1 | /* |
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2 | * Copyright © 2005-2014 Rich Felker, et al. |
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3 | * |
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4 | * Permission is hereby granted, free of charge, to any person obtaining |
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5 | * a copy of this software and associated documentation files (the |
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6 | * "Software"), to deal in the Software without restriction, including |
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7 | * without limitation the rights to use, copy, modify, merge, publish, |
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8 | * distribute, sublicense, and/or sell copies of the Software, and to |
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9 | * permit persons to whom the Software is furnished to do so, subject to |
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10 | * the following conditions: |
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11 | * |
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12 | * The above copyright notice and this permission notice shall be |
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13 | * included in all copies or substantial portions of the Software. |
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14 | * |
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15 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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16 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
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17 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
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18 | * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
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19 | * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
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20 | * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
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21 | * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
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22 | */ |
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23 | |
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24 | #include <math.h> |
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25 | #include <inttypes.h> |
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26 | #include "local.h" |
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27 | |
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28 | union fshape { |
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29 | float value; |
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30 | uint32_t bits; |
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31 | }; |
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32 | |
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33 | // This is only necessary because the implementation of isnan only works |
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34 | // properly when long double == double. |
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35 | // See: https://sourceware.org/ml/newlib/2014/msg00684.html |
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36 | #ifdef _LDBL_EQ_DOUBLE |
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37 | |
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38 | float |
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39 | nexttowardf (float x, long double y) |
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40 | { |
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41 | union fshape ux; |
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42 | uint32_t e; |
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43 | |
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44 | if (isnan(x) || isnan(y)) |
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45 | return x + y; |
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46 | if (x == y) |
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47 | return y; |
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48 | ux.value = x; |
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49 | if (x == 0) { |
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50 | ux.bits = 1; |
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51 | if (signbit(y)) |
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52 | ux.bits |= 0x80000000; |
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53 | } else if (x < y) { |
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54 | if (signbit(x)) |
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55 | ux.bits--; |
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56 | else |
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57 | ux.bits++; |
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58 | } else { |
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59 | if (signbit(x)) |
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60 | ux.bits++; |
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61 | else |
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62 | ux.bits--; |
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63 | } |
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64 | e = ux.bits & 0x7f800000; |
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65 | /* raise overflow if ux.value is infinite and x is finite */ |
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66 | if (e == 0x7f800000) { |
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67 | volatile float force_eval; |
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68 | force_eval = x + x; |
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69 | } |
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70 | /* raise underflow if ux.value is subnormal or zero */ |
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71 | if (e == 0) { |
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72 | volatile float force_eval; |
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73 | force_eval = x*x + ux.value*ux.value; |
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74 | } |
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75 | return ux.value; |
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76 | } |
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77 | |
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78 | #endif // _LDBL_EQ_DOUBLE |
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