| Aleksandar Markovic | 3ec404d | 2017-08-21 14:24:48 +0200 | [diff] [blame] | 1 | /* IEEE754 floating point arithmetic |
| 2 | * single precision |
| 3 | */ |
| 4 | /* |
| 5 | * MIPS floating point support |
| 6 | * Copyright (C) 1994-2000 Algorithmics Ltd. |
| 7 | * Copyright (C) 2017 Imagination Technologies, Ltd. |
| 8 | * Author: Aleksandar Markovic <aleksandar.markovic@imgtec.com> |
| 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. |
| 21 | */ |
| 22 | |
| 23 | #include "ieee754sp.h" |
| 24 | |
| 25 | union ieee754sp ieee754sp_rint(union ieee754sp x) |
| 26 | { |
| 27 | union ieee754sp ret; |
| 28 | u32 residue; |
| 29 | int sticky; |
| 30 | int round; |
| 31 | int odd; |
| 32 | |
| 33 | COMPXDP; /* <-- DP needed for 64-bit mantissa tmp */ |
| 34 | |
| 35 | ieee754_clearcx(); |
| 36 | |
| 37 | EXPLODEXSP; |
| 38 | FLUSHXSP; |
| 39 | |
| 40 | if (xc == IEEE754_CLASS_SNAN) |
| 41 | return ieee754sp_nanxcpt(x); |
| 42 | |
| 43 | if ((xc == IEEE754_CLASS_QNAN) || |
| 44 | (xc == IEEE754_CLASS_INF) || |
| 45 | (xc == IEEE754_CLASS_ZERO)) |
| 46 | return x; |
| 47 | |
| 48 | if (xe >= SP_FBITS) |
| 49 | return x; |
| 50 | |
| 51 | if (xe < -1) { |
| 52 | residue = xm; |
| 53 | round = 0; |
| 54 | sticky = residue != 0; |
| 55 | xm = 0; |
| 56 | } else { |
| 57 | residue = xm << (xe + 1); |
| 58 | residue <<= 31 - SP_FBITS; |
| 59 | round = (residue >> 31) != 0; |
| 60 | sticky = (residue << 1) != 0; |
| 61 | xm >>= SP_FBITS - xe; |
| 62 | } |
| 63 | |
| 64 | odd = (xm & 0x1) != 0x0; |
| 65 | |
| 66 | switch (ieee754_csr.rm) { |
| 67 | case FPU_CSR_RN: /* toward nearest */ |
| 68 | if (round && (sticky || odd)) |
| 69 | xm++; |
| 70 | break; |
| 71 | case FPU_CSR_RZ: /* toward zero */ |
| 72 | break; |
| 73 | case FPU_CSR_RU: /* toward +infinity */ |
| 74 | if ((round || sticky) && !xs) |
| 75 | xm++; |
| 76 | break; |
| 77 | case FPU_CSR_RD: /* toward -infinity */ |
| 78 | if ((round || sticky) && xs) |
| 79 | xm++; |
| 80 | break; |
| 81 | } |
| 82 | |
| 83 | if (round || sticky) |
| 84 | ieee754_setcx(IEEE754_INEXACT); |
| 85 | |
| 86 | ret = ieee754sp_flong(xm); |
| 87 | SPSIGN(ret) = xs; |
| 88 | |
| 89 | return ret; |
| 90 | } |