projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
1 | /* IEEE754 floating point arithmetic |
| 2 | * double precision: common utilities | |
| 3 | */ | |
| 4 | /* | |
| 5 | * MIPS floating point support | |
| 6 | * Copyright (C) 1994-2000 Algorithmics Ltd. | |
| 1da177e4 LT |
7 | * |
| 8 | * ######################################################################## | |
| 9 | * | |
| 10 | * This program is free software; you can distribute it and/or modify it | |
| 11 | * under the terms of the GNU General Public License (Version 2) as | |
| 12 | * published by the Free Software Foundation. | |
| 13 | * | |
| 14 | * This program is distributed in the hope it will be useful, but WITHOUT | |
| 15 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 16 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 17 | * for more details. | |
| 18 | * | |
| 19 | * You should have received a copy of the GNU General Public License along | |
| 20 | * with this program; if not, write to the Free Software Foundation, Inc., | |
| 21 | * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA. | |
| 22 | * | |
| 23 | * ######################################################################## | |
| 24 | */ | |
| 25 | ||
| 26 | ||
| 27 | #include "ieee754dp.h" | |
| 28 | ||
| 29 | /* modf function is always exact for a finite number | |
| 30 | */ | |
| 055899a0 | 31 | ieee754dp ieee754dp_modf(ieee754dp x, ieee754dp *ip) |
| 1da177e4 LT |
32 | { |
| 33 | COMPXDP; | |
| 34 | ||
| 35 | CLEARCX; | |
| 36 | ||
| 37 | EXPLODEXDP; | |
| 38 | ||
| 39 | switch (xc) { | |
| 40 | case IEEE754_CLASS_SNAN: | |
| 41 | case IEEE754_CLASS_QNAN: | |
| 42 | case IEEE754_CLASS_INF: | |
| 43 | case IEEE754_CLASS_ZERO: | |
| 44 | *ip = x; | |
| 45 | return x; | |
| 46 | case IEEE754_CLASS_DNORM: | |
| 47 | /* far to small */ | |
| 48 | *ip = ieee754dp_zero(xs); | |
| 49 | return x; | |
| 50 | case IEEE754_CLASS_NORM: | |
| 51 | break; | |
| 52 | } | |
| 53 | if (xe < 0) { | |
| 54 | *ip = ieee754dp_zero(xs); | |
| 55 | return x; | |
| 56 | } | |
| 57 | if (xe >= DP_MBITS) { | |
| 58 | *ip = x; | |
| 59 | return ieee754dp_zero(xs); | |
| 60 | } | |
| 61 | /* generate ipart mantissa by clearing bottom bits | |
| 62 | */ | |
| 63 | *ip = builddp(xs, xe + DP_EBIAS, | |
| 64 | ((xm >> (DP_MBITS - xe)) << (DP_MBITS - xe)) & | |
| 65 | ~DP_HIDDEN_BIT); | |
| 66 | ||
| 67 | /* generate fpart mantissa by clearing top bits | |
| 68 | * and normalizing (must be able to normalize) | |
| 69 | */ | |
| 70 | xm = (xm << (64 - (DP_MBITS - xe))) >> (64 - (DP_MBITS - xe)); | |
| 71 | if (xm == 0) | |
| 72 | return ieee754dp_zero(xs); | |
| 73 | ||
| 74 | while ((xm >> DP_MBITS) == 0) { | |
| 75 | xm <<= 1; | |
| 76 | xe--; | |
| 77 | } | |
| 78 | return builddp(xs, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT); | |
| 79 | } |