1 files changed, 69 insertions, 0 deletions
diff --git a/pl/math/v_tanhf_2u6.c b/pl/math/v_tanhf_2u6.c
new file mode 100644
index 0000000..3616611
--- /dev/null
+++ b/pl/math/v_tanhf_2u6.c
@@ -0,0 +1,69 @@
+/*
+ * Single-precision vector tanh(x) function.
+ *
+ * Copyright (c) 2022-2023, Arm Limited.
+ * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
+ */
+
+#include "v_math.h"
+#include "pl_sig.h"
+#include "pl_test.h"
+
+#if V_SUPPORTED
+
+#include "v_expm1f_inline.h"
+
+#define BoringBound                                                            \
+  0x41102cb3 /* 0x1.205966p+3, above which tanhf rounds to 1 (or -1 for        \
+		negative).  */
+#define AbsMask 0x7fffffff
+
+static NOINLINE v_f32_t
+special_case (v_f32_t x, v_f32_t y, v_u32_t special)
+{
+  return v_call_f32 (tanhf, x, y, special);
+}
+
+/* Approximation for single-precision vector tanh(x), using a simplified version
+   of expm1f. The maximum error is 2.58 ULP:
+   __v_tanhf(0x1.fa5eep-5) got 0x1.f9ba02p-5
+			  want 0x1.f9ba08p-5.  */
+VPCS_ATTR v_f32_t V_NAME (tanhf) (v_f32_t x)
+{
+  v_u32_t ix = v_as_u32_f32 (x);
+  v_u32_t iax = ix & AbsMask;
+  v_u32_t sign = ix & ~AbsMask;
+  v_u32_t is_boring = v_cond_u32 (iax > BoringBound);
+  v_f32_t boring = v_as_f32_u32 (sign | One);
+
+#if WANT_SIMD_EXCEPT
+  /* If fp exceptions are to be triggered properly, set all special and boring
+     lanes to 1, which will trigger no exceptions, and fix them up later.  */
+  v_u32_t special = v_cond_u32 ((iax > 0x7f800000) | (iax < 0x34000000));
+  ix = v_sel_u32 (is_boring, v_u32 (One), ix);
+  if (unlikely (v_any_u32 (special)))
+    ix = v_sel_u32 (special, v_u32 (One), ix);
+#else
+  v_u32_t special = v_cond_u32 ((iax > 0x7f800000) | (iax == 0));
+#endif
+
+  /* tanh(x) = (e^2x - 1) / (e^2x + 1).  */
+  v_f32_t q = expm1f_inline (2 * v_as_f32_u32 (ix));
+  v_f32_t y = q / (q + 2);
+  y = v_sel_f32 (is_boring, boring, y);
+  if (unlikely (v_any_u32 (special)))
+    return special_case (x, y, special);
+  return y;
+}
+VPCS_ALIAS
+
+PL_SIG (V, F, 1, tanh, -10.0, 10.0)
+PL_TEST_ULP (V_NAME (tanhf), 2.09)
+PL_TEST_EXPECT_FENV (V_NAME (tanhf), WANT_SIMD_EXCEPT)
+PL_TEST_INTERVAL (V_NAME (tanhf), 0, 0x1p-23, 1000)
+PL_TEST_INTERVAL (V_NAME (tanhf), -0, -0x1p-23, 1000)
+PL_TEST_INTERVAL (V_NAME (tanhf), 0x1p-23, 0x1.205966p+3, 100000)
+PL_TEST_INTERVAL (V_NAME (tanhf), -0x1p-23, -0x1.205966p+3, 100000)
+PL_TEST_INTERVAL (V_NAME (tanhf), 0x1.205966p+3, inf, 100)
+PL_TEST_INTERVAL (V_NAME (tanhf), -0x1.205966p+3, -inf, 100)
+#endif