1 files changed, 90 insertions, 0 deletions
diff --git a/pl/math/v_atan2_3u.c b/pl/math/v_atan2_3u.c
new file mode 100644
index 0000000..6327fea
--- /dev/null
+++ b/pl/math/v_atan2_3u.c
@@ -0,0 +1,90 @@
+/*
+ * Double-precision vector atan2(x) function.
+ *
+ * Copyright (c) 2021-2023, 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 "atan_common.h"
+
+#define PiOver2 v_f64 (0x1.921fb54442d18p+0)
+#define SignMask v_u64 (0x8000000000000000)
+
+/* Special cases i.e. 0, infinity, NaN (fall back to scalar calls).  */
+VPCS_ATTR
+NOINLINE static v_f64_t
+specialcase (v_f64_t y, v_f64_t x, v_f64_t ret, v_u64_t cmp)
+{
+  return v_call2_f64 (atan2, y, x, ret, cmp);
+}
+
+/* Returns 1 if input is the bit representation of 0, infinity or nan.  */
+static inline v_u64_t
+zeroinfnan (v_u64_t i)
+{
+  return v_cond_u64 (2 * i - 1 >= v_u64 (2 * asuint64 (INFINITY) - 1));
+}
+
+/* Fast implementation of vector atan2.
+   Maximum observed error is 2.8 ulps:
+   v_atan2(0x1.9651a429a859ap+5, 0x1.953075f4ee26p+5)
+	got 0x1.92d628ab678ccp-1
+       want 0x1.92d628ab678cfp-1.  */
+VPCS_ATTR
+v_f64_t V_NAME (atan2) (v_f64_t y, v_f64_t x)
+{
+  v_u64_t ix = v_as_u64_f64 (x);
+  v_u64_t iy = v_as_u64_f64 (y);
+
+  v_u64_t special_cases = zeroinfnan (ix) | zeroinfnan (iy);
+
+  v_u64_t sign_x = ix & SignMask;
+  v_u64_t sign_y = iy & SignMask;
+  v_u64_t sign_xy = sign_x ^ sign_y;
+
+  v_f64_t ax = v_abs_f64 (x);
+  v_f64_t ay = v_abs_f64 (y);
+
+  v_u64_t pred_xlt0 = x < 0.0;
+  v_u64_t pred_aygtax = ay > ax;
+
+  /* Set up z for call to atan.  */
+  v_f64_t n = v_sel_f64 (pred_aygtax, -ax, ay);
+  v_f64_t d = v_sel_f64 (pred_aygtax, ay, ax);
+  v_f64_t z = v_div_f64 (n, d);
+
+  /* Work out the correct shift.  */
+  v_f64_t shift = v_sel_f64 (pred_xlt0, v_f64 (-2.0), v_f64 (0.0));
+  shift = v_sel_f64 (pred_aygtax, shift + 1.0, shift);
+  shift *= PiOver2;
+
+  v_f64_t ret = eval_poly (z, z, shift);
+
+  /* Account for the sign of x and y.  */
+  ret = v_as_f64_u64 (v_as_u64_f64 (ret) ^ sign_xy);
+
+  if (unlikely (v_any_u64 (special_cases)))
+    {
+      return specialcase (y, x, ret, special_cases);
+    }
+
+  return ret;
+}
+VPCS_ALIAS
+
+/* Arity of 2 means no mathbench entry emitted. See test/mathbench_funcs.h.  */
+PL_SIG (V, D, 2, atan2)
+// TODO tighten this once __v_atan2 is fixed
+PL_TEST_ULP (V_NAME (atan2), 2.9)
+PL_TEST_INTERVAL (V_NAME (atan2), -10.0, 10.0, 50000)
+PL_TEST_INTERVAL (V_NAME (atan2), -1.0, 1.0, 40000)
+PL_TEST_INTERVAL (V_NAME (atan2), 0.0, 1.0, 40000)
+PL_TEST_INTERVAL (V_NAME (atan2), 1.0, 100.0, 40000)
+PL_TEST_INTERVAL (V_NAME (atan2), 1e6, 1e32, 40000)
+#endif