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1 /*-------------------------------------------------------------------- |
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2 *© Portions copyright (c) 2006 Nokia Corporation. All rights reserved. |
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3 *-------------------------------------------------------------------- |
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4 */ |
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5 /* @(#)s_floor.c 5.1 93/09/24 */ |
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6 /* |
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7 * ==================================================== |
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8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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9 * |
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10 * Developed at SunPro, a Sun Microsystems, Inc. business. |
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11 * Permission to use, copy, modify, and distribute this |
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12 * software is freely granted, provided that this notice |
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13 * is preserved. |
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14 * ==================================================== |
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15 */ |
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16 #ifndef __SYMBIAN32__ |
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17 #ifndef lint |
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18 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_floor.c,v 1.9 2003/07/23 04:53:46 peter Exp $"; |
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19 #endif |
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20 #endif //__SYMBIAN32__ |
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21 |
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22 /* |
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23 * floor(x) |
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24 * Return x rounded toward -inf to integral value |
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25 * Method: |
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26 * Bit twiddling. |
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27 * Exception: |
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28 * Inexact flag raised if x not equal to floor(x). |
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29 */ |
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30 |
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31 #include <math.h> |
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32 #include "math_private.h" |
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33 |
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34 static const double huge = 1.0e300; |
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35 |
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36 EXPORT_C double floor(double x) |
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37 { |
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38 int32_t i0,i1,j0; |
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39 u_int32_t i,j; |
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40 EXTRACT_WORDS(i0,i1,x); |
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41 j0 = ((i0>>20)&0x7ff)-0x3ff; |
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42 if(j0<20) { |
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43 if(j0<0) { /* raise inexact if x != 0 */ |
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44 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ |
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45 if(i0>=0) {i0=i1=0;} |
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46 else if(((i0&0x7fffffff)|i1)!=0) |
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47 { i0=0xbff00000;i1=0;} |
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48 } |
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49 } else { |
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50 i = (0x000fffff)>>j0; |
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51 if(((i0&i)|i1)==0) return x; /* x is integral */ |
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52 if(huge+x>0.0) { /* raise inexact flag */ |
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53 if(i0<0) i0 += (0x00100000)>>j0; |
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54 i0 &= (~i); i1=0; |
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55 } |
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56 } |
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57 } else if (j0>51) { |
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58 if(j0==0x400) return x+x; /* inf or NaN */ |
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59 else return x; /* x is integral */ |
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60 } else { |
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61 i = ((u_int32_t)(0xffffffff))>>(j0-20); |
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62 if((i1&i)==0) return x; /* x is integral */ |
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63 if(huge+x>0.0) { /* raise inexact flag */ |
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64 if(i0<0) { |
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65 if(j0==20) i0+=1; |
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66 else { |
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67 j = i1+(1<<(52-j0)); |
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68 if(j<i1) i0 +=1 ; /* got a carry */ |
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69 i1=j; |
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70 } |
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71 } |
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72 i1 &= (~i); |
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73 } |
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74 } |
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75 INSERT_WORDS(x,i0,i1); |
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76 return x; |
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77 } |