Math.mutiplyHigh() is signed

[Raffaello Giulietti]

Hi,

in defense of the current spec, integer arithmetic is signed by default 
and unsigned behavior is evident from the method names, like 
Long::compareUnsigned or Long::divideUnsigned

But your spec is even clearer ;-)


Greetings
Raffaello



> In retrospect I don't know why I expected Math.multiplyHigh() to
> return the high word of the unsigned product of two 64-bit numbers,
> given that long is signed; in my defence however, the docs don't
> actually seem to specify.
> 
> WDYT about a patch like this to clarify?
> 
> diff --git a/src/java.base/share/classes/java/lang/Math.java
> b/src/java.base/share/classes/java/lang/Math.java
> index 8147b7109e2..552501ca6d7 100644
> --- a/src/java.base/share/classes/java/lang/Math.java
> +++ b/src/java.base/share/classes/java/lang/Math.java
> @@ -1095,8 +1095,8 @@ public final class Math {
>      }
> 
>      /**
> -     * Returns as a {@code long} the most significant 64 bits of the 128-bit
> -     * product of two 64-bit factors.
> +     * Returns as a {@code long} the most significant 64 bits of the
> signed 128-bit
> +     * product of two 64-bit signed factors.
>       *
>       * @param x the first value
>       * @param y the second value
> 
> 
> -- 
> - DML