Prefer bitwise OR over addition for UTF-8 multi-byte encoding

src/main/java/com/fasterxml/jackson/core/base/GeneratorBase.java

@@ -533,8 +533,7 @@ protected final int _decodeSurrogate(int surr1, int surr2) throws IOException
 "Incomplete surrogate pair: first char 0x%04X, second 0x%04X", surr1, surr2);
             _reportError(msg);
         }
-        int c = 0x10000 + ((surr1 - SURR1_FIRST) << 10) + (surr2 - SURR2_FIRST);
-        return c;
+        return 0x10000 + ((surr1 - SURR1_FIRST) << 10) | (surr2 - SURR2_FIRST);
     }
 
     /*

src/main/java/com/fasterxml/jackson/core/io/JsonStringEncoder.java

@@ -659,7 +659,7 @@ private static int _convert(int p1, int p2) {
         if (p2 < SURR2_FIRST || p2 > SURR2_LAST) {
             throw new IllegalArgumentException("Broken surrogate pair: first char 0x"+Integer.toHexString(p1)+", second 0x"+Integer.toHexString(p2)+"; illegal combination");
         }
-        return 0x10000 + ((p1 - SURR1_FIRST) << 10) + (p2 - SURR2_FIRST);
+        return 0x10000 + ((p1 - SURR1_FIRST) << 10) | (p2 - SURR2_FIRST);
     }
 
     private static void _illegal(int c) {

src/main/java/com/fasterxml/jackson/core/io/UTF32Reader.java

@@ -159,7 +159,7 @@ public int read(char[] cbuf, int start, int len) throws IOException
                     reportInvalid(ch, outPtr-start,
                             String.format(" (above 0x%08x)", LAST_VALID_UNICODE_CHAR));
                 }
-                cbuf[outPtr++] = (char) (0xD800 + (ch >> 10));
+                cbuf[outPtr++] = (char) (0xD800 | (ch >> 10));
                 // hmmh. can this ever be 0? (not legal, at least?)
                 lo = (0xDC00 | (ch & 0x03FF));
                 // Room for second part?

src/main/java/com/fasterxml/jackson/core/io/UTF8Writer.java

@@ -369,7 +369,7 @@ protected int convertSurrogate(int secondPart)
         if (secondPart < SURR2_FIRST || secondPart > SURR2_LAST) {
             throw new IOException("Broken surrogate pair: first char 0x"+Integer.toHexString(firstPart)+", second 0x"+Integer.toHexString(secondPart)+"; illegal combination");
         }
-        return 0x10000 + ((firstPart - SURR1_FIRST) << 10) + (secondPart - SURR2_FIRST);
+        return 0x10000 + ((firstPart - SURR1_FIRST) << 10) | (secondPart - SURR2_FIRST);
     }
 
     protected static void illegalSurrogate(int code) throws IOException {

src/main/java/com/fasterxml/jackson/core/json/UTF8DataInputJsonParser.java

@@ -1919,7 +1919,7 @@ private final String addName(int[] quads, int qlen, int lastQuadBytes)
                     if (cix >= cbuf.length) {
                         cbuf = _textBuffer.expandCurrentSegment();
                     }
-                    cbuf[cix++] = (char) (0xD800 + (ch >> 10));
+                    cbuf[cix++] = (char) (0xD800 | (ch >> 10));
                     ch = 0xDC00 | (ch & 0x03FF);
                 }
             }

src/main/java/com/fasterxml/jackson/core/json/UTF8StreamJsonParser.java

@@ -2474,7 +2474,7 @@ private final String addName(int[] quads, int qlen, int lastQuadBytes)
                     if (cix >= cbuf.length) {
                         cbuf = _textBuffer.expandCurrentSegment();
                     }
-                    cbuf[cix++] = (char) (0xD800 + (ch >> 10));
+                    cbuf[cix++] = (char) (0xD800 | (ch >> 10));
                     ch = 0xDC00 | (ch & 0x03FF);
                 }
             }

src/main/java/com/fasterxml/jackson/core/json/async/NonBlockingJsonParserBase.java

@@ -793,7 +793,7 @@ protected final String _addName(int[] quads, int qlen, int lastQuadBytes)
                     if (cix >= cbuf.length) {
                         cbuf = _textBuffer.expandCurrentSegment();
                     }
-                    cbuf[cix++] = (char) (0xD800 + (ch >> 10));
+                    cbuf[cix++] = (char) (0xD800 | (ch >> 10));
                     ch = 0xDC00 | (ch & 0x03FF);
                 }
             }