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                 fallthrough;
  97         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
  98                 SPDNORMY;
  99                 break;
 100
 101         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
 102                 SPDNORMX;
 103         }
 104
 105         /* Finally get to do some computation */
 106
 107         assert(xm & SP_HIDDEN_BIT);
 108         assert(ym & SP_HIDDEN_BIT);
 109
 110         /* Compare signs */
 111         if (xs > ys)
 112                 return y;
 113         else if (xs < ys)
 114                 return x;
 115
 116         /* Signs of inputs are equal, let's compare exponents */
 117         if (xs == 0) {
 118                 /* Inputs are both positive */
 119                 if (xe > ye)
 120                         return x;
 121                 else if (xe < ye)
 122                         return y;
 123         } else {
 124                 /* Inputs are both negative */
 125                 if (xe > ye)
 126                         return y;
 127                 else if (xe < ye)
 128                         return x;
 129         }
 130
 131         /* Signs and exponents of inputs are equal, let's compare mantissas */
 132         if (xs == 0) {
 133                 /* Inputs are both positive, with equal signs and exponents */
 134                 if (xm <= ym)
 135                         return y;
 136                 return x;
 137         }
 138         /* Inputs are both negative, with equal signs and exponents */
 139         if (xm <= ym)
 140                 return x;
 141         return y;
 142 }
 143
 144 union ieee754sp ieee754sp_fmaxa(union ieee754sp x, union ieee754sp y)
 145 {
 146         COMPXSP;
 147         COMPYSP;
 148
 149         EXPLODEXSP;
 150         EXPLODEYSP;
 151
 152         FLUSHXSP;
 153         FLUSHYSP;
 154
 155         ieee754_clearcx();
 156
 157         switch (CLPAIR(xc, yc)) {
 158         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
 159         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
 160         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
 161         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
 162         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
 163                 return ieee754sp_nanxcpt(y);
 164
 165         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
 166         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
 167         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
 168         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
 169         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
 170         case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
 171                 return ieee754sp_nanxcpt(x);
 172
 173         /*
 174          * Quiet NaN handling
 175          */
 176
 177         /*
 178          *    The case of both inputs quiet NaNs
 179          */
 180         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
 181                 return x;
 182
 183         /*
 184          *    The cases of exactly one input quiet NaN (numbers
 185          *    are here preferred as returned values to NaNs)
 186          */
 187         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
 188         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
 189         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
 190         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
 191                 return x;
 192
 193         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
 194         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
 195         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
 196         case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
 197                 return y;
 198
 199         /*
 200          * Infinity and zero handling
 201          */
 202         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
 203                 return ieee754sp_inf(xs & ys);
 204
 205         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
 206         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
 207         case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
 208         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
 209         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
 210                 return x;
 211
 212         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
 213         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
 214         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
 215         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
 216         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
 217                 return y;
 218
 219         case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
 220                 return ieee754sp_zero(xs & ys);
 221
 222         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 223                 SPDNORMX;
 224                 fallthrough;
 225         case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
 226                 SPDNORMY;
 227                 break;
 228
 229         case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
 230                 SPDNORMX;
 231         }
 232
 233         /* Finally get to do some computation */
 234
 235         assert(xm & SP_HIDDEN_BIT);
 236         assert(ym & SP_HIDDEN_BIT);
 237
 238         /* Compare exponent */
 239         if (xe > ye)
 240                 return x;
 241         else if (xe < ye)
 242                 return y;
 243
 244         /* Compare mantissa */
 245         if (xm < ym)
 246                 return y;
 247         else if (xm > ym)
 248                 return x;
 249         else if (xs == 0)
 250                 return x;
 251         return y;
 252 }