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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libm/] [common/] [s_lrint.c] - Rev 286
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/* @(#)s_lrint.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 <<lrint>>, <<lrintf>>, <<llrint>>, <<llrintf>>--round to integer INDEX lrint INDEX lrintf INDEX llrint INDEX llrintf ANSI_SYNOPSIS #include <math.h> long int lrint(double <[x]>); long int lrintf(float <[x]>); long long int llrint(double <[x]>); long long int llrintf(float <[x]>); DESCRIPTION The <<lrint>> and <<llrint>> functions round their argument to the nearest integer value, using the current rounding direction. If the rounded value is outside the range of the return type, the numeric result is unspecified. A range error may occur if the magnitude of <[x]> is too large. The "inexact" floating-point exception is raised in implementations that support it when the result differs in value from the argument (i.e., when a fraction actually has been truncated). RETURNS <[x]> rounded to an integral value, using the current rounding direction. SEEALSO <<lround>> PORTABILITY ANSI C, POSIX */ /* * lrint(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 lrint(x). */ #include "fdlibm.h" #ifndef _DOUBLE_IS_32BITS #ifdef __STDC__ static const double #else static double #endif /* Adding a double, x, to 2^52 will cause the result to be rounded based on the fractional part of x, according to the implementation's current rounding mode. 2^52 is the smallest double that can be represented using all 52 significant digits. */ TWO52[2]={ 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */ -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */ }; #ifdef __STDC__ long int lrint(double x) #else long int lrint(x) double x; #endif { __int32_t i0,j0,sx; __uint32_t i1; double t; volatile double w; long int result; EXTRACT_WORDS(i0,i1,x); /* Extract sign bit. */ sx = (i0>>31)&1; /* Extract exponent field. */ j0 = ((i0 & 0x7ff00000) >> 20) - 1023; if(j0 < 20) { if(j0 < -1) return 0; else { w = TWO52[sx] + x; t = w - TWO52[sx]; GET_HIGH_WORD(i0, t); /* Detect the all-zeros representation of plus and minus zero, which fails the calculation below. */ if ((i0 & ~(1L << 31)) == 0) return 0; j0 = ((i0 & 0x7ff00000) >> 20) - 1023; i0 &= 0x000fffff; i0 |= 0x00100000; result = i0 >> (20 - j0); } } else if (j0 < (int)(8 * sizeof (long int)) - 1) { if (j0 >= 52) result = ((long int) ((i0 & 0x000fffff) | 0x0010000) << (j0 - 20)) | (i1 << (j0 - 52)); else { w = TWO52[sx] + x; t = w - TWO52[sx]; EXTRACT_WORDS (i0, i1, t); j0 = ((i0 & 0x7ff00000) >> 20) - 1023; i0 &= 0x000fffff; i0 |= 0x00100000; result = ((long int) i0 << (j0 - 20)) | (i1 >> (52 - j0)); } } else { return (long int) x; } return sx ? -result : result; } #endif /* _DOUBLE_IS_32BITS */
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