//! Processor state stored in the RFLAGS register.

//!

//! In 64-bit mode, EFLAGS is extended to 64 bits and called RFLAGS.

//! The upper 32 bits of RFLAGS register is reserved.

//! The lower 32 bits of RFLAGS is the same as EFLAGS.

use bitflags::*;

use crate::Ring;

#[cfg(target_arch = "x86_64")]

use core::arch::asm;

bitflags! {

    /// The RFLAGS register.

    /// This is duplicated code from bits32 eflags.rs.

    pub struct RFlags: u64 {

        /// ID Flag (ID)

        const FLAGS_ID = 1 << 21;

        /// Virtual Interrupt Pending (VIP)

        const FLAGS_VIP = 1 << 20;

        /// Virtual Interrupt Flag (VIF)

        const FLAGS_VIF = 1 << 19;

        /// Alignment Check (AC)

        const FLAGS_AC = 1 << 18;

        /// Virtual-8086 Mode (VM)

        const FLAGS_VM = 1 << 17;

        /// Resume Flag (RF)

        const FLAGS_RF = 1 << 16;

        /// Nested Task (NT)

        const FLAGS_NT = 1 << 14;

        /// I/O Privilege Level (IOPL) 0

        const FLAGS_IOPL0 = 0b00 << 12;

        /// I/O Privilege Level (IOPL) 1

        const FLAGS_IOPL1 = 0b01 << 12;

        /// I/O Privilege Level (IOPL) 2

        const FLAGS_IOPL2 = 0b10 << 12;

        /// I/O Privilege Level (IOPL) 3

        const FLAGS_IOPL3 = 0b11 << 12;

        /// Overflow Flag (OF)

        const FLAGS_OF = 1 << 11;

        /// Direction Flag (DF)

        const FLAGS_DF = 1 << 10;

        /// Interrupt Enable Flag (IF)

        const FLAGS_IF = 1 << 9;

        /// Trap Flag (TF)

        const FLAGS_TF = 1 << 8;

        /// Sign Flag (SF)

        const FLAGS_SF = 1 << 7;

        /// Zero Flag (ZF)

        const FLAGS_ZF = 1 << 6;

        /// Auxiliary Carry Flag (AF)

        const FLAGS_AF = 1 << 4;

        /// Parity Flag (PF)

        const FLAGS_PF = 1 << 2;

        /// Bit 1 is always 1.

        const FLAGS_A1 = 1 << 1;

        /// Carry Flag (CF)

        const FLAGS_CF = 1 << 0;

    }

}

impl RFlags {

    /// Creates a new Flags entry. Ensures bit 1 is set.

    pub const fn new() -> RFlags {

        RFlags::FLAGS_A1

    }

    /// Creates a new Flags with the given I/O privilege level.

    pub const fn from_priv(iopl: Ring) -> RFlags {

        RFlags {

            bits: (iopl as u64) << 12,

        }

    }

    pub const fn from_raw(bits: u64) -> RFlags {

        RFlags { bits }

    }

}

#[cfg(target_arch = "x86_64")]

#[inline(always)]

pub fn read() -> RFlags {

    let r: u64;

    unsafe { asm!("pushfq; popq {0}", out(reg) r, options(att_syntax)) };

    RFlags::from_bits_truncate(r)

}

#[cfg(target_arch = "x86_64")]

#[inline(always)]

pub fn set(val: RFlags) {

    unsafe {

        asm!("pushq {0}; popfq", in(reg) val.bits(), options(att_syntax));

    }

}

// clac and stac are also usable in 64-bit mode

pub use crate::bits32::eflags::{clac, stac};