1 files changed, 38 insertions, 0 deletions
diff --git a/library/compiler-builtins/libm/src/math/tanhf.rs b/library/compiler-builtins/libm/src/math/tanhf.rs
new file mode 100644
index 00000000000..fffbba6c6ec
--- /dev/null
+++ b/library/compiler-builtins/libm/src/math/tanhf.rs
@@ -0,0 +1,38 @@
+use super::expm1f;
+
+/// The hyperbolic tangent of `x` (f32).
+///
+/// `x` is specified in radians.
+#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
+pub fn tanhf(mut x: f32) -> f32 {
+    /* x = |x| */
+    let mut ix = x.to_bits();
+    let sign = (ix >> 31) != 0;
+    ix &= 0x7fffffff;
+    x = f32::from_bits(ix);
+    let w = ix;
+
+    let tt = if w > 0x3f0c9f54 {
+        /* |x| > log(3)/2 ~= 0.5493 or nan */
+        if w > 0x41200000 {
+            /* |x| > 10 */
+            1. + 0. / x
+        } else {
+            let t = expm1f(2. * x);
+            1. - 2. / (t + 2.)
+        }
+    } else if w > 0x3e82c578 {
+        /* |x| > log(5/3)/2 ~= 0.2554 */
+        let t = expm1f(2. * x);
+        t / (t + 2.)
+    } else if w >= 0x00800000 {
+        /* |x| >= 0x1p-126 */
+        let t = expm1f(-2. * x);
+        -t / (t + 2.)
+    } else {
+        /* |x| is subnormal */
+        force_eval!(x * x);
+        x
+    };
+    if sign { -tt } else { tt }
+}