enum USB_bDescriptorType {
    DESCRIPTOR_DEVICE = 0x1,
    DESCRIPTOR_CONFIGURATION = 0x2,
    DESCRIPTOR_CONFIGURATION = 0x4,
    DESCRIPTOR_ENDPOINT = 0x5
};

enum USB_Type_BCD {
    USB20 = 0x0200,
    USB11 = 0x0110,
    USB10 = 0x0100
};



enum USB_PID {
    // Token Packets
    OUT_TOKEN   = 0b0001,
    IN_TOKEN    = 0b1001,
    SOF_TOKEN   = 0b0101,
    SETUP_TOKEN = 0b1101,

    // Data Packets
    DATA0_DATA  = 0b0011,
    DATA1_DATA  = 0b1011,
    DATA2_DATA  = 0b0111,
    MDATA_DATA  = 0b1111,

    // Handshake Packets
    ACK_HANDSHAKE   = 0b0010,
    NAK_HANDSHAKE   = 0b1010,
    STALL_HANDSHAKE = 0b1110,
    NYET_HANDSHAKE  = 0b0110,

    // Special & Other Packets
    PRE_SPECIAL   = 0b1100, // PREamble shares value with ERR
    ERR_SPECIAL   = 0b1100, 
    SPLIT_SPECIAL = 0b1000,
    PING_SPECIAL  = 0b0100
};


enum Configuration_bmAttributes{
    USB_BUS_POWERED = (1 << 7),
    SELF_POWERED = (1 << 6),
    REMOTE_WAKEUP = (1 << 5),
};


enum Endpoint_bmAttributes {
    // Bits 1..0: Transfer Type
    TRANSFER_TYPE_MASK        = 0b00000011,
    TRANSFER_CONTROL          = 0b00000000,
    TRANSFER_ISOCHRONOUS      = 0b00000001,
    TRANSFER_BULK             = 0b00000010,
    TRANSFER_INTERRUPT        = 0b00000011,

    // Bits 3..2: Synchronization Type (Isochronous Mode only)
    SYNC_TYPE_MASK            = 0b00001100,
    SYNC_NOSYNC               = (0b00 << 2), // No Synchronization
    SYNC_ASYNC                = (0b01 << 2), // Asynchronous
    SYNC_ADAPTIVE             = (0b10 << 2), // Adaptive
    SYNC_SYNCHRONOUS          = (0b11 << 2), // Synchronous

    // Bits 5..4: Usage Type (Isochronous Mode only)
    USAGE_TYPE_MASK           = 0b00110000,
    USAGE_DATA                = (0b00 << 4), // Data Endpoint
    USAGE_FEEDBACK            = (0b01 << 4), // Feedback Endpoint
    USAGE_EXPLICIT_FEEDBACK   = (0b10 << 4), // Explicit Feedback Data Endpoint
    USAGE_RESERVED            = (0b11 << 4)  // Reserved
};

enum Setup_bmRequestType {
    // Bit 7: Data Phase Transfer Direction
    DIR_MASK         = (1 << 7),
    HOST_TO_DEVICE   = (0 << 7),
    DEVICE_TO_HOST   = (1 << 7),

    // Bits 6..5: Type
    TYPE_MASK        = (0b11 << 5),
    TYPE_STANDARD    = (0b00 << 5),
    TYPE_CLASS       = (0b01 << 5),
    TYPE_VENDOR      = (0b10 << 5),
    TYPE_RESERVED    = (0b11 << 5),

    // Bits 4..0: Recipient
    RECIPIENT_MASK   = 0b11111,
    RECIPIENT_DEVICE    = 0,
    RECIPIENT_INTERFACE = 1,
    RECIPIENT_ENDPOINT  = 2,
    RECIPIENT_OTHER      = 3
};


enum Standard__Device_Requests {
    GET_STATUS = 0x00,
    /**
     * GET_STATUS will reuturn a 16bit word. 
     * D0 is "Self Powered" bit, if D0 == 0, then the device is powered by the bus
     * D1 is the "Remote Wakeup" bit, if D1 == 1, then the host can wake up this device from suspend
     */

    CLEAR_FEATURE = 0x01,
    SET_FEATURE = 0x03,
    SET_ADDRESS = 0x05,
    GET_DESCRIPTOR = 0x06,
    SET_DESCRIPTOR = 0x07,
    GET_CONFIGURATION = 0x08,
    SET_CONFIGURATION = 0x09
};

enum Standard_Interface_Requests {
    GET_STATUS = 0x00,
    CLEAR_FEATURE = 0x01,
    SET_FEATURE = 0x03,
    GET_INTERFACE = 0x0A,
    SET_INTERFACE = 0x11,
};

enum Standard_Endpoint_Requests {
    GET_STATUS = 0x00,
    CLEAR_FEATURE = 0x01,
    SET_FEATURE = 0x03,
    /**
     * Clear Feature and Set Feature are used to set Endpoint Features. 
     * The standard currently defines one endpoint feature selector, 
     * ENDPOINT_HALT (0x00) which allows the host to stall and clear an endpoint.
     */
    SYNCH_FRAME  = 0x12,
};