1 /* 2 * Copyright (C) 2007, 2009 Free Software Foundation, Inc. 3 * 4 * This file is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License as published by the 6 * Free Software Foundation; either version 3, or (at your option) any 7 * later version. 8 * 9 * This file is distributed in the hope that it will be useful, but 10 * WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 12 * General Public License for more details. 13 * 14 * Under Section 7 of GPL version 3, you are granted additional 15 * permissions described in the GCC Runtime Library Exception, version 16 * 3.1, as published by the Free Software Foundation. 17 * 18 * You should have received a copy of the GNU General Public License and 19 * a copy of the GCC Runtime Library Exception along with this program; 20 * see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 21 * <http://www.gnu.org/licenses/>. 22 */ 23 24 #if __PREC == 32 25 #define X87CW (0 << 8) /* Single precision (24 bits) */ 26 #elif __PREC == 64 27 #define X87CW (2 << 8) /* Double precision (53 bits) */ 28 #elif __PREC == 80 29 #define X87CW (3 << 8) /* Extended precision (64 bits) */ 30 #else 31 #error "Wrong precision requested." 32 #endif 33 34 #define X87CW_PCMASK (3 << 8) 35 36 static void __attribute__((constructor)) 37 set_precision (void) 38 { 39 unsigned short int cwd; 40 41 asm volatile ("fstcw\t%0" : "=m" (cwd)); 42 43 cwd &= ~X87CW_PCMASK; 44 cwd |= X87CW; 45 46 asm volatile ("fldcw\t%0" : : "m" (cwd)); 47 } 48