diff options
Diffstat (limited to 'sysdeps/aarch64/fpu/sv_log1pf_inline.h')
| -rw-r--r-- | sysdeps/aarch64/fpu/sv_log1pf_inline.h | 76 |
1 files changed, 76 insertions, 0 deletions
diff --git a/sysdeps/aarch64/fpu/sv_log1pf_inline.h b/sysdeps/aarch64/fpu/sv_log1pf_inline.h new file mode 100644 index 0000000000..b94b2da055 --- /dev/null +++ b/sysdeps/aarch64/fpu/sv_log1pf_inline.h @@ -0,0 +1,76 @@ +/* Helper for single-precision SVE routines which depend on log1p + + Copyright (C) 2024 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +#ifndef AARCH64_FPU_SV_LOG1PF_INLINE_H +#define AARCH64_FPU_SV_LOG1PF_INLINE_H + +#include "sv_math.h" +#include "vecmath_config.h" +#include "poly_sve_f32.h" + +static const struct sv_log1pf_data +{ + float32_t poly[9]; + float32_t ln2; + float32_t scale_back; +} sv_log1pf_data = { + /* Polynomial generated using FPMinimax in [-0.25, 0.5]. */ + .poly = { -0x1p-1f, 0x1.5555aap-2f, -0x1.000038p-2f, 0x1.99675cp-3f, + -0x1.54ef78p-3f, 0x1.28a1f4p-3f, -0x1.0da91p-3f, 0x1.abcb6p-4f, + -0x1.6f0d5ep-5f }, + .scale_back = 0x1.0p-23f, + .ln2 = 0x1.62e43p-1f, +}; + +static inline svfloat32_t +eval_poly (svfloat32_t m, const float32_t *c, svbool_t pg) +{ + svfloat32_t p_12 = svmla_x (pg, sv_f32 (c[0]), m, sv_f32 (c[1])); + svfloat32_t m2 = svmul_x (pg, m, m); + svfloat32_t q = svmla_x (pg, m, m2, p_12); + svfloat32_t p = sv_pw_horner_6_f32_x (pg, m, m2, c + 2); + p = svmul_x (pg, m2, p); + + return svmla_x (pg, q, m2, p); +} + +static inline svfloat32_t +sv_log1pf_inline (svfloat32_t x, svbool_t pg) +{ + const struct sv_log1pf_data *d = ptr_barrier (&sv_log1pf_data); + + svfloat32_t m = svadd_x (pg, x, 1.0f); + + svint32_t ks = svsub_x (pg, svreinterpret_s32 (m), + svreinterpret_s32 (svdup_f32 (0.75f))); + ks = svand_x (pg, ks, 0xff800000); + svuint32_t k = svreinterpret_u32 (ks); + svfloat32_t s = svreinterpret_f32 ( + svsub_x (pg, svreinterpret_u32 (svdup_f32 (4.0f)), k)); + + svfloat32_t m_scale + = svreinterpret_f32 (svsub_x (pg, svreinterpret_u32 (x), k)); + m_scale + = svadd_x (pg, m_scale, svmla_x (pg, sv_f32 (-1.0f), sv_f32 (0.25f), s)); + svfloat32_t p = eval_poly (m_scale, d->poly, pg); + svfloat32_t scale_back = svmul_x (pg, svcvt_f32_x (pg, k), d->scale_back); + return svmla_x (pg, p, scale_back, d->ln2); +} + +#endif |