softfloat/s_roundPackToI32.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_fast32_t
   9  softfloat_roundPackToI32(
  10      bool sign, uint_fast64_t sig, int_fast8_t roundingMode, bool exact )
  11 {
  12     bool roundNearestEven;
  13     int roundIncrement, roundBits;
  14     uint_fast32_t sig32;
  15     union { uint32_t ui; int32_t i; } uZ;
  16     int_fast32_t z;
  17
  18     roundNearestEven = ( roundingMode == softfloat_round_nearest_even );
  19     roundIncrement = 0x40;
  20     if (
  21            ! roundNearestEven
  22         && ( roundingMode != softfloat_round_nearest_maxMag )
  23     ) {
  24         roundIncrement =
  25                ( roundingMode == softfloat_round_minMag )
  26             || ( roundingMode
  27                      == ( sign ? softfloat_round_max : softfloat_round_min ) )
  28                 ? 0
  29                 : 0x7F;
  30     }
  31     roundBits = sig & 0x7F;
  32     sig += roundIncrement;
  33     if ( sig & UINT64_C( 0xFFFFFF8000000000 ) ) goto invalid;
  34     sig32 = sig>>7;
  35     sig32 &= ~ ( ! ( roundBits ^ 0x40 ) & roundNearestEven );
  36     uZ.ui = sign ? - sig32 : sig32;
  37     z = uZ.i;
  38     if ( z && ( ( z < 0 ) ^ sign ) ) goto invalid;
  39     if ( exact && roundBits ) {
  40         softfloat_exceptionFlags |= softfloat_flag_inexact;
  41     }
  42     return z;
  43  invalid:
  44     softfloat_raiseFlags( softfloat_flag_invalid );
  45     return sign ? -0x7FFFFFFF - 1 : 0x7FFFFFFF;
  46
  47 }
  48