diff options
| author | Roland McGrath <roland@gnu.org> | 1996-03-05 21:41:30 +0000 |
|---|---|---|
| committer | Roland McGrath <roland@gnu.org> | 1996-03-05 21:41:30 +0000 |
| commit | f7eac6eb504f4baf13dbb4d26717942df050ebe6 (patch) | |
| tree | 95ff129c06c7f6f246a5e2bfa489ba6382659d19 /sysdeps/libm-ieee754/s_scalbn.c | |
| parent | 1521668f2afae1dc2ef5d7ffaeb84353b36874dd (diff) | |
| download | glibc-f7eac6eb504f4baf13dbb4d26717942df050ebe6.tar.gz | |
Mon Mar 4 20:54:40 1996 Andreas Schwab <schwab@issan.informatik.uni-dortmund.de>
* Makeconfig ($(common-objpfx)config.make): Depend on config.h.in.
Mon Mar 4 17:35:09 1996 Roland McGrath <roland@charlie-brown.gnu.ai.mit.edu>
* hurd/catch-signal.c (hurd_safe_memmove): New function.
(hurd_safe_copyin, hurd_safe_copyout): New functions.
* hurd/hurd/sigpreempt.h: Declare them.
Sun Mar 3 08:43:44 1996 Roland McGrath <roland@charlie-brown.gnu.ai.mit.edu>
Replace math code with fdlibm from Sun as modified for netbsd by
JT Conklin and Ian Taylor, including x86 FPU support.
* sysdeps/libm-ieee754, sysdeps/libm-i387: New directories.
* math/math_private.h: New file.
* sysdeps/i386/fpu/Implies: New file.
* sysdeps/ieee754/Implies: New file.
* math/machine/asm.h, math/machine/endian.h: New files.
* math/Makefile, math/math.h: Rewritten.
* mathcalls.h, math/mathcalls.h: New file, broken out of math.h.
* math/finite.c: File removed.
* sysdeps/generic/Makefile [$(subdir)=math]: Frobnication removed.
* math/test-math.c: Include errno.h and string.h.
* sysdeps/unix/bsd/dirstream.h: File removed.
* sysdeps/unix/bsd/readdir.c: File removed.
Diffstat (limited to 'sysdeps/libm-ieee754/s_scalbn.c')
| -rw-r--r-- | sysdeps/libm-ieee754/s_scalbn.c | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/sysdeps/libm-ieee754/s_scalbn.c b/sysdeps/libm-ieee754/s_scalbn.c new file mode 100644 index 0000000000..835f00ea77 --- /dev/null +++ b/sysdeps/libm-ieee754/s_scalbn.c @@ -0,0 +1,67 @@ +/* @(#)s_scalbn.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. + * ==================================================== + */ + +#if defined(LIBM_SCCS) && !defined(lint) +static char rcsid[] = "$NetBSD: s_scalbn.c,v 1.8 1995/05/10 20:48:08 jtc Exp $"; +#endif + +/* + * scalbn (double x, int n) + * scalbn(x,n) returns x* 2**n computed by exponent + * manipulation rather than by actually performing an + * exponentiation or a multiplication. + */ + +#include "math.h" +#include "math_private.h" + +#ifdef __STDC__ +static const double +#else +static double +#endif +two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */ +twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */ +huge = 1.0e+300, +tiny = 1.0e-300; + +#ifdef __STDC__ + double scalbn (double x, int n) +#else + double scalbn (x,n) + double x; int n; +#endif +{ + int32_t k,hx,lx; + EXTRACT_WORDS(hx,lx,x); + k = (hx&0x7ff00000)>>20; /* extract exponent */ + if (k==0) { /* 0 or subnormal x */ + if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */ + x *= two54; + GET_HIGH_WORD(hx,x); + k = ((hx&0x7ff00000)>>20) - 54; + if (n< -50000) return tiny*x; /*underflow*/ + } + if (k==0x7ff) return x+x; /* NaN or Inf */ + 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 (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)); + return x*twom54; +} +weak_alias (__scalbn, scalbn) |