1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 */ 26 27 /* 28 * Copyright (c) 1990, 1991 UNIX System Laboratories, Inc. 29 * Copyright (c) 1988 AT&T 30 * All Rights Reserved 31 */ 32 33 /* 34 * Establish the default settings for the floating-point state for a C language 35 * program: 36 * rounding mode -- round to nearest default by OS, 37 * exceptions enabled -- all masked 38 * sticky bits -- all clear by default by OS. 39 * precision control -- double extended 40 * Set _fp_hw according to what floating-point hardware is available. 41 * Set _sse_hw according to what SSE hardware is available. 42 * Set __flt_rounds according to the rounding mode. 43 */ 44 45 #pragma weak _fpstart = __fpstart 46 47 #include "lint.h" 48 #include <sys/types.h> 49 #include <sys/sysi86.h> /* for SI86FPHW/SI86FPSTART definitions */ 50 #include <sys/fp.h> /* for FPU_CW_INIT and SSE_MXCSR_INIT */ 51 52 extern int __fltrounds(); 53 54 int _fp_hw; /* default: bss: 0 == no hardware */ 55 int _sse_hw; /* default: bss: 0 == no sse */ 56 int __flt_rounds; /* ANSI rounding mode */ 57 58 void 59 __fpstart() 60 { 61 /* 62 * query OS for HW status and ensure the x87 and (optional) 63 * SSE control words are (will be) set correctly. 64 */ 65 if ((_sse_hw = sysi86(SI86FPSTART, 66 &_fp_hw, FPU_CW_INIT, SSE_MXCSR_INIT)) == -1) { 67 extern void _putcw(); 68 69 /* 70 * (fallback to old syscall on old kernels) 71 */ 72 _sse_hw = 0; 73 (void) sysi86(SI86FPHW, &_fp_hw); 74 _putcw(0x133f); 75 } 76 77 /* 78 * At this point the x87 fp environment that has been (or more 79 * hopefully, will be) established by the kernel is: 80 * 81 * affine infinity 0x1000 82 * round to nearest 0x0000 83 * 64-bit doubles 0x0300 84 * precision, underflow, overflow, zero-divide, denorm, invalid masked 85 * 0x003f 86 * 87 * which conforms to the 4th edition i386 ABI definition. 88 * 89 * Additionally, if we have SSE hardware, we've also masked all 90 * the same traps, and have round to nearest. 91 */ 92 93 __flt_rounds = 1; /* ANSI way of saying round-to-nearest */ 94 } 95