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 * Copyright (C) 2017 Imagination Technologies, Ltd.
   8 * Author: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
   9 *
  10 *  This program is free software; you can distribute it and/or modify it
  11 *  under the terms of the GNU General Public License (Version 2) as
  12 *  published by the Free Software Foundation.
  13 *
  14 *  This program is distributed in the hope it will be useful, but WITHOUT
  15 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  16 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  17 *  for more details.
  18 *
  19 *  You should have received a copy of the GNU General Public License along
  20 *  with this program.
  21 */
  22
  23#include "ieee754sp.h"
  24
  25union ieee754sp ieee754sp_rint(union ieee754sp x)
  26{
  27        union ieee754sp ret;
  28        u32 residue;
  29        int sticky;
  30        int round;
  31        int odd;
  32
  33        COMPXDP;                /* <-- DP needed for 64-bit mantissa tmp */
  34
  35        ieee754_clearcx();
  36
  37        EXPLODEXSP;
  38        FLUSHXSP;
  39
  40        if (xc == IEEE754_CLASS_SNAN)
  41                return ieee754sp_nanxcpt(x);
  42
  43        if ((xc == IEEE754_CLASS_QNAN) ||
  44            (xc == IEEE754_CLASS_INF) ||
  45            (xc == IEEE754_CLASS_ZERO))
  46                return x;
  47
  48        if (xe >= SP_FBITS)
  49                return x;
  50
  51        if (xe < -1) {
  52                residue = xm;
  53                round = 0;
  54                sticky = residue != 0;
  55                xm = 0;
  56        } else {
  57                residue = xm << (xe + 1);
  58                residue <<= 31 - SP_FBITS;
  59                round = (residue >> 31) != 0;
  60                sticky = (residue << 1) != 0;
  61                xm >>= SP_FBITS - xe;
  62        }
  63
  64        odd = (xm & 0x1) != 0x0;
  65
  66        switch (ieee754_csr.rm) {
  67        case FPU_CSR_RN:        /* toward nearest */
  68                if (round && (sticky || odd))
  69                        xm++;
  70                break;
  71        case FPU_CSR_RZ:        /* toward zero */
  72                break;
  73        case FPU_CSR_RU:        /* toward +infinity */
  74                if ((round || sticky) && !xs)
  75                        xm++;
  76                break;
  77        case FPU_CSR_RD:        /* toward -infinity */
  78                if ((round || sticky) && xs)
  79                        xm++;
  80                break;
  81        }
  82
  83        if (round || sticky)
  84                ieee754_setcx(IEEE754_INEXACT);
  85
  86        ret = ieee754sp_flong(xm);
  87        SPSIGN(ret) = xs;
  88
  89        return ret;
  90}
  91