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 | 7 | * |
| 1da177e4 LT |
8 | * This program is free software; you can distribute it and/or modify it |
| 9 | * under the terms of the GNU General Public License (Version 2) as | |
| 10 | * published by the Free Software Foundation. | |
| 11 | * | |
| 12 | * This program is distributed in the hope it will be useful, but WITHOUT | |
| 13 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 14 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 15 | * for more details. | |
| 16 | * | |
| 17 | * You should have received a copy of the GNU General Public License along | |
| 18 | * with this program; if not, write to the Free Software Foundation, Inc., | |
| 3f7cac41 | 19 | * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 1da177e4 LT |
20 | */ |
| 21 | ||
| 1da177e4 LT |
22 | #include "ieee754dp.h" |
| 23 | ||
| 2209bcb1 | 24 | s64 ieee754dp_tlong(union ieee754dp x) |
| 1da177e4 | 25 | { |
| 3f7cac41 RB |
26 | u64 residue; |
| 27 | int round; | |
| 28 | int sticky; | |
| 29 | int odd; | |
| 30 | ||
| 1da177e4 LT |
31 | COMPXDP; |
| 32 | ||
| 9e8bad1f | 33 | ieee754_clearcx(); |
| 1da177e4 LT |
34 | |
| 35 | EXPLODEXDP; | |
| 36 | FLUSHXDP; | |
| 37 | ||
| 38 | switch (xc) { | |
| 39 | case IEEE754_CLASS_SNAN: | |
| 40 | case IEEE754_CLASS_QNAN: | |
| 9e8bad1f | 41 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
| 90efba36 | 42 | return ieee754di_indef(); |
| 3f7cac41 | 43 | |
| 90d53a91 MR |
44 | case IEEE754_CLASS_INF: |
| 45 | ieee754_setcx(IEEE754_INVALID_OPERATION); | |
| 46 | return ieee754di_overflow(xs); | |
| 47 | ||
| 1da177e4 LT |
48 | case IEEE754_CLASS_ZERO: |
| 49 | return 0; | |
| 3f7cac41 | 50 | |
| 1da177e4 LT |
51 | case IEEE754_CLASS_DNORM: |
| 52 | case IEEE754_CLASS_NORM: | |
| 53 | break; | |
| 54 | } | |
| 55 | if (xe >= 63) { | |
| 56 | /* look for valid corner case */ | |
| 57 | if (xe == 63 && xs && xm == DP_HIDDEN_BIT) | |
| 58 | return -0x8000000000000000LL; | |
| 59 | /* Set invalid. We will only use overflow for floating | |
| 60 | point overflow */ | |
| 9e8bad1f | 61 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
| 90d53a91 | 62 | return ieee754di_overflow(xs); |
| 1da177e4 LT |
63 | } |
| 64 | /* oh gawd */ | |
| ad8fb553 RB |
65 | if (xe > DP_FBITS) { |
| 66 | xm <<= xe - DP_FBITS; | |
| 67 | } else if (xe < DP_FBITS) { | |
| 1da177e4 LT |
68 | if (xe < -1) { |
| 69 | residue = xm; | |
| 70 | round = 0; | |
| 71 | sticky = residue != 0; | |
| 72 | xm = 0; | |
| c273625b | 73 | } else { |
| 1da177e4 LT |
74 | /* Shifting a u64 64 times does not work, |
| 75 | * so we do it in two steps. Be aware that xe | |
| 76 | * may be -1 */ | |
| 77 | residue = xm << (xe + 1); | |
| ad8fb553 | 78 | residue <<= 63 - DP_FBITS; |
| 1da177e4 LT |
79 | round = (residue >> 63) != 0; |
| 80 | sticky = (residue << 1) != 0; | |
| ad8fb553 | 81 | xm >>= DP_FBITS - xe; |
| 1da177e4 LT |
82 | } |
| 83 | odd = (xm & 0x1) != 0x0; | |
| 84 | switch (ieee754_csr.rm) { | |
| 56a64733 | 85 | case FPU_CSR_RN: |
| 1da177e4 LT |
86 | if (round && (sticky || odd)) |
| 87 | xm++; | |
| 88 | break; | |
| 56a64733 | 89 | case FPU_CSR_RZ: |
| 1da177e4 | 90 | break; |
| 56a64733 | 91 | case FPU_CSR_RU: /* toward +Infinity */ |
| 1da177e4 LT |
92 | if ((round || sticky) && !xs) |
| 93 | xm++; | |
| 94 | break; | |
| 56a64733 | 95 | case FPU_CSR_RD: /* toward -Infinity */ |
| 1da177e4 LT |
96 | if ((round || sticky) && xs) |
| 97 | xm++; | |
| 98 | break; | |
| 99 | } | |
| 100 | if ((xm >> 63) != 0) { | |
| 101 | /* This can happen after rounding */ | |
| 9e8bad1f | 102 | ieee754_setcx(IEEE754_INVALID_OPERATION); |
| 90d53a91 | 103 | return ieee754di_overflow(xs); |
| 1da177e4 LT |
104 | } |
| 105 | if (round || sticky) | |
| 9e8bad1f | 106 | ieee754_setcx(IEEE754_INEXACT); |
| 1da177e4 LT |
107 | } |
| 108 | if (xs) | |
| 109 | return -xm; | |
| 110 | else | |
| 111 | return xm; | |
| 112 | } |