arch/mips/math-emu/sp_fmax.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * IEEE754 floating point arithmetic
   4  * single precision: MAX{,A}.f
   5  * MAX : Scalar Floating-Point Maximum
   6  * MAXA: Scalar Floating-Point argument with Maximum Absolute Value
   7  *
   8  * MAX.S : FPR[fd] = maxNum(FPR[fs],FPR[ft])
   9  * MAXA.S: FPR[fd] = maxNumMag(FPR[fs],FPR[ft])
  10  *
  11  * MIPS floating point support
  12  * Copyright (C) 2015 Imagination Technologies, Ltd.
  13  * Author: Markos Chandras <markos.chandras@imgtec.com>
  14  */
  15
  16 #include "ieee754sp.h"
  17
  18 union ieee754sp ieee754sp_fmax(union ieee754sp x, union ieee754sp y)
  19 {
  20         COMPXSP;
  21         COMPYSP;
  22
  23         EXPLODEXSP;
  24         EXPLODEYSP;
  25
  26         FLUSHXSP;
  27         FLUSHYSP;
  28
  29         ieee754_clearcx();
  30
  31         switch (CLPAIR(xc, yc)) {
  32         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
  33         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
  34         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
  35         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
  36         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
  37                 return ieee754sp_nanxcpt(y);
  38
  39         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
  40         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
  41         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
  42         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
  43         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
  44         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
  45                 return ieee754sp_nanxcpt(x);
  46
  47         /*
  48          * Quiet NaN handling
  49          */
  50
  51         /*
  52          *    The case of both inputs quiet NaNs
  53          */
  54         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
  55                 return x;
  56
  57         /*
  58          *    The cases of exactly one input quiet NaN (numbers
  59          *    are here preferred as returned values to NaNs)
  60          */
  61         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
  62         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
  63         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
  64         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
  65                 return x;
  66
  67         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
  68         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
  69         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
  70         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
  71                 return y;
  72
  73         /*
  74          * Infinity and zero handling
  75          */
  76         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
  77         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
  78         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
  79         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
  80         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
  81                 return xs ? y : x;
  82
  83         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
  84         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
  85         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
  86         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
  87         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
  88         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
  89                 return ys ? x : y;
  90
  91         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
  92                 return ieee754sp_zero(xs & ys);
  93
  94         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
  95                 SPDNORMX;
  96                 /* fall through */
  97
  98         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
  99                 SPDNORMY;
 100                 break;
 101
 102         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
 103                 SPDNORMX;
 104         }
 105
 106         /* Finally get to do some computation */
 107
 108         assert(xm & SP_HIDDEN_BIT);
 109         assert(ym & SP_HIDDEN_BIT);
 110
 111         /* Compare signs */
 112         if (xs > ys)
 113                 return y;
 114         else if (xs < ys)
 115                 return x;
 116
 117         /* Signs of inputs are equal, let's compare exponents */
 118         if (xs == 0) {
 119                 /* Inputs are both positive */
 120                 if (xe > ye)
 121                         return x;
 122                 else if (xe < ye)
 123                         return y;
 124         } else {
 125                 /* Inputs are both negative */
 126                 if (xe > ye)
 127                         return y;
 128                 else if (xe < ye)
 129                         return x;
 130         }
 131
 132         /* Signs and exponents of inputs are equal, let's compare mantissas */
 133         if (xs == 0) {
 134                 /* Inputs are both positive, with equal signs and exponents */
 135                 if (xm <= ym)
 136                         return y;
 137                 return x;
 138         }
 139         /* Inputs are both negative, with equal signs and exponents */
 140         if (xm <= ym)
 141                 return x;
 142         return y;
 143 }
 144
 145 union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y)
 146 {
 147         COMPXSP;
 148         COMPYSP;
 149
 150         EXPLODEXSP;
 151         EXPLODEYSP;
 152
 153         FLUSHXSP;
 154         FLUSHYSP;
 155
 156         ieee754_clearcx();
 157
 158         switch (CLPAIR(xc, yc)) {
 159         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
 160         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
 161         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
 162         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
 163         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
 164                 return ieee754sp_nanxcpt(y);
 165
 166         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
 167         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 168         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
 169         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
 170         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
 171         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
 172                 return ieee754sp_nanxcpt(x);
 173
 174         /*
 175          * Quiet NaN handling
 176          */
 177
 178         /*
 179          *    The case of both inputs quiet NaNs
 180          */
 181         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
 182                 return x;
 183
 184         /*
 185          *    The cases of exactly one input quiet NaN (numbers
 186          *    are here preferred as returned values to NaNs)
 187          */
 188         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
 189         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
 190         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
 191         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
 192                 return x;
 193
 194         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
 195         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
 196         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
 197         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
 198                 return y;
 199
 200         /*
 201          * Infinity and zero handling
 202          */
 203         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
 204                 return ieee754sp_inf(xs & ys);
 205
 206         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
 207         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
 208         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
 209         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
 210         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
 211                 return x;
 212
 213         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
 214         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
 215         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
 216         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
 217         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
 218                 return y;
 219
 220         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
 221                 return ieee754sp_zero(xs & ys);
 222
 223         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 224                 SPDNORMX;
 225                 /* fall through */
 226
 227         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
 228                 SPDNORMY;
 229                 break;
 230
 231         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
 232                 SPDNORMX;
 233         }
 234
 235         /* Finally get to do some computation */
 236
 237         assert(xm & SP_HIDDEN_BIT);
 238         assert(ym & SP_HIDDEN_BIT);
 239
 240         /* Compare exponent */
 241         if (xe > ye)
 242                 return x;
 243         else if (xe < ye)
 244                 return y;
 245
 246         /* Compare mantissa */
 247         if (xm < ym)
 248                 return y;
 249         else if (xm > ym)
 250                 return x;
 251         else if (xs == 0)
 252                 return x;
 253         return y;
 254 }