1 files changed, 81 insertions, 0 deletions
diff --git a/library/compiler-builtins/libm/src/math/tanf.rs b/library/compiler-builtins/libm/src/math/tanf.rs
new file mode 100644
index 00000000000..8bcf9581ff6
--- /dev/null
+++ b/library/compiler-builtins/libm/src/math/tanf.rs
@@ -0,0 +1,81 @@
+/* origin: FreeBSD /usr/src/lib/msun/src/s_tanf.c */
+/*
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
+ * Optimized by Bruce D. Evans.
+ */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+use core::f64::consts::FRAC_PI_2;
+
+use super::{k_tanf, rem_pio2f};
+
+/* Small multiples of pi/2 rounded to double precision. */
+const T1_PIO2: f64 = 1. * FRAC_PI_2; /* 0x3FF921FB, 0x54442D18 */
+const T2_PIO2: f64 = 2. * FRAC_PI_2; /* 0x400921FB, 0x54442D18 */
+const T3_PIO2: f64 = 3. * FRAC_PI_2; /* 0x4012D97C, 0x7F3321D2 */
+const T4_PIO2: f64 = 4. * FRAC_PI_2; /* 0x401921FB, 0x54442D18 */
+
+/// The tangent of `x` (f32).
+///
+/// `x` is specified in radians.
+#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
+pub fn tanf(x: f32) -> f32 {
+    let x64 = x as f64;
+
+    let x1p120 = f32::from_bits(0x7b800000); // 0x1p120f === 2 ^ 120
+
+    let mut ix = x.to_bits();
+    let sign = (ix >> 31) != 0;
+    ix &= 0x7fffffff;
+
+    if ix <= 0x3f490fda {
+        /* |x| ~<= pi/4 */
+        if ix < 0x39800000 {
+            /* |x| < 2**-12 */
+            /* raise inexact if x!=0 and underflow if subnormal */
+            force_eval!(if ix < 0x00800000 {
+                x / x1p120
+            } else {
+                x + x1p120
+            });
+            return x;
+        }
+        return k_tanf(x64, false);
+    }
+    if ix <= 0x407b53d1 {
+        /* |x| ~<= 5*pi/4 */
+        if ix <= 0x4016cbe3 {
+            /* |x| ~<= 3pi/4 */
+            return k_tanf(if sign { x64 + T1_PIO2 } else { x64 - T1_PIO2 }, true);
+        } else {
+            return k_tanf(if sign { x64 + T2_PIO2 } else { x64 - T2_PIO2 }, false);
+        }
+    }
+    if ix <= 0x40e231d5 {
+        /* |x| ~<= 9*pi/4 */
+        if ix <= 0x40afeddf {
+            /* |x| ~<= 7*pi/4 */
+            return k_tanf(if sign { x64 + T3_PIO2 } else { x64 - T3_PIO2 }, true);
+        } else {
+            return k_tanf(if sign { x64 + T4_PIO2 } else { x64 - T4_PIO2 }, false);
+        }
+    }
+
+    /* tan(Inf or NaN) is NaN */
+    if ix >= 0x7f800000 {
+        return x - x;
+    }
+
+    /* argument reduction */
+    let (n, y) = rem_pio2f(x);
+    k_tanf(y, n & 1 != 0)
+}