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/* FPU control word bits. Alpha version.
Copyright (C) 1996 Free Software Foundation, Inc.
Contributed by Olaf Flebbe.
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 Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#ifndef _ALPHA_FPU_CONTROL_H
#define _ALPHA_FPU_CONTROL_H
/*
* Since many programs seem to hardcode the values passed to __setfpucw()
* (rather than using the manifest constants) we emulate the x87 interface
* here (at least where this makes sense).
*
* 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. I choose 0x1372.
*/
#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 /* RECOMMENDED */
#define _FPU_DOUBLE 0x200
#define _FPU_SINGLE 0x0 /* DO NOT USE */
/*
* rounding control---notice that on the Alpha this affects only
* instructions with the dynamic rounding mode qualifier (/d).
*/
#define _FPU_RC_NEAREST 0x000 /* RECOMMENDED */
#define _FPU_RC_DOWN 0x400
#define _FPU_RC_UP 0x800
#define _FPU_RC_ZERO 0xC00
#define _FPU_RESERVED 0xF0C0 /* Reserved bits in cw */
/* Now two recommended cw */
/* Linux default:
- extended precision
- rounding to positive infinity. There is no /p instruction
qualifier. By setting the dynamic rounding mode to +infinity,
one can use /d to get round to +infinity with no extra overhead
(so long as the default isn't changed, of course...)
- exceptions on overflow, zero divide and NaN */
#define _FPU_DEFAULT 0x1f72
/* IEEE: same as above, but exceptions */
#define _FPU_IEEE 0x1f7f
/* Type of the control word. */
typedef unsigned int fpu_control_t;
/* Default control word set at startup. */
extern fpu_control_t __fpu_control;
__BEGIN_DECLS
/* called by start.o. It can be used to manipulate fpu control word. */
extern void __setfpucw __P ((unsigned short));
__END_DECLS
#endif /* _ALPHA_FPU_CONTROL */
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