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1 /* |
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2 * ==================================================== |
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3 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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4 * |
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5 * Developed at SunPro, a Sun Microsystems, Inc. business. |
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6 * Permission to use, copy, modify, and distribute this |
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7 * software is freely granted, provided that this notice |
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8 * is preserved. |
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9 * ==================================================== |
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10 */ |
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11 |
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12 /* |
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13 * from: @(#)fdlibm.h 5.1 93/09/24 |
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14 * $Id: math_private.h 1969 2006-02-24 09:57:14Z slouken $ |
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15 */ |
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16 |
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17 #ifndef _MATH_PRIVATE_H_ |
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18 #define _MATH_PRIVATE_H_ |
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19 |
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20 #include "SDL_name.h" |
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21 #include "SDL_endian.h" |
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22 |
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23 #define huge really_big /* huge is a reserved keyword in VC++ 6.0 */ |
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24 #define u_int32_t uint32_t |
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25 |
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26 /* The original fdlibm code used statements like: |
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27 n0 = ((*(int*)&one)>>29)^1; * index of high word * |
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28 ix0 = *(n0+(int*)&x); * high word of x * |
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29 ix1 = *((1-n0)+(int*)&x); * low word of x * |
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30 to dig two 32 bit words out of the 64 bit IEEE floating point |
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31 value. That is non-ANSI, and, moreover, the gcc instruction |
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32 scheduler gets it wrong. We instead use the following macros. |
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33 Unlike the original code, we determine the endianness at compile |
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34 time, not at run time; I don't see much benefit to selecting |
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35 endianness at run time. */ |
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36 |
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37 /* A union which permits us to convert between a double and two 32 bit |
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38 ints. */ |
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39 |
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40 /* |
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41 * Math on arm is special: |
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42 * For FPA, float words are always big-endian. |
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43 * For VFP, floats words follow the memory system mode. |
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44 */ |
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45 |
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46 #if (SDL_BYTEORDER == SDL_BIG_ENDIAN) || \ |
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47 (!defined(__VFP_FP__) && (defined(__arm__) || defined(__thumb__))) |
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48 |
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49 typedef union |
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50 { |
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51 double value; |
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52 struct |
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53 { |
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54 u_int32_t msw; |
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55 u_int32_t lsw; |
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56 } parts; |
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57 } ieee_double_shape_type; |
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58 |
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59 #else |
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60 |
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61 typedef union |
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62 { |
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63 double value; |
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64 struct |
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65 { |
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66 u_int32_t lsw; |
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67 u_int32_t msw; |
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68 } parts; |
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69 } ieee_double_shape_type; |
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70 |
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71 #endif |
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72 |
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73 /* Get two 32 bit ints from a double. */ |
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74 |
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75 #define EXTRACT_WORDS(ix0,ix1,d) \ |
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76 do { \ |
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77 ieee_double_shape_type ew_u; \ |
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78 ew_u.value = (d); \ |
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79 (ix0) = ew_u.parts.msw; \ |
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80 (ix1) = ew_u.parts.lsw; \ |
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81 } while (0) |
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82 |
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83 /* Get the more significant 32 bit int from a double. */ |
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84 |
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85 #define GET_HIGH_WORD(i,d) \ |
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86 do { \ |
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87 ieee_double_shape_type gh_u; \ |
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88 gh_u.value = (d); \ |
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89 (i) = gh_u.parts.msw; \ |
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90 } while (0) |
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91 |
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92 /* Get the less significant 32 bit int from a double. */ |
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93 |
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94 #define GET_LOW_WORD(i,d) \ |
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95 do { \ |
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96 ieee_double_shape_type gl_u; \ |
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97 gl_u.value = (d); \ |
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98 (i) = gl_u.parts.lsw; \ |
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99 } while (0) |
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100 |
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101 /* Set a double from two 32 bit ints. */ |
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102 |
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103 #define INSERT_WORDS(d,ix0,ix1) \ |
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104 do { \ |
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105 ieee_double_shape_type iw_u; \ |
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106 iw_u.parts.msw = (ix0); \ |
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107 iw_u.parts.lsw = (ix1); \ |
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108 (d) = iw_u.value; \ |
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109 } while (0) |
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110 |
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111 /* Set the more significant 32 bits of a double from an int. */ |
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112 |
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113 #define SET_HIGH_WORD(d,v) \ |
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114 do { \ |
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115 ieee_double_shape_type sh_u; \ |
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116 sh_u.value = (d); \ |
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117 sh_u.parts.msw = (v); \ |
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118 (d) = sh_u.value; \ |
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119 } while (0) |
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120 |
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121 /* Set the less significant 32 bits of a double from an int. */ |
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122 |
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123 #define SET_LOW_WORD(d,v) \ |
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124 do { \ |
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125 ieee_double_shape_type sl_u; \ |
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126 sl_u.value = (d); \ |
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127 sl_u.parts.lsw = (v); \ |
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128 (d) = sl_u.value; \ |
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129 } while (0) |
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130 |
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131 /* A union which permits us to convert between a float and a 32 bit |
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132 int. */ |
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133 |
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134 typedef union |
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135 { |
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136 float value; |
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137 u_int32_t word; |
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138 } ieee_float_shape_type; |
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139 |
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140 /* Get a 32 bit int from a float. */ |
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141 |
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142 #define GET_FLOAT_WORD(i,d) \ |
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143 do { \ |
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144 ieee_float_shape_type gf_u; \ |
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145 gf_u.value = (d); \ |
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146 (i) = gf_u.word; \ |
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147 } while (0) |
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148 |
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149 /* Set a float from a 32 bit int. */ |
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150 |
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151 #define SET_FLOAT_WORD(d,i) \ |
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152 do { \ |
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153 ieee_float_shape_type sf_u; \ |
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154 sf_u.word = (i); \ |
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155 (d) = sf_u.value; \ |
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156 } while (0) |
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157 |
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158 |
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159 #ifdef __STDC__ |
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160 static const double |
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161 #else |
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162 static double |
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163 #endif |
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164 zero = 0.0, |
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165 one = 1.0, |
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166 two = 2.0, |
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167 two53 = 9007199254740992.0, /* 0x43400000, 0x00000000 */ |
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168 two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */ |
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169 twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */ |
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170 huge = 1.0e+300, |
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171 tiny = 1.0e-300; |
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172 |
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173 #endif /* _MATH_PRIVATE_H_ */ |