5 files changed, 114 insertions, 0 deletions
diff --git a/library/std/src/f128.rs b/library/std/src/f128.rs
new file mode 100644
index 00000000000..4710d7c50b4
--- /dev/null
+++ b/library/std/src/f128.rs
@@ -0,0 +1,11 @@
+//! Constants for the `f128` double-precision floating point type.
+//!
+//! *[See also the `f128` primitive type](primitive@f128).*
+//!
+//! Mathematically significant numbers are provided in the `consts` sub-module.
+
+#[cfg(test)]
+mod tests;
+
+#[unstable(feature = "f128", issue = "116909")]
+pub use core::f128::consts;
diff --git a/library/std/src/f128/tests.rs b/library/std/src/f128/tests.rs
new file mode 100644
index 00000000000..b64c7f856a1
--- /dev/null
+++ b/library/std/src/f128/tests.rs
@@ -0,0 +1,40 @@
+#![allow(dead_code)] // FIXME(f16_f128): remove once constants are used
+
+/// Smallest number
+const TINY_BITS: u128 = 0x1;
+/// Next smallest number
+const TINY_UP_BITS: u128 = 0x2;
+/// Exponent = 0b11...10, Sifnificand 0b1111..10. Min val > 0
+const MAX_DOWN_BITS: u128 = 0x7ffeffffffffffffffffffffffffffff;
+/// Zeroed exponent, full significant
+const LARGEST_SUBNORMAL_BITS: u128 = 0x0000ffffffffffffffffffffffffffff;
+/// Exponent = 0b1, zeroed significand
+const SMALLEST_NORMAL_BITS: u128 = 0x00010000000000000000000000000000;
+/// First pattern over the mantissa
+const NAN_MASK1: u128 = 0x0000aaaaaaaaaaaaaaaaaaaaaaaaaaaa;
+/// Second pattern over the mantissa
+const NAN_MASK2: u128 = 0x00005555555555555555555555555555;
+
+/// Compare by value
+#[allow(unused_macros)]
+macro_rules! assert_f128_eq {
+    ($a:expr, $b:expr) => {
+        let (l, r): (&f128, &f128) = (&$a, &$b);
+        assert_eq!(*l, *r, "\na: {:#0130x}\nb: {:#0130x}", l.to_bits(), r.to_bits())
+    };
+}
+
+/// Compare by representation
+#[allow(unused_macros)]
+macro_rules! assert_f128_biteq {
+    ($a:expr, $b:expr) => {
+        let (l, r): (&f128, &f128) = (&$a, &$b);
+        let lb = l.to_bits();
+        let rb = r.to_bits();
+        assert_eq!(
+            lb, rb,
+            "float {:?} is not bitequal to {:?}.\na: {:#0130x}\nb: {:#0130x}",
+            *l, *r, lb, rb
+        );
+    };
+}
diff --git a/library/std/src/f16.rs b/library/std/src/f16.rs
new file mode 100644
index 00000000000..c36f9f5d4c6
--- /dev/null
+++ b/library/std/src/f16.rs
@@ -0,0 +1,11 @@
+//! Constants for the `f16` double-precision floating point type.
+//!
+//! *[See also the `f16` primitive type](primitive@f16).*
+//!
+//! Mathematically significant numbers are provided in the `consts` sub-module.
+
+#[cfg(test)]
+mod tests;
+
+#[unstable(feature = "f16", issue = "116909")]
+pub use core::f16::consts;
diff --git a/library/std/src/f16/tests.rs b/library/std/src/f16/tests.rs
new file mode 100644
index 00000000000..d65c43eca4b
--- /dev/null
+++ b/library/std/src/f16/tests.rs
@@ -0,0 +1,46 @@
+#![allow(dead_code)] // FIXME(f16_f128): remove once constants are used
+
+// We run out of precision pretty quickly with f16
+const F16_APPROX_L1: f16 = 0.001;
+const F16_APPROX_L2: f16 = 0.01;
+const F16_APPROX_L3: f16 = 0.1;
+const F16_APPROX_L4: f16 = 0.5;
+
+/// Smallest number
+const TINY_BITS: u16 = 0x1;
+/// Next smallest number
+const TINY_UP_BITS: u16 = 0x2;
+/// Exponent = 0b11...10, Sifnificand 0b1111..10. Min val > 0
+const MAX_DOWN_BITS: u16 = 0x7bfe;
+/// Zeroed exponent, full significant
+const LARGEST_SUBNORMAL_BITS: u16 = 0x03ff;
+/// Exponent = 0b1, zeroed significand
+const SMALLEST_NORMAL_BITS: u16 = 0x0400;
+/// First pattern over the mantissa
+const NAN_MASK1: u16 = 0x02aa;
+/// Second pattern over the mantissa
+const NAN_MASK2: u16 = 0x0155;
+
+/// Compare by value
+#[allow(unused_macros)]
+macro_rules! assert_f16_eq {
+    ($a:expr, $b:expr) => {
+        let (l, r): (&f16, &f16) = (&$a, &$b);
+        assert_eq!(*l, *r, "\na: {:#018x}\nb: {:#018x}", l.to_bits(), r.to_bits())
+    };
+}
+
+/// Compare by representation
+#[allow(unused_macros)]
+macro_rules! assert_f16_biteq {
+    ($a:expr, $b:expr) => {
+        let (l, r): (&f16, &f16) = (&$a, &$b);
+        let lb = l.to_bits();
+        let rb = r.to_bits();
+        assert_eq!(
+            lb, rb,
+            "float {:?} is not bitequal to {:?}.\na: {:#018x}\nb: {:#018x}",
+            *l, *r, lb, rb
+        );
+    };
+}
diff --git a/library/std/src/lib.rs b/library/std/src/lib.rs
index c713eefc72c..2d7a9b7ce33 100644
--- a/library/std/src/lib.rs
+++ b/library/std/src/lib.rs
@@ -283,6 +283,8 @@
 #![feature(doc_masked)]
 #![feature(doc_notable_trait)]
 #![feature(dropck_eyepatch)]
+#![feature(f128)]
+#![feature(f16)]
 #![feature(if_let_guard)]
 #![feature(intra_doc_pointers)]
 #![feature(lang_items)]
@@ -558,6 +560,10 @@ pub use core::u8;
 #[allow(deprecated, deprecated_in_future)]
 pub use core::usize;
 
+#[unstable(feature = "f128", issue = "116909")]
+pub mod f128;
+#[unstable(feature = "f16", issue = "116909")]
+pub mod f16;
 pub mod f32;
 pub mod f64;