| 1 | /* Set the FPU control word for x86. |
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| 2 | Copyright (C) 2003-2022 Free Software Foundation, Inc. |
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| 3 | This file is part of the GNU C Library. |
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| 4 | |
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| 5 | The GNU C Library is free software; you can redistribute it and/or |
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| 6 | modify it under the terms of the GNU Lesser General Public |
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| 7 | License as published by the Free Software Foundation; either |
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| 8 | version 2.1 of the License, or (at your option) any later version. |
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| 9 | |
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| 10 | The GNU C Library is distributed in the hope that it will be useful, |
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 13 | Lesser General Public License for more details. |
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| 14 | |
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| 15 | You should have received a copy of the GNU Lesser General Public |
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| 16 | License along with the GNU C Library; if not, see |
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| 17 | <https://www.gnu.org/licenses/>. */ |
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| 18 | |
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| 19 | #include <math.h> |
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| 20 | #include <fpu_control.h> |
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| 21 | #include <fenv.h> |
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| 22 | #include <unistd.h> |
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| 23 | #include <ldsodefs.h> |
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| 24 | #include <dl-procinfo.h> |
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| 25 | |
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| 26 | void |
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| 27 | __setfpucw (fpu_control_t set) |
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| 28 | { |
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| 29 | fpu_control_t cw; |
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| 30 | |
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| 31 | /* Fetch the current control word. */ |
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| 32 | __asm__ ("fnstcw %0" : "=m" (*&cw)); |
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| 33 | |
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| 34 | /* Preserve the reserved bits, and set the rest as the user |
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| 35 | specified (or the default, if the user gave zero). */ |
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| 36 | cw &= _FPU_RESERVED; |
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| 37 | cw |= set & ~_FPU_RESERVED; |
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| 38 | |
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| 39 | __asm__ ("fldcw %0" : : "m" (*&cw)); |
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| 40 | |
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| 41 | /* If the CPU supports SSE, we set the MXCSR as well. */ |
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| 42 | if (CPU_FEATURE_USABLE (SSE)) |
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| 43 | { |
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| 44 | unsigned int xnew_exc; |
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| 45 | |
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| 46 | /* Get the current MXCSR. */ |
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| 47 | __asm__ ("stmxcsr %0" : "=m" (*&xnew_exc)); |
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| 48 | |
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| 49 | xnew_exc &= ~((0xc00 << 3) | (FE_ALL_EXCEPT << 7)); |
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| 50 | xnew_exc |= ((set & 0xc00) << 3) | ((set & FE_ALL_EXCEPT) << 7); |
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| 51 | |
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| 52 | __asm__ ("ldmxcsr %0" : : "m" (*&xnew_exc)); |
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| 53 | } |
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| 54 | } |
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| 55 | |
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