diff options
Diffstat (limited to 'usr/src/lib/libc/amd64/fp/fpstart.c')
| -rw-r--r-- | usr/src/lib/libc/amd64/fp/fpstart.c | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/usr/src/lib/libc/amd64/fp/fpstart.c b/usr/src/lib/libc/amd64/fp/fpstart.c new file mode 100644 index 0000000000..e8ab8159eb --- /dev/null +++ b/usr/src/lib/libc/amd64/fp/fpstart.c @@ -0,0 +1,85 @@ +/* + * CDDL HEADER START + * + * The contents of this file are subject to the terms of the + * Common Development and Distribution License, Version 1.0 only + * (the "License"). You may not use this file except in compliance + * with the License. + * + * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE + * or http://www.opensolaris.org/os/licensing. + * See the License for the specific language governing permissions + * and limitations under the License. + * + * When distributing Covered Code, include this CDDL HEADER in each + * file and include the License file at usr/src/OPENSOLARIS.LICENSE. + * If applicable, add the following below this CDDL HEADER, with the + * fields enclosed by brackets "[]" replaced with your own identifying + * information: Portions Copyright [yyyy] [name of copyright owner] + * + * CDDL HEADER END + */ +/* + * Copyright (c) 1990, 1991 UNIX System Laboratories, Inc. + * Copyright (c) 1988 AT&T + * All Rights Reserved + */ + +/* + * Copyright 2004 Sun Microsystems, Inc. All rights reserved. + * Use is subject to license terms. + */ + +#pragma ident "%Z%%M% %I% %E% SMI" + +/* + * Establish the default settings for the floating-point state for a C language + * program: + * rounding mode -- round to nearest default by OS, + * exceptions enabled -- all masked + * sticky bits -- all clear by default by OS. + * precision control -- double extended + */ + +#pragma weak _fpstart = __fpstart + +#include "synonyms.h" +#include <sys/types.h> +#include <sys/sysi86.h> /* for SI86FPHW/SI86FPSTART definitions */ +#include <sys/fp.h> /* for FPU_CW_INIT and SSE_MXCSR_INIT */ + +extern int _private_sysi86(); + +int __flt_rounds; /* ANSI rounding mode */ + +void +__fpstart() +{ + int _fp_hw; /* default: bss: 0 == no hardware */ + + /* + * query OS for HW status and ensure the x87 and (optional) + * SSE control words are (will be) set correctly. + * This "cannot fail". + */ + (void) _private_sysi86(SI86FPSTART, + &_fp_hw, FPU_CW_INIT, SSE_MXCSR_INIT); + + /* + * At this point the x87 fp environment that has been (or more + * hopefully, will be) established by the kernel is: + * + * affine infinity 0x1000 + * round to nearest 0x0000 + * 64-bit doubles 0x0300 + * precision, underflow, overflow, zero-divide, denorm, invalid masked + * 0x003f + * + * which conforms to the 4th edition i386 ABI definition. + * + * Additionally, if we have SSE hardware, we've also masked all + * the same traps, and have round to nearest. + */ + + __flt_rounds = 1; /* ANSI way of saying round-to-nearest */ +} |