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1 /* S_CEIL.C |
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2 * |
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3 * Portions Copyright (c) 1993-1999 Nokia Corporation and/or its subsidiary(-ies). |
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4 * All rights reserved. |
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5 */ |
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6 |
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7 |
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8 /* @(#)s_ceil.c 5.1 93/09/24 */ |
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9 /* |
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10 * ==================================================== |
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11 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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12 * |
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13 * Developed at SunPro, a Sun Microsystems, Inc. business. |
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14 * Permission to use, copy, modify, and distribute this |
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15 * software is freely granted, provided that this notice |
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16 * is preserved. |
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17 * ==================================================== |
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18 */ |
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19 |
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20 /* |
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21 * ceil(x) |
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22 * Return x rounded toward -inf to integral value |
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23 * Method: |
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24 * Bit twiddling. |
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25 * Exception: |
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26 * Inexact flag raised if x not equal to ceil(x). |
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27 */ |
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28 |
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29 #include "FDLIBM.H" |
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30 |
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31 static const double huge = 1.0e300; |
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32 |
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33 /** |
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34 Round up a value. |
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35 Returns the smallest integer that is greater or equal to x |
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36 @return Ceiling of x. |
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37 @param x Floating point value |
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38 */ |
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39 EXPORT_C double ceil(double x) __SOFTFP |
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40 { |
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41 __int32_t i0,i1,j0; |
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42 __uint32_t i,j; |
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43 EXTRACT_WORDS(i0,i1,x); |
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44 j0 = ((i0>>20)&0x7ff)-0x3ff; |
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45 if(j0<20) { |
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46 if(j0<0) { /* raise inexact if x != 0 */ |
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47 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */ |
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48 if(i0<0) {i0=0x80000000;i1=0;} |
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49 else if((i0|i1)!=0) { i0=0x3ff00000;i1=0;} |
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50 } |
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51 } else { |
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52 i = (0x000fffff)>>j0; |
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53 if(((i0&i)|i1)==0) return x; /* x is integral */ |
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54 if(huge+x>0.0) { /* raise inexact flag */ |
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55 if(i0>0) i0 += (0x00100000)>>j0; |
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56 i0 &= (~i); i1=0; |
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57 } |
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58 } |
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59 } else if (j0>51) { |
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60 if(j0==0x400) return x+x; /* inf or NaN */ |
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61 else return x; /* x is integral */ |
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62 } else { |
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63 i = ((__uint32_t)(0xffffffff))>>(j0-20); |
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64 if((i1&i)==0) return x; /* x is integral */ |
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65 if(huge+x>0.0) { /* raise inexact flag */ |
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66 if(i0>0) { |
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67 if(j0==20) i0+=1; |
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68 else { |
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69 j = i1 + (1<<(52-j0)); |
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70 if(j<i1) i0+=1; /* got a carry */ |
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71 i1 = j; |
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72 } |
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73 } |
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74 i1 &= (~i); |
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75 } |
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76 } |
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77 INSERT_WORDS(x,i0,i1); |
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78 return x; |
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79 } |