
 132                 }
 133                 /*
 134                  * return quiet NaN
 135                  */
 136                 *dstptr = opnd2;
 137                 return(NOEXCEPTION);
 138         }
 139         /*
 140          * check second operand for zero
 141          */
 142         if (Sgl_iszero_exponentmantissa(opnd2)) {
 143                 /* invalid since second operand is zero */
 144                 if (Is_invalidtrap_enabled()) return(INVALIDEXCEPTION);
 145                 Set_invalidflag();
 146                 Sgl_makequietnan(result);
 147                 *dstptr = result;
 148                 return(NOEXCEPTION);
 149         }
 150
 151         /*
 152          * get sign of result
 153          */
 154         result = opnd1;
 155
 156         /*
 157          * check for denormalized operands
 158          */
 159         if (opnd1_exponent == 0) {
 160                 /* check for zero */
 161                 if (Sgl_iszero_mantissa(opnd1)) {
 162                         *dstptr = opnd1;
 163                         return(NOEXCEPTION);
 164                 }
 165                 /* normalize, then continue */
 166                 opnd1_exponent = 1;
 167                 Sgl_normalize(opnd1,opnd1_exponent);
 168         }
 169         else {
 170                 Sgl_clear_signexponent_set_hidden(opnd1);
 171         }
 172         if (opnd2_exponent == 0) {
 173                 /* normalize, then continue */
 174                 opnd2_exponent = 1;
 175                 Sgl_normalize(opnd2,opnd2_exponent);
 176         }
 177         else {
 178                 Sgl_clear_signexponent_set_hidden(opnd2);
 179         }
 180
 181         /* find result exponent and divide step loop count */
 182         dest_exponent = opnd2_exponent - 1;
 183         stepcount = opnd1_exponent - opnd2_exponent;
 184
 185         /*
 186          * check for opnd1/opnd2 < 1
 187          */
 188         if (stepcount < 0) {
 189                 /*
 190                  * check for opnd1/opnd2 > 1/2
 191                  *
 192                  * In this case n will round to 1, so
 193                  *    r = opnd1 - opnd2
 194                  */
 195                 if (stepcount == -1 && Sgl_isgreaterthan(opnd1,opnd2)) {
 196                         Sgl_all(result) = ~Sgl_all(result);   /* set sign */
 197                         /* align opnd2 with opnd1 */
 198                         Sgl_leftshiftby1(opnd2);
 199                         Sgl_subtract(opnd2,opnd1,opnd2);
 200                         /* now normalize */
 201                         while (Sgl_iszero_hidden(opnd2)) {
 202                                 Sgl_leftshiftby1(opnd2);
 203                                 dest_exponent--;
 204                         }
 205                         Sgl_set_exponentmantissa(result,opnd2);
 206                         goto testforunderflow;
 207                 }
 208                 /*
 209                  * opnd1/opnd2 <= 1/2
 210                  *
 211                  * In this case n will round to zero, so
 212                  *    r = opnd1
 213                  */
 214                 Sgl_set_exponentmantissa(result,opnd1);
 215                 dest_exponent = opnd1_exponent;
 216                 goto testforunderflow;
 217         }
 218
 219         /*
 220          * Generate result
 221          *
 222          * Do iterative subtract until remainder is less than operand 2.
 223          */
 224         while (stepcount-- > 0 && Sgl_all(opnd1)) {
 225                 if (Sgl_isnotlessthan(opnd1,opnd2))
 226                         Sgl_subtract(opnd1,opnd2,opnd1);
 227                 Sgl_leftshiftby1(opnd1);
 228         }
 229         /*
 230          * Do last subtract, then determine which way to round if remainder
 231          * is exactly 1/2 of opnd2
 232          */
 233         if (Sgl_isnotlessthan(opnd1,opnd2)) {
 234                 Sgl_subtract(opnd1,opnd2,opnd1);
 235                 roundup = true;
 236         }
 237         if (stepcount > 0 || Sgl_iszero(opnd1)) {
 238                 /* division is exact, remainder is zero */
 239                 Sgl_setzero_exponentmantissa(result);
 240                 *dstptr = result;
 241                 return(NOEXCEPTION);
 242         }
 243
 244         /*
 245          * Check for cases where opnd1/opnd2 < n
 246          *
 247          * In this case the result's sign will be opposite that of
 248          * opnd1.  The mantissa also needs some correction.
 249          */
 250         Sgl_leftshiftby1(opnd1);
 251         if (Sgl_isgreaterthan(opnd1,opnd2)) {
 252                 Sgl_invert_sign(result);
 253                 Sgl_subtract((opnd2<<1),opnd1,opnd1);
 254         }
 255         /* check for remainder being exactly 1/2 of opnd2 */
 256         else if (Sgl_isequal(opnd1,opnd2) && roundup) {
 257                 Sgl_invert_sign(result);
 258         }
 259
 260         /* normalize result's mantissa */
 261         while (Sgl_iszero_hidden(opnd1)) {
 262                 dest_exponent--;
 263                 Sgl_leftshiftby1(opnd1);
 264         }
 265         Sgl_set_exponentmantissa(result,opnd1);
 266
 267         /*
 268          * Test for underflow
 269          */
 270     testforunderflow:
 271         if (dest_exponent <= 0) {
 272                 /* trap if UNDERFLOWTRAP enabled */
 273                 if (Is_underflowtrap_enabled()) {
 274                         /*
 275                          * Adjust bias of result
 276                          */
 277                         Sgl_setwrapped_exponent(result,dest_exponent,unfl);
 278                         *dstptr = result;
 279                         /* frem is always exact */
 280                         return(UNDERFLOWEXCEPTION);
 281                 }
 282                 /*
 283                  * denormalize result or set to signed zero
 284                  */
 285                 if (dest_exponent >= (1 - SGL_P)) {
 286                         Sgl_rightshift_exponentmantissa(result,1-dest_exponent);
 287                 } else {
 288                         Sgl_setzero_exponentmantissa(result);
 289                 }
 290         }
 291         else Sgl_set_exponent(result,dest_exponent);
 292         *dstptr = result;
 293         return(NOEXCEPTION);
 294 }