softfloat/s_roundPackToI64.c

   1
   2 #include <stdbool.h>
   3 #include <stdint.h>
   4 #include "platform.h"
   5 #include "internals.h"
   6 #include "softfloat.h"
   7
   8 int_fast64_t
   9  softfloat_roundPackToI64(
  10      bool sign,
  11      uint_fast64_t sig64,
  12      uint_fast64_t sig0,
  13      int_fast8_t roundingMode,
  14      bool exact
  15  )
  16 {
  17     bool roundNearestEven, increment;
  18     union { uint64_t ui; int64_t i; } uZ;
  19     int_fast64_t z;
  20
  21     roundNearestEven = ( roundingMode == softfloat_round_nearest_even );
  22     increment = ( UINT64_C( 0x8000000000000000 ) <= sig0 );
  23     if (
  24            ! roundNearestEven
  25         && ( roundingMode != softfloat_round_nearest_maxMag )
  26     ) {
  27         increment =
  28                ( roundingMode != softfloat_round_minMag )
  29             && ( roundingMode
  30                      == ( sign ? softfloat_round_min : softfloat_round_max ) )
  31             && sig0;
  32     }
  33     if ( increment ) {
  34         ++sig64;
  35         if ( ! sig64 ) goto invalid;
  36         sig64 &=
  37             ~ ( ! ( sig0 & UINT64_C( 0x7FFFFFFFFFFFFFFF ) )
  38                     & roundNearestEven );
  39     }
  40     uZ.ui = sign ? - sig64 : sig64;
  41     z = uZ.i;
  42     if ( z && ( ( z < 0 ) ^ sign ) ) goto invalid;
  43     if ( exact && sig0 ) softfloat_exceptionFlags |= softfloat_flag_inexact;
  44     return z;
  45  invalid:
  46     softfloat_raiseFlags( softfloat_flag_invalid );
  47     return
  48         sign ? - INT64_C( 0x7FFFFFFFFFFFFFFF ) - 1
  49             : INT64_C( 0x7FFFFFFFFFFFFFFF );
  50
  51 }
  52