/* 68k FPU control word definitions. Copyright (C) 1996, 1997, 1998 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 <http://www.gnu.org/licenses/>. */ #ifndef _FPU_CONTROL_H #define _FPU_CONTROL_H /* * Motorola floating point control register bits. * * 31-16 -> reserved (read as 0, ignored on write) * 15 -> enable trap for BSUN exception * 14 -> enable trap for SNAN exception * 13 -> enable trap for OPERR exception * 12 -> enable trap for OVFL exception * 11 -> enable trap for UNFL exception * 10 -> enable trap for DZ exception * 9 -> enable trap for INEX2 exception * 8 -> enable trap for INEX1 exception * 7-6 -> Precision Control * 5-4 -> Rounding Control * 3-0 -> zero (read as 0, write as 0) * * * Precision Control: * 00 - round to extended precision * 01 - round to single precision * 10 - round to double precision * 11 - undefined * * Rounding Control: * 00 - rounding to nearest (RN) * 01 - rounding toward zero (RZ) * 10 - rounding (down)toward minus infinity (RM) * 11 - rounding (up) toward plus infinity (RP) * * The hardware default is 0x0000. I choose 0x5400. */ #include <features.h> /* masking of interrupts */ #define _FPU_MASK_BSUN 0x8000 #define _FPU_MASK_SNAN 0x4000 #define _FPU_MASK_OPERR 0x2000 #define _FPU_MASK_OVFL 0x1000 #define _FPU_MASK_UNFL 0x0800 #define _FPU_MASK_DZ 0x0400 #define _FPU_MASK_INEX1 0x0200 #define _FPU_MASK_INEX2 0x0100 /* precision control */ #define _FPU_EXTENDED 0x00 /* RECOMMENDED */ #define _FPU_DOUBLE 0x80 #define _FPU_SINGLE 0x40 /* DO NOT USE */ /* rounding control */ #define _FPU_RC_NEAREST 0x00 /* RECOMMENDED */ #define _FPU_RC_ZERO 0x10 #define _FPU_RC_DOWN 0x20 #define _FPU_RC_UP 0x30 #define _FPU_RESERVED 0xFFFF000F /* Reserved bits in fpucr */ /* Now two recommended fpucr */ /* The fdlibm code requires no interrupts for exceptions. Don't change the rounding mode, it would break long double I/O! */ #define _FPU_DEFAULT 0x00000000 /* IEEE: same as above, but exceptions. We must make it non-zero so that __setfpucw works. This bit will be ignored. */ #define _FPU_IEEE 0x00000001 /* Type of the control word. */ typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__SI__))); /* Macros for accessing the hardware control word. */ #define _FPU_GETCW(cw) __asm__ ("fmove%.l %!, %0" : "=dm" (cw)) #define _FPU_SETCW(cw) __asm__ __volatile__ ("fmove%.l %0, %!" : : "dm" (cw)) #if 0 /* Default control word set at startup. */ extern fpu_control_t __fpu_control; #endif #endif /* _M68K_FPU_CONTROL_H */