1 files changed, 92 insertions, 0 deletions
diff --git a/math/aarch64/sinpif_2u5.c b/math/aarch64/sinpif_2u5.c
new file mode 100644
index 000000000000..b5d9cd914577
--- /dev/null
+++ b/math/aarch64/sinpif_2u5.c
@@ -0,0 +1,92 @@
+/*
+ * Single-precision scalar sinpi function.
+ *
+ * Copyright (c) 2023-2024, Arm Limited.
+ * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
+ */
+
+#include "mathlib.h"
+#include "math_config.h"
+#include "test_sig.h"
+#include "test_defs.h"
+
+/* Taylor series coefficents for sin(pi * x).  */
+#define C0 0x1.921fb6p1f
+#define C1 -0x1.4abbcep2f
+#define C2 0x1.466bc6p1f
+#define C3 -0x1.32d2ccp-1f
+#define C4 0x1.50783p-4f
+#define C5 -0x1.e30750p-8f
+
+#define Shift 0x1.0p+23f
+
+/* Approximation for scalar single-precision sinpi(x) - sinpif.
+   Maximum error: 2.48 ULP:
+   sinpif(0x1.d062b6p-2) got 0x1.fa8c06p-1
+			want 0x1.fa8c02p-1.  */
+float
+arm_math_sinpif (float x)
+{
+  if (isinf (x) || isnan (x))
+    return __math_invalidf (x);
+
+  float r = asfloat (asuint (x) & ~0x80000000);
+  uint32_t sign = asuint (x) & 0x80000000;
+
+  /* Edge cases for when sinpif should be exactly 0. (Integers)
+     0x1p23 is the limit for single precision to store any decimal places.  */
+  if (r >= 0x1p23f)
+    return asfloat (sign);
+
+  int32_t m = roundf (r);
+  if (m == r)
+    return asfloat (sign);
+
+  /* For very small inputs, squaring r causes underflow.
+     Values below this threshold can be approximated via sinpi(x) ~= pi*x.  */
+  if (r < 0x1p-31f)
+    return C0 * x;
+
+  /* Any non-integer values >= 0x1p22f will be int + 0.5.
+     These values should return exactly 1 or -1.  */
+  if (r >= 0x1p22f)
+    {
+      uint32_t iy = ((m & 1) << 31) ^ asuint (-1.0f);
+      return asfloat (sign ^ iy);
+    }
+
+  /* n = rint(|x|).  */
+  float n = r + Shift;
+  sign ^= (asuint (n) << 31);
+  n = n - Shift;
+
+  /* r = |x| - n (range reduction into -1/2 .. 1/2).  */
+  r = r - n;
+
+  /* y = sin(pi * r).  */
+  float r2 = r * r;
+  float y = fmaf (C5, r2, C4);
+  y = fmaf (y, r2, C3);
+  y = fmaf (y, r2, C2);
+  y = fmaf (y, r2, C1);
+  y = fmaf (y, r2, C0);
+
+  /* Copy sign of x to sin(|x|).  */
+  return asfloat (asuint (y * r) ^ sign);
+}
+
+#if WANT_EXPERIMENTAL_MATH
+float
+sinpif (float x)
+{
+  return arm_math_sinpif (x);
+}
+#endif
+
+#if WANT_TRIGPI_TESTS
+TEST_ULP (arm_math_sinpif, 1.99)
+TEST_SYM_INTERVAL (arm_math_sinpif, 0, 0x1p-31, 5000)
+TEST_SYM_INTERVAL (arm_math_sinpif, 0x1p-31, 0.5, 10000)
+TEST_SYM_INTERVAL (arm_math_sinpif, 0.5, 0x1p22f, 10000)
+TEST_SYM_INTERVAL (arm_math_sinpif, 0x1p22f, inf, 10000)
+#endif