Combine Interface: (|E|R)Flags; libcpu: assembly load/store functions

1 files changed, 102 insertions, 0 deletions

diff --git a/src/shared/flags.rs b/src/shared/flags.rs
new file mode 100644
index 0000000..55dad6d
--- /dev/null
+++ b/src/shared/flags.rs
@@ -0,0 +1,102 @@
+//! 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) }
+}