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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [common/] [s_rint.c] - Rev 298
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/* @(#)s_rint.c 5.1 93/09/24 */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunPro, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ /* FUNCTION <<rint>>, <<rintf>>--round to integer INDEX rint INDEX rintf ANSI_SYNOPSIS #include <math.h> double rint(double <[x]>); float rintf(float <[x]>); DESCRIPTION The <<rint>> functions round their argument to an integer value in floating-point format, using the current rounding direction. They raise the "inexact" floating-point exception if the result differs in value from the argument. See the <<nearbyint>> functions for the same function with the "inexact" floating-point exception never being raised. Newlib does not directly support floating-point exceptions. The <<rint>> functions are written so that the "inexact" exception is raised in hardware implementations that support it, even though Newlib does not provide access. RETURNS <[x]> rounded to an integral value, using the current rounding direction. PORTABILITY ANSI C, POSIX SEEALSO <<nearbyint>>, <<round>> */ /* * rint(x) * Return x rounded to integral value according to the prevailing * rounding mode. * Method: * Using floating addition. * Exception: * Inexact flag raised if x not equal to rint(x). */ #include "fdlibm.h" #ifndef _DOUBLE_IS_32BITS #ifdef __STDC__ static const double #else static double #endif TWO52[2]={ 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */ -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */ }; #ifdef __STDC__ double rint(double x) #else double rint(x) double x; #endif { __int32_t i0,j0,sx; __uint32_t i,i1; double t; volatile double w; EXTRACT_WORDS(i0,i1,x); sx = (i0>>31)&1; j0 = ((i0>>20)&0x7ff)-0x3ff; if(j0<20) { if(j0<0) { if(((i0&0x7fffffff)|i1)==0) return x; i1 |= (i0&0x0fffff); i0 &= 0xfffe0000; i0 |= ((i1|-i1)>>12)&0x80000; SET_HIGH_WORD(x,i0); w = TWO52[sx]+x; t = w-TWO52[sx]; GET_HIGH_WORD(i0,t); SET_HIGH_WORD(t,(i0&0x7fffffff)|(sx<<31)); return t; } else { i = (0x000fffff)>>j0; if(((i0&i)|i1)==0) return x; /* x is integral */ i>>=1; if(((i0&i)|i1)!=0) { if(j0==19) i1 = 0x40000000; else i0 = (i0&(~i))|((0x20000)>>j0); } } } else if (j0>51) { if(j0==0x400) return x+x; /* inf or NaN */ else return x; /* x is integral */ } else { i = ((__uint32_t)(0xffffffff))>>(j0-20); if((i1&i)==0) return x; /* x is integral */ i>>=1; if((i1&i)!=0) i1 = (i1&(~i))|((0x40000000)>>(j0-20)); } INSERT_WORDS(x,i0,i1); w = TWO52[sx]+x; return w-TWO52[sx]; } #endif /* _DOUBLE_IS_32BITS */
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