1 files changed, 81 insertions, 0 deletions
diff --git a/vendor/portable-atomic/src/imp/interrupt/riscv.rs b/vendor/portable-atomic/src/imp/interrupt/riscv.rs
new file mode 100644
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+++ b/vendor/portable-atomic/src/imp/interrupt/riscv.rs
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+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+// Refs:
+// - https://five-embeddev.com/riscv-isa-manual/latest/machine.html#machine-status-registers-mstatus-and-mstatush
+// - https://five-embeddev.com/riscv-isa-manual/latest/supervisor.html#sstatus
+//
+// Generated asm:
+// - riscv64gc https://godbolt.org/z/osbzsT679
+
+#[cfg(not(portable_atomic_no_asm))]
+use core::arch::asm;
+
+pub(super) use super::super::riscv as atomic;
+
+// Status register
+#[cfg(not(portable_atomic_s_mode))]
+macro_rules! status {
+    () => {
+        "mstatus"
+    };
+}
+#[cfg(portable_atomic_s_mode)]
+macro_rules! status {
+    () => {
+        "sstatus"
+    };
+}
+
+// MIE (Machine Interrupt Enable) bit (1 << 3)
+#[cfg(not(portable_atomic_s_mode))]
+const MASK: State = 0x8;
+#[cfg(not(portable_atomic_s_mode))]
+macro_rules! mask {
+    () => {
+        "0x8"
+    };
+}
+// SIE (Supervisor Interrupt Enable) bit (1 << 1)
+#[cfg(portable_atomic_s_mode)]
+const MASK: State = 0x2;
+#[cfg(portable_atomic_s_mode)]
+macro_rules! mask {
+    () => {
+        "0x2"
+    };
+}
+
+#[cfg(target_arch = "riscv32")]
+pub(super) type State = u32;
+#[cfg(target_arch = "riscv64")]
+pub(super) type State = u64;
+
+/// Disables interrupts and returns the previous interrupt state.
+#[inline]
+pub(super) fn disable() -> State {
+    let r: State;
+    // SAFETY: reading mstatus and disabling interrupts is safe.
+    // (see module-level comments of interrupt/mod.rs on the safety of using privileged instructions)
+    unsafe {
+        // Do not use `nomem` and `readonly` because prevent subsequent memory accesses from being reordered before interrupts are disabled.
+        asm!(concat!("csrrci {0}, ", status!(), ", ", mask!()), out(reg) r, options(nostack, preserves_flags));
+    }
+    r
+}
+
+/// Restores the previous interrupt state.
+///
+/// # Safety
+///
+/// The state must be the one retrieved by the previous `disable`.
+#[inline]
+pub(super) unsafe fn restore(r: State) {
+    if r & MASK != 0 {
+        // SAFETY: the caller must guarantee that the state was retrieved by the previous `disable`,
+        // and we've checked that interrupts were enabled before disabling interrupts.
+        unsafe {
+            // Do not use `nomem` and `readonly` because prevent preceding memory accesses from being reordered after interrupts are enabled.
+            asm!(concat!("csrsi ", status!(), ", ", mask!()), options(nostack, preserves_flags));
+        }
+    }
+}