Optimize EOS check

amphp · Jul 25, 2019 · ec57850 · ec57850
1 parent a0617ee
commit ec57850
Showing 1 changed file with 13 additions and 14 deletions.
diff --git a/src/HPack.php b/src/HPack.php
@@ -205,28 +205,27 @@ public static function huffmanDecode(string $input) /* : ?string */
         $length = \strlen($input);
         $out = \str_repeat("\0", $length / 5 * 8 + 1); // max length
 
-        for ($bitCount = $off = $i = 0; $i < $length; $i++) {
-            // Fail if EOS symbol is found.
-            if ($input[$i] === "\x3f"
-                && ($input[$i + 1] ?? null) === "\xff"
-                && ($input[$i + 2] ?? null) === "\xff"
-                && ($input[$i + 3] ?? null) === "\xff"
-            ) {
-                return null;
-            }
+        // Fail if EOS symbol is found.
+        if (\strpos($input, "\x3f\xff\xff\xff") !== false) {
+            return null;
+        }
 
-            list($lookup, $chr) = $lookup[$input[$i]];
+        for ($bitCount = $off = $i = 0; $i < $length; $i++) {
+            $currentByte = $input[$i];
 
-            if ($chr == null) { // Loose type check intentional to match both null and empty string.
-                if ($chr === "") {
-                    return null;
-                }
+            list($lookup, $chr) = $lookup[$currentByte];
 
+            if ($chr === null) {
                 continue;
             }
 
+            if ($chr === "") {
+                return null;
+            }
+
             $out[$off++] = $chr[0];
             $bitCount += $lengths[$chr[0]];
+
             if (isset($chr[1])) {
                 $out[$off++] = $chr[1];
                 $bitCount += $lengths[$chr[1]];