1 | /* Copyright (C) 2002 by Red Hat, Incorporated. All rights reserved. |
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2 | * |
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3 | * Permission to use, copy, modify, and distribute this software |
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4 | * is freely granted, provided that this notice is preserved. |
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5 | */ |
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6 | /* |
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7 | FUNCTION |
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8 | <<signbit>>---Does floating-point number have negative sign? |
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9 | |
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10 | INDEX |
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11 | signbit |
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12 | |
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13 | SYNOPSIS |
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14 | #include <math.h> |
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15 | int signbit(real-floating <[x]>); |
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16 | |
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17 | DESCRIPTION |
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18 | The <<signbit>> macro determines whether the sign of its argument value is |
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19 | negative. The macro reports the sign of all values, including infinities, |
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20 | zeros, and NaNs. If zero is unsigned, it is treated as positive. As shown in |
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21 | the synopsis, the argument is "real-floating," meaning that any of the real |
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22 | floating-point types (float, double, etc.) may be given to it. |
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23 | |
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24 | Note that because of the possibilities of signed 0 and NaNs, the expression |
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25 | "<[x]> < 0.0" does not give the same result as <<signbit>> in all cases. |
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26 | |
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27 | RETURNS |
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28 | The <<signbit>> macro returns a nonzero value if and only if the sign of its |
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29 | argument value is negative. |
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30 | |
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31 | PORTABILITY |
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32 | C99, POSIX. |
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33 | |
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34 | */ |
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35 | |
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36 | #include "fdlibm.h" |
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37 | |
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38 | int __signbitf (float x); |
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39 | int __signbitd (double x); |
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40 | |
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41 | int |
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42 | __signbitf (float x) |
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43 | { |
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44 | __uint32_t w; |
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45 | |
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46 | GET_FLOAT_WORD(w,x); |
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47 | |
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48 | return (w & 0x80000000) != 0; |
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49 | } |
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50 | |
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51 | int |
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52 | __signbitd (double x) |
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53 | { |
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54 | __uint32_t msw; |
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55 | |
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56 | GET_HIGH_WORD(msw, x); |
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57 | |
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58 | return (msw & 0x80000000) != 0; |
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59 | } |
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