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 #pragma ident "%Z%%M% %I% %E% SMI" 34 35 /* 36 * Establish the default settings for the floating-point state for a C language 37 * program: 38 * rounding mode -- round to nearest default by OS, 39 * exceptions enabled -- all masked 40 * sticky bits -- all clear by default by OS. 41 * precision control -- double extended 42 * Set _fp_hw according to what floating-point hardware is available. 43 * Set _sse_hw according to what SSE hardware is available. 44 * Set __flt_rounds according to the rounding mode. 45 */ 46 47 #pragma weak _fpstart = __fpstart 48 49 #include "lint.h" 50 #include <sys/types.h> 51 #include <sys/sysi86.h> /* for SI86FPHW/SI86FPSTART definitions */ 52 #include <sys/fp.h> /* for FPU_CW_INIT and SSE_MXCSR_INIT */ 53 54 extern int __fltrounds(); 55 56 int _fp_hw; /* default: bss: 0 == no hardware */ 57 int _sse_hw; /* default: bss: 0 == no sse */ 58 int __flt_rounds; /* ANSI rounding mode */ 59 60 void 61 __fpstart() 62 { 63 /* 64 * query OS for HW status and ensure the x87 and (optional) 65 * SSE control words are (will be) set correctly. 66 */ 67 if ((_sse_hw = sysi86(SI86FPSTART, 68 &_fp_hw, FPU_CW_INIT, SSE_MXCSR_INIT)) == -1) { 69 extern void _putcw(); 70 71 /* 72 * (fallback to old syscall on old kernels) 73 */ 74 _sse_hw = 0; 75 (void) sysi86(SI86FPHW, &_fp_hw); 76 _putcw(0x133f); 77 } 78 79 /* 80 * At this point the x87 fp environment that has been (or more 81 * hopefully, will be) established by the kernel is: 82 * 83 * affine infinity 0x1000 84 * round to nearest 0x0000 85 * 64-bit doubles 0x0300 86 * precision, underflow, overflow, zero-divide, denorm, invalid masked 87 * 0x003f 88 * 89 * which conforms to the 4th edition i386 ABI definition. 90 * 91 * Additionally, if we have SSE hardware, we've also masked all 92 * the same traps, and have round to nearest. 93 */ 94 95 __flt_rounds = 1; /* ANSI way of saying round-to-nearest */ 96 } 97