| 1 | /* FPU control word bits. i387 version.
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| 2 | Copyright (C) 1993,1995-1998,2000,2001,2003 Free Software Foundation, Inc.
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| 3 | This file is part of the GNU C Library.
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| 4 | Contributed by Olaf Flebbe.
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| 5 |
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| 6 | The GNU C Library is free software; you can redistribute it and/or
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| 7 | modify it under the terms of the GNU Lesser General Public
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| 8 | License as published by the Free Software Foundation; either
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| 9 | version 2.1 of the License, or (at your option) any later version.
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| 10 |
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| 11 | The GNU C Library is distributed in the hope that it will be useful,
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 14 | Lesser General Public License for more details.
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| 15 |
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| 16 | You should have received a copy of the GNU Lesser General Public
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| 17 | License along with the GNU C Library; if not, write to the Free
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| 18 | Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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| 19 | 02111-1307 USA. */
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| 20 | /**
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| 21 | * GLIBC 2.3.x CVS
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| 22 | */
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| 23 |
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| 24 | #ifndef _FPU_CONTROL_H
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| 25 | #define _FPU_CONTROL_H 1
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| 26 |
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| 27 | /* Here is the dirty part. Set up your 387 through the control word
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| 28 | * (cw) register.
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| 29 | *
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| 30 | * 15-13 12 11-10 9-8 7-6 5 4 3 2 1 0
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| 31 | * | reserved | IC | RC | PC | reserved | PM | UM | OM | ZM | DM | IM
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| 32 | *
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| 33 | * IM: Invalid operation mask
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| 34 | * DM: Denormalized operand mask
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| 35 | * ZM: Zero-divide mask
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| 36 | * OM: Overflow mask
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| 37 | * UM: Underflow mask
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| 38 | * PM: Precision (inexact result) mask
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| 39 | *
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| 40 | * Mask bit is 1 means no interrupt.
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| 41 | *
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| 42 | * PC: Precision control
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| 43 | * 11 - round to extended precision
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| 44 | * 10 - round to double precision
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| 45 | * 00 - round to single precision
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| 46 | *
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| 47 | * RC: Rounding control
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| 48 | * 00 - rounding to nearest
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| 49 | * 01 - rounding down (toward - infinity)
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| 50 | * 10 - rounding up (toward + infinity)
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| 51 | * 11 - rounding toward zero
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| 52 | *
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| 53 | * IC: Infinity control
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| 54 | * That is for 8087 and 80287 only.
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| 55 | *
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| 56 | * The hardware default is 0x037f which we use.
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| 57 | */
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| 58 |
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| 59 | #include <features.h>
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| 60 |
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| 61 | /* masking of interrupts */
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| 62 | #define _FPU_MASK_IM 0x01
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| 63 | #define _FPU_MASK_DM 0x02
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| 64 | #define _FPU_MASK_ZM 0x04
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| 65 | #define _FPU_MASK_OM 0x08
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| 66 | #define _FPU_MASK_UM 0x10
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| 67 | #define _FPU_MASK_PM 0x20
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| 68 |
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| 69 | /* precision control */
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| 70 | #define _FPU_EXTENDED 0x300 /* libm requires double extended precision. */
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| 71 | #define _FPU_DOUBLE 0x200
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| 72 | #define _FPU_SINGLE 0x0
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| 73 |
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| 74 | /* rounding control */
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| 75 | #define _FPU_RC_NEAREST 0x0 /* RECOMMENDED */
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| 76 | #define _FPU_RC_DOWN 0x400
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| 77 | #define _FPU_RC_UP 0x800
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| 78 | #define _FPU_RC_ZERO 0xC00
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| 79 |
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| 80 | #define _FPU_RESERVED 0xF0C0 /* Reserved bits in cw */
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| 81 |
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| 82 |
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| 83 | /* The fdlibm code requires strict IEEE double precision arithmetic,
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| 84 | and no interrupts for exceptions, rounding to nearest. */
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| 85 |
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| 86 | #define _FPU_DEFAULT 0x037f
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| 87 |
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| 88 | /* IEEE: same as above. */
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| 89 | #define _FPU_IEEE 0x037f
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| 90 |
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| 91 | /* Type of the control word. */
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| 92 | typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__HI__)));
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| 93 |
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| 94 | /* Macros for accessing the hardware control word.
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| 95 |
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| 96 | Note that the use of these macros is no sufficient anymore with
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| 97 | recent hardware. Some floating point operations are executed in
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| 98 | the SSE/SSE2 engines which have their own control and status register. */
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| 99 | #define _FPU_GETCW(cw) __asm__ __volatile__ ("fnstcw %0" : "=m" (*&cw))
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| 100 | #define _FPU_SETCW(cw) __asm__ __volatile__ ("fldcw %0" : : "m" (*&cw))
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| 101 |
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| 102 | /* Default control word set at startup. */
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| 103 | extern fpu_control_t __fpu_control;
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| 104 |
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| 105 | #endif /* fpu_control.h */
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