1 | /* Boost interval/detail/x86gcc_rounding_control.hpp file |
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2 | * |
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3 | * This header provides a rounding control policy |
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4 | * that avoids flushing results to memory. In |
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5 | * order for this optimization to be reliable, it |
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6 | * should be used only when no underflow or |
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7 | * overflow would happen without it. Indeed, only |
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8 | * values in range are correctly rounded. |
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9 | * |
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10 | * Copyright 2002 Hervé Brönnimann, Guillaume Melquiond, Sylvain Pion |
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11 | * |
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12 | * Distributed under the Boost Software License, Version 1.0. |
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13 | * (See accompanying file LICENSE_1_0.txt or |
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14 | * copy at http://www.boost.org/LICENSE_1_0.txt) |
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15 | */ |
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16 | |
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17 | #ifndef BOOST_NUMERIC_INTERVAL_EXT_X86_FAST_ROUNDING_CONTROL_HPP |
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18 | #define BOOST_NUMERIC_INTERVAL_EXT_X86_FAST_ROUNDING_CONTROL_HPP |
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19 | |
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20 | namespace boost { |
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21 | namespace numeric { |
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22 | namespace interval_lib { |
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23 | |
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24 | namespace detail { |
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25 | |
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26 | // exceptions masked, expected precision (the mask is 0x0300) |
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27 | static const fpu_rounding_modes rnd_mode_f = { 0x107f, 0x147f, 0x187f, 0x1c7f }; |
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28 | static const fpu_rounding_modes rnd_mode_d = { 0x127f, 0x167f, 0x1a7f, 0x1e7f }; |
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29 | static const fpu_rounding_modes rnd_mode_l = { 0x137f, 0x177f, 0x1b7f, 0x1f7f }; |
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30 | |
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31 | } // namespace detail |
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32 | |
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33 | template<class T> |
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34 | struct x86_fast_rounding_control; |
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35 | |
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36 | template<> |
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37 | struct x86_fast_rounding_control<float>: detail::x86_rounding |
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38 | { |
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39 | static void to_nearest() { set_rounding_mode(detail::rnd_mode_f.to_nearest); } |
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40 | static void downward() { set_rounding_mode(detail::rnd_mode_f.downward); } |
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41 | static void upward() { set_rounding_mode(detail::rnd_mode_f.upward); } |
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42 | static void toward_zero() { set_rounding_mode(detail::rnd_mode_f.toward_zero); } |
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43 | static const float& force_rounding(const float& r) { return r; } |
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44 | }; |
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45 | |
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46 | template<> |
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47 | struct x86_fast_rounding_control<double>: detail::x86_rounding |
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48 | { |
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49 | static void to_nearest() { set_rounding_mode(detail::rnd_mode_d.to_nearest); } |
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50 | static void downward() { set_rounding_mode(detail::rnd_mode_d.downward); } |
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51 | static void upward() { set_rounding_mode(detail::rnd_mode_d.upward); } |
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52 | static void toward_zero() { set_rounding_mode(detail::rnd_mode_d.toward_zero); } |
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53 | static const double& force_rounding(const double& r) { return r; } |
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54 | }; |
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55 | |
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56 | template<> |
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57 | struct x86_fast_rounding_control<long double>: detail::x86_rounding |
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58 | { |
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59 | static void to_nearest() { set_rounding_mode(detail::rnd_mode_l.to_nearest); } |
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60 | static void downward() { set_rounding_mode(detail::rnd_mode_l.downward); } |
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61 | static void upward() { set_rounding_mode(detail::rnd_mode_l.upward); } |
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62 | static void toward_zero() { set_rounding_mode(detail::rnd_mode_l.toward_zero); } |
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63 | static const long double& force_rounding(const long double& r) { return r; } |
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64 | }; |
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65 | |
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66 | } // namespace interval_lib |
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67 | } // namespace numeric |
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68 | } // namespace boost |
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69 | |
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70 | #endif // BOOST_NUMERIC_INTERVAL_EXT_X86_FAST_ROUNDING_CONTROL_HPP |
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