diff options
Diffstat (limited to 'libjava/classpath/native/fdlibm/s_scalbn.c')
| -rw-r--r-- | libjava/classpath/native/fdlibm/s_scalbn.c | 61 |
1 files changed, 11 insertions, 50 deletions
diff --git a/libjava/classpath/native/fdlibm/s_scalbn.c b/libjava/classpath/native/fdlibm/s_scalbn.c index 36ee88981ba..b1464881e66 100644 --- a/libjava/classpath/native/fdlibm/s_scalbn.c +++ b/libjava/classpath/native/fdlibm/s_scalbn.c @@ -1,57 +1,20 @@ -/* @(#)s_scalbn.c 5.1 93/09/24 */ +/* @(#)s_scalbn.c 1.3 95/01/18 */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * - * Developed at SunPro, a Sun Microsystems, Inc. business. + * Developed at SunSoft, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this - * software is freely granted, provided that this notice + * software is freely granted, provided that this notice * is preserved. * ==================================================== */ -/* -FUNCTION -<<scalbn>>, <<scalbnf>>---scale by integer -INDEX - scalbn -INDEX - scalbnf - -ANSI_SYNOPSIS - #include <math.h> - double scalbn(double <[x]>, int <[y]>); - float scalbnf(float <[x]>, int <[y]>); - -TRAD_SYNOPSIS - #include <math.h> - double scalbn(<[x]>,<[y]>) - double <[x]>; - int <[y]>; - float scalbnf(<[x]>,<[y]>) - float <[x]>; - int <[y]>; - -DESCRIPTION -<<scalbn>> and <<scalbnf>> scale <[x]> by <[n]>, returning <[x]> times -2 to the power <[n]>. The result is computed by manipulating the -exponent, rather than by actually performing an exponentiation or -multiplication. - -RETURNS -<[x]> times 2 to the power <[n]>. - -PORTABILITY -Neither <<scalbn>> nor <<scalbnf>> is required by ANSI C or by the System V -Interface Definition (Issue 2). - -*/ - -/* +/* * scalbn (double x, int n) - * scalbn(x,n) returns x* 2**n computed by exponent - * manipulation rather than by actually performing an + * scalbn(x,n) returns x* 2**n computed by exponent + * manipulation rather than by actually performing an * exponentiation or a multiplication. */ @@ -81,24 +44,22 @@ tiny = 1.0e-300; k = (hx&0x7ff00000)>>20; /* extract exponent */ if (k==0) { /* 0 or subnormal x */ if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */ - x *= two54; + x *= two54; GET_HIGH_WORD(hx,x); - k = ((hx&0x7ff00000)>>20) - 54; + k = ((hx&0x7ff00000)>>20) - 54; if (n< -50000) return tiny*x; /*underflow*/ } if (k==0x7ff) return x+x; /* NaN or Inf */ - k = k+n; + k = k+n; if (k > 0x7fe) return huge*copysign(huge,x); /* overflow */ if (k > 0) /* normal result */ {SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20)); return x;} - if (k <= -54) { + if (k <= -54) if (n > 50000) /* in case integer overflow in n+k */ return huge*copysign(huge,x); /*overflow*/ else return tiny*copysign(tiny,x); /*underflow*/ - } k += 54; /* subnormal result */ - SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20)); + SET_HIGH_WORD(x,(hx&0x800fffff)|(k<<20)); return x*twom54; } - #endif /* _DOUBLE_IS_32BITS */ |