function encodeURL(str){
    var s0, i, s, u;
    s0 = "";                // encoded str
    for (i = 0; i < str.length; i++){   // scan the source
        s = str.charAt(i);
        u = str.charCodeAt(i);          // get unicode of the char
        if (s == " "){s0 += "+";}       // SP should be converted to "+"
        else {
            if ( u == 0x2a || u == 0x2d || u == 0x2e || u == 0x5f || ((u >= 0x30) && (u <= 0x39)) || ((u >= 0x41) && (u <= 0x5a)) || ((u >= 0x61) && (u <= 0x7a))){       // check for escape
                s0 = s0 + s;            // don't escape
            }
            else {                  // escape
                if ((u >= 0x0) && (u <= 0x7f)){     // single byte format
                    s = "0"+u.toString(16);
                    s0 += "%"+ s.substr(s.length-2);
                }
                else if (u > 0x1fffff){     // quaternary byte format (extended)
                    s0 += "%" + (0xf0 + ((u & 0x1c0000) >> 18)).toString(16);
                    s0 += "%" + (0x80 + ((u & 0x3f000) >> 12)).toString(16);
                    s0 += "%" + (0x80 + ((u & 0xfc0) >> 6)).toString(16);
                    s0 += "%" + (0x80 + (u & 0x3f)).toString(16);
                }
                else if (u > 0x7ff){        // triple byte format
                    s0 += "%" + (0xe0 + ((u & 0xf000) >> 12)).toString(16);
                    s0 += "%" + (0x80 + ((u & 0xfc0) >> 6)).toString(16);
                    s0 += "%" + (0x80 + (u & 0x3f)).toString(16);
                }
                else {                      // double byte format
                    s0 += "%" + (0xc0 + ((u & 0x7c0) >> 6)).toString(16);
                    s0 += "%" + (0x80 + (u & 0x3f)).toString(16);
                }
            }
        }
    } 
    return s0;
}

function decodeURL(str)
{
    var s0, i, j, s, ss, u, n, f;
    s0 = "";                // decoded str
    for (i = 0; i < str.length; i++){   // scan the source str
        s = str.charAt(i);
        if (s == "+"){s0 += " ";}       // "+" should be changed to SP
        else {
            if (s != "%"){s0 += s;}     // add an unescaped char
            else{               // escape sequence decoding
                u = 0;          // unicode of the character
                f = 1;          // escape flag, zero means end of this sequence
                while (true) {
                    ss = "";        // local str to parse as int
                        for (j = 0; j < 2; j++ ) {  // get two maximum hex characters for parse
                            sss = str.charAt(++i);
                            if (((sss >= "0") && (sss <= "9")) || ((sss >= "a") && (sss <= "f"))  || ((sss >= "A") && (sss <= "F"))) {
                                ss += sss;      // if hex, add the hex character
                            } else {--i; break;}    // not a hex char., exit the loop
                        }
                    n = parseInt(ss, 16);           // parse the hex str as byte
                    if (n <= 0x7f){u = n; f = 1;}   // single byte format
                    if ((n >= 0xc0) && (n <= 0xdf)){u = n & 0x1f; f = 2;}   // double byte format
                    if ((n >= 0xe0) && (n <= 0xef)){u = n & 0x0f; f = 3;}   // triple byte format
                    if ((n >= 0xf0) && (n <= 0xf7)){u = n & 0x07; f = 4;}   // quaternary byte format (extended)
                    if ((n >= 0x80) && (n <= 0xbf)){u = (u << 6) + (n & 0x3f); --f;}         // not a first, shift and add 6 lower bits
                    if (f <= 1){break;}         // end of the utf byte sequence
                    if (str.charAt(i + 1) == "%"){ i++ ;}                   // test for the next shift byte
                    else {break;}                   // abnormal, format error
                }
            s0 += String.fromCharCode(u);           // add the escaped character
            }
        }
    }
    return s0;
}
