1 /* FPU control word bits. Alpha-mapped-to-Intel version. 2 Copyright (C) 1996, 1998, 2000, 2002 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 Contributed by Olaf Flebbe. 5 6 The GNU C Library is free software; you can redistribute it and/or 7 modify it under the terms of the GNU Lesser General Public 8 License as published by the Free Software Foundation; either 9 version 2.1 of the License, or (at your option) any later version. 10 11 The GNU C Library is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 Lesser General Public License for more details. 15 16 You should have received a copy of the GNU Lesser General Public 17 License along with the GNU C Library; if not, see 18 <http://www.gnu.org/licenses/>. */ 19 20 #ifndef _ALPHA_FPU_CONTROL_H 21 #define _ALPHA_FPU_CONTROL_H 22 23 /* 24 * Since many programs seem to hardcode the values passed to __setfpucw() 25 * (rather than using the manifest constants) we emulate the x87 interface 26 * here (at least where this makes sense). 27 * 28 * 15-13 12 11-10 9-8 7-6 5 4 3 2 1 0 29 * | reserved | IC | RC | PC | reserved | PM | UM | OM | ZM | DM | IM 30 * 31 * IM: Invalid operation mask 32 * DM: Denormalized operand mask 33 * ZM: Zero-divide mask 34 * OM: Overflow mask 35 * UM: Underflow mask 36 * PM: Precision (inexact result) mask 37 * 38 * Mask bit is 1 means no interrupt. 39 * 40 * PC: Precision control 41 * 11 - round to extended precision 42 * 10 - round to double precision 43 * 00 - round to single precision 44 * 45 * RC: Rounding control 46 * 00 - rounding to nearest 47 * 01 - rounding down (toward - infinity) 48 * 10 - rounding up (toward + infinity) 49 * 11 - rounding toward zero 50 * 51 * IC: Infinity control 52 * That is for 8087 and 80287 only. 53 * 54 * The hardware default is 0x037f. I choose 0x1372. 55 */ 56 57 #include <features.h> 58 59 /* masking of interrupts */ 60 #define _FPU_MASK_IM 0x01 61 #define _FPU_MASK_DM 0x02 62 #define _FPU_MASK_ZM 0x04 63 #define _FPU_MASK_OM 0x08 64 #define _FPU_MASK_UM 0x10 65 #define _FPU_MASK_PM 0x20 66 67 /* precision control -- without effect on Alpha */ 68 #define _FPU_EXTENDED 0x300 /* RECOMMENDED */ 69 #define _FPU_DOUBLE 0x200 70 #define _FPU_SINGLE 0x0 /* DO NOT USE */ 71 72 /* 73 * rounding control---notice that on the Alpha this affects only 74 * instructions with the dynamic rounding mode qualifier (/d). 75 */ 76 #define _FPU_RC_NEAREST 0x000 /* RECOMMENDED */ 77 #define _FPU_RC_DOWN 0x400 78 #define _FPU_RC_UP 0x800 79 #define _FPU_RC_ZERO 0xC00 80 81 #define _FPU_RESERVED 0xF0C0 /* Reserved bits in cw */ 82 83 84 /* Now two recommended cw */ 85 86 /* Linux default: 87 - extended precision 88 - rounding to positive infinity. There is no /p instruction 89 qualifier. By setting the dynamic rounding mode to +infinity, 90 one can use /d to get round to +infinity with no extra overhead 91 (so long as the default isn't changed, of course...) 92 - no exceptions enabled. */ 93 94 #define _FPU_DEFAULT 0x137f 95 96 /* IEEE: same as above. */ 97 #define _FPU_IEEE 0x137f 98 99 /* Type of the control word. */ 100 typedef unsigned int fpu_control_t; 101 102 #if 0 103 /* Default control word set at startup. */ 104 extern fpu_control_t __fpu_control; 105 #endif 106 107 #endif /* _ALPHA_FPU_CONTROL */ 108