softfloat/f32_to_f64.c

   1
   2 #include <stdbool.h>
   3 #include <stdint.h>
   4 #include "platform.h"
   5 #include "internals.h"
   6 #include "specialize.h"
   7 #include "softfloat.h"
   8
   9 float64_t f32_to_f64( float32_t a )
  10 {
  11     union ui32_f32 uA;
  12     uint_fast32_t uiA;
  13     bool sign;
  14     int_fast16_t exp;
  15     uint_fast32_t sig;
  16     uint_fast64_t uiZ;
  17     struct exp16_sig32 normExpSig;
  18     union ui64_f64 uZ;
  19
  20     uA.f = a;
  21     uiA = uA.ui;
  22     sign = signF32UI( uiA );
  23     exp = expF32UI( uiA );
  24     sig = fracF32UI( uiA );
  25     if ( exp == 0xFF ) {
  26         uiZ =
  27             sig ? softfloat_commonNaNToF64UI(
  28                       softfloat_f32UIToCommonNaN( uiA ) )
  29                 : packToF64UI( sign, 0x7FF, 0 );
  30         goto uiZ;
  31     }
  32     if ( ! exp ) {
  33         if ( ! sig ) {
  34             uiZ = packToF64UI( sign, 0, 0 );
  35             goto uiZ;
  36         }
  37         normExpSig = softfloat_normSubnormalF32Sig( sig );
  38         exp = normExpSig.exp - 1;
  39         sig = normExpSig.sig;
  40     }
  41     uiZ = packToF64UI( sign, exp + 0x380, (uint_fast64_t) sig<<29 );
  42  uiZ:
  43     uZ.ui = uiZ;
  44     return uZ.f;
  45
  46 }
  47