arch/mips/math-emu/sp_fmax.c

   1 /*
   2  * IEEE754 floating point arithmetic
   3  * single precision: MAX{,A}.f
   4  * MAX : Scalar Floating-Point Maximum
   5  * MAXA: Scalar Floating-Point argument with Maximum Absolute Value
   6  *
   7  * MAX.S : FPR[fd] = maxNum(FPR[fs],FPR[ft])
   8  * MAXA.S: FPR[fd] = maxNumMag(FPR[fs],FPR[ft])
   9  *
  10  * MIPS floating point support
  11  * Copyright (C) 2015 Imagination Technologies, Ltd.
  12  * Author: Markos Chandras <markos.chandras@imgtec.com>
  13  *
  14  *  This program is free software; you can distribute it and/or modify it
  15  *  under the terms of the GNU General Public License as published by the
  16  *  Free Software Foundation; version 2 of the License.
  17  */
  18
  19 #include "ieee754sp.h"
  20
  21 union ieee754sp ieee754sp_fmax(union ieee754sp x, union ieee754sp y)
  22 {
  23         COMPXSP;
  24         COMPYSP;
  25
  26         EXPLODEXSP;
  27         EXPLODEYSP;
  28
  29         FLUSHXSP;
  30         FLUSHYSP;
  31
  32         ieee754_clearcx();
  33
  34         switch (CLPAIR(xc, yc)) {
  35         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
  36         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
  37         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
  38         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
  39         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
  40                 return ieee754sp_nanxcpt(y);
  41
  42         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
  43         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
  44         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
  45         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
  46         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
  47         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
  48                 return ieee754sp_nanxcpt(x);
  49
  50         /*
  51          * Quiet NaN handling
  52          */
  53
  54         /*
  55          *    The case of both inputs quiet NaNs
  56          */
  57         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
  58                 return x;
  59
  60         /*
  61          *    The cases of exactly one input quiet NaN (numbers
  62          *    are here preferred as returned values to NaNs)
  63          */
  64         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
  65         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
  66         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
  67         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
  68                 return x;
  69
  70         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
  71         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
  72         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
  73         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
  74                 return y;
  75
  76         /*
  77          * Infinity and zero handling
  78          */
  79         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
  80         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
  81         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
  82         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
  83         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
  84                 return xs ? y : x;
  85
  86         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
  87         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
  88         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
  89         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
  90         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
  91         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
  92                 return ys ? x : y;
  93
  94         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
  95                 return ieee754sp_zero(xs & ys);
  96
  97         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
  98                 SPDNORMX;
  99                 /* fall through */
 100
 101         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
 102                 SPDNORMY;
 103                 break;
 104
 105         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
 106                 SPDNORMX;
 107         }
 108
 109         /* Finally get to do some computation */
 110
 111         assert(xm & SP_HIDDEN_BIT);
 112         assert(ym & SP_HIDDEN_BIT);
 113
 114         /* Compare signs */
 115         if (xs > ys)
 116                 return y;
 117         else if (xs < ys)
 118                 return x;
 119
 120         /* Signs of inputs are equal, let's compare exponents */
 121         if (xs == 0) {
 122                 /* Inputs are both positive */
 123                 if (xe > ye)
 124                         return x;
 125                 else if (xe < ye)
 126                         return y;
 127         } else {
 128                 /* Inputs are both negative */
 129                 if (xe > ye)
 130                         return y;
 131                 else if (xe < ye)
 132                         return x;
 133         }
 134
 135         /* Signs and exponents of inputs are equal, let's compare mantissas */
 136         if (xs == 0) {
 137                 /* Inputs are both positive, with equal signs and exponents */
 138                 if (xm <= ym)
 139                         return y;
 140                 return x;
 141         }
 142         /* Inputs are both negative, with equal signs and exponents */
 143         if (xm <= ym)
 144                 return x;
 145         return y;
 146 }
 147
 148 union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y)
 149 {
 150         COMPXSP;
 151         COMPYSP;
 152
 153         EXPLODEXSP;
 154         EXPLODEYSP;
 155
 156         FLUSHXSP;
 157         FLUSHYSP;
 158
 159         ieee754_clearcx();
 160
 161         switch (CLPAIR(xc, yc)) {
 162         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
 163         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
 164         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
 165         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
 166         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
 167                 return ieee754sp_nanxcpt(y);
 168
 169         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
 170         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 171         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
 172         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
 173         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
 174         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
 175                 return ieee754sp_nanxcpt(x);
 176
 177         /*
 178          * Quiet NaN handling
 179          */
 180
 181         /*
 182          *    The case of both inputs quiet NaNs
 183          */
 184         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
 185                 return x;
 186
 187         /*
 188          *    The cases of exactly one input quiet NaN (numbers
 189          *    are here preferred as returned values to NaNs)
 190          */
 191         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
 192         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
 193         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
 194         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
 195                 return x;
 196
 197         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
 198         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
 199         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
 200         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
 201                 return y;
 202
 203         /*
 204          * Infinity and zero handling
 205          */
 206         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
 207                 return ieee754sp_inf(xs & ys);
 208
 209         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
 210         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
 211         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
 212         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
 213         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
 214                 return x;
 215
 216         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
 217         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
 218         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
 219         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
 220         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
 221                 return y;
 222
 223         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
 224                 return ieee754sp_zero(xs & ys);
 225
 226         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 227                 SPDNORMX;
 228                 /* fall through */
 229
 230         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
 231                 SPDNORMY;
 232                 break;
 233
 234         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
 235                 SPDNORMX;
 236         }
 237
 238         /* Finally get to do some computation */
 239
 240         assert(xm & SP_HIDDEN_BIT);
 241         assert(ym & SP_HIDDEN_BIT);
 242
 243         /* Compare exponent */
 244         if (xe > ye)
 245                 return x;
 246         else if (xe < ye)
 247                 return y;
 248
 249         /* Compare mantissa */
 250         if (xm < ym)
 251                 return y;
 252         else if (xm > ym)
 253                 return x;
 254         else if (xs == 0)
 255                 return x;
 256         return y;
 257 }