1 files changed, 51 insertions, 0 deletions
diff --git a/library/compiler-builtins/libm/src/math/sinh.rs b/library/compiler-builtins/libm/src/math/sinh.rs
new file mode 100644
index 00000000000..79184198263
--- /dev/null
+++ b/library/compiler-builtins/libm/src/math/sinh.rs
@@ -0,0 +1,51 @@
+use super::{expm1, expo2};
+
+// sinh(x) = (exp(x) - 1/exp(x))/2
+//         = (exp(x)-1 + (exp(x)-1)/exp(x))/2
+//         = x + x^3/6 + o(x^5)
+//
+
+/// The hyperbolic sine of `x` (f64).
+#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
+pub fn sinh(x: f64) -> f64 {
+    // union {double f; uint64_t i;} u = {.f = x};
+    // uint32_t w;
+    // double t, h, absx;
+
+    let mut uf: f64 = x;
+    let mut ui: u64 = f64::to_bits(uf);
+    let w: u32;
+    let t: f64;
+    let mut h: f64;
+    let absx: f64;
+
+    h = 0.5;
+    if ui >> 63 != 0 {
+        h = -h;
+    }
+    /* |x| */
+    ui &= !1 / 2;
+    uf = f64::from_bits(ui);
+    absx = uf;
+    w = (ui >> 32) as u32;
+
+    /* |x| < log(DBL_MAX) */
+    if w < 0x40862e42 {
+        t = expm1(absx);
+        if w < 0x3ff00000 {
+            if w < 0x3ff00000 - (26 << 20) {
+                /* note: inexact and underflow are raised by expm1 */
+                /* note: this branch avoids spurious underflow */
+                return x;
+            }
+            return h * (2.0 * t - t * t / (t + 1.0));
+        }
+        /* note: |x|>log(0x1p26)+eps could be just h*exp(x) */
+        return h * (t + t / (t + 1.0));
+    }
+
+    /* |x| > log(DBL_MAX) or nan */
+    /* note: the result is stored to handle overflow */
+    t = 2.0 * h * expo2(absx);
+    t
+}