projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 15637ed4 RG |
1 | /*- |
| 2 | * Copyright (c) 1990 The Regents of the University of California. | |
| 3 | * All rights reserved. | |
| 4 | * | |
| 5 | * This code is derived from software contributed to Berkeley by | |
| 6 | * Sean Eric Fagan. | |
| 7 | * | |
| 8 | * Redistribution and use in source and binary forms, with or without | |
| 9 | * modification, are permitted provided that the following conditions | |
| 10 | * are met: | |
| 11 | * 1. Redistributions of source code must retain the above copyright | |
| 12 | * notice, this list of conditions and the following disclaimer. | |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright | |
| 14 | * notice, this list of conditions and the following disclaimer in the | |
| 15 | * documentation and/or other materials provided with the distribution. | |
| 16 | * 3. All advertising materials mentioning features or use of this software | |
| 17 | * must display the following acknowledgement: | |
| 18 | * This product includes software developed by the University of | |
| 19 | * California, Berkeley and its contributors. | |
| 20 | * 4. Neither the name of the University nor the names of its contributors | |
| 21 | * may be used to endorse or promote products derived from this software | |
| 22 | * without specific prior written permission. | |
| 23 | * | |
| 24 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
| 25 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 26 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 27 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
| 28 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
| 29 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
| 30 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
| 31 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
| 32 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
| 33 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
| 34 | * SUCH DAMAGE. | |
| 35 | */ | |
| 36 | ||
| 37 | #if defined(LIBC_SCCS) && !defined(lint) | |
| 38 | static char sccsid[] = "@(#)ldexp.c 5.1 (Berkeley) 4/23/90"; | |
| 39 | #endif /* LIBC_SCCS and not lint */ | |
| 40 | ||
| 41 | /* | |
| 42 | * ldexp(value, exp): return value * (2 ** exp). | |
| 43 | * | |
| 44 | * Written by Sean Eric Fagan (sef@kithrup.COM) | |
| 45 | * Sun Mar 11 20:27:09 PST 1990 | |
| 46 | */ | |
| 47 | ||
| 48 | /* | |
| 49 | * We do the conversion in C to let gcc optimize it away, if possible. | |
| 50 | * The "fxch ; fstp" stuff is because value is still on the stack | |
| 51 | * (stupid 8087!). | |
| 52 | */ | |
| 53 | double | |
| 54 | ldexp (double value, int exp) | |
| 55 | { | |
| 56 | double temp, texp, temp2; | |
| 57 | texp = exp; | |
| 78ed81a3 | 58 | #ifdef __GNUC__ |
| 59 | #if __GNUC__ >= 2 | |
| 60 | asm ("fscale " | |
| 61 | : "=u" (temp2), "=t" (temp) | |
| 62 | : "0" (texp), "1" (value)); | |
| 63 | #else | |
| 15637ed4 RG |
64 | asm ("fscale ; fxch %%st(1) ; fstp%L1 %1 " |
| 65 | : "=f" (temp), "=0" (temp2) | |
| 66 | : "0" (texp), "f" (value)); | |
| 78ed81a3 | 67 | #endif |
| 68 | #else | |
| 69 | error unknown asm | |
| 70 | #endif | |
| 15637ed4 RG |
71 | return (temp); |
| 72 | } |