modf.s

来自「基于组件方式开发操作系统的OSKIT源代码」· S 代码 · 共 80 行

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Sean Eric Fagan.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	$Id: modf.S,v 1.5 1997/02/22 14:58:39 peter Exp $
 */

#if defined(LIBC_RCS) && !defined(lint)
	.text
	.asciz "$Id: modf.S,v 1.5 1997/02/22 14:58:39 peter Exp $"
#endif /* LIBC_RCS and not lint */

/*
 * modf(value, iptr): return fractional part of value, and stores the
 * integral part into iptr (a pointer to double).
 *
 * Written by Sean Eric Fagan ([e-mail])
 * Sun Mar 11 20:27:30 PST 1990
 */

/* With CHOP mode on, frndint behaves as TRUNC does.  Useful. */

#include "DEFS.h"

ENTRY(modf)
	pushl %ebp
	movl %esp,%ebp
	subl $16,%esp
	fnstcw -12(%ebp)
	movw -12(%ebp),%dx
	orw $3072,%dx
	movw %dx,-16(%ebp)
	fldcw -16(%ebp)
	fldl 8(%ebp)
	frndint
	fstpl -8(%ebp)
	fldcw -12(%ebp)
	movl 16(%ebp),%eax
	movl -8(%ebp),%edx
	movl -4(%ebp),%ecx
	movl %edx,(%eax)
	movl %ecx,4(%eax)
	fldl 8(%ebp)
	fsubl -8(%ebp)
	jmp L1
L1:
	leave
	ret