LXR linux/arch/mips/math-emu/sp

   1/* IEEE754 floating point arithmetic
   2 * single precision
   3 */
   4/*
   5 * MIPS floating point support
   6 * Copyright (C) 1994-2000 Algorithmics Ltd.
   7 *
   8 *  This program is free software; you can distribute it and/or modify it
   9 *  under the terms of the GNU General Public License (Version 2) as
  10 *  published by the Free Software Foundation.
  11 *
  12 *  This program is distributed in the hope it will be useful, but WITHOUT
  13 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 *  for more details.
  16 *
  17 *  You should have received a copy of the GNU General Public License along
  18 *  with this program; if not, write to the Free Software Foundation, Inc.,
  19 *  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA.
  20 */
  21
  22#include "ieee754sp.h"
  23#include "ieee754dp.h"
  24
  25static inline union ieee754sp ieee754sp_nan_fdp(int xs, u64 xm)
  26{
  27        return buildsp(xs, SP_EMAX + 1 + SP_EBIAS,
  28                       xm >> (DP_FBITS - SP_FBITS));
  29}
  30
  31union ieee754sp ieee754sp_fdp(union ieee754dp x)
  32{
  33        union ieee754sp y;
  34        u32 rm;
  35
  36        COMPXDP;
  37        COMPYSP;
  38
  39        EXPLODEXDP;
  40
  41        ieee754_clearcx();
  42
  43        FLUSHXDP;
  44
  45        switch (xc) {
  46        case IEEE754_CLASS_SNAN:
  47                x = ieee754dp_nanxcpt(x);
  48                EXPLODEXDP;
  49                /* Fall through.  */
  50        case IEEE754_CLASS_QNAN:
  51                y = ieee754sp_nan_fdp(xs, xm);
  52                if (!ieee754_csr.nan2008) {
  53                        EXPLODEYSP;
  54                        if (!ieee754_class_nan(yc))
  55                                y = ieee754sp_indef();
  56                }
  57                return y;
  58
  59        case IEEE754_CLASS_INF:
  60                return ieee754sp_inf(xs);
  61
  62        case IEEE754_CLASS_ZERO:
  63                return ieee754sp_zero(xs);
  64
  65        case IEEE754_CLASS_DNORM:
  66                /* can't possibly be sp representable */
  67                ieee754_setcx(IEEE754_UNDERFLOW);
  68                ieee754_setcx(IEEE754_INEXACT);
  69                if ((ieee754_csr.rm == FPU_CSR_RU && !xs) ||
  70                                (ieee754_csr.rm == FPU_CSR_RD && xs))
  71                        return ieee754sp_mind(xs);
  72                return ieee754sp_zero(xs);
  73
  74        case IEEE754_CLASS_NORM:
  75                break;
  76        }
  77
  78        /*
  79         * Convert from DP_FBITS to SP_FBITS+3 with sticky right shift.
  80         */
  81        rm = (xm >> (DP_FBITS - (SP_FBITS + 3))) |
  82             ((xm << (64 - (DP_FBITS - (SP_FBITS + 3)))) != 0);
  83
  84        return ieee754sp_format(xs, xe, rm);
  85}
  86