//! Register information and driver to program xAPIC, X2APIC and I/O APIC

pub mod ioapic;
pub mod x2apic;
pub mod xapic;

/// Specify IPI Delivery Mode
#[derive(Debug, Eq, PartialEq)]
#[repr(u64)]
pub enum DeliveryMode {
    /// Delivers the interrupt specified in the vector field to the target processor or processors.
    Fixed = 0b000,
    /// Same as fixed mode, except that the interrupt is delivered to the processor executing at the
    /// lowest priority among the set of processors specified in the destination field. The ability
    /// for a processor to send a lowest priority IPI is model specific and should be avoided by
    /// BIOS and operating system software.
    LowestPriority = 0b001,
    /// Delivers an SMI interrupt to the target processor or processors.
    /// The vector field must be programmed to 00H for future compatibility.
    SMI = 0b010,
    /// Reserved
    _Reserved = 0b11,
    /// Delivers an NMI interrupt to the target processor or processors.
    /// The vector information is ignored.
    NMI = 0b100,
    /// Delivers an INIT request to the target processor or processors, which causes them to perform an INIT.
    Init = 0b101,
    /// Sends a special start-up IPI (called a SIPI) to the target processor or processors.
    /// The vector typically points to a start-up routine that is part of the
    /// BIOS boot-strap code (see Section 8.4, Multiple-Processor (MP) Initialization). I
    /// PIs sent with this delivery mode are not automatically retried if the source
    /// APIC is unable to deliver it. It is up to the software to deter- mine if the
    /// SIPI was not successfully delivered and to reissue the SIPI if necessary.
    StartUp = 0b110,
}

/// Sepcify IPI Destination Mode.
#[derive(Debug, Eq, PartialEq)]
#[repr(u64)]
pub enum DestinationMode {
    Physical = 0,
    Logical = 1,
}

/// Specify Delivery Status
#[derive(Debug, Eq, PartialEq)]
#[repr(u64)]
pub enum DeliveryStatus {
    Idle = 0,
    SendPending = 1,
}

/// IPI Level
#[derive(Debug, Eq, PartialEq)]
#[repr(u64)]
pub enum Level {
    Deassert = 0,
    Assert = 1,
}

/// IPI Trigger Mode
#[derive(Debug, Eq, PartialEq)]
#[repr(u64)]
pub enum TriggerMode {
    Edge = 0,
    Level = 1,
}

/// IPI Destination Shorthand
#[derive(Debug, Eq, PartialEq)]
#[repr(u64)]
pub enum DestinationShorthand {
    NoShorthand = 0b00,
    Myself = 0b01,
    AllIncludingSelf = 0b10,
    AllExcludingSelf = 0b11,
}

/// Abstract the IPI control register
#[derive(Debug, Eq, PartialEq)]
pub struct Icr(u64);

impl Icr {
    /// Short-hand to create a Icr value.
    #[allow(clippy::too_many_arguments)]
    pub fn new(
        vector: u8,
        destination: ApicId,
        destination_shorthand: DestinationShorthand,
        delivery_mode: DeliveryMode,
        destination_mode: DestinationMode,
        delivery_status: DeliveryStatus,
        level: Level,
        trigger_mode: TriggerMode,
    ) -> Icr {
        let destination: u8 = match destination {
            ApicId::XApic(d) => d,
            ApicId::X2Apic(_d) => {
                unreachable!("x2APIC destinations currently unsupported, adjust Icr construction!")
            }
        };

        Icr((destination as u64) << 56
            | (destination_shorthand as u64) << 18
            | (trigger_mode as u64) << 15
            | (level as u64) << 14
            | (delivery_status as u64) << 12
            | (destination_mode as u64) << 11
            | (delivery_mode as u64) << 8
            | (vector as u64))
    }

    /// Get lower 32-bits of the Icr register.
    pub fn lower(&self) -> u32 {
        self.0 as u32
    }

    /// Get upper 32-bits of the Icr register.
    pub fn upper(&self) -> u32 {
        (self.0 >> 32) as u32
    }
}

/// Encodes the id of a core.
#[derive(Debug, Eq, PartialEq, Copy, Clone)]
pub enum ApicId {
    /// A core destination encoded as an xAPIC ID.
    XApic(u8),
    /// A core destination encoded as an x2APIC ID.
    X2Apic(u32),
}

/// Abstracts common interface of local APIC (x2APIC, xAPIC) hardware devices.
pub trait ApicControl {
    /// Is a bootstrap processor?
    fn bsp(&self) -> bool;

    /// Return APIC ID.
    fn id(&self) -> u32;

    /// Read APIC version
    fn version(&self) -> u32;

    /// End Of Interrupt -- Acknowledge interrupt delivery.
    fn eoi(&mut self);

    /// Enable TSC deadline timer.
    fn tsc_enable(&mut self);

    /// Set TSC deadline value.
    fn tsc_set(&self, value: u64);

    /// Send a INIT IPI to a core.
    unsafe fn ipi_init(&mut self, core: ApicId);

    /// Deassert INIT IPI.
    unsafe fn ipi_init_deassert(&mut self);

    /// Send a STARTUP IPI to a core.
    unsafe fn ipi_startup(&mut self, core: ApicId, start_page: u8);

    /// Send a generic IPI.
    unsafe fn send_ipi(&mut self, icr: Icr);
}