Question

I have some binary data that had to be percent encoded to transfer to a remote service via a length-restricted query string parameter.

When it comes back to me some of the values are encoded like this:

\u2014

I wish to convert this value back to binary data. The Unicode character is the same as the original value in extended ASCII.

How can I convert the above back to extended ASCII?
Edit: Windows-1252

I would prefer a Javascript solution but can work with: PHP, Python, C, C++.

Answer 1

Here’s the mapping:

var windows1252 = [
         0x0000,0x0001,0x0002,0x0003,0x0004,0x0005,0x0006,0x0007,0x0008,0x0009,0x000A,0x000B,0x000C,0x000D,0x000E,0x000F
        ,0x0010,0x0011,0x0012,0x0013,0x0014,0x0015,0x0016,0x0017,0x0018,0x0019,0x001A,0x001B,0x001C,0x001D,0x001E,0x001F
        ,0x0020,0x0021,0x0022,0x0023,0x0024,0x0025,0x0026,0x0027,0x0028,0x0029,0x002A,0x002B,0x002C,0x002D,0x002E,0x002F
        ,0x0030,0x0031,0x0032,0x0033,0x0034,0x0035,0x0036,0x0037,0x0038,0x0039,0x003A,0x003B,0x003C,0x003D,0x003E,0x003F
        ,0x0040,0x0041,0x0042,0x0043,0x0044,0x0045,0x0046,0x0047,0x0048,0x0049,0x004A,0x004B,0x004C,0x004D,0x004E,0x004F
        ,0x0050,0x0051,0x0052,0x0053,0x0054,0x0055,0x0056,0x0057,0x0058,0x0059,0x005A,0x005B,0x005C,0x005D,0x005E,0x005F
        ,0x0060,0x0061,0x0062,0x0063,0x0064,0x0065,0x0066,0x0067,0x0068,0x0069,0x006A,0x006B,0x006C,0x006D,0x006E,0x006F
        ,0x0070,0x0071,0x0072,0x0073,0x0074,0x0075,0x0076,0x0077,0x0078,0x0079,0x007A,0x007B,0x007C,0x007D,0x007E,0x007F
        ,0x20AC,0xFFFD,0x201A,0x0192,0x201E,0x2026,0x2020,0x2021,0x02C6,0x2030,0x0160,0x2039,0x0152,0xFFFD,0x017D,0xFFFD
        ,0xFFFD,0x2018,0x2019,0x201C,0x201D,0x2022,0x2013,0x2014,0x02DC,0x2122,0x0161,0x203A,0x0153,0xFFFD,0x017E,0x0178
        ,0x00A0,0x00A1,0x00A2,0x00A3,0x00A4,0x00A5,0x00A6,0x00A7,0x00A8,0x00A9,0x00AA,0x00AB,0x00AC,0x00AD,0x00AE,0x00AF
        ,0x00B0,0x00B1,0x00B2,0x00B3,0x00B4,0x00B5,0x00B6,0x00B7,0x00B8,0x00B9,0x00BA,0x00BB,0x00BC,0x00BD,0x00BE,0x00BF
        ,0x00C0,0x00C1,0x00C2,0x00C3,0x00C4,0x00C5,0x00C6,0x00C7,0x00C8,0x00C9,0x00CA,0x00CB,0x00CC,0x00CD,0x00CE,0x00CF
        ,0x00D0,0x00D1,0x00D2,0x00D3,0x00D4,0x00D5,0x00D6,0x00D7,0x00D8,0x00D9,0x00DA,0x00DB,0x00DC,0x00DD,0x00DE,0x00DF
        ,0x00E0,0x00E1,0x00E2,0x00E3,0x00E4,0x00E5,0x00E6,0x00E7,0x00E8,0x00E9,0x00EA,0x00EB,0x00EC,0x00ED,0x00EE,0x00EF
        ,0x00F0,0x00F1,0x00F2,0x00F3,0x00F4,0x00F5,0x00F6,0x00F7,0x00F8,0x00F9,0x00FA,0x00FB,0x00FC,0x00FD,0x00FE,0x00FF
];

var unicodeToWindows1252 = {};

for( var i = 0; i < windows1252.length; ++i ) {
    unicodeToWindows1252[String.fromCharCode(windows1252[i])] = i;
}

I don’t know how you mean to represent binary in js, but I am using normal array and pushing the windows-1252
byte values there as integers.

var str = "\u2014";

var character, i = 0;
var ret = [];
while( character = str.charAt(i++) ) {
    if( !(character in unicodeToWindows1252 ) ) {
        throw new TypeError( character + " is unrepresentable in windows-1252, unable to convert" );
    }
    ret.push( unicodeToWindows1252[character] );
}
console.log( ret ) //[151]
//ret contains the integer 151, which is Windows-1252 for "\u2014"