| 1 | /* Set current rounding direction. |
|---|
| 2 | Copyright (C) 2001-2022 Free Software Foundation, Inc. |
|---|
| 3 | This file is part of the GNU C Library. |
|---|
| 4 | |
|---|
| 5 | The GNU C Library is free software; you can redistribute it and/or |
|---|
| 6 | modify it under the terms of the GNU Lesser General Public |
|---|
| 7 | License as published by the Free Software Foundation; either |
|---|
| 8 | version 2.1 of the License, or (at your option) any later version. |
|---|
| 9 | |
|---|
| 10 | The GNU C Library is distributed in the hope that it will be useful, |
|---|
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
|---|
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
|---|
| 13 | Lesser General Public License for more details. |
|---|
| 14 | |
|---|
| 15 | You should have received a copy of the GNU Lesser General Public |
|---|
| 16 | License along with the GNU C Library; if not, see |
|---|
| 17 | <https://www.gnu.org/licenses/>. */ |
|---|
| 18 | |
|---|
| 19 | #include <fenv.h> |
|---|
| 20 | |
|---|
| 21 | int |
|---|
| 22 | __fesetround (int round) |
|---|
| 23 | { |
|---|
| 24 | unsigned short int cw; |
|---|
| 25 | int mxcsr; |
|---|
| 26 | |
|---|
| 27 | if ((round & ~0xc00) != 0) |
|---|
| 28 | /* ROUND is no valid rounding mode. */ |
|---|
| 29 | return 1; |
|---|
| 30 | |
|---|
| 31 | /* First set the x87 FPU. */ |
|---|
| 32 | asm ("fnstcw %0" : "=m" (*&cw)); |
|---|
| 33 | cw &= ~0xc00; |
|---|
| 34 | cw |= round; |
|---|
| 35 | asm ("fldcw %0" : : "m" (*&cw)); |
|---|
| 36 | |
|---|
| 37 | /* And now the MSCSR register for SSE, the precision is at different bit |
|---|
| 38 | positions in the different units, we need to shift it 3 bits. */ |
|---|
| 39 | asm ("stmxcsr %0" : "=m" (*&mxcsr)); |
|---|
| 40 | mxcsr &= ~ 0x6000; |
|---|
| 41 | mxcsr |= round << 3; |
|---|
| 42 | asm ("ldmxcsr %0" : : "m" (*&mxcsr)); |
|---|
| 43 | |
|---|
| 44 | return 0; |
|---|
| 45 | } |
|---|
| 46 | libm_hidden_def (__fesetround) |
|---|
| 47 | weak_alias (__fesetround, fesetround) |
|---|
| 48 | libm_hidden_weak (fesetround) |
|---|
| 49 | |
|---|
