1 | // |
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2 | // Lol Engine |
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3 | // |
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4 | // Copyright: (c) 2010-2011 Sam Hocevar <sam@hocevar.net> |
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5 | // This program is free software; you can redistribute it and/or |
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6 | // modify it under the terms of the Do What The Fuck You Want To |
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7 | // Public License, Version 2, as published by Sam Hocevar. See |
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8 | // http://sam.zoy.org/projects/COPYING.WTFPL for more details. |
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9 | // |
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10 | |
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11 | #if defined HAVE_CONFIG_H |
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12 | # include "config.h" |
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13 | #endif |
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14 | |
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15 | #include <cstring> |
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16 | #include <cstdio> |
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17 | |
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18 | #include "core.h" |
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19 | |
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20 | using namespace std; |
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21 | |
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22 | namespace lol |
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23 | { |
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24 | |
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25 | real::real(float f) |
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26 | { |
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27 | union { float f; uint32_t x; } u = { f }; |
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28 | |
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29 | uint32_t sign = u.x & 0x80000000u; |
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30 | int e = ((u.x >> 23) & 0xff) + (1 << 30) - (1 << 7); |
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31 | |
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32 | m_signexp = sign | e; |
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33 | m_mantissa[0] = u.x >> 7; |
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34 | m_mantissa[1] = u.x << 9; |
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35 | memset(m_mantissa + 2, 0, sizeof(m_mantissa) - sizeof(m_mantissa[0])); |
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36 | } |
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37 | |
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38 | real::operator float() const |
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39 | { |
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40 | union { float f; uint32_t x; } u; |
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41 | |
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42 | u.x = m_mantissa[0] << 7; |
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43 | u.x |= m_mantissa[1] >> 9; |
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44 | u.x |= ((m_signexp & 0x7fffffffu) - (1 << 30) + (1 << 7)) << 23; |
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45 | u.x |= m_signexp & 0x80000000u; |
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46 | |
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47 | return u.f; |
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48 | } |
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49 | |
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50 | real real::operator *(real const &x) const |
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51 | { |
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52 | real ret; |
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53 | |
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54 | ret.m_signexp = (m_signexp ^ x.m_signexp) & 0x80000000u; |
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55 | int e = (m_signexp & 0x7fffffffu) - (1 << 30) + 1 |
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56 | + (x.m_signexp & 0x7fffffffu) - (1 << 30) + 1; |
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57 | |
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58 | /* Accumulate low order product; no need to store it, we just |
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59 | * want the carry value */ |
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60 | uint32_t carry = 0; |
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61 | for (int i = 0; i < BIGITS; i++) |
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62 | { |
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63 | for (int j = 0; j < i + 1; j++) |
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64 | carry += m_mantissa[BIGITS - 1 - j] |
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65 | * x.m_mantissa[BIGITS - 1 + j - i]; |
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66 | carry >>= 16; |
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67 | } |
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68 | |
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69 | for (int i = 0; i < BIGITS; i++) |
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70 | { |
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71 | for (int j = i + 1; j < BIGITS; j++) |
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72 | carry += m_mantissa[BIGITS - 1 - j] |
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73 | * x.m_mantissa[j - 1 - i]; |
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74 | |
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75 | carry += m_mantissa[BIGITS - 1 - i]; |
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76 | carry += x.m_mantissa[BIGITS - 1 - i]; |
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77 | ret.m_mantissa[BIGITS - 1 - i] = carry & 0xffffu; |
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78 | carry >>= 16; |
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79 | } |
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80 | |
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81 | /* Renormalise in case we overflowed the mantissa */ |
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82 | if (carry) |
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83 | { |
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84 | carry--; |
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85 | for (int i = 0; i < BIGITS; i++) |
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86 | { |
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87 | uint16_t tmp = ret.m_mantissa[i]; |
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88 | ret.m_mantissa[i] = (carry << 15) | (tmp >> 1); |
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89 | carry = tmp & 0x0001u; |
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90 | } |
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91 | e++; |
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92 | } |
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93 | |
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94 | ret.m_signexp |= e + (1 << 30) - 1; |
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95 | |
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96 | return ret; |
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97 | } |
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98 | |
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99 | void real::print() const |
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100 | { |
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101 | printf("%x %08x ", m_signexp >> 31, (m_signexp << 1) >> 1); |
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102 | for (int i = 0; i < BIGITS; i++) |
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103 | printf("%04x ", m_mantissa[i]); |
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104 | printf("\n"); |
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105 | } |
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106 | |
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107 | } /* namespace lol */ |
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108 | |
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