Request Xerox HFD1-T tonerchip file pattern

[JeroenSteen]

I would like some help to make a file pattern for Xerox HFD1-T tonerchips. By setting up a pattern file it would be easier to analyse the tonerchip data further. Unfortunately I'm not familiair yet with the pattern code syntax and how it works. I would like some suggestions of good tutorials or example code. I need to select multiple different bits in a certain order, and use encryption/decryption (so files can be encrypted and need decryption, or files can be already decrypted and can maybe have some extra information), and bit shifting function for the data. I think hexpat works with setting up a struct, but I'm confused on how to select the data and twist it to make it work. Here is just a start:

struct TonerChipData {
 decryptionKey;
 partNumber;
 date;
 serialNumber;
};

[JeroenSteen]

//Pattern made by Jeroen van der Steen (@JeroenSteen), with help from @AxCut, @somemadeupname in Discord.
//Pattern build with knowledge of the Proxmark source (@iceman1001, @horror)

import std.io;

//Used for infoblocks, 5 blocks (5*4=20): Partnumber, Date, Serial, Type
//block 0x15 (21), 0x15 * 4
u8 infoPart1 @ 0x54; //Partnumber
u8 infoPart2 @ 0x55; //Partnumber
u8 infoPart3 @ 0x56; //Partnumber
u8 infoPart4 @ 0x57; //Partnumber
//block 0x16 (22), 0x16 * 4
u8 infoPart5 @ 0x58; //Partnumber
u8 infoPart6 @ 0x59; //Partnumber
u8 infoPart7 @ 0x5A; //-
u8 infoPart8 @ 0x5B; //-
//block 0x17 (23), 0x17 * 4
u8 infoPart9 @ 0x5C; //Date
u8 infoPart10 @ 0x5D; //Date
u8 infoPart11 @ 0x5E; //Date
u8 infoPart12 @ 0x5F; //-
//block 0x18 (24), 0x18 * 4
u8 infoPart13 @ 0x60; //Serial
u8 infoPart14 @ 0x61; //Serial
u8 infoPart15 @ 0x62; //Serial
u8 infoPart16 @ 0x63; //-
//block 0x22 (34), 0x22 * 4
u8 infoPart17 @ 0x88; //-
u8 infoPart18 @ 0x89; //-
u8 infoPart19 @ 0x8A; //Type
u8 infoPart20 @ 0x8B; //-


//Used for decrypting (RC2_cbc)
u8 decryptKeyPart1 @ 0x08; //8
u8 decryptKeyPart2 @ 0x05; //5
u8 decryptKeyPart3 @ 0x06; //6
u8 decryptKeyPart4 @ 0x07; //7
u8 decryptKeyPart5 @ 0x60; //0x18 * 4 + 0
u8 decryptKeyPart6 @ 0x61; //0x18 * 4 + 1
u8 decryptKeyPart7 @ 0x88; //0x22 * 4 + 0


//Used for secret blocks, 16 blocks (16*4=64)
//Todo research these items of Meaning
//block 0x1c (28), 0x1c * 4
u8 varPart1  @ 0x70; // Block 28
u8 varPart2  @ 0x71;
u8 varPart3  @ 0x72;
u8 varPart4  @ 0x73;

//block 0x1e (29), 0x1e * 4
u8 varPart5  @ 0x78; // Block 29
u8 varPart6  @ 0x79;
u8 varPart7  @ 0x7A;
u8 varPart8  @ 0x7B;

//block 0x20 (30), 0x20 * 4
u8 varPart9  @ 0x80; // Block 30
u8 varPart10 @ 0x81;
u8 varPart11 @ 0x82;
u8 varPart12 @ 0x83;

//block 0x26 (31), 0x26 * 4
u8 varPart13 @ 0x98; // Block 31
u8 varPart14 @ 0x99;
u8 varPart15 @ 0x9A;
u8 varPart16 @ 0x9B;

//block 0x28 (32), 0x28 * 4
u8 varPart17 @ 0xA0; // Block 32
u8 varPart18 @ 0xA1;
u8 varPart19 @ 0xA2;
u8 varPart20 @ 0xA3;

//block 0x2a (33), 0x2a * 4
u8 varPart21 @ 0xA8; // Block 33
u8 varPart22 @ 0xA9;
u8 varPart23 @ 0xAA;
u8 varPart24 @ 0xAB;

//block 0x2c (38), 0x2c * 4
u8 varPart25 @ 0xB0; // Block 38
u8 varPart26 @ 0xB1;
u8 varPart27 @ 0xB2;
u8 varPart28 @ 0xB3;

//block 0x2e (39), 0x2e * 4
u8 varPart29 @ 0xB8; // Block 39
u8 varPart30 @ 0xB9;
u8 varPart31 @ 0xBA;
u8 varPart32 @ 0xBB;

//block 0x30 (40), 0x30 * 4
u8 varPart33 @ 0xC0; // Block 40
u8 varPart34 @ 0xC1;
u8 varPart35 @ 0xC2;
u8 varPart36 @ 0xC3;

//block 0x32 (41), 0x32 * 4
u8 varPart37 @ 0xC8; // Block 41
u8 varPart38 @ 0xC9;
u8 varPart39 @ 0xCA;
u8 varPart40 @ 0xCB;

//block 0x34 (42), 0x34 * 4
u8 varPart41 @ 0xD0; // Block 42
u8 varPart42 @ 0xD1;
u8 varPart43 @ 0xD2;
u8 varPart44 @ 0xD3;

//block 0x36 (43), 0x36 * 4
u8 varPart45 @ 0xD8; // Block 43
u8 varPart46 @ 0xD9;
u8 varPart47 @ 0xDA;
u8 varPart48 @ 0xDB;

//block 0x38 (44), 0x38 * 4
u8 varPart49 @ 0xE0; // Block 44
u8 varPart50 @ 0xE1;
u8 varPart51 @ 0xE2;
u8 varPart52 @ 0xE3;

//block 0x3A (45), 0x3A * 4
u8 varPart53 @ 0xE8; // Block 45
u8 varPart54 @ 0xE9;
u8 varPart55 @ 0xEA;
u8 varPart56 @ 0xEB;

//block 0x3C (46), 0x3C * 4
u8 varPart57 @ 0xF0; // Block 46
u8 varPart58 @ 0xF1;
u8 varPart59 @ 0xF2;
u8 varPart60 @ 0xF3;

//block 0x3E (47), 0x3E * 4
u8 varPart61 @ 0xF8; // Block 47
u8 varPart62 @ 0xF9;
u8 varPart63 @ 0xFA;
u8 varPart64 @ 0xFB;


fn dec_digit(u8 dig) {
    if(dig <= 9) {
        return char(dig + '0');
    } 
    return char('?');
};

fn format_part_number(ref auto v) {
    //Example of partnumber 006R01734(-01)
    str result;
    
    result += dec_digit(v[0] >> 4); //0
    result += dec_digit(v[0] & 0xF); //0
    result += dec_digit(v[1] >> 4); //6  
    
    char sym = ((v[1] & 0xF) << 4) | (v[2] >> 4);
    result += char((sym >= 'A' && sym <= 'Z') ? sym : '?'); //R
    
    result += dec_digit(v[2] & 0xF); //0
    result += dec_digit(v[3] >> 4); //1
    result += dec_digit(v[3] & 0xF); //6
    result += dec_digit(v[4] >> 4); //
    result += dec_digit(v[4] & 0xF); //

    result += "-"; //-
    result += dec_digit(v[5] >> 4); //0
    result += dec_digit(v[5] & 0xF); //1
    result += "0"; //o
    
    return result;
};

fn construct_decrypt_key(u8 p1, u8 p2, u8 p3, u8 p4, u8 p5, u8 p6) {
    str result;
    
    result += char(p1);
    result += char(p2);
    result += char(p3);
    result += char(p4);
    result += char(p5);
    result += char(p6);
    
    std::print("{}", "Decrypt key: "+result);
    
    return result;
};

//Find the partnumber of the consumable
char partNumber[0x06] @ 0x54[[format("format_part_number")]];
//Construct the decruption key, to decrypt the var/secret blocks
construct_decrypt_key(decryptKeyPart1, decryptKeyPart2, decryptKeyPart3, decryptKeyPart4, decryptKeyPart5, decryptKeyPart6);

struct Date {
    u8 day, month, year; //0x03
} [[format("format_date")]];

fn format_date(ref auto d) {
    return std::format("{:2}/{:2}/{:2}", d.day, d.month, d.year+2000);
};
//Find the date of the consumable
Date date @ 0x5C; //Look at 3 items (day, month, year from the start position)

fn format_serial_number(ref auto d) {
    return (d[2] << 16) | (d[1] << 8) | d[0];
};
//Find the serial number of the tonerchip
char serialNumber[0x03] @ 0x60[[format("format_serial_number")]];

fn format_consumable_type(u8 d) { 
    str consumable_types[5] = {"drum", "yellow", "magenta", "cyan", "black"};
    
    return (d <= 4) ? consumable_types[d] : "Unknown";
};
//find the type of consumable
u8 consumableType @ 0x8A[[format("format_consumable_type")]];