1 files changed, 93 insertions, 0 deletions
diff --git a/pl/math/sv_atan2_2u5.c b/pl/math/sv_atan2_2u5.c
new file mode 100644
index 0000000..a4bea1d
--- /dev/null
+++ b/pl/math/sv_atan2_2u5.c
@@ -0,0 +1,93 @@
+/*
+ * Double-precision vector atan2(x) function.
+ *
+ * Copyright (c) 2021-2023, Arm Limited.
+ * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
+ */
+
+#include "sv_math.h"
+#include "pl_sig.h"
+#include "pl_test.h"
+
+#if SV_SUPPORTED
+
+#include "sv_atan_common.h"
+
+/* Useful constants.  */
+#define PiOver2 sv_f64 (0x1.921fb54442d18p+0)
+#define SignMask sv_u64 (0x8000000000000000)
+
+/* Special cases i.e. 0, infinity, nan (fall back to scalar calls).  */
+__attribute__ ((noinline)) static sv_f64_t
+specialcase (sv_f64_t y, sv_f64_t x, sv_f64_t ret, const svbool_t cmp)
+{
+  return sv_call2_f64 (atan2, y, x, ret, cmp);
+}
+
+/* Returns a predicate indicating true if the input is the bit representation of
+   0, infinity or nan.  */
+static inline svbool_t
+zeroinfnan (sv_u64_t i, const svbool_t pg)
+{
+  return svcmpge_u64 (pg, svsub_n_u64_x (pg, svlsl_n_u64_x (pg, i, 1), 1),
+		      sv_u64 (2 * asuint64 (INFINITY) - 1));
+}
+
+/* Fast implementation of SVE atan2. Errors are greatest when y and
+   x are reasonably close together. The greatest observed error is 2.28 ULP:
+   sv_atan2(-0x1.5915b1498e82fp+732, 0x1.54d11ef838826p+732)
+   got -0x1.954f42f1fa841p-1 want -0x1.954f42f1fa843p-1.  */
+sv_f64_t
+__sv_atan2_x (sv_f64_t y, sv_f64_t x, const svbool_t pg)
+{
+  sv_u64_t ix = sv_as_u64_f64 (x);
+  sv_u64_t iy = sv_as_u64_f64 (y);
+
+  svbool_t cmp_x = zeroinfnan (ix, pg);
+  svbool_t cmp_y = zeroinfnan (iy, pg);
+  svbool_t cmp_xy = svorr_b_z (pg, cmp_x, cmp_y);
+
+  sv_u64_t sign_x = svand_u64_x (pg, ix, SignMask);
+  sv_u64_t sign_y = svand_u64_x (pg, iy, SignMask);
+  sv_u64_t sign_xy = sveor_u64_x (pg, sign_x, sign_y);
+
+  sv_f64_t ax = svabs_f64_x (pg, x);
+  sv_f64_t ay = svabs_f64_x (pg, y);
+
+  svbool_t pred_xlt0 = svcmplt_f64 (pg, x, sv_f64 (0.0));
+  svbool_t pred_aygtax = svcmpgt_f64 (pg, ay, ax);
+
+  /* Set up z for call to atan.  */
+  sv_f64_t n = svsel_f64 (pred_aygtax, svneg_f64_x (pg, ax), ay);
+  sv_f64_t d = svsel_f64 (pred_aygtax, ay, ax);
+  sv_f64_t z = svdiv_f64_x (pg, n, d);
+
+  /* Work out the correct shift.  */
+  sv_f64_t shift = svsel_f64 (pred_xlt0, sv_f64 (-2.0), sv_f64 (0.0));
+  shift = svsel_f64 (pred_aygtax, svadd_n_f64_x (pg, shift, 1.0), shift);
+  shift = svmul_f64_x (pg, shift, PiOver2);
+
+  sv_f64_t ret = __sv_atan_common (pg, pg, z, z, shift);
+
+  /* Account for the sign of x and y.  */
+  ret = sv_as_f64_u64 (sveor_u64_x (pg, sv_as_u64_f64 (ret), sign_xy));
+
+  if (unlikely (svptest_any (pg, cmp_xy)))
+    {
+      return specialcase (y, x, ret, cmp_xy);
+    }
+
+  return ret;
+}
+
+PL_ALIAS (__sv_atan2_x, _ZGVsMxvv_atan2)
+
+/* Arity of 2 means no mathbench entry emitted. See test/mathbench_funcs.h.  */
+PL_SIG (SV, D, 2, atan2)
+PL_TEST_ULP (__sv_atan2, 1.78)
+PL_TEST_INTERVAL (__sv_atan2, -10.0, 10.0, 50000)
+PL_TEST_INTERVAL (__sv_atan2, -1.0, 1.0, 40000)
+PL_TEST_INTERVAL (__sv_atan2, 0.0, 1.0, 40000)
+PL_TEST_INTERVAL (__sv_atan2, 1.0, 100.0, 40000)
+PL_TEST_INTERVAL (__sv_atan2, 1e6, 1e32, 40000)
+#endif