@Immutable
    public static Memory substr_compare(Environment env, TraceInfo trace, String mainStr, String str, int offset) {
        return substr_compare(env, trace, mainStr, str, offset, null, false);
    }
Parses the cslashes bitmap returning an actual bitmap.

@param charset the bitmap string

@return the actual bitmap
exts/jphp-zend-ext/src/main/java/org/develnext/jphp/zend/ext/standard/StringFunctions.java