1 files changed, 101 insertions, 0 deletions
diff --git a/math/aarch64/sve/exp10f.c b/math/aarch64/sve/exp10f.c
new file mode 100644
index 000000000000..8679df87702f
--- /dev/null
+++ b/math/aarch64/sve/exp10f.c
@@ -0,0 +1,101 @@
+/*
+ * Single-precision SVE 10^x function.
+ *
+ * Copyright (c) 2023-2024, Arm Limited.
+ * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
+ */
+
+#define _GNU_SOURCE
+#include "sv_math.h"
+#include "test_sig.h"
+#include "test_defs.h"
+#include "sv_poly_f32.h"
+
+/* For x < -Thres, the result is subnormal and not handled correctly by
+   FEXPA.  */
+#define Thres 37.9
+
+static const struct data
+{
+  float log2_10_lo, c0, c2, c4;
+  float c1, c3, log10_2;
+  float shift, log2_10_hi, thres;
+} data = {
+  /* Coefficients generated using Remez algorithm with minimisation of relative
+     error.
+     rel error: 0x1.89dafa3p-24
+     abs error: 0x1.167d55p-23 in [-log10(2)/2, log10(2)/2]
+     maxerr: 0.52 +0.5 ulp.  */
+  .c0 = 0x1.26bb16p+1f,
+  .c1 = 0x1.5350d2p+1f,
+  .c2 = 0x1.04744ap+1f,
+  .c3 = 0x1.2d8176p+0f,
+  .c4 = 0x1.12b41ap-1f,
+  /* 1.5*2^17 + 127, a shift value suitable for FEXPA.  */
+  .shift = 0x1.803f8p17f,
+  .log10_2 = 0x1.a934fp+1,
+  .log2_10_hi = 0x1.344136p-2,
+  .log2_10_lo = -0x1.ec10cp-27,
+  .thres = Thres,
+};
+
+static inline svfloat32_t
+sv_exp10f_inline (svfloat32_t x, const svbool_t pg, const struct data *d)
+{
+  /* exp10(x) = 2^(n/N) * 10^r = 2^n * (1 + poly (r)),
+     with poly(r) in [1/sqrt(2), sqrt(2)] and
+     x = r + n * log10(2) / N, with r in [-log10(2)/2N, log10(2)/2N].  */
+
+  svfloat32_t lane_consts = svld1rq (svptrue_b32 (), &d->log2_10_lo);
+
+  /* n = round(x/(log10(2)/N)).  */
+  svfloat32_t shift = sv_f32 (d->shift);
+  svfloat32_t z = svmad_x (pg, sv_f32 (d->log10_2), x, shift);
+  svfloat32_t n = svsub_x (svptrue_b32 (), z, shift);
+
+  /* r = x - n*log10(2)/N.  */
+  svfloat32_t r = svmsb_x (pg, sv_f32 (d->log2_10_hi), n, x);
+  r = svmls_lane (r, n, lane_consts, 0);
+
+  svfloat32_t scale = svexpa (svreinterpret_u32 (z));
+
+  /* Polynomial evaluation: poly(r) ~ exp10(r)-1.  */
+  svfloat32_t p12 = svmla_lane (sv_f32 (d->c1), r, lane_consts, 2);
+  svfloat32_t p34 = svmla_lane (sv_f32 (d->c3), r, lane_consts, 3);
+  svfloat32_t r2 = svmul_x (svptrue_b32 (), r, r);
+  svfloat32_t p14 = svmla_x (pg, p12, p34, r2);
+  svfloat32_t p0 = svmul_lane (r, lane_consts, 1);
+  svfloat32_t poly = svmla_x (pg, p0, r2, p14);
+
+  return svmla_x (pg, scale, scale, poly);
+}
+
+static svfloat32_t NOINLINE
+special_case (svfloat32_t x, svbool_t special, const struct data *d)
+{
+  return sv_call_f32 (exp10f, x, sv_exp10f_inline (x, svptrue_b32 (), d),
+		      special);
+}
+
+/* Single-precision SVE exp10f routine. Implements the same algorithm
+   as AdvSIMD exp10f.
+   Worst case error is 1.02 ULPs.
+   _ZGVsMxv_exp10f(-0x1.040488p-4) got 0x1.ba5f9ep-1
+				  want 0x1.ba5f9cp-1.  */
+svfloat32_t SV_NAME_F1 (exp10) (svfloat32_t x, const svbool_t pg)
+{
+  const struct data *d = ptr_barrier (&data);
+  svbool_t special = svacgt (pg, x, d->thres);
+  if (unlikely (svptest_any (special, special)))
+    return special_case (x, special, d);
+  return sv_exp10f_inline (x, pg, d);
+}
+
+#if WANT_EXP10_TESTS
+TEST_SIG (SV, F, 1, exp10, -9.9, 9.9)
+TEST_ULP (SV_NAME_F1 (exp10), 0.52)
+TEST_DISABLE_FENV (SV_NAME_F1 (exp10))
+TEST_SYM_INTERVAL (SV_NAME_F1 (exp10), 0, Thres, 50000)
+TEST_SYM_INTERVAL (SV_NAME_F1 (exp10), Thres, inf, 50000)
+#endif
+CLOSE_SVE_ATTR