projects / mirror_ubuntu-jammy-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| f6cc69f1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
| 3ec404d8 AM |
2 | /* IEEE754 floating point arithmetic |
| 3 | * double precision: common utilities | |
| 4 | */ | |
| 5 | /* | |
| 6 | * MIPS floating point support | |
| 7 | * Copyright (C) 1994-2000 Algorithmics Ltd. | |
| 8 | * Copyright (C) 2017 Imagination Technologies, Ltd. | |
| 9 | * Author: Aleksandar Markovic <aleksandar.markovic@imgtec.com> | |
| 3ec404d8 AM |
10 | */ |
| 11 | ||
| 12 | #include "ieee754dp.h" | |
| 13 | ||
| 14 | union ieee754dp ieee754dp_rint(union ieee754dp x) | |
| 15 | { | |
| 16 | union ieee754dp ret; | |
| 17 | u64 residue; | |
| 18 | int sticky; | |
| 19 | int round; | |
| 20 | int odd; | |
| 21 | ||
| 22 | COMPXDP; | |
| 23 | ||
| 24 | ieee754_clearcx(); | |
| 25 | ||
| 26 | EXPLODEXDP; | |
| 27 | FLUSHXDP; | |
| 28 | ||
| 29 | if (xc == IEEE754_CLASS_SNAN) | |
| 30 | return ieee754dp_nanxcpt(x); | |
| 31 | ||
| 32 | if ((xc == IEEE754_CLASS_QNAN) || | |
| 33 | (xc == IEEE754_CLASS_INF) || | |
| 34 | (xc == IEEE754_CLASS_ZERO)) | |
| 35 | return x; | |
| 36 | ||
| 37 | if (xe >= DP_FBITS) | |
| 38 | return x; | |
| 39 | ||
| 40 | if (xe < -1) { | |
| 41 | residue = xm; | |
| 42 | round = 0; | |
| 43 | sticky = residue != 0; | |
| 44 | xm = 0; | |
| 45 | } else { | |
| 46 | residue = xm << (64 - DP_FBITS + xe); | |
| 47 | round = (residue >> 63) != 0; | |
| 48 | sticky = (residue << 1) != 0; | |
| 49 | xm >>= DP_FBITS - xe; | |
| 50 | } | |
| 51 | ||
| 52 | odd = (xm & 0x1) != 0x0; | |
| 53 | ||
| 54 | switch (ieee754_csr.rm) { | |
| 55 | case FPU_CSR_RN: /* toward nearest */ | |
| 56 | if (round && (sticky || odd)) | |
| 57 | xm++; | |
| 58 | break; | |
| 59 | case FPU_CSR_RZ: /* toward zero */ | |
| 60 | break; | |
| 61 | case FPU_CSR_RU: /* toward +infinity */ | |
| 62 | if ((round || sticky) && !xs) | |
| 63 | xm++; | |
| 64 | break; | |
| 65 | case FPU_CSR_RD: /* toward -infinity */ | |
| 66 | if ((round || sticky) && xs) | |
| 67 | xm++; | |
| 68 | break; | |
| 69 | } | |
| 70 | ||
| 71 | if (round || sticky) | |
| 72 | ieee754_setcx(IEEE754_INEXACT); | |
| 73 | ||
| 74 | ret = ieee754dp_flong(xm); | |
| 75 | DPSIGN(ret) = xs; | |
| 76 | ||
| 77 | return ret; | |
| 78 | } |