Thy branchy code is faster than the branch-less code in method lookup…

…Hex(char).
wrandelshofer · Feb 26, 2023 · 52d3686 · 52d3686
1 parent a8c0bdc
commit 52d3686
Showing 1 changed file with 6 additions and 2 deletions.
diff --git a/....randelshofer.fastdoubleparser/ch/randelshofer/fastdoubleparser/AbstractNumberParser.java b/....randelshofer.fastdoubleparser/ch/randelshofer/fastdoubleparser/AbstractNumberParser.java
@@ -104,7 +104,9 @@ protected static char charAt(CharSequence str, int i, int endIndex) {
      * @return the hex value or a value &lt; 0.
      */
     protected static int lookupHex(byte ch) {
-        return CHAR_TO_HEX_MAP[ch & 127] | (ch >> 31);
+        // The branchy code is faster than the branch-less code.
+        // Branch-less code: return CHAR_TO_HEX_MAP[ch & 127] | (ch >> 31);
+        return ch > 0 ? CHAR_TO_HEX_MAP[ch] : -1;
     }
 
     /**
@@ -117,7 +119,9 @@ protected static int lookupHex(byte ch) {
      * @return the hex value or a value &lt; 0.
      */
     protected static int lookupHex(char ch) {
-        return CHAR_TO_HEX_MAP[ch & 127] | (127 - ch) >> 31;
+        // The branchy code is faster than the branch-less code.
+        // Branch-less code: return CHAR_TO_HEX_MAP[ch & 127] | (127 - ch) >> 31;
+        return ch < 128 ? CHAR_TO_HEX_MAP[ch] : -1;
     }
 
 }