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875c76c704
Similar to the new logf: double precision arithmetics and a small lookup table is used. The argument reduction step is the same as in the new logf. without wrapper on aarch64: log2f reciprocal-throughput: 2.3x faster log2f latency: 2.1x faster old worst case error: 1.72 ulp new worst case error: 0.75 ulp aarch64 .text size: -252 bytes aarch64 .rodata size: +244 bytes * math/Makefile (type-float-routines): Add e_log2f_data. * sysdeps/ieee754/flt-32/e_log2f.c: New implementation. * sysdeps/ieee754/flt-32/e_log2f_data.c: New file. * sysdeps/ieee754/flt-32/math_config.h (__log2f_data): Define. (LOG2F_TABLE_BITS, LOG2F_POLY_ORDER): Define. * sysdeps/i386/fpu/e_log2f_data.c: New file. * sysdeps/ia64/fpu/e_log2f_data.c: New file. * sysdeps/m68k/m680x0/fpu/e_log2f_data.c: New file.
45 lines
1.7 KiB
C
45 lines
1.7 KiB
C
/* Data definition for log2f.
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Copyright (C) 2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include "math_config.h"
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const struct log2f_data __log2f_data = {
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.tab = {
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{ 0x1.661ec79f8f3bep+0, -0x1.efec65b963019p-2 },
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{ 0x1.571ed4aaf883dp+0, -0x1.b0b6832d4fca4p-2 },
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{ 0x1.49539f0f010bp+0, -0x1.7418b0a1fb77bp-2 },
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{ 0x1.3c995b0b80385p+0, -0x1.39de91a6dcf7bp-2 },
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{ 0x1.30d190c8864a5p+0, -0x1.01d9bf3f2b631p-2 },
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{ 0x1.25e227b0b8eap+0, -0x1.97c1d1b3b7afp-3 },
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{ 0x1.1bb4a4a1a343fp+0, -0x1.2f9e393af3c9fp-3 },
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{ 0x1.12358f08ae5bap+0, -0x1.960cbbf788d5cp-4 },
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{ 0x1.0953f419900a7p+0, -0x1.a6f9db6475fcep-5 },
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{ 0x1p+0, 0x0p+0 },
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{ 0x1.e608cfd9a47acp-1, 0x1.338ca9f24f53dp-4 },
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{ 0x1.ca4b31f026aap-1, 0x1.476a9543891bap-3 },
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{ 0x1.b2036576afce6p-1, 0x1.e840b4ac4e4d2p-3 },
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{ 0x1.9c2d163a1aa2dp-1, 0x1.40645f0c6651cp-2 },
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{ 0x1.886e6037841edp-1, 0x1.88e9c2c1b9ff8p-2 },
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{ 0x1.767dcf5534862p-1, 0x1.ce0a44eb17bccp-2 },
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},
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.poly = {
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-0x1.712b6f70a7e4dp-2, 0x1.ecabf496832ep-2, -0x1.715479ffae3dep-1,
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0x1.715475f35c8b8p0,
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}
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};
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