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// Optimizations for random number functions, x86 version -*- C++ -*- |
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|
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// Copyright (C) 2012-2021 Free Software Foundation, Inc. |
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// |
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// This file is part of the GNU ISO C++ Library. This library is free |
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// software; you can redistribute it and/or modify it under the |
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// terms of the GNU General Public License as published by the |
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// Free Software Foundation; either version 3, or (at your option) |
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// any later version. |
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|
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// This 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 |
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// GNU General Public License for more details. |
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|
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// Under Section 7 of GPL version 3, you are granted additional |
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// permissions described in the GCC Runtime Library Exception, version |
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// 3.1, as published by the Free Software Foundation. |
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|
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// You should have received a copy of the GNU General Public License and |
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// a copy of the GCC Runtime Library Exception along with this program; |
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
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// <http://www.gnu.org/licenses/>. |
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|
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/** @file bits/opt_random.h |
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* This is an internal header file, included by other library headers. |
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* Do not attempt to use it directly. @headername{random} |
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*/ |
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|
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#ifndef _BITS_OPT_RANDOM_H |
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#define _BITS_OPT_RANDOM_H 1 |
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|
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#ifdef __SSE3__ |
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#include <pmmintrin.h> |
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#endif |
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|
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|
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#pragma GCC system_header |
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|
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|
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namespace std _GLIBCXX_VISIBILITY(default) |
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{ |
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_GLIBCXX_BEGIN_NAMESPACE_VERSION |
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|
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#ifdef __SSE3__ |
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template<> |
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template<typename _UniformRandomNumberGenerator> |
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void |
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normal_distribution<double>:: |
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__generate(typename normal_distribution<double>::result_type* __f, |
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typename normal_distribution<double>::result_type* __t, |
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_UniformRandomNumberGenerator& __urng, |
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const param_type& __param) |
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{ |
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typedef uint64_t __uctype; |
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|
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if (__f == __t) |
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return; |
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|
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if (_M_saved_available) |
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{ |
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_M_saved_available = false; |
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*__f++ = _M_saved * __param.stddev() + __param.mean(); |
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|
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if (__f == __t) |
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return; |
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} |
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|
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constexpr uint64_t __maskval = 0xfffffffffffffull; |
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static const __m128i __mask = _mm_set1_epi64x(__maskval); |
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static const __m128i __two = _mm_set1_epi64x(0x4000000000000000ull); |
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static const __m128d __three = _mm_set1_pd(3.0); |
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const __m128d __av = _mm_set1_pd(__param.mean()); |
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|
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const __uctype __urngmin = __urng.min(); |
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const __uctype __urngmax = __urng.max(); |
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const __uctype __urngrange = __urngmax - __urngmin; |
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const __uctype __uerngrange = __urngrange + 1; |
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|
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while (__f + 1 < __t) |
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{ |
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double __le; |
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__m128d __x; |
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do |
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{ |
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union |
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{ |
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__m128i __i; |
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__m128d __d; |
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} __v; |
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|
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if (__urngrange > __maskval) |
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{ |
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if (__detail::_Power_of_2(__uerngrange)) |
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__v.__i = _mm_and_si128(_mm_set_epi64x(__urng(), |
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__urng()), |
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__mask); |
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else |
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{ |
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const __uctype __uerange = __maskval + 1; |
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const __uctype __scaling = __urngrange / __uerange; |
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const __uctype __past = __uerange * __scaling; |
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uint64_t __v1; |
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do |
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__v1 = __uctype(__urng()) - __urngmin; |
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while (__v1 >= __past); |
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__v1 /= __scaling; |
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uint64_t __v2; |
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do |
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__v2 = __uctype(__urng()) - __urngmin; |
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while (__v2 >= __past); |
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__v2 /= __scaling; |
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|
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__v.__i = _mm_set_epi64x(__v1, __v2); |
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} |
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} |
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else if (__urngrange == __maskval) |
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__v.__i = _mm_set_epi64x(__urng(), __urng()); |
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else if ((__urngrange + 2) * __urngrange >= __maskval |
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&& __detail::_Power_of_2(__uerngrange)) |
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{ |
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uint64_t __v1 = __urng() * __uerngrange + __urng(); |
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uint64_t __v2 = __urng() * __uerngrange + __urng(); |
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|
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__v.__i = _mm_and_si128(_mm_set_epi64x(__v1, __v2), |
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__mask); |
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} |
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else |
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{ |
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size_t __nrng = 2; |
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__uctype __high = __maskval / __uerngrange / __uerngrange; |
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while (__high > __uerngrange) |
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{ |
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++__nrng; |
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__high /= __uerngrange; |
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} |
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const __uctype __highrange = __high + 1; |
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const __uctype __scaling = __urngrange / __highrange; |
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const __uctype __past = __highrange * __scaling; |
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__uctype __tmp; |
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|
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uint64_t __v1; |
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do |
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{ |
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do |
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__tmp = __uctype(__urng()) - __urngmin; |
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while (__tmp >= __past); |
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__v1 = __tmp / __scaling; |
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for (size_t __cnt = 0; __cnt < __nrng; ++__cnt) |
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{ |
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__tmp = __v1; |
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__v1 *= __uerngrange; |
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__v1 += __uctype(__urng()) - __urngmin; |
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} |
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} |
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while (__v1 > __maskval || __v1 < __tmp); |
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|
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uint64_t __v2; |
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do |
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{ |
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do |
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__tmp = __uctype(__urng()) - __urngmin; |
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while (__tmp >= __past); |
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__v2 = __tmp / __scaling; |
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for (size_t __cnt = 0; __cnt < __nrng; ++__cnt) |
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{ |
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__tmp = __v2; |
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__v2 *= __uerngrange; |
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__v2 += __uctype(__urng()) - __urngmin; |
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} |
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} |
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while (__v2 > __maskval || __v2 < __tmp); |
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|
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__v.__i = _mm_set_epi64x(__v1, __v2); |
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} |
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|
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__v.__i = _mm_or_si128(__v.__i, __two); |
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__x = _mm_sub_pd(__v.__d, __three); |
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__m128d __m = _mm_mul_pd(__x, __x); |
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__le = _mm_cvtsd_f64(_mm_hadd_pd (__m, __m)); |
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} |
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while (__le == 0.0 || __le >= 1.0); |
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|
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double __mult = (std::sqrt(-2.0 * std::log(__le) / __le) |
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* __param.stddev()); |
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|
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__x = _mm_add_pd(_mm_mul_pd(__x, _mm_set1_pd(__mult)), __av); |
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|
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_mm_storeu_pd(__f, __x); |
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__f += 2; |
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} |
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|
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if (__f != __t) |
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{ |
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result_type __x, __y, __r2; |
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|
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__detail::_Adaptor<_UniformRandomNumberGenerator, result_type> |
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__aurng(__urng); |
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|
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do |
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{ |
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__x = result_type(2.0) * __aurng() - 1.0; |
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__y = result_type(2.0) * __aurng() - 1.0; |
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__r2 = __x * __x + __y * __y; |
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} |
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while (__r2 > 1.0 || __r2 == 0.0); |
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|
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const result_type __mult = std::sqrt(-2 * std::log(__r2) / __r2); |
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_M_saved = __x * __mult; |
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_M_saved_available = true; |
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*__f = __y * __mult * __param.stddev() + __param.mean(); |
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} |
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} |
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#endif |
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|
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|
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_GLIBCXX_END_NAMESPACE_VERSION |
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} // namespace |
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|
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|
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#endif // _BITS_OPT_RANDOM_H |
