projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 91073d83 WN |
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 | * %sccs.include.redist.c% | |
| 9 | */ | |
| 10 | ||
| 11 | #if defined(LIBC_SCCS) && !defined(lint) | |
| 12 | static char sccsid[] = "@(#)modf.s 5.1 (Berkeley) %G%"; | |
| 13 | #endif /* LIBC_SCCS and not lint */ | |
| 14 | ||
| 15 | /* | |
| 16 | * modf(value, iptr): return fractional part of value, and stores the | |
| 17 | * integral part into iptr (a pointer to double). | |
| 18 | * | |
| 19 | * Written by Sean Eric Fagan (sef@kithrup.COM) | |
| 20 | * Sun Mar 11 20:27:30 PST 1990 | |
| 21 | */ | |
| 22 | ||
| 23 | /* With CHOP mode on, frndint behaves as TRUNC does. Useful. */ | |
| 24 | double | |
| 25 | modf(double value, double *iptr) | |
| 26 | { | |
| 27 | double temp; | |
| 28 | short i87flag, i87temp; | |
| 29 | __asm ("fnstcw %0" : "=g" (i87flag) : ); | |
| 30 | i87temp = i87flag | 0xc00 ; /* turn on chop mode [truncation] */ | |
| 31 | __asm ("fldcw %0" : : "g" (i87temp)); | |
| 32 | __asm ("frndint" : "=f" (temp) : "0" (value)); /* temp = int of value */ | |
| 33 | __asm ("fldcw %0" : : "g" (i87flag)); | |
| 34 | *iptr = temp; | |
| 35 | return (value - temp); | |
| 36 | } |