projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 54a39327 | 1 | /*- |
| f7e479c4 KB |
2 | * Copyright (c) 1992, 1993 |
| 3 | * The Regents of the University of California. All rights reserved. | |
| 54a39327 CT |
4 | * |
| 5 | * This software was developed by the Computer Systems Engineering group | |
| 6 | * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and | |
| 7 | * contributed to Berkeley. | |
| 8 | * | |
| 9 | * %sccs.include.redist.c% | |
| 10 | */ | |
| 11 | ||
| 12 | #if defined(LIBC_SCCS) && !defined(lint) | |
| f7e479c4 | 13 | static char sccsid[] = "@(#)floatdisf.c 8.1 (Berkeley) %G%"; |
| 54a39327 CT |
14 | #endif /* LIBC_SCCS and not lint */ |
| 15 | ||
| 16 | #include "quad.h" | |
| 17 | ||
| 18 | /* | |
| 19 | * Convert (signed) quad to float. | |
| 20 | */ | |
| 21 | float | |
| 22 | __floatdisf(x) | |
| 23 | quad_t x; | |
| 24 | { | |
| 25 | float f; | |
| 26 | union uu u; | |
| 27 | int neg; | |
| 28 | ||
| 29 | /* | |
| 30 | * Get an unsigned number first, by negating if necessary. | |
| 31 | */ | |
| 32 | if (x < 0) | |
| 33 | u.q = -x, neg = 1; | |
| 34 | else | |
| 35 | u.q = x, neg = 0; | |
| 36 | ||
| 37 | /* | |
| 38 | * Now u.ul[H] has the factor of 2^32 (or whatever) and u.ul[L] | |
| 39 | * has the units. Ideally we could just set f, add LONG_BITS to | |
| 40 | * its exponent, and then add the units, but this is portable | |
| 41 | * code and does not know how to get at an exponent. Machine- | |
| 42 | * specific code may be able to do this more efficiently. | |
| 43 | * | |
| 44 | * Using double here may be excessive paranoia. | |
| 45 | */ | |
| 46 | f = (double)u.ul[H] * ((1 << (LONG_BITS - 2)) * 4.0); | |
| 47 | f += u.ul[L]; | |
| 48 | ||
| 49 | return (neg ? -f : f); | |
| 50 | } |