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| author | Pierre Blanchard <pierre.blanchard@arm.com> | 2022-12-19 12:06:01 +0000 |
|---|---|---|
| committer | Pierre Blanchard <pierre.blanchard@arm.com> | 2022-12-19 12:06:09 +0000 |
| commit | 0976cbd22158e1152070079642c21a6e02c21141 (patch) | |
| tree | 255f11ec0de7218a7311401e6f9b2a8b3c92ae21 /pl/math/v_log2f_data.c | |
| parent | 202e46317ee8983516b6413066a57bd624ffa044 (diff) | |
| download | arm-optimized-routines-0976cbd22158e1152070079642c21a6e02c21141.tar.gz | |
pl/math: Improve vector/Neon log2f
A new implementation based on the same approach as
Neon logf, that is accurate to 2.48 ULPs.
Flags set correctly regardless of WANT_ERRNO.
Diffstat (limited to 'pl/math/v_log2f_data.c')
| -rw-r--r-- | pl/math/v_log2f_data.c | 36 |
1 files changed, 7 insertions, 29 deletions
diff --git a/pl/math/v_log2f_data.c b/pl/math/v_log2f_data.c index e6c1f71..7e5cb1e 100644 --- a/pl/math/v_log2f_data.c +++ b/pl/math/v_log2f_data.c @@ -1,5 +1,5 @@ /* - * Coefficients and table entries for vector log2f + * Coefficients for vector log2f * * Copyright (c) 2022, Arm Limited. * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception @@ -7,31 +7,9 @@ #include "math_config.h" -const struct v_log2f_data __v_log2f_data = { -/* All values here are derived from the values in math/log2f_data.c. - For all i: - tab[i].invc_hi = (float) log2f_data.invc - tab[i].invc_lo = log2f_data.invc - (double) tab[i].invc_hi - tab[i].logc = (float) log2f_data.logc - poly[i] = (float) log2f_data.poly[i]. */ - .tab = { - { 0x1.661ec8p+0, -0x1.81c31p-26, -0x1.efec66p-2, 0}, - { 0x1.571ed4p+0, 0x1.55f108p-25, -0x1.b0b684p-2, 0}, - { 0x1.4953ap+0, -0x1.e1fdeap-25, -0x1.7418bp-2, 0}, - { 0x1.3c995cp+0, -0x1.e8ff9p-25, -0x1.39de92p-2, 0}, - { 0x1.30d19p+0, 0x1.910c94p-25, -0x1.01d9cp-2, 0}, - { 0x1.25e228p+0, -0x1.3d1c58p-26, -0x1.97c1d2p-3, 0}, - { 0x1.1bb4a4p+0, 0x1.434688p-25, -0x1.2f9e3ap-3, 0}, - { 0x1.12359p+0, -0x1.eea348p-25, -0x1.960cbcp-4, 0}, - { 0x1.0953f4p+0, 0x1.9900a8p-28, -0x1.a6f9dcp-5, 0}, - { 0x1p+0, 0x0p+0, 0x0p+0, 0}, - { 0x1.e608dp-1, -0x1.32dc2ap-28, 0x1.338caap-4, 0}, - { 0x1.ca4b32p-1, -0x1.fb2acp-30, 0x1.476a96p-3, 0}, - { 0x1.b20366p-1, -0x1.12a064p-26, 0x1.e840b4p-3, 0}, - { 0x1.9c2d16p-1, 0x1.d0d516p-28, 0x1.40646p-2, 0}, - { 0x1.886e6p-1, 0x1.bc20f6p-28, 0x1.88e9c2p-2, 0}, - { 0x1.767ddp-1, -0x1.5596f4p-26, 0x1.ce0a44p-2, 0}, - }, - .poly = { -0x1.712b70p-2, 0x1.ecabf4p-2, - -0x1.71547ap-1, 0x1.715476p+0 } -}; +/* See tools/v_log2f.sollya for the algorithm used to generate these + coefficients. */ +const struct v_log2f_data __v_log2f_data + = {.poly = {0x1.715476p0f, /* (float)(1 / ln(2)). */ + -0x1.715458p-1f, 0x1.ec701cp-2f, -0x1.7171a4p-2f, 0x1.27a0b8p-2f, + -0x1.e5143ep-3f, 0x1.9d8ecap-3f, -0x1.c675bp-3f, 0x1.9e495p-3f}}; |