f_frexp.s

Newlib 嵌入式 C库 标准实现代码

/*
 * ====================================================
 * Copyright (C) 1998, 2002 by Red Hat Inc. All rights reserved.
 *
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

#if !defined(_SOFT_FLOAT)

/*
Fast version of frexp using Intel float instructions.

   double _f_frexp (double x, int *exp);

Function splits x into y * 2 ** z.  It then
returns the value of y and updates *exp with z.
There is no error checking or setting of errno.
*/

	#include "i386mach.h"

	.global SYM (_f_frexp)
       SOTYPE_FUNCTION(_f_frexp)

SYM (_f_frexp):
	pushl ebp
	movl esp,ebp
	fldl 8(ebp)
	movl 16(ebp),eax

	fxtract
	fld1
	fchs
	fxch
	fscale
	fstp st1
	fxch
	fld1
	faddp
	fistpl 0(eax)

	leave
	ret

#endif