1 // softclip 2 // Copyright (C) 2008, 2009 Tim Blechmann 3 // 4 // This program is free software; you can redistribute it and/or modify 5 // it under the terms of the GNU General Public License as published by 6 // the Free Software Foundation; either version 2 of the License, or 7 // (at your option) any later version. 8 // 9 // This program is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU General Public License for more details. 13 // 14 // You should have received a copy of the GNU General Public License 15 // along with this program; see the file COPYING. If not, write to 16 // the Free Software Foundation, Inc., 59 Temple Place - Suite 330, 17 // Boston, MA 02111-1307, USA. 18 19 #ifndef SIMD_SOFTCLIP_HPP 20 #define SIMD_SOFTCLIP_HPP 21 22 #include <cassert> 23 #include <cmath> 24 25 #include "vec.hpp" 26 27 #include "detail/define_macros.hpp" 28 29 #if defined(__GNUC__) && defined(NDEBUG) 30 #define always_inline inline __attribute__((always_inline)) 31 #else 32 #define always_inline inline 33 #endif 34 35 namespace nova { 36 namespace detail { 37 38 struct softclip 39 { 40 template <typename FloatType> s_runnova::detail::softclip41 static FloatType s_run(FloatType arg) 42 { 43 FloatType abs = std::fabs(arg); 44 if (abs < FloatType(0.5)) 45 return arg; 46 else 47 return (abs - FloatType(0.25)) / arg; 48 } 49 50 template <typename FloatType> operator ()nova::detail::softclip51 always_inline FloatType operator()(FloatType arg) const 52 { 53 return s_run(arg); 54 } 55 56 #if defined(__SSE__) || defined(__AVX__) 57 /* this computes both parts of the branch 58 * 59 * benchmarks (core2) showed: 60 * 6.5 seconds for simdfied code 61 * 5.3 seconds for non-simd code for samples with abs(sample) < 0.5 62 * 17 seconds when 50% of the samples have abs(sample) < 0.5 63 * 26 seconds for samples with abs(sample) > 0.5 64 * 65 * on intel nethalem cpus, the simdfied code is faster than all non-simd code 66 * */ 67 68 template <typename FloatType> operator ()nova::detail::softclip69 always_inline vec<FloatType> operator()(vec<FloatType> arg) const 70 { 71 typedef vec<FloatType> vec_type; 72 73 const vec_type const05 = vec_type::gen_05(); 74 const vec_type const025 (0.25); 75 76 vec_type abs_ = abs(arg); 77 vec_type selecter = mask_lt(abs_, const05); 78 vec_type alt_ret = (abs_ - const025) / arg; 79 80 return select(alt_ret, arg, selecter); 81 } 82 #else 83 template <typename FloatType> operator ()nova::detail::softclip84 always_inline vec<FloatType> operator()(vec<FloatType> arg) const 85 { 86 return arg.collect(softclip::s_run<FloatType>); 87 } 88 #endif 89 }; 90 91 } /* namespace detail */ 92 93 NOVA_SIMD_DEFINE_UNARY_WRAPPER(softclip, detail::softclip) 94 95 96 } /* namespace nova */ 97 98 #undef always_inline 99 100 #endif /* SIMD_SOFTCLIP_HPP */ 101