sys/external/bsd/compiler_rt/dist/lib/builtins/ppc/floatditf.c

   1 /* This file is distributed under the University of Illinois Open Source
   2  * License. See LICENSE.TXT for details.
   3  */
   4
   5 /* long double __floatditf(long long x); */
   6 /* This file implements the PowerPC long long -> long double conversion */
   7
   8 #include "DD.h"
   9
  10 long double __floatditf(int64_t a) {
  11
  12         static const double twop32 = 0x1.0p32;
  13         static const double twop52 = 0x1.0p52;
  14
  15         doublebits low  = { .d = twop52 };
  16         low.x |= a & UINT64_C(0x00000000ffffffff);      /* 0x1.0p52 + low 32 bits of a. */
  17
  18         const double high_addend = (double)((int32_t)(a >> 32))*twop32 - twop52;
  19
  20         /* At this point, we have two double precision numbers
  21          * high_addend and low.d, and we wish to return their sum
  22          * as a canonicalized long double:
  23          */
  24
  25         /* This implementation sets the inexact flag spuriously.
  26          * This could be avoided, but at some substantial cost.
  27         */
  28
  29         DD result;
  30
  31         result.s.hi = high_addend + low.d;
  32         result.s.lo = (high_addend - result.s.hi) + low.d;
  33
  34         return result.ld;
  35
  36 }