| /* FPU control word bits. i387 version. |
| Copyright (C) 1993,1995-1998,2000,2001,2003 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Contributed by Olaf Flebbe. |
| |
| 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, write to the Free |
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. */ |
| |
| #ifndef _FPU_CONTROL_H |
| #define _FPU_CONTROL_H 1 |
| |
| /* Here is the dirty part. Set up your 387 through the control word |
| * (cw) register. |
| * |
| * 15-13 12 11-10 9-8 7-6 5 4 3 2 1 0 |
| * | reserved | IC | RC | PC | reserved | PM | UM | OM | ZM | DM | IM |
| * |
| * IM: Invalid operation mask |
| * DM: Denormalized operand mask |
| * ZM: Zero-divide mask |
| * OM: Overflow mask |
| * UM: Underflow mask |
| * PM: Precision (inexact result) mask |
| * |
| * Mask bit is 1 means no interrupt. |
| * |
| * PC: Precision control |
| * 11 - round to extended precision |
| * 10 - round to double precision |
| * 00 - round to single precision |
| * |
| * RC: Rounding control |
| * 00 - rounding to nearest |
| * 01 - rounding down (toward - infinity) |
| * 10 - rounding up (toward + infinity) |
| * 11 - rounding toward zero |
| * |
| * IC: Infinity control |
| * That is for 8087 and 80287 only. |
| * |
| * The hardware default is 0x037f which we use. |
| */ |
| |
| #include <features.h> |
| |
| /* masking of interrupts */ |
| #define _FPU_MASK_IM 0x01 |
| #define _FPU_MASK_DM 0x02 |
| #define _FPU_MASK_ZM 0x04 |
| #define _FPU_MASK_OM 0x08 |
| #define _FPU_MASK_UM 0x10 |
| #define _FPU_MASK_PM 0x20 |
| |
| /* precision control */ |
| #define _FPU_EXTENDED 0x300 /* libm requires double extended precision. */ |
| #define _FPU_DOUBLE 0x200 |
| #define _FPU_SINGLE 0x0 |
| |
| /* rounding control */ |
| #define _FPU_RC_NEAREST 0x0 /* RECOMMENDED */ |
| #define _FPU_RC_DOWN 0x400 |
| #define _FPU_RC_UP 0x800 |
| #define _FPU_RC_ZERO 0xC00 |
| |
| #define _FPU_RESERVED 0xF0C0 /* Reserved bits in cw */ |
| |
| |
| /* The fdlibm code requires strict IEEE double precision arithmetic, |
| and no interrupts for exceptions, rounding to nearest. */ |
| |
| #define _FPU_DEFAULT 0x037f |
| |
| /* IEEE: same as above. */ |
| #define _FPU_IEEE 0x037f |
| |
| /* Type of the control word. */ |
| typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__HI__))); |
| |
| /* Macros for accessing the hardware control word. |
| |
| Note that the use of these macros is no sufficient anymore with |
| recent hardware. Some floating point operations are executed in |
| the SSE/SSE2 engines which have their own control and status register. */ |
| #define _FPU_GETCW(cw) __asm__ __volatile__ ("fnstcw %0" : "=m" (*&cw)) |
| #define _FPU_SETCW(cw) __asm__ __volatile__ ("fldcw %0" : : "m" (*&cw)) |
| |
| /* Default control word set at startup. */ |
| extern fpu_control_t __fpu_control; |
| |
| #endif /* fpu_control.h */ |
