On Fri, 15 Sep 2023 18:04:29 GMT, 温绍锦 <d...@openjdk.org> wrote:
> In the improvement of @cl4es PR #15591, the advantages of non-lookup-table
> were discussed.
>
> But if the input is byte[], using lookup table can improve performance.
>
> For HexFormat#formatHex(Appendable, byte[]) and HexFormat#formatHex(byte[]),
> If the length of byte[] is larger, the performance of table lookup will be
> improved more obviously.
src/java.base/share/classes/jdk/internal/util/HexDigits.java line 101:
> 99: public static short digitPair(int i) {
> 100: return DIGITS[i & 0xff];
> 101: }
DigitPair(i) appears to be unused and is redundant with DigitPair(i,boolean).
src/java.base/share/classes/jdk/internal/util/HexDigits.java line 112:
> 110: short v = DIGITS[i & 0xff];
> 111: return ucase
> 112: ? (short) (v & ~((v & 0b0100_0000_0100_0000) >> 1)) //
> really: to uppper
Clever but perhaps ('a' - 'A') to make it clearer where the constant came from
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PR Review Comment: https://git.openjdk.org/jdk/pull/15768#discussion_r1329173096
PR Review Comment: https://git.openjdk.org/jdk/pull/15768#discussion_r1329067559
