00001 #if !defined(__ppc__)
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00014 #if defined(LIBM_SCCS) && !defined(lint)
00015 static char rcsid[] = "$NetBSD: s_rint.c,v 1.8 1995/05/10 20:48:04 jtc Exp $";
00016 #endif
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00028 #include "math.h"
00029 #include "mathP.h"
00030
00031 #ifdef __STDC__
00032 static const double
00033 #else
00034 static double
00035 #endif
00036 TWO52[2]={
00037 4.50359962737049600000e+15,
00038 -4.50359962737049600000e+15,
00039 };
00040
00041 #ifdef __STDC__
00042 double rint(double x)
00043 #else
00044 double rint(x)
00045 double x;
00046 #endif
00047 {
00048 int32_t i0,j0,sx;
00049 u_int32_t i,i1;
00050 double w,t;
00051 EXTRACT_WORDS(i0,i1,x);
00052 sx = (i0>>31)&1;
00053 j0 = ((i0>>20)&0x7ff)-0x3ff;
00054 if(j0<20) {
00055 if(j0<0) {
00056 if(((i0&0x7fffffff)|i1)==0) return x;
00057 i1 |= (i0&0x0fffff);
00058 i0 &= 0xfffe0000;
00059 i0 |= ((i1|-i1)>>12)&0x80000;
00060 SET_HIGH_WORD(x,i0);
00061 w = TWO52[sx]+x;
00062 t = w-TWO52[sx];
00063 GET_HIGH_WORD(i0,t);
00064 SET_HIGH_WORD(t,(i0&0x7fffffff)|(sx<<31));
00065 return t;
00066 } else {
00067 i = (0x000fffff)>>j0;
00068 if(((i0&i)|i1)==0) return x;
00069 i>>=1;
00070 if(((i0&i)|i1)!=0) {
00071 if(j0==19) i1 = 0x40000000; else
00072 i0 = (i0&(~i))|((0x20000)>>j0);
00073 }
00074 }
00075 } else if (j0>51) {
00076 if(j0==0x400) return x+x;
00077 else return x;
00078 } else {
00079 i = ((u_int32_t)(0xffffffff))>>(j0-20);
00080 if((i1&i)==0) return x;
00081 i>>=1;
00082 if((i1&i)!=0) i1 = (i1&(~i))|((0x40000000)>>(j0-20));
00083 }
00084 INSERT_WORDS(x,i0,i1);
00085 w = TWO52[sx]+x;
00086 return w-TWO52[sx];
00087 }
00088 #endif