softfloat/f64_to_i64.c

   1
   2 #include <stdbool.h>
   3 #include <stdint.h>
   4 #include "platform.h"
   5 #include "primitives.h"
   6 #include "internals.h"
   7 #include "softfloat.h"
   8
   9 int_fast64_t f64_to_i64( float64_t a, int_fast8_t roundingMode, bool exact )
  10 {
  11     union ui64_f64 uA;
  12     uint_fast64_t uiA;
  13     bool sign;
  14     int_fast16_t exp;
  15     uint_fast64_t sig;
  16     int_fast16_t shiftCount;
  17     struct uint64_extra sigExtra;
  18
  19     uA.f = a;
  20     uiA = uA.ui;
  21     sign = signF64UI( uiA );
  22     exp = expF64UI( uiA );
  23     sig = fracF64UI( uiA );
  24     if ( exp ) sig |= UINT64_C( 0x0010000000000000 );
  25     shiftCount = 0x433 - exp;
  26     if ( shiftCount <= 0 ) {
  27         if ( 0x43E < exp ) {
  28             softfloat_raiseFlags( softfloat_flag_invalid );
  29             return
  30                 ! sign
  31                     || ( ( exp == 0x7FF )
  32                              && ( sig != UINT64_C( 0x0010000000000000 ) ) )
  33                     ? INT64_C( 0x7FFFFFFFFFFFFFFF )
  34                     : - INT64_C( 0x7FFFFFFFFFFFFFFF ) - 1;
  35         }
  36         sigExtra.v = sig<<( - shiftCount );
  37         sigExtra.extra = 0;
  38     } else {
  39         sigExtra = softfloat_shift64ExtraRightJam( sig, 0, shiftCount );
  40     }
  41     return
  42         softfloat_roundPackToI64(
  43             sign, sigExtra.v, sigExtra.extra, roundingMode, exact );
  44
  45 }
  46