src/float/conv/cl_FF_to_double.cc

   1 // cl_FF_to_double().
   2
   3 // General includes.
   4 #include "base/cl_sysdep.h"
   5
   6 // Specification.
   7 #include "cln/ffloat.h"
   8
   9
  10 // Implementation.
  11
  12 #include "float/ffloat/cl_FF.h"
  13 #include "float/dfloat/cl_DF.h"
  14
  15 namespace cln {
  16
  17 double double_approx (const cl_FF& x)
  18 {
  19         // x entpacken:
  20         var cl_signean sign;
  21         var sintL exp;
  22         var uint32 mant;
  23         FF_decode(x, { return 0.0; }, sign=,exp=,mant=);
  24         // Mantisse um 52-23=29 Nullbits erweitern:
  25         union { dfloat eksplicit; double machine_double; } u;
  26         #if (cl_word_size==64)
  27         if (((sintL)(FF_exp_high-FF_exp_mid) > (sintL)(DF_exp_high-DF_exp_mid))
  28             && (exp > (sintL)(DF_exp_high-DF_exp_mid)))
  29           { u.eksplicit =
  30                 ((sint64)sign & bit(63))
  31               | ((uint64)(bit(DF_exp_len)-1) << DF_mant_len); // Infinity
  32           }
  33         else
  34         if (((sintL)(FF_exp_low-FF_exp_mid) < (sintL)(DF_exp_low-DF_exp_mid))
  35             && (exp < (sintL)(DF_exp_low-DF_exp_mid)))
  36           { u.eksplicit = ((sint64)sign & bit(63)); } // 0.0
  37         else
  38           { u.eksplicit =
  39                 ((sint64)sign & bit(63))                  /* Vorzeichen */
  40               | ((uint64)(exp+DF_exp_mid) << DF_mant_len) /* Exponent   */
  41               | (((uint64)mant<<(DF_mant_len-FF_mant_len)) & (bit(DF_mant_len)-1)); /* Mantisse   */
  42           }
  43         #else
  44         if (((sintL)(FF_exp_high-FF_exp_mid) > (sintL)(DF_exp_high-DF_exp_mid))
  45             && (exp > (sintL)(DF_exp_high-DF_exp_mid)))
  46           { u.eksplicit.semhi =
  47                 ((sint32)sign & bit(31))
  48               | ((uint32)(bit(DF_exp_len)-1) << (DF_mant_len-32)); // Infinity
  49             u.eksplicit.mlo = 0;
  50           }
  51         else
  52         if (((sintL)(FF_exp_low-FF_exp_mid) < (sintL)(DF_exp_low-DF_exp_mid))
  53             && (exp < (sintL)(DF_exp_low-DF_exp_mid)))
  54           { u.eksplicit.semhi = ((sint32)sign & bit(31)); // 0.0
  55             u.eksplicit.mlo = 0;
  56           }
  57         else
  58           { u.eksplicit.semhi =
  59                 ((sint32)sign & bit(31))                       /* Vorzeichen */
  60               | ((uint32)(exp+DF_exp_mid) << (DF_mant_len-32)) /* Exponent   */
  61               | (((uint32)mant>>(32-(DF_mant_len-FF_mant_len))) & (bit(DF_mant_len-32)-1)); /* Mantisse   */
  62             u.eksplicit.mlo = mant<<(DF_mant_len-FF_mant_len);
  63           }
  64         #endif
  65         return u.machine_double;
  66 }
  67
  68 }  // namespace cln