uuid.inc

/*
notes:

- random function may not generate cryptographically secure values
- guid usually refers to microsofts implementation of uuid standard
- this is by no means a perfect implementation of guid/uuid (there are plugins for that which uses the uuid library)
- this is my own implementation of uuidv4 (which is normally generated randomly (or pseudo-randomly)) with some googling


                [https://tools.ietf.org/html/rfc4122]

     The formal definition of the UUID string representation is
      provided by the following ABNF [7]:

      UUID                   = time-low "-" time-mid "-"
                               time-high-and-version "-"
                               clock-seq-and-reserved
                               clock-seq-low "-" node

      time-low               = 4hexOctet
      time-mid               = 2hexOctet
      time-high-and-version  = 2hexOctet
      clock-seq-and-reserved = hexOctet
      clock-seq-low          = hexOctet
      node                   = 6hexOctet

      hexOctet               = hexDigit hexDigit
      hexDigit =
            "0" / "1" / "2" / "3" / "4" / "5" / "6" / "7" / "8" / "9" /
            "a" / "b" / "c" / "d" / "e" / "f" /
            "A" / "B" / "C" / "D" / "E" / "F"

                      randomly or pseudo-randomly
                      generated value may be used

*/

#define UUID_MAX_LEN 37


stock UUIDv4(string[], sz = sizeof string)
{
    if(sz < UUID_MAX_LEN) return printf("error: \n sizeof string (%d) less than UUID_MAX_LEN ("#UUID_MAX_LEN") ", sz);

    format(string, sz, "%04x%04x-%04x-%04x-%04x-%04x%04x%04x",

    random(0) & 0xFFFF, random(0) & 0xFFFF, // "time_low": 16+16 = 32 bits
    random(0) & 0xFFFF, // "time_mid": 16 bits
    random(0) & 0x0FFF | 0x4000, // "time_hi_and_version": 16 bits (+ version 4)
    random(0) & 0x3FFF | 0x8000, // "clock_seq_hi_res" & "clock_seq_low": 8+8 = 16 bits
    random(0) & 0xFFFF, random(0) & 0xFFFF,random(0) & 0xFFFF); // "node": 16+16+16 = 48 bits
    
    for(new i; i < strlen(string); i++) string[i] = tolower(string[i]);
    
    return 1;
}