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Diffstat (limited to 'pl/math/v_log1p_inline.h')
| -rw-r--r-- | pl/math/v_log1p_inline.h | 91 |
1 files changed, 0 insertions, 91 deletions
diff --git a/pl/math/v_log1p_inline.h b/pl/math/v_log1p_inline.h deleted file mode 100644 index bd57bfc6fe6e..000000000000 --- a/pl/math/v_log1p_inline.h +++ /dev/null @@ -1,91 +0,0 @@ -/* - * Helper for vector double-precision routines which calculate log(1 + x) and do - * not need special-case handling - * - * Copyright (c) 2022-2023, Arm Limited. - * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception - */ -#ifndef PL_MATH_V_LOG1P_INLINE_H -#define PL_MATH_V_LOG1P_INLINE_H - -#include "v_math.h" -#include "poly_advsimd_f64.h" - -struct v_log1p_data -{ - float64x2_t poly[19], ln2[2]; - uint64x2_t hf_rt2_top, one_m_hf_rt2_top, umask; - int64x2_t one_top; -}; - -/* Coefficients generated using Remez, deg=20, in [sqrt(2)/2-1, sqrt(2)-1]. */ -#define V_LOG1P_CONSTANTS_TABLE \ - { \ - .poly = { V2 (-0x1.ffffffffffffbp-2), V2 (0x1.55555555551a9p-2), \ - V2 (-0x1.00000000008e3p-2), V2 (0x1.9999999a32797p-3), \ - V2 (-0x1.555555552fecfp-3), V2 (0x1.249248e071e5ap-3), \ - V2 (-0x1.ffffff8bf8482p-4), V2 (0x1.c71c8f07da57ap-4), \ - V2 (-0x1.9999ca4ccb617p-4), V2 (0x1.7459ad2e1dfa3p-4), \ - V2 (-0x1.554d2680a3ff2p-4), V2 (0x1.3b4c54d487455p-4), \ - V2 (-0x1.2548a9ffe80e6p-4), V2 (0x1.0f389a24b2e07p-4), \ - V2 (-0x1.eee4db15db335p-5), V2 (0x1.e95b494d4a5ddp-5), \ - V2 (-0x1.15fdf07cb7c73p-4), V2 (0x1.0310b70800fcfp-4), \ - V2 (-0x1.cfa7385bdb37ep-6) }, \ - .ln2 = { V2 (0x1.62e42fefa3800p-1), V2 (0x1.ef35793c76730p-45) }, \ - .hf_rt2_top = V2 (0x3fe6a09e00000000), \ - .one_m_hf_rt2_top = V2 (0x00095f6200000000), \ - .umask = V2 (0x000fffff00000000), .one_top = V2 (0x3ff) \ - } - -#define BottomMask v_u64 (0xffffffff) - -static inline float64x2_t -log1p_inline (float64x2_t x, const struct v_log1p_data *d) -{ - /* Helper for calculating log(x + 1). Copied from v_log1p_2u5.c, with several - modifications: - - No special-case handling - this should be dealt with by the caller. - - Pairwise Horner polynomial evaluation for improved accuracy. - - Optionally simulate the shortcut for k=0, used in the scalar routine, - using v_sel, for improved accuracy when the argument to log1p is close to - 0. This feature is enabled by defining WANT_V_LOG1P_K0_SHORTCUT as 1 in - the source of the caller before including this file. - See v_log1pf_2u1.c for details of the algorithm. */ - float64x2_t m = vaddq_f64 (x, v_f64 (1)); - uint64x2_t mi = vreinterpretq_u64_f64 (m); - uint64x2_t u = vaddq_u64 (mi, d->one_m_hf_rt2_top); - - int64x2_t ki - = vsubq_s64 (vreinterpretq_s64_u64 (vshrq_n_u64 (u, 52)), d->one_top); - float64x2_t k = vcvtq_f64_s64 (ki); - - /* Reduce x to f in [sqrt(2)/2, sqrt(2)]. */ - uint64x2_t utop = vaddq_u64 (vandq_u64 (u, d->umask), d->hf_rt2_top); - uint64x2_t u_red = vorrq_u64 (utop, vandq_u64 (mi, BottomMask)); - float64x2_t f = vsubq_f64 (vreinterpretq_f64_u64 (u_red), v_f64 (1)); - - /* Correction term c/m. */ - float64x2_t cm = vdivq_f64 (vsubq_f64 (x, vsubq_f64 (m, v_f64 (1))), m); - -#ifndef WANT_V_LOG1P_K0_SHORTCUT -#error \ - "Cannot use v_log1p_inline.h without specifying whether you need the k0 shortcut for greater accuracy close to 0" -#elif WANT_V_LOG1P_K0_SHORTCUT - /* Shortcut if k is 0 - set correction term to 0 and f to x. The result is - that the approximation is solely the polynomial. */ - uint64x2_t k0 = vceqzq_f64 (k); - cm = v_zerofy_f64 (cm, k0); - f = vbslq_f64 (k0, x, f); -#endif - - /* Approximate log1p(f) on the reduced input using a polynomial. */ - float64x2_t f2 = vmulq_f64 (f, f); - float64x2_t p = v_pw_horner_18_f64 (f, f2, d->poly); - - /* Assemble log1p(x) = k * log2 + log1p(f) + c/m. */ - float64x2_t ylo = vfmaq_f64 (cm, k, d->ln2[1]); - float64x2_t yhi = vfmaq_f64 (f, k, d->ln2[0]); - return vfmaq_f64 (vaddq_f64 (ylo, yhi), f2, p); -} - -#endif // PL_MATH_V_LOG1P_INLINE_H |