Rearrange AHCI code, attempt to read WIP

src/kernel/ahci/port.h

@@ -0,0 +1,68 @@
+#pragma once
+/// \file port.h
+/// Definition for AHCI ports
+#include <stddef.h>
+#include <stdint.h>
+
+namespace ahci {
+
+struct cmd_list_entry;
+struct cmd_table;
+enum class port_cmd : uint32_t;
+struct port_data;
+
+
+/// A port on an AHCI HBA
+class port
+{
+public:
+	/// Constructor.
+	/// \arg data  Pointer to the device's registers for this port
+	/// \arg impl  Whether this port is marked as implemented in the HBA
+	port(port_data *data, bool impl);
+
+	/// Destructor
+	~port();
+
+	enum class state { unimpl, inactive, active };
+
+	/// Get the current state of this device
+	/// \returns  An enum representing the state
+	state get_state() const { return m_state; }
+
+	/// Update the state of this object from the register data
+	void update();
+
+	/// Return whether the port is currently busy
+	bool busy();
+
+	/// Start command processing from this port
+	void start_commands();
+
+	/// Stop command processing from this port
+	void stop_commands();
+
+	/// Read data from the drive.
+	/// \arg sector  Starting sector to read
+	/// \arg length  Number of bytes to read
+	/// \returns     True if the command succeeded
+	bool read(uint64_t sector, size_t length); 
+
+private:
+	/// Rebase the port command structures to a new location in system
+	/// memory, to be allocated from the page manager.
+	void rebase();
+
+	/// Get a free command slot
+	/// \returns  The index of the command slot, or -1 if none available
+	int get_cmd_slot();
+
+	state m_state;
+	port_data *m_data;
+
+	void *m_fis;
+	cmd_list_entry *m_cmd_list;
+	cmd_table *m_cmd_table;
+};
+
+} // namespace ahci