softfloat/s_subMagsF64.c

   1
   2 #include <stdbool.h>
   3 #include <stdint.h>
   4 #include "platform.h"
   5 #include "primitives.h"
   6 #include "internals.h"
   7 #include "specialize.h"
   8 #include "softfloat.h"
   9
  10 float64_t
  11  softfloat_subMagsF64( uint_fast64_t uiA, uint_fast64_t uiB, bool signZ )
  12 {
  13     int_fast16_t expA;
  14     uint_fast64_t sigA;
  15     int_fast16_t expB;
  16     uint_fast64_t sigB;
  17     int_fast16_t expDiff;
  18     uint_fast64_t uiZ;
  19     int_fast16_t expZ;
  20     uint_fast64_t sigZ;
  21     union ui64_f64 uZ;
  22
  23     expA = expF64UI( uiA );
  24     sigA = fracF64UI( uiA );
  25     expB = expF64UI( uiB );
  26     sigB = fracF64UI( uiB );
  27     expDiff = expA - expB;
  28     sigA <<= 10;
  29     sigB <<= 10;
  30     if ( 0 < expDiff ) goto expABigger;
  31     if ( expDiff < 0 ) goto expBBigger;
  32     if ( expA == 0x7FF ) {
  33         if ( sigA | sigB ) goto propagateNaN;
  34         softfloat_raiseFlags( softfloat_flag_invalid );
  35         uiZ = defaultNaNF64UI;
  36         goto uiZ;
  37     }
  38     if ( ! expA ) {
  39         expA = 1;
  40         expB = 1;
  41     }
  42     if ( sigB < sigA ) goto aBigger;
  43     if ( sigA < sigB ) goto bBigger;
  44     uiZ = packToF64UI( softfloat_roundingMode == softfloat_round_min, 0, 0 );
  45     goto uiZ;
  46  expBBigger:
  47     if ( expB == 0x7FF ) {
  48         if ( sigB ) goto propagateNaN;
  49         uiZ = packToF64UI( signZ ^ 1, 0x7FF, 0 );
  50         goto uiZ;
  51     }
  52     sigA += expA ? UINT64_C( 0x4000000000000000 ) : sigA;
  53     sigA = softfloat_shift64RightJam( sigA, - expDiff );
  54     sigB |= UINT64_C( 0x4000000000000000 );
  55  bBigger:
  56     signZ ^= 1;
  57     expZ = expB;
  58     sigZ = sigB - sigA;
  59     goto normRoundPack;
  60  expABigger:
  61     if ( expA == 0x7FF ) {
  62         if ( sigA ) goto propagateNaN;
  63         uiZ = uiA;
  64         goto uiZ;
  65     }
  66     sigB += expB ? UINT64_C( 0x4000000000000000 ) : sigB;
  67     sigB = softfloat_shift64RightJam( sigB, expDiff );
  68     sigA |= UINT64_C( 0x4000000000000000 );
  69  aBigger:
  70     expZ = expA;
  71     sigZ = sigA - sigB;
  72  normRoundPack:
  73     return softfloat_normRoundPackToF64( signZ, expZ - 1, sigZ );
  74  propagateNaN:
  75     uiZ = softfloat_propagateNaNF64UI( uiA, uiB );
  76  uiZ:
  77     uZ.ui = uiZ;
  78     return uZ.f;
  79
  80 }
  81