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////////////////////////////////////////////////////////////////////////////////
//
// Check if this is a sector we can compress
//
// Sector types:
//   0: Literal bytes (not a sector)
//   1: 2352 mode 1         predict sync, mode, reserved, edc, ecc
//   2: 2336 mode 2 form 1  predict redundant flags, edc, ecc
//   3: 2336 mode 2 form 2  predict redundant flags, edc
//
static int8_t detect_sector(const uint8_t* sector, size_t size_available) {
    if (
        size_available >= 2352 &&
        sector[0x000] == 0x00 && // sync (12 bytes)
        sector[0x001] == 0xFF &&
        sector[0x002] == 0xFF &&
        sector[0x003] == 0xFF &&
        sector[0x004] == 0xFF &&
        sector[0x005] == 0xFF &&
        sector[0x006] == 0xFF &&
        sector[0x007] == 0xFF &&
        sector[0x008] == 0xFF &&
        sector[0x009] == 0xFF &&
        sector[0x00A] == 0xFF &&
        sector[0x00B] == 0x00 &&
        sector[0x00F] == 0x01 && // mode (1 byte)
        sector[0x814] == 0x00 && // reserved (8 bytes)
        sector[0x815] == 0x00 &&
        sector[0x816] == 0x00 &&
        sector[0x817] == 0x00 &&
        sector[0x818] == 0x00 &&
        sector[0x819] == 0x00 &&
        sector[0x81A] == 0x00 &&
        sector[0x81B] == 0x00
        ) {
        //
        // Might be Mode 1
        //
        if (
            ecc_checksector(
            sector + 0xC,
            sector + 0x10,
            sector + 0x81C
            ) &&
            edc_compute(0, sector, 0x810) == get32lsb(sector + 0x810)
            ) {
            return 1; // Mode 1
        }

    }
    else if (
        size_available >= 2336 &&
        sector[0x10] == sector[0x14] && // flags (4 bytes)
        sector[0x11] == sector[0x15] && //   versus redundant copy
        sector[0x12] == sector[0x16] &&
        sector[0x13] == sector[0x17]
        ) {
        //
        // Might be Mode 2, Form 1 or 2
        //
        if (
            ecc_checksector(
            zeroaddress,
            sector + 0x10,
            sector + 0x10 + 0x80C
            ) &&
            edc_compute(0, sector + 0x10, 0x808) == get32lsb(sector + 0x10 + 0x808)
            ) {
            return 2; // Mode 2, Form 1
        }
        //
        // Might be Mode 2, Form 2
        //
        if (
            edc_compute(0, sector + 0x10, 0x91C) == get32lsb(sector + 0x10 + 0x91C)
            ) {
            return 3; // Mode 2, Form 2
        }
        else {
            return 4; // Mode 2, No EDC (for PlayStation)
        }
    }

    //
    // Nothing
    //
    return 0;
}