diff --git a/src/drivers/atapi/mod.rs b/src/drivers/atapi/mod.rs
index 849e611..17f6b91 100644
--- a/src/drivers/atapi/mod.rs
+++ b/src/drivers/atapi/mod.rs
@@ -3,3 +3,50 @@ const CD_SECTOR_SIZE: usize = 2048;
 
 const ATA_BUS_PRIMARY: u16= 0x1f0;
 const ATA_BUS_SECONDARY: u16 = 0x170;
+
+const ATA_DRIVE_MASTER: u16 = 0xa0;
+const ATA_DRIVE_SLAVE: u16 = 0xb0;
+
+macro_rules! ATA_DATA {
+    ($reg:expr) => (reg);
+}
+
+macro_rules! ATA_ERROR {
+    ($reg:expr) => (reg + 1); // read
+}
+
+macro_rules! ATA_FEATURES {
+    ($reg:expr) => (reg + 1); // write
+}
+
+macro_rules! ATA_SECTOR_COUNT {
+    ($reg:expr) => (reg + 2);
+}
+
+macro_rules! ATA_ADDRESS1 {
+    ($reg:expr) => (reg + 3);
+}
+
+macro_rules! ATA_ADDRESS2 {
+    ($reg:expr) => (reg + 4);
+}
+
+macro_rules! ATA_ADDRESS3 {
+    ($reg:expr) => (reg + 5);
+}
+
+macro_rules! ATA_DRIVE_SELECT {
+    ($reg:expr) => (reg + 6);
+}
+
+macro_rules! ATA_STATUS {
+    ($reg:expr) => (reg + 7); // read
+}
+
+macro_rules! ATA_COMMAND {
+    ($reg:expr) => (reg + 7); // write
+}
+
+macro_rules! ATA_DCR {
+    ($reg:expr) => (reg + 0x206);
+}
\ No newline at end of file
diff --git a/src/drivers/mod.rs b/src/drivers/mod.rs
index fffbe08..238be6f 100644
--- a/src/drivers/mod.rs
+++ b/src/drivers/mod.rs
@@ -1,2 +1,3 @@
 pub mod serial;
 pub mod vga;
+pub mod atapi;