@HotSpotIntrinsicCandidate
public static native double longBitsToDouble (long bits)

Returns the ` double` value corresponding to a given bit representation. The argument is considered to be a representation of a floating-point value according to the IEEE 754 floating-point "double format" bit layout.

If the argument is ` 0x7ff0000000000000L`, the result is positive infinity.

If the argument is ` 0xfff0000000000000L`, the result is negative infinity.

If the argument is any value in the range ` 0x7ff0000000000001L` through ` 0x7fffffffffffffffL` or in the range ` 0xfff0000000000001L` through ` 0xffffffffffffffffL`, the result is a NaN. No IEEE 754 floating-point operation provided by Java can distinguish between two NaN values of the same type with different bit patterns. Distinct values of NaN are only distinguishable by use of the ` Double.doubleToRawLongBits` method.

In all other cases, let s, e, and m be three values that can be computed from the argument:

``````
int s = ((bits >> 63) == 0) ? 1 : -1;
int e = (int)((bits >> 52) & 0x7ffL);
long m = (e == 0) ?
(bits & 0xfffffffffffffL) << 1 :
(bits & 0xfffffffffffffL) | 0x10000000000000L;
``````
Then the floating-point result equals the value of the mathematical expression s·m·2e-1075.

Note that this method may not be able to return a ` double` NaN with exactly same bit pattern as the ` long` argument. IEEE 754 distinguishes between two kinds of NaNs, quiet NaNs and signaling NaNs. The differences between the two kinds of NaN are generally not visible in Java. Arithmetic operations on signaling NaNs turn them into quiet NaNs with a different, but often similar, bit pattern. However, on some processors merely copying a signaling NaN also performs that conversion. In particular, copying a signaling NaN to return it to the calling method may perform this conversion. So ` longBitsToDouble` may not be able to return a ` double` with a signaling NaN bit pattern. Consequently, for some ` long` values, ` doubleToRawLongBits(longBitsToDouble(start))` may not equal ` start`. Moreover, which particular bit patterns represent signaling NaNs is platform dependent; although all NaN bit patterns, quiet or signaling, must be in the NaN range identified above.

Parameters:
 `bits` any ` long` integer.

Returns:  the ` double` floating-point value with the same bit pattern.