arch/mips/math-emu/sp_fdp.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* IEEE754 floating point arithmetic
   3  * single precision
   4  */
   5 /*
   6  * MIPS floating point support
   7  * Copyright (C) 1994-2000 Algorithmics Ltd.
   8  */
   9
  10 #include "ieee754sp.h"
  11 #include "ieee754dp.h"
  12
  13 static inline union ieee754sp ieee754sp_nan_fdp(int xs, u64 xm)
  14 {
  15         return buildsp(xs, SP_EMAX + 1 + SP_EBIAS,
  16                        xm >> (DP_FBITS - SP_FBITS));
  17 }
  18
  19 union ieee754sp ieee754sp_fdp(union ieee754dp x)
  20 {
  21         union ieee754sp y;
  22         u32 rm;
  23
  24         COMPXDP;
  25         COMPYSP;
  26
  27         EXPLODEXDP;
  28
  29         ieee754_clearcx();
  30
  31         FLUSHXDP;
  32
  33         switch (xc) {
  34         case IEEE754_CLASS_SNAN:
  35                 x = ieee754dp_nanxcpt(x);
  36                 EXPLODEXDP;
  37                 fallthrough;
  38         case IEEE754_CLASS_QNAN:
  39                 y = ieee754sp_nan_fdp(xs, xm);
  40                 if (!ieee754_csr.nan2008) {
  41                         EXPLODEYSP;
  42                         if (!ieee754_class_nan(yc))
  43                                 y = ieee754sp_indef();
  44                 }
  45                 return y;
  46
  47         case IEEE754_CLASS_INF:
  48                 return ieee754sp_inf(xs);
  49
  50         case IEEE754_CLASS_ZERO:
  51                 return ieee754sp_zero(xs);
  52
  53         case IEEE754_CLASS_DNORM:
  54                 /* can't possibly be sp representable */
  55                 ieee754_setcx(IEEE754_UNDERFLOW);
  56                 ieee754_setcx(IEEE754_INEXACT);
  57                 if ((ieee754_csr.rm == FPU_CSR_RU && !xs) ||
  58                                 (ieee754_csr.rm == FPU_CSR_RD && xs))
  59                         return ieee754sp_mind(xs);
  60                 return ieee754sp_zero(xs);
  61
  62         case IEEE754_CLASS_NORM:
  63                 break;
  64         }
  65
  66         /*
  67          * Convert from DP_FBITS to SP_FBITS+3 with sticky right shift.
  68          */
  69         rm = (xm >> (DP_FBITS - (SP_FBITS + 3))) |
  70              ((xm << (64 - (DP_FBITS - (SP_FBITS + 3)))) != 0);
  71
  72         return ieee754sp_format(xs, xe, rm);
  73 }