git://sourceware.org / glibc.git / blame
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| 2a072de4 | 1 | /* Copyright (C) 1993, 1995, 1996 Free Software Foundation, Inc. |
| d2f5be2a UD |
2 | This file is part of the GNU C Library. |
| 3 | Contributed by Olaf Flebbe. | |
| 4 | ||
| 5 | The GNU C Library is free software; you can redistribute it and/or | |
| 6 | modify it under the terms of the GNU Library General Public License as | |
| 7 | published by the Free Software Foundation; either version 2 of the | |
| 8 | License, or (at your option) any later version. | |
| 9 | ||
| 10 | The GNU C Library is distributed in the hope that it will be useful, | |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 13 | Library General Public License for more details. | |
| 14 | ||
| 15 | You should have received a copy of the GNU Library General Public | |
| 16 | License along with the GNU C Library; see the file COPYING.LIB. If | |
| 17 | not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
| 18 | Boston, MA 02111-1307, USA. */ | |
| 19 | ||
| 20 | #ifndef _FPU_CONTROL_H | |
| 21 | #define _FPU_CONTROL_H | |
| 22 | ||
| 23 | /* Here is the dirty part. Settup up your 387 through the control word | |
| 42d2676e | 24 | * (cw) register. |
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25 | * |
| 26 | * 15-13 12 11-10 9-8 7-6 5 4 3 2 1 0 | |
| 27 | * | reserved | IC | RC | PC | reserved | PM | UM | OM | ZM | DM | IM | |
| 28 | * | |
| 29 | * IM: Invalid operation mask | |
| 30 | * DM: Denormalized operand mask | |
| 31 | * ZM: Zero-divide mask | |
| 32 | * OM: Overflow mask | |
| 33 | * UM: Underflow mask | |
| 34 | * PM: Precision (inexact result) mask | |
| 42d2676e | 35 | * |
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36 | * Mask bit is 1 means no interrupt. |
| 37 | * | |
| 38 | * PC: Precision control | |
| 39 | * 11 - round to extended precision | |
| 40 | * 10 - round to double precision | |
| 41 | * 00 - round to single precision | |
| 42 | * | |
| 43 | * RC: Rounding control | |
| 44 | * 00 - rounding to nearest | |
| 45 | * 01 - rounding down (toward - infinity) | |
| 46 | * 10 - rounding up (toward + infinity) | |
| 47 | * 11 - rounding toward zero | |
| 48 | * | |
| 49 | * IC: Infinity control | |
| 50 | * That is for 8087 and 80287 only. | |
| 51 | * | |
| 52 | * The hardware default is 0x037f. I choose 0x1372. | |
| 53 | */ | |
| 54 | ||
| 55 | #include <features.h> | |
| 56 | ||
| 57 | /* masking of interrupts */ | |
| 42d2676e | 58 | #define _FPU_MASK_IM 0x01 |
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59 | #define _FPU_MASK_DM 0x02 |
| 60 | #define _FPU_MASK_ZM 0x04 | |
| 61 | #define _FPU_MASK_OM 0x08 | |
| 62 | #define _FPU_MASK_UM 0x10 | |
| 63 | #define _FPU_MASK_PM 0x20 | |
| 64 | ||
| 65 | /* precision control */ | |
| 66 | #define _FPU_EXTENDED 0x300 /* RECOMMENDED */ | |
| 67 | #define _FPU_DOUBLE 0x200 | |
| 68 | #define _FPU_SINGLE 0x0 /* DO NOT USE */ | |
| 69 | ||
| 70 | /* rounding control */ | |
| 71 | #define _FPU_RC_NEAREST 0x0 /* RECOMMENDED */ | |
| 72 | #define _FPU_RC_DOWN 0x400 | |
| 73 | #define _FPU_RC_UP 0x800 | |
| 74 | #define _FPU_RC_ZERO 0xC00 | |
| 75 | ||
| 76 | #define _FPU_RESERVED 0xF0C0 /* Reserved bits in cw */ | |
| 77 | ||
| 78 | ||
| 79 | /* Now two recommended cw */ | |
| 80 | ||
| 81 | /* Linux default: | |
| 82 | - extended precision | |
| 83 | - rounding to nearest | |
| 84 | - exceptions on overflow, zero divide and NaN */ | |
| 42d2676e | 85 | #define _FPU_DEFAULT 0x1372 |
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86 | |
| 87 | /* IEEE: same as above, but exceptions */ | |
| 88 | #define _FPU_IEEE 0x137f | |
| 89 | ||
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90 | /* Type of the control word. */ |
| 91 | typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__HI__))); | |
| 92 | ||
| 93 | /* Macros for accessing the hardware control word. */ | |
| 94 | #define _FPU_GETCW(cw) __asm__ ("fnstcw %0" : "=m" (cw)) | |
| 95 | #define _FPU_SETCW(cw) __asm__ ("fldcw %0" : "m" (cw)) | |
| 96 | ||
| 97 | /* Default control word set at startup. */ | |
| 98 | extern fpu_control_t __fpu_control; | |
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99 | |
| 100 | __BEGIN_DECLS | |
| 101 | ||
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102 | /* Called at startup. It can be used to manipulate fpu control register. */ |
| 103 | extern void __setfpucw __P ((fpu_control_t)); | |
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104 | |
| 105 | __END_DECLS | |
| 106 | ||
| 107 | #endif /* fpu_control.h */ |