sub IEEE80toIEEE64 {
    my( $discard, $mantissa, $hidden, $exponent, $sign ) =
        unpack 'a11 a52 a1 a15 a1', unpack 'b80', $_[ 0 ];
    $exponent = unpack( 'v', pack 'b15', $exponent ) - 16383 + 1023;
    $exponent = 32767, $mantissa = '0' x 52
        if $exponent < 0 or $exponent > 2047;
    $exponent = unpack 'b11', pack 'v', $exponent;
    return unpack 'd', pack 'b64', $mantissa . $exponent . $sign;
}


##</code><code>##

realtest x.bin                  C:\dmd\test>\test\80bit.pl
-1.0935598595647423806e-4950    -1.#INF
 1.0935598595647423806e-4950     1.#INF
-1.2345678901234567887e-4932    -1.#INF
 1.2345678901234567887e-4932     1.#INF
-1.2345678901234567887e-309     -1.#INF
 1.2345678901234567887e-309      1.#INF
-1.2345678901234567912e-206     -1.2345678901234567e-206
 1.2345678901234567912e-206      1.2345678901234567e-206
-1.2345678901234567937e-103     -1.2345678901234568e-103
 1.2345678901234567937e-103      1.2345678901234568e-103
-1.234567890123456796           -1.2345678901234567
 1.234567890123456796            1.2345678901234567
-1.2345678901234567983e+103     -1.2345678901234567e+103
 1.2345678901234567983e+103      1.2345678901234567e+103
-1.2345678901234568006e+206     -1.2345678901234568e+206
 1.2345678901234568006e+206      1.2345678901234568e+206
-1.2345678901234568031e+309     -1.#INF
 1.2345678901234568031e+309      1.#INF
-1.2345678901234567889e+4930    -1.#INF
 1.2345678901234567889e+4930     1.#INF
-1.2345678901234567892e+4931    -1.#INF
 1.2345678901234567892e+4931     1.#INF
 0.005000                        0.0049999999999999992
-0.005000                       -0.0049999999999999992
 0.050000                        0.049999999999999996
-0.050000                       -0.049999999999999996
 0.500000                        0.5
-0.500000                       -0.5
 5.000000                        5
-5.000000                       -5
 50.000000                       50
-50.000000                      -50