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Diffstat (limited to 'lib/libc/amd64/gen/ldexp.c')
-rw-r--r-- | lib/libc/amd64/gen/ldexp.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/lib/libc/amd64/gen/ldexp.c b/lib/libc/amd64/gen/ldexp.c new file mode 100644 index 0000000..8b63f52 --- /dev/null +++ b/lib/libc/amd64/gen/ldexp.c @@ -0,0 +1,74 @@ +/*- + * Copyright (c) 1990, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Sean Eric Fagan. + * + * 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. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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. + * + * $Id$ + */ + +#if defined(LIBC_RCS) && !defined(lint) +static const char rcsid[] = "$Id$"; +#endif /* LIBC_RCS and not lint */ + +/* + * ldexp(value, exp): return value * (2 ** exp). + * + * Written by Sean Eric Fagan (sef@kithrup.COM) + * Sun Mar 11 20:27:09 PST 1990 + */ + +/* + * We do the conversion in C to let gcc optimize it away, if possible. + * The "fxch ; fstp" stuff is because value is still on the stack + * (stupid 8087!). + */ +double +ldexp (double value, int exp) +{ + double temp, texp, temp2; + texp = exp; +#ifdef __GNUC__ +#if __GNUC__ >= 2 + asm ("fscale " + : "=u" (temp2), "=t" (temp) + : "0" (texp), "1" (value)); +#else + asm ("fscale ; fxch %%st(1) ; fstp%L1 %1 " + : "=f" (temp), "=0" (temp2) + : "0" (texp), "f" (value)); +#endif +#else +error unknown asm +#endif + return (temp); +} |