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4349 | Serge | 1 | |
2 | /* |
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3 | * ==================================================== |
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4 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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5 | * |
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6 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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7 | * Permission to use, copy, modify, and distribute this |
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8 | * software is freely granted, provided that this notice |
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9 | * is preserved. |
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10 | * ==================================================== |
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11 | */ |
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12 | |||
13 | |||
14 | FUNCTION |
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15 | < |
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16 | |||
17 | |||
18 | INDEX |
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19 | fpclassify |
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20 | INDEX |
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21 | isfinite |
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22 | INDEX |
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23 | isinf |
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24 | INDEX |
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25 | isnan |
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26 | INDEX |
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27 | isnormal |
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28 | @c C99 end) |
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29 | @c SUSv2 (start |
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30 | INDEX |
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31 | isnan |
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32 | INDEX |
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33 | isinf |
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34 | INDEX |
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35 | finite |
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36 | |||
37 | |||
38 | isnanf |
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39 | INDEX |
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40 | isinff |
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41 | INDEX |
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42 | finitef |
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43 | @c SUSv2 end) |
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44 | |||
45 | |||
46 | [C99 standard macros:] |
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47 | #include |
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48 | int fpclassify(real-floating <[x]>); |
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49 | int isfinite(real-floating <[x]>); |
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50 | int isinf(real-floating <[x]>); |
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51 | int isnan(real-floating <[x]>); |
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52 | int isnormal(real-floating <[x]>); |
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53 | |||
54 | |||
55 | #include |
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56 | int isnan(double <[arg]>); |
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57 | int isinf(double <[arg]>); |
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58 | int finite(double <[arg]>); |
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59 | int isnanf(float <[arg]>); |
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60 | int isinff(float <[arg]>); |
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61 | int finitef(float <[arg]>); |
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62 | |||
63 | |||
64 | < |
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65 | defined for use in classifying floating-point numbers. This is a help because |
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66 | of special "values" like NaN and infinities. In the synopses shown, |
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67 | "real-floating" indicates that the argument is an expression of real floating |
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68 | type. These function-like macros are C99 and POSIX-compliant, and should be |
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69 | used instead of the now-archaic SUSv2 functions. |
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70 | |||
71 | |||
72 | subnormal, zero, or into another implementation-defined category. First, an |
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73 | argument represented in a format wider than its semantic type is converted to |
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74 | its semantic type. Then classification is based on the type of the argument. |
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75 | The < |
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76 | appropriate to the value of its argument: |
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77 | |||
78 | |||
79 | o FP_INFINITE |
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80 | <[x]> is either plus or minus infinity; |
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81 | o FP_NAN |
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82 | <[x]> is "Not A Number" (plus or minus); |
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83 | o FP_NORMAL |
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84 | <[x]> is a "normal" number (i.e. is none of the other special forms); |
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85 | o FP_SUBNORMAL |
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86 | <[x]> is too small be stored as a regular normalized number (i.e. loss of precision is likely); or |
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87 | o FP_ZERO |
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88 | <[x]> is 0 (either plus or minus). |
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89 | o- |
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90 | |||
91 | |||
92 | classifying floating-point numbers, providing the following equivalent |
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93 | relations: |
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94 | |||
95 | |||
96 | o < |
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97 | returns non-zero if <[x]> is finite. (It is equivalent to |
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98 | (< |
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99 | |||
100 | |||
101 | returns non-zero if <[x]> is infinite. (It is equivalent to |
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102 | (< |
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103 | |||
104 | |||
105 | returns non-zero if <[x]> is NaN. (It is equivalent to |
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106 | (< |
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107 | |||
108 | |||
109 | returns non-zero if <[x]> is normal. (It is equivalent to |
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110 | (< |
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111 | o- |
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112 | |||
113 | |||
114 | argument supplied. |
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115 | |||
116 | |||
117 | biased exponent in the binary-encoded number): |
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118 | o+ |
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119 | o zero |
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120 | A number which contains all zero bits, excluding the sign bit. |
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121 | o subnormal |
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122 | A number with a zero exponent but a nonzero fraction. |
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123 | o normal |
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124 | A number with an exponent and a fraction. |
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125 | o infinity |
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126 | A number with an all 1's exponent and a zero fraction. |
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127 | o NAN |
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128 | A number with an all 1's exponent and a nonzero fraction. |
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129 | |||
130 | |||
131 | |||
132 | |||
133 | returns 1 if the argument is infinity. < |
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134 | argument is zero, subnormal or normal. |
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135 | |||
136 | |||
137 | operations as their < |
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138 | counterparts, but on single-precision floating-point numbers. |
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139 | |||
140 | |||
141 | and < |
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142 | floating-point. The SUSv2 standard declares < |
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143 | a function taking double. Newlib has decided to declare |
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144 | them both as macros in math.h and as functions in ieeefp.h to |
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145 | maintain backward compatibility. |
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146 | |||
147 | |||
148 | @comment Formatting note: "$@" forces a new line |
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149 | The fpclassify macro returns the value corresponding to the appropriate FP_ macro.@* |
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150 | The isfinite macro returns nonzero if <[x]> is finite, else 0.@* |
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151 | The isinf macro returns nonzero if <[x]> is infinite, else 0.@* |
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152 | The isnan macro returns nonzero if <[x]> is an NaN, else 0.@* |
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153 | The isnormal macro returns nonzero if <[x]> has a normal value, else 0. |
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154 | |||
155 | |||
156 | math.h macros are C99, POSIX. |
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157 | |||
158 | |||
159 | |||
160 | |||
161 | isnan - pure |
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162 | QUICKREF |
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163 | isinf - pure |
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164 | QUICKREF |
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165 | finite - pure |
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166 | QUICKREF |
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167 | isnan - pure |
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168 | QUICKREF |
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169 | isinf - pure |
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170 | QUICKREF |
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171 | finite - pure |
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172 | */ |
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173 | |||
174 | |||
175 | * isnan(x) returns 1 is x is nan, else 0; |
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176 | * no branching! |
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177 | * |
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178 | * The C99 standard dictates that isnan is a macro taking |
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179 | * multiple floating-point types while the SUSv2 standard |
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180 | * notes it is a function taking a double argument. Newlib |
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181 | * has chosen to implement it as a macro in |
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182 | * declare it as a function in |
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183 | */ |
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184 | |||
185 | |||
186 | #include |
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187 | |||
188 | |||
189 | |||
190 | |||
191 | int isnan(double x) |
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192 | #else |
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193 | int isnan(x) |
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194 | double x; |
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195 | #endif |
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196 | { |
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197 | __int32_t hx,lx; |
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198 | EXTRACT_WORDS(hx,lx,x); |
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199 | hx &= 0x7fffffff; |
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200 | hx |= (__uint32_t)(lx|(-lx))>>31; |
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201 | hx = 0x7ff00000 - hx; |
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202 | return (int)(((__uint32_t)(hx))>>31); |
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203 | } |
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204 | |||
205 | |||
206 |