/* Set given exception flags. i386 version. Copyright (C) 2016-2024 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. The GNU C Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU C Library; if not, see . */ #include #include int fesetexcept (int excepts) { /* The flags can be set in the 387 unit or in the SSE unit. To set a flag, it is sufficient to do it in the SSE unit, because that is guaranteed to not trap. However, on i386 CPUs that have only a 387 unit, set the flags in the 387, as long as this cannot trap. */ excepts &= FE_ALL_EXCEPT; if (CPU_FEATURE_USABLE (SSE)) { /* Get the control word of the SSE unit. */ unsigned int mxcsr; __asm__ ("stmxcsr %0" : "=m" (*&mxcsr)); /* Set relevant flags. */ mxcsr |= excepts; /* Put the new data in effect. */ __asm__ ("ldmxcsr %0" : : "m" (*&mxcsr)); } else { fenv_t temp; /* Note: fnstenv masks all floating-point exceptions until the fldenv or fldcw below. */ __asm__ ("fnstenv %0" : "=m" (*&temp)); /* Set relevant flags. */ temp.__status_word |= excepts; if ((~temp.__control_word) & excepts) { /* Setting the exception flags may trigger a trap (at the next floating-point instruction, but that does not matter). ISO C23 (7.6.4.4) does not allow it. */ __asm__ volatile ("fldcw %0" : : "m" (*&temp.__control_word)); return -1; } /* Store the new status word (along with the rest of the environment). */ __asm__ ("fldenv %0" : : "m" (*&temp)); } return 0; }