static public int decodeToCharArray()

in ch-commons-charset/src/main/java/com/cloudhopper/commons/charset/ModifiedUTF8Charset.java [276:339]
54 lines of code
20 McCabe index (conditional complexity)

    static public int decodeToCharArray(byte[] byteBuffer, int byteOffset, int byteLength, char[] charBuffer, int charOffset) {
        int c = 0, char2 = 0, char3 = 0;
        int bytePos = byteOffset;
        int byteAbsLength = byteOffset + byteLength;
        int charPos = charOffset;

        // optimization - do simple conversion of ascii-only chars 
        while (bytePos < byteAbsLength) {
            c = (int) byteBuffer[bytePos] & 0xff;
            if (c > 127)
                break;
            bytePos++;
            charBuffer[charPos++] = (char)c;
        }

        while (bytePos < byteAbsLength) {
            c = (int) byteBuffer[bytePos] & 0xff;
            switch (c >> 4) {
            // cases 0000 thru 0111
            case 0:
            case 1:
            case 2:
            case 3:
            case 4:
            case 5:
            case 6:
            case 7:
                // 0xxxxxxx
                bytePos++;
                charBuffer[charPos++] = (char)c;
                break;
            // why not case 8, 9, 10, or 11? (are those invalid UTF-8 sequences?
            case 12:
            case 13:
                // 110x xxxx then 10xx xxxx
                bytePos += 2;
                if (bytePos > byteAbsLength)
                    throw new IllegalArgumentException("malformed input: partial character at end");
                char2 = (int) byteBuffer[bytePos - 1];
                if ((char2 & 0xC0) != 0x80)
                    throw new IllegalArgumentException("malformed input around byte " + bytePos);
                charBuffer[charPos++] = (char) (((c & 0x1F) << 6) | (char2 & 0x3F));
                break;
            case 14:
                // 1110 xxxx then 10xx xxxx then 10xx xxxx
                bytePos += 3;
                if (bytePos > byteAbsLength)
                    throw new IllegalArgumentException("malformed input: partial character at end");
                char2 = (int) byteBuffer[bytePos - 2];
                char3 = (int) byteBuffer[bytePos - 1];
                if (((char2 & 0xC0) != 0x80)
                        || ((char3 & 0xC0) != 0x80))
                    throw new IllegalArgumentException("malformed input around byte " + (bytePos - 1));
                charBuffer[charPos++] = (char) (((c & 0x0F) << 12)
                        | ((char2 & 0x3F) << 6) | (char3 & 0x3F));
                break;
            default:
                // 10xx xxxx,  1111 xxxx
                throw new IllegalArgumentException("malformed input around byte " + bytePos);
            }
        }
        
        return (charPos - charOffset);
    }