1 files changed, 125 insertions, 0 deletions
diff --git a/library/stdarch/crates/core_arch/src/arm/ex.rs b/library/stdarch/crates/core_arch/src/arm/ex.rs
new file mode 100644
index 000000000..75f378642
--- /dev/null
+++ b/library/stdarch/crates/core_arch/src/arm/ex.rs
@@ -0,0 +1,125 @@
+// Reference: Section 5.4.4 "LDREX / STREX" of ACLE
+
+/// Removes the exclusive lock created by LDREX
+// Supported: v6, v6K, v7-M, v7-A, v7-R
+// Not supported: v5, v6-M
+// NOTE: there's no dedicated CLREX instruction in v6 (<v6k); to clear the exclusive monitor users
+// have to do a dummy STREX operation
+#[cfg(any(
+    all(target_feature = "v6k", not(target_feature = "mclass")), // excludes v6-M
+    all(target_feature = "v7", target_feature = "mclass"), // v7-M
+    doc
+))]
+pub unsafe fn __clrex() {
+    extern "unadjusted" {
+        #[link_name = "llvm.arm.clrex"]
+        fn clrex();
+    }
+
+    clrex()
+}
+
+/// Executes an exclusive LDR instruction for 8 bit value.
+// Supported: v6K, v7-M, v7-A, v7-R
+// Not supported: v5, v6, v6-M
+#[cfg(any(
+    target_feature = "v6k", // includes v7-M but excludes v6-M
+    doc
+))]
+pub unsafe fn __ldrexb(p: *const u8) -> u8 {
+    extern "unadjusted" {
+        #[link_name = "llvm.arm.ldrex.p0i8"]
+        fn ldrex8(p: *const u8) -> u32;
+    }
+
+    ldrex8(p) as u8
+}
+
+/// Executes an exclusive LDR instruction for 16 bit value.
+// Supported: v6K, v7-M, v7-A, v7-R, v8
+// Not supported: v5, v6, v6-M
+#[cfg(any(
+    target_feature = "v6k", // includes v7-M but excludes v6-M
+    doc
+))]
+pub unsafe fn __ldrexh(p: *const u16) -> u16 {
+    extern "unadjusted" {
+        #[link_name = "llvm.arm.ldrex.p0i16"]
+        fn ldrex16(p: *const u16) -> u32;
+    }
+
+    ldrex16(p) as u16
+}
+
+/// Executes an exclusive LDR instruction for 32 bit value.
+// Supported: v6, v7-M, v6K, v7-A, v7-R, v8
+// Not supported: v5, v6-M
+#[cfg(any(
+    all(target_feature = "v6", not(target_feature = "mclass")), // excludes v6-M
+    all(target_feature = "v7", target_feature = "mclass"), // v7-M
+    doc
+))]
+pub unsafe fn __ldrex(p: *const u32) -> u32 {
+    extern "unadjusted" {
+        #[link_name = "llvm.arm.ldrex.p0i32"]
+        fn ldrex32(p: *const u32) -> u32;
+    }
+
+    ldrex32(p)
+}
+
+/// Executes an exclusive STR instruction for 8 bit values
+///
+/// Returns `0` if the operation succeeded, or `1` if it failed
+// supported: v6K, v7-M, v7-A, v7-R
+// Not supported: v5, v6, v6-M
+#[cfg(any(
+    target_feature = "v6k", // includes v7-M but excludes v6-M
+    doc
+))]
+pub unsafe fn __strexb(value: u32, addr: *mut u8) -> u32 {
+    extern "unadjusted" {
+        #[link_name = "llvm.arm.strex.p0i8"]
+        fn strex8(value: u32, addr: *mut u8) -> u32;
+    }
+
+    strex8(value, addr)
+}
+
+/// Executes an exclusive STR instruction for 16 bit values
+///
+/// Returns `0` if the operation succeeded, or `1` if it failed
+// Supported: v6K, v7-M, v7-A, v7-R, v8
+// Not supported: v5, v6, v6-M
+#[cfg(target_feature = "aarch64")]
+#[cfg(any(
+    target_feature = "v6k", // includes v7-M but excludes v6-M
+    doc
+))]
+pub unsafe fn __strexh(value: u16, addr: *mut u16) -> u32 {
+    extern "unadjusted" {
+        #[link_name = "llvm.arm.strex.p0i16"]
+        fn strex16(value: u32, addr: *mut u16) -> u32;
+    }
+
+    strex16(value as u32, addr)
+}
+
+/// Executes an exclusive STR instruction for 32 bit values
+///
+/// Returns `0` if the operation succeeded, or `1` if it failed
+// Supported: v6, v7-M, v6K, v7-A, v7-R, v8
+// Not supported: v5, v6-M
+#[cfg(any(
+    all(target_feature = "v6", not(target_feature = "mclass")), // excludes v6-M
+    all(target_feature = "v7", target_feature = "mclass"), // v7-M
+    doc
+))]
+pub unsafe fn __strex(value: u32, addr: *mut u32) -> u32 {
+    extern "unadjusted" {
+        #[link_name = "llvm.arm.strex.p0i32"]
+        fn strex32(value: u32, addr: *mut u32) -> u32;
+    }
+
+    strex32(value, addr)
+}