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Diffstat (limited to 'newlib/libm/common/s_logb.c')
| -rw-r--r-- | newlib/libm/common/s_logb.c | 110 |
1 files changed, 0 insertions, 110 deletions
diff --git a/newlib/libm/common/s_logb.c b/newlib/libm/common/s_logb.c deleted file mode 100644 index 1be4cddb3..000000000 --- a/newlib/libm/common/s_logb.c +++ /dev/null @@ -1,110 +0,0 @@ -/* 2009 for Newlib: Sun's s_ilogb.c converted to be s_logb.c. */ -/* @(#)s_ilogb.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 - <<logb>>, <<logbf>>--get exponent of floating-point number -INDEX - logb -INDEX - logbf - -ANSI_SYNOPSIS - #include <math.h> - double logb(double <[x]>); - float logbf(float <[x]>); - -DESCRIPTION -The <<logb>> functions extract the exponent of <[x]>, as a signed integer value -in floating-point format. If <[x]> is subnormal it is treated as though it were -normalized; thus, for positive finite <[x]>, -@ifnottex -1 <= (<[x]> * FLT_RADIX to the power (-logb(<[x]>))) < FLT_RADIX. -@end ifnottex -@tex -$1 \leq ( x \cdot FLT\_RADIX ^ {-logb(x)} ) < FLT\_RADIX$. -@end tex -A domain error may occur if the argument is zero. -In this floating-point implementation, FLT_RADIX is 2. Which also means -that for finite <[x]>, <<logb>>(<[x]>) = <<floor>>(<<log2>>(<<fabs>>(<[x]>))). - -All nonzero, normal numbers can be described as -@ifnottex -<[m]> * 2**<[p]>, where 1.0 <= <[m]> < 2.0. -@end ifnottex -@tex -$m \cdot 2^p$, where $1.0 \leq m < 2.0$. -@end tex -The <<logb>> functions examine the argument <[x]>, and return <[p]>. -The <<frexp>> functions are similar to the <<logb>> functions, but -returning <[m]> adjusted to the interval [.5, 1) or 0, and <[p]>+1. - -RETURNS -@comment Formatting note: "$@" forces a new line -When <[x]> is:@* -+inf or -inf, +inf is returned;@* -NaN, NaN is returned;@* -0, -inf is returned, and the divide-by-zero exception is raised;@* -otherwise, the <<logb>> functions return the signed exponent of <[x]>. - -PORTABILITY -ANSI C, POSIX - -SEEALSO -frexp, ilogb -*/ - -/* double logb(double x) - * return the binary exponent of non-zero x - * logb(0) = -inf, raise divide-by-zero floating point exception - * logb(+inf|-inf) = +inf (no signal is raised) - * logb(NaN) = NaN (no signal is raised) - * Per C99 recommendation, a NaN argument is returned unchanged. - */ - -#include "fdlibm.h" - -#ifndef _DOUBLE_IS_32BITS - -double -#ifdef __STDC__ -logb(double x) -#else -logb(x) -double x; -#endif -{ - __int32_t hx,lx,ix; - - EXTRACT_WORDS(hx,lx,x); - hx &= 0x7fffffff; /* high |x| */ - if(hx<0x00100000) { /* 0 or subnormal */ - if((hx|lx)==0) { - double xx; - /* arg==0: return -inf and raise divide-by-zero exception */ - INSERT_WORDS(xx,hx,lx); /* +0.0 */ - return -1./xx; /* logb(0) = -inf */ - } - else /* subnormal x */ - if(hx==0) { - for (ix = -1043; lx>0; lx<<=1) ix -=1; - } else { - for (ix = -1022,hx<<=11; hx>0; hx<<=1) ix -=1; - } - return (double) ix; - } - else if (hx<0x7ff00000) return (hx>>20)-1023; /* normal # */ - else if (hx>0x7ff00000 || lx) return x; /* x==NaN */ - else return HUGE_VAL; /* x==inf (+ or -) */ -} - -#endif /* _DOUBLE_IS_32BITS */ |