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Diffstat (limited to 'pl/math/v_acosh_3u5.c')
-rw-r--r-- | pl/math/v_acosh_3u5.c | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/pl/math/v_acosh_3u5.c b/pl/math/v_acosh_3u5.c new file mode 100644 index 0000000..22f69d7 --- /dev/null +++ b/pl/math/v_acosh_3u5.c @@ -0,0 +1,51 @@ +/* + * Single-precision vector acosh(x) function. + * Copyright (c) 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" + +#define WANT_V_LOG1P_K0_SHORTCUT 1 +#include "v_log1p_inline.h" + +#define BigBoundTop 0x5fe /* top12 (asuint64 (0x1p511)). */ + +#if V_SUPPORTED + +static NOINLINE VPCS_ATTR v_f64_t +special_case (v_f64_t x) +{ + return v_call_f64 (acosh, x, x, v_u64 (-1)); +} + +/* Vector approximation for double-precision acosh, based on log1p. + The largest observed error is 3.02 ULP in the region where the + argument to log1p falls in the k=0 interval, i.e. x close to 1: + __v_acosh(0x1.00798aaf80739p+0) got 0x1.f2d6d823bc9dfp-5 + want 0x1.f2d6d823bc9e2p-5. */ +VPCS_ATTR v_f64_t V_NAME (acosh) (v_f64_t x) +{ + v_u64_t itop = v_as_u64_f64 (x) >> 52; + v_u64_t special = v_cond_u64 ((itop - OneTop) >= (BigBoundTop - OneTop)); + + /* Fall back to scalar routine for all lanes if any of them are special. */ + if (unlikely (v_any_u64 (special))) + return special_case (x); + + v_f64_t xm1 = x - 1; + v_f64_t u = xm1 * (x + 1); + return log1p_inline (xm1 + v_sqrt_f64 (u)); +} +VPCS_ALIAS + +PL_SIG (V, D, 1, acosh, 1.0, 10.0) +PL_TEST_ULP (V_NAME (acosh), 2.53) +PL_TEST_EXPECT_FENV_ALWAYS (V_NAME (acosh)) +PL_TEST_INTERVAL (V_NAME (acosh), 1, 0x1p511, 90000) +PL_TEST_INTERVAL (V_NAME (acosh), 0x1p511, inf, 10000) +PL_TEST_INTERVAL (V_NAME (acosh), 0, 1, 1000) +PL_TEST_INTERVAL (V_NAME (acosh), -0, -inf, 10000) +#endif |