diff --git a/Cargo.toml b/Cargo.toml
index b881be2..3a97bf2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,6 +4,7 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+bitfield-struct = "0.10.1"
 md5 = "0.7.0"
 nix = { version = "0.29.0", features = ["ioctl"] }
 num-derive = "0.4.2"
diff --git a/src/packet_commands.rs b/src/packet_commands.rs
new file mode 100644
index 0000000..c903fde
--- /dev/null
+++ b/src/packet_commands.rs
@@ -0,0 +1,171 @@
+use std::{fmt::{write, Debug}, os::raw::c_void};
+
+#[repr(C)]
+#[derive(Clone, Copy, Debug)]
+pub struct GenericCommand {
+    pub cdb: [u8; CDROM_PACKET_SIZE],
+    pub buffer: *mut u8,
+    pub buflen: u32,
+    pub stat: i32,
+    pub sense: *mut RequestSense,
+    pub data_direction: DataDirection,
+    pub quiet: i32,
+    pub timeout: i32,
+    pub u: U
+}
+
+#[repr(C)]
+#[derive(Clone, Copy, Debug)]
+pub struct RequestSense {
+    pub valid_error: ValidError,
+    pub segment_number: u8,
+    pub reserved: Reserved,
+    pub information: [u8; 4],
+    pub addditional_sense_len: u8,
+    pub command_info: [u8; 4],
+    pub asc: u8,
+    pub ascq: u8,
+    pub fruc: u8,
+    pub sks: [u8; 3],
+    pub asb: [u8; 46]
+}
+
+#[cfg(target_endian = "big")]
+#[bitfield_struct::bitfield(u8)]
+pub struct ValidError {
+    #[bits(1)]
+    pub valid: u8,
+    #[bits(7)]
+    pub error_code: u8,
+}
+
+#[cfg(target_endian = "little")]
+#[bitfield_struct::bitfield(u8)]
+pub struct ValidError {
+    #[bits(7)]
+    pub error_code: u8,
+    #[bits(1)]
+    pub valid: u8,
+}
+
+#[cfg(target_endian = "big")]
+#[bitfield_struct::bitfield(u8)]
+pub struct Reserved {
+    #[bits(2)]
+    pub reserved1: u8,
+    #[bits(1)]
+    pub ili: u8,
+    #[bits(1)]
+    pub reserved2: u8,
+    #[bits(4)]
+    pub sense_key: u8
+}
+
+#[cfg(target_endian = "little")]
+#[bitfield_struct::bitfield(u8)]
+pub struct Reserved {
+    #[bits(4)]
+    pub sense_key: u8,
+    #[bits(1)]
+    pub reserved2: u8,
+    #[bits(1)]
+    pub ili: u8,
+    #[bits(2)]
+    pub reserved1: u8,
+}
+
+#[repr(C)]
+#[derive(Clone, Copy)]
+pub union U {
+    pub reserved: *const [c_void; 1],
+    pub unused: *const c_void
+}
+
+impl Debug for U {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write(f, format_args!("type U here"))
+    }
+}
+
+pub const CDROM_PACKET_SIZE: usize = 12;
+/// The generic packet command opcodes for CD/DVD Logical Units,
+/// From Table 57 of the SFF8090 Ver. 3 (Mt. Fuji) draft standard.
+#[derive(FromPrimitive, ToPrimitive)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum GenericPacketCommand {
+    Blank = 0xa1,
+    CloseTrack = 0x5b,
+    FlushCache = 0x35,
+    FormatUnit = 0x04,
+    GetConfiguration = 0x46,
+    GetEventStatus = 0x4a,
+    GetPerformance = 0xac,
+    GetInquiry = 0x12,
+    LoadUnload = 0xa6,
+    MechanismStatus = 0xbd,
+    ModeSelect10 = 0x55,
+    ModeSense10 = 0x5a,
+    PauseResume = 0x4b,
+    PlayAudio10 = 0x45,
+    PlayAudioMsf = 0x47,
+
+    /// This seems to be a SCSI specific CD-ROM opcode
+    /// to play data at track/index
+    PlayAudioTi = 0x48,
+    PlayCd = 0xbc,
+    PreventAllowMediumRemoval = 0x1e,
+    Read10 = 0x28,
+    Read12 = 0xa8,
+    ReadBuffer = 0x3c,
+    ReadBufferCapacity = 0x5c,
+    ReadCdvdCapacity = 0x25,
+    ReadCd = 0xbe,
+    ReadCdMsf = 0xb9,
+    ReadDiscInfo = 0x51,
+    ReadDvdStructure = 0xad,
+    ReadFormatCapabilities = 0x23,
+    ReadHeader = 0x44,
+    ReadTrackRzoneInfo = 0x52,
+    ReadSubchannel = 0x42,
+    ReadTocPmaAtip = 0x43,
+    RepairRzoneTrack = 0x58,
+    ReportKey = 0xa4,
+    RequestSense = 0x03,
+    ReserveRzoneTrack = 0x53,
+    SendCueSheet = 0x5d,
+    Scan = 0xba,
+    Seek = 0x2b,
+    SendDvdStructure = 0xbf,
+    SendEvent = 0xa2,
+    SendKey = 0xa3,
+    SendOpc = 0x54,
+    SetReadAhead = 0xa7,
+    SetStreaming = 0xb6,
+    StartStopUnit = 0x1b,
+    StopPlayScan = 0x4e,
+    TestUnitReady = 0x00,
+    Verify10 = 0x2f,
+    Write10 = 0x2a,
+    Write12 = 0xaa,
+    WriteAndVerify10 = 0x2e,
+    WriteBuffer = 0x3b,
+
+    /// This is listed as optional in ATAPI 2.6, but is (curiously)
+    /// missing from Mt. Fuji, Table 57.  It _is_ mentioned in Mt. Fuji
+    /// Table 377 as an MMC command for SCSi devices though...  Most ATAPI
+    /// drives support it.
+    SetSpeed = 0xbb,
+
+    /// From MS Media Status Notification Support Specification. For
+    /// older drives only.
+    GetMediaStatus = 0xda,
+}
+
+#[repr(u8)]
+#[derive(Clone, Copy, Debug)]
+pub enum DataDirection {
+    Unknown,
+    Write,
+    Read,
+    None
+}
\ No newline at end of file