1 files changed, 135 insertions, 0 deletions
diff --git a/library/stdarch/crates/core_arch/src/x86/bt.rs b/library/stdarch/crates/core_arch/src/x86/bt.rs
new file mode 100644
index 000000000..338cb97a3
--- /dev/null
+++ b/library/stdarch/crates/core_arch/src/x86/bt.rs
@@ -0,0 +1,135 @@
+use crate::arch::asm;
+#[cfg(test)]
+use stdarch_test::assert_instr;
+
+// x32 wants to use a 32-bit address size, but asm! defaults to using the full
+// register name (e.g. rax). We have to explicitly override the placeholder to
+// use the 32-bit register name in that case.
+#[cfg(target_pointer_width = "32")]
+macro_rules! bt {
+    ($inst:expr) => {
+        concat!($inst, " {b:e}, ({p:e})")
+    };
+}
+#[cfg(target_pointer_width = "64")]
+macro_rules! bt {
+    ($inst:expr) => {
+        concat!($inst, " {b:e}, ({p})")
+    };
+}
+
+/// Returns the bit in position `b` of the memory addressed by `p`.
+#[inline]
+#[cfg_attr(test, assert_instr(bt))]
+#[stable(feature = "simd_x86_bittest", since = "1.55.0")]
+pub unsafe fn _bittest(p: *const i32, b: i32) -> u8 {
+    let r: u8;
+    asm!(
+        bt!("btl"),
+        "setc {r}",
+        p = in(reg) p,
+        b = in(reg) b,
+        r = out(reg_byte) r,
+        options(readonly, nostack, pure, att_syntax)
+    );
+    r
+}
+
+/// Returns the bit in position `b` of the memory addressed by `p`, then sets the bit to `1`.
+#[inline]
+#[cfg_attr(test, assert_instr(bts))]
+#[stable(feature = "simd_x86_bittest", since = "1.55.0")]
+pub unsafe fn _bittestandset(p: *mut i32, b: i32) -> u8 {
+    let r: u8;
+    asm!(
+        bt!("btsl"),
+        "setc {r}",
+        p = in(reg) p,
+        b = in(reg) b,
+        r = out(reg_byte) r,
+        options(nostack, att_syntax)
+    );
+    r
+}
+
+/// Returns the bit in position `b` of the memory addressed by `p`, then resets that bit to `0`.
+#[inline]
+#[cfg_attr(test, assert_instr(btr))]
+#[stable(feature = "simd_x86_bittest", since = "1.55.0")]
+pub unsafe fn _bittestandreset(p: *mut i32, b: i32) -> u8 {
+    let r: u8;
+    asm!(
+        bt!("btrl"),
+        "setc {r}",
+        p = in(reg) p,
+        b = in(reg) b,
+        r = out(reg_byte) r,
+        options(nostack, att_syntax)
+    );
+    r
+}
+
+/// Returns the bit in position `b` of the memory addressed by `p`, then inverts that bit.
+#[inline]
+#[cfg_attr(test, assert_instr(btc))]
+#[stable(feature = "simd_x86_bittest", since = "1.55.0")]
+pub unsafe fn _bittestandcomplement(p: *mut i32, b: i32) -> u8 {
+    let r: u8;
+    asm!(
+        bt!("btcl"),
+        "setc {r}",
+        p = in(reg) p,
+        b = in(reg) b,
+        r = out(reg_byte) r,
+        options(nostack, att_syntax)
+    );
+    r
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::core_arch::x86::*;
+
+    #[test]
+    fn test_bittest() {
+        unsafe {
+            let a = 0b0101_0000i32;
+            assert_eq!(_bittest(&a as _, 4), 1);
+            assert_eq!(_bittest(&a as _, 5), 0);
+        }
+    }
+
+    #[test]
+    fn test_bittestandset() {
+        unsafe {
+            let mut a = 0b0101_0000i32;
+            assert_eq!(_bittestandset(&mut a as _, 4), 1);
+            assert_eq!(_bittestandset(&mut a as _, 4), 1);
+            assert_eq!(_bittestandset(&mut a as _, 5), 0);
+            assert_eq!(_bittestandset(&mut a as _, 5), 1);
+        }
+    }
+
+    #[test]
+    fn test_bittestandreset() {
+        unsafe {
+            let mut a = 0b0101_0000i32;
+            assert_eq!(_bittestandreset(&mut a as _, 4), 1);
+            assert_eq!(_bittestandreset(&mut a as _, 4), 0);
+            assert_eq!(_bittestandreset(&mut a as _, 5), 0);
+            assert_eq!(_bittestandreset(&mut a as _, 5), 0);
+        }
+    }
+
+    #[test]
+    fn test_bittestandcomplement() {
+        unsafe {
+            let mut a = 0b0101_0000i32;
+            assert_eq!(_bittestandcomplement(&mut a as _, 4), 1);
+            assert_eq!(_bittestandcomplement(&mut a as _, 4), 0);
+            assert_eq!(_bittestandcomplement(&mut a as _, 4), 1);
+            assert_eq!(_bittestandcomplement(&mut a as _, 5), 0);
+            assert_eq!(_bittestandcomplement(&mut a as _, 5), 1);
+        }
+    }
+}