softfloat/8086/s_propagateNaNF64UI.c

   1
   2 /*** UPDATE COMMENTS. ***/
   3
   4 #include <stdbool.h>
   5 #include <stdint.h>
   6 #include "platform.h"
   7 #include "internals.h"
   8 #include "specialize.h"
   9 #include "softfloat.h"
  10
  11 /*----------------------------------------------------------------------------
  12 | Takes two double-precision floating-point values `a' and `b', one of which
  13 | is a NaN, and returns the appropriate NaN result.  If either `a' or `b' is a
  14 | signaling NaN, the invalid exception is raised.
  15 *----------------------------------------------------------------------------*/
  16
  17 uint_fast64_t
  18  softfloat_propagateNaNF64UI( uint_fast64_t uiA, uint_fast64_t uiB )
  19 {
  20     bool isNaNA, isSigNaNA, isNaNB, isSigNaNB;
  21     uint_fast64_t uiMagA, uiMagB;
  22
  23     /*------------------------------------------------------------------------
  24     *------------------------------------------------------------------------*/
  25     isNaNA = isNaNF64UI( uiA );
  26     isSigNaNA = softfloat_isSigNaNF64UI( uiA );
  27     isNaNB = isNaNF64UI( uiB );
  28     isSigNaNB = softfloat_isSigNaNF64UI( uiB );
  29     /*------------------------------------------------------------------------
  30     | Make NaNs non-signaling.
  31     *------------------------------------------------------------------------*/
  32     uiA |= UINT64_C( 0x0008000000000000 );
  33     uiB |= UINT64_C( 0x0008000000000000 );
  34     /*------------------------------------------------------------------------
  35     *------------------------------------------------------------------------*/
  36     if ( isSigNaNA | isSigNaNB ) {
  37         softfloat_raiseFlags( softfloat_flag_invalid );
  38     }
  39     if ( isSigNaNA ) {
  40         if ( isSigNaNB ) goto returnLargerSignificand;
  41         return isNaNB ? uiB : uiA;
  42     } else if ( isNaNA ) {
  43         if ( isSigNaNB || ! isNaNB ) return uiA;
  44  returnLargerSignificand:
  45         uiMagA = uiA & UINT64_C( 0x7FFFFFFFFFFFFFFF );
  46         uiMagB = uiB & UINT64_C( 0x7FFFFFFFFFFFFFFF );
  47         if ( uiMagA < uiMagB ) return uiB;
  48         if ( uiMagB < uiMagA ) return uiA;
  49         return ( uiA < uiB ) ? uiA : uiB;
  50     } else {
  51         return uiB;
  52     }
  53
  54 }
  55