1 files changed, 76 insertions, 0 deletions
diff --git a/pl/math/sinhf_2u3.c b/pl/math/sinhf_2u3.c
new file mode 100644
index 0000000..de94428
--- /dev/null
+++ b/pl/math/sinhf_2u3.c
@@ -0,0 +1,76 @@
+/*
+ * Single-precision sinh(x) function.
+ *
+ * Copyright (c) 2022-2023, Arm Limited.
+ * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
+ */
+
+#include "math_config.h"
+#include "pl_sig.h"
+#include "pl_test.h"
+
+#define AbsMask 0x7fffffff
+#define Half 0x3f000000
+#define Expm1OFlowLimit                                                        \
+  0x42b17218 /* 0x1.62e43p+6, 2^7*ln2, minimum value for which expm1f          \
+		overflows.  */
+#define OFlowLimit                                                             \
+  0x42b2d4fd /* 0x1.65a9fap+6, minimum positive value for which sinhf should   \
+		overflow.  */
+
+float
+optr_aor_exp_f32 (float);
+
+/* Approximation for single-precision sinh(x) using expm1.
+   sinh(x) = (exp(x) - exp(-x)) / 2.
+   The maximum error is 2.26 ULP:
+   sinhf(0x1.e34a9ep-4) got 0x1.e469ep-4 want 0x1.e469e4p-4.  */
+float
+sinhf (float x)
+{
+  uint32_t ix = asuint (x);
+  uint32_t iax = ix & AbsMask;
+  float ax = asfloat (iax);
+  uint32_t sign = ix & ~AbsMask;
+  float halfsign = asfloat (Half | sign);
+
+  if (unlikely (iax >= Expm1OFlowLimit))
+    {
+      /* Special values and overflow.  */
+      if (iax >= 0x7fc00001 || iax == 0x7f800000)
+	return x;
+      if (iax >= 0x7f800000)
+	return __math_invalidf (x);
+      if (iax >= OFlowLimit)
+	return __math_oflowf (sign);
+
+      /* expm1f overflows a little before sinhf, (~88.7 vs ~89.4). We have to
+	 fill this gap by using a different algorithm, in this case we use a
+	 double-precision exp helper. For large x sinh(x) dominated by exp(x),
+	 however we cannot compute exp without overflow either. We use the
+	 identity:
+	 exp(a) = (exp(a / 2)) ^ 2.
+	 to compute sinh(x) ~= (exp(|x| / 2)) ^ 2 / 2    for x > 0
+			    ~= (exp(|x| / 2)) ^ 2 / -2   for x < 0.
+	 Greatest error in this region is 1.89 ULP:
+	 sinhf(0x1.65898cp+6) got 0x1.f00aep+127  want 0x1.f00adcp+127.  */
+      float e = optr_aor_exp_f32 (ax / 2);
+      return (e * halfsign) * e;
+    }
+
+  /* Use expm1f to retain acceptable precision for small numbers.
+     Let t = e^(|x|) - 1.  */
+  float t = expm1f (ax);
+  /* Then sinh(x) = (t + t / (t + 1)) / 2   for x > 0
+		    (t + t / (t + 1)) / -2  for x < 0.  */
+  return (t + t / (t + 1)) * halfsign;
+}
+
+PL_SIG (S, F, 1, sinh, -10.0, 10.0)
+PL_TEST_ULP (sinhf, 1.76)
+PL_TEST_INTERVAL (sinhf, 0, 0x1.62e43p+6, 100000)
+PL_TEST_INTERVAL (sinhf, -0, -0x1.62e43p+6, 100000)
+PL_TEST_INTERVAL (sinhf, 0x1.62e43p+6, 0x1.65a9fap+6, 100)
+PL_TEST_INTERVAL (sinhf, -0x1.62e43p+6, -0x1.65a9fap+6, 100)
+PL_TEST_INTERVAL (sinhf, 0x1.65a9fap+6, inf, 100)
+PL_TEST_INTERVAL (sinhf, -0x1.65a9fap+6, -inf, 100)