RFR: JDK-8289551: Conversions between bit representations of half precision values and floats

[Joe Darcy]

On Wed, 13 Jul 2022 13:11:33 GMT, Raffaello Giulietti <duke at openjdk.org> wrote:

>> Initial implementation.
>
> src/java.base/share/classes/java/lang/Float.java line 1174:
> 
>> 1172: 
>> 1173:             short result = 0;
>> 1174:             result = (short)(((exp + 15) << 10) | signif_bits);
> 
> result = (short)(((exp + 15) << 10) + signif_bits);
> 
> The final exponent needs to be incremented when `signif_bits == 0x400`. The `|` is not enough for this to happen.

Good catch; I'll correct this bug in the next push.

I'll be adding a test to verify correct rounding of all the values in a binade - the set of floating-point values with the same exponent. That test reveals this issue.

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PR: https://git.openjdk.org/jdk/pull/9422