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/* Copyright (C) 1993 Olaf Flebbe
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This file is part of the Linux C Library.
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The Linux C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The Linux C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details. */
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#ifndef _M68K_FPU_CONTROL_H
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#define _M68K_FPU_CONTROL_H
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/*
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* Motorola floating point control register bits.
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*
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* 31-16 -> reserved (read as 0, ignored on write)
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* 15 -> enable trap for BSUN exception
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* 14 -> enable trap for SNAN exception
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* 13 -> enable trap for OPERR exception
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* 12 -> enable trap for OVFL exception
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* 11 -> enable trap for UNFL exception
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* 10 -> enable trap for DZ exception
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* 9 -> enable trap for INEX2 exception
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* 8 -> enable trap for INEX1 exception
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* 7-6 -> Precision Control
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* 5-4 -> Rounding Control
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* 3-0 -> zero (read as 0, write as 0)
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*
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*
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* Precision Control:
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* 00 - round to extended precision
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* 01 - round to single precision
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* 10 - round to double precision
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* 11 - undefined
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*
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* Rounding Control:
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* 00 - rounding to nearest (RN)
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* 01 - rounding toward zero (RZ)
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* 10 - rounding (down)toward minus infinity (RM)
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* 11 - rounding (up) toward plus infinity (RP)
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*
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* The hardware default is 0x0000. I choose 0x5400.
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*/
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#include <features.h>
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/* masking of interrupts */
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#define _FPU_MASK_BSUN 0x8000
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#define _FPU_MASK_SNAN 0x4000
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#define _FPU_MASK_OPERR 0x2000
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#define _FPU_MASK_OVFL 0x1000
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#define _FPU_MASK_UNFL 0x0800
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#define _FPU_MASK_DZ 0x0400
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#define _FPU_MASK_INEX1 0x0200
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#define _FPU_MASK_INEX2 0x0100
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/* precision control */
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#define _FPU_EXTENDED 0x00 /* RECOMMENDED */
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#define _FPU_DOUBLE 0x80
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#define _FPU_SINGLE 0x40 /* DO NOT USE */
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/* rounding control */
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#define _FPU_RC_NEAREST 0x00 /* RECOMMENDED */
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#define _FPU_RC_ZERO 0x10
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#define _FPU_RC_DOWN 0x20
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#define _FPU_RC_UP 0x30
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#define _FPU_RESERVED 0xFFFF000F /* Reserved bits in cw */
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/* Now two recommended cw */
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/* Linux default:
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- extended precision
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- rounding to nearest
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- exceptions on overflow, zero divide and NaN */
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#if 0
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#define _FPU_DEFAULT 0x00005400
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#else
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/* Don't enable execptions any more. It caused too much grief. */
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#define _FPU_DEFAULT 0x00000000
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#endif
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/* IEEE: same as above, but exceptions. We must make it non-zero so
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that __setfpucw works. This bit will be ignored. */
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#define _FPU_IEEE 0x00000001
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/* private namespace. It should only be used by crt0.o. */
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extern unsigned long __fpu_control;
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__BEGIN_DECLS
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/* called by crt0.o. It can be used to manipulate fpu control register. */
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extern void __setfpucw __P ((unsigned long));
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__END_DECLS
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#endif /* _M68K_FPU_CONTROL_H */
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