diff options
Diffstat (limited to 'lib/libc/gen/frexp.c')
-rw-r--r-- | lib/libc/gen/frexp.c | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/lib/libc/gen/frexp.c b/lib/libc/gen/frexp.c new file mode 100644 index 0000000..53483da --- /dev/null +++ b/lib/libc/gen/frexp.c @@ -0,0 +1,57 @@ +/*- + * Copyright (c) 2004 David Schultz <das@FreeBSD.ORG> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#include <math.h> + +#include "fpmath.h" + +double +frexp(double d, int *ex) +{ + union IEEEd2bits u; + + u.d = d; + switch (u.bits.exp) { + case 0: /* 0 or subnormal */ + if ((u.bits.manl | u.bits.manh) == 0) { + *ex = 0; + } else { + u.d *= 0x1.0p514; + *ex = u.bits.exp - 1536; + u.bits.exp = 1022; + } + break; + case 2047: /* infinity or NaN; value of *ex is unspecified */ + break; + default: /* normal */ + *ex = u.bits.exp - 1022; + u.bits.exp = 1022; + break; + } + return (u.d); +} |