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//! Processor state stored in the FLAGS, EFLAGS, or RFLAGS register.
use shared::PrivilegeLevel;
/// The RFLAGS register. All variants are backwards compatable so only one
/// bitflags struct needed.
bitflags! {
pub flags Flags: usize {
/// 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 = 0 << 12,
/// I/O Privilege Level (IOPL) 1
const FLAGS_IOPL1 = 1 << 12,
/// I/O Privilege Level (IOPL) 2
const FLAGS_IOPL2 = 2 << 12,
/// I/O Privilege Level (IOPL) 3
const FLAGS_IOPL3 = 3 << 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 Flags {
/// Creates a new Flags entry. Ensures bit 1 is set.
pub const fn new() -> Flags {
FLAGS_A1
}
/// Creates a new Flags with the given I/O privilege level.
pub const fn from_priv(iopl: PrivilegeLevel) -> Flags {
Flags { bits: (iopl as usize) << 12 }
}
}
pub fn flags() -> Flags {
#[cfg(target_arch="x86")]
#[inline(always)]
unsafe fn inner() -> Flags {
let r: usize;
asm!("pushfl; popl $0" : "=r"(r) :: "memory");
Flags::from_bits_truncate(r)
}
#[cfg(target_arch="x86_64")]
#[inline(always)]
unsafe fn inner() -> Flags {
let r: usize;
asm!("pushfq; popq $0" : "=r"(r) :: "memory");
Flags::from_bits_truncate(r)
}
unsafe { inner() }
}
pub fn set(val: Flags) {
#[cfg(target_arch="x86")]
#[inline(always)]
unsafe fn inner(val: Flags) {
asm!("pushl $0; popfl" :: "r"(val.bits()) : "memory" "flags");
}
#[cfg(target_arch="x86_64")]
#[inline(always)]
unsafe fn inner(val: Flags) {
asm!("pushq $0; popfq" :: "r"(val.bits()) : "memory" "flags");
}
unsafe { inner(val) }
}