1 /* FPU control word bits. Alpha-mapped-to-Intel version. 2 Copyright (C) 1996-2022 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the 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 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library. If not, see 17 <https://www.gnu.org/licenses/>. */ 18 19 #ifndef _ALPHA_FPU_CONTROL_H 20 #define _ALPHA_FPU_CONTROL_H 21 22 /* 23 * Since many programs seem to hardcode the values passed to __setfpucw() 24 * (rather than using the manifest constants) we emulate the x87 interface 25 * here (at least where this makes sense). 26 * 27 * 15-13 12 11-10 9-8 7-6 5 4 3 2 1 0 28 * | reserved | IC | RC | PC | reserved | PM | UM | OM | ZM | DM | IM 29 * 30 * IM: Invalid operation mask 31 * DM: Denormalized operand mask 32 * ZM: Zero-divide mask 33 * OM: Overflow mask 34 * UM: Underflow mask 35 * PM: Precision (inexact result) mask 36 * 37 * Mask bit is 1 means no interrupt. 38 * 39 * PC: Precision control 40 * 11 - round to extended precision 41 * 10 - round to double precision 42 * 00 - round to single precision 43 * 44 * RC: Rounding control 45 * 00 - rounding to nearest 46 * 01 - rounding down (toward - infinity) 47 * 10 - rounding up (toward + infinity) 48 * 11 - rounding toward zero 49 * 50 * IC: Infinity control 51 * That is for 8087 and 80287 only. 52 * 53 * The hardware default is 0x037f. I choose 0x1372. 54 */ 55 56 #include <features.h> 57 58 /* masking of interrupts */ 59 #define _FPU_MASK_IM 0x01 60 #define _FPU_MASK_DM 0x02 61 #define _FPU_MASK_ZM 0x04 62 #define _FPU_MASK_OM 0x08 63 #define _FPU_MASK_UM 0x10 64 #define _FPU_MASK_PM 0x20 65 66 /* precision control -- without effect on Alpha */ 67 #define _FPU_EXTENDED 0x300 /* RECOMMENDED */ 68 #define _FPU_DOUBLE 0x200 69 #define _FPU_SINGLE 0x0 /* DO NOT USE */ 70 71 /* 72 * rounding control---notice that on the Alpha this affects only 73 * instructions with the dynamic rounding mode qualifier (/d). 74 */ 75 #define _FPU_RC_NEAREST 0x000 /* RECOMMENDED */ 76 #define _FPU_RC_DOWN 0x400 77 #define _FPU_RC_UP 0x800 78 #define _FPU_RC_ZERO 0xC00 79 80 #define _FPU_RESERVED 0xF0C0 /* Reserved bits in cw */ 81 82 83 /* Now two recommended cw */ 84 85 /* Linux default: 86 - extended precision 87 - rounding to positive infinity. There is no /p instruction 88 qualifier. By setting the dynamic rounding mode to +infinity, 89 one can use /d to get round to +infinity with no extra overhead 90 (so long as the default isn't changed, of course...) 91 - no exceptions enabled. */ 92 93 #define _FPU_DEFAULT 0x137f 94 95 /* IEEE: same as above. */ 96 #define _FPU_IEEE 0x137f 97 98 /* Type of the control word. */ 99 typedef unsigned int fpu_control_t; 100 101 /* Default control word set at startup. */ 102 extern fpu_control_t __fpu_control; 103 104 #endif /* _ALPHA_FPU_CONTROL */ 105