/*******************************************************************
*                                                                  *
*             This software is part of the ast package             *
*                Copyright (c) 1985-2004 AT&T Corp.                *
*        and it may only be used by you under license from         *
*                       AT&T Corp. ("AT&T")                        *
*         A copy of the Source Code Agreement is available         *
*                at the AT&T Internet web site URL                 *
*                                                                  *
*       http://www.research.att.com/sw/license/ast-open.html       *
*                                                                  *
*    If you have copied or used this software without agreeing     *
*        to the terms of the license you are infringing on         *
*           the license and copyright and are violating            *
*               AT&T's intellectual property rights.               *
*                                                                  *
*            Information and Software Systems Research             *
*                        AT&T Labs Research                        *
*                         Florham Park NJ                          *
*                                                                  *
*               Glenn Fowler <gsf@research.att.com>                *
*                David Korn <dgk@research.att.com>                 *
*                 Phong Vo <kpv@research.att.com>                  *
*                                                                  *
*******************************************************************/
#include	"sfhdr.h"

/*	Write out a floating point value in a portable format
**
**	Written by Kiem-Phong Vo.
*/

#if __STD_C
int _sfputd(Sfio_t* f, Sfdouble_t v)
#else
int _sfputd(f,v)
Sfio_t*		f;
Sfdouble_t	v;
#endif
{
#define N_ARRAY		(16*sizeof(Sfdouble_t))
	reg ssize_t	n, w;
	reg uchar	*s, *ends;
	int		exp;
	uchar		c[N_ARRAY];
	Sfdouble_t	x;

	SFMTXSTART(f,-1);

	if(f->mode != SF_WRITE && _sfmode(f,SF_WRITE,0) < 0)
		SFMTXRETURN(f, -1);
	SFLOCK(f,0);

	/* get the sign of v */
	if(v < 0.)
	{	v = -v;
		n = 1;
	}
	else	n = 0;

	/* make the magnitude of v < 1 */
	if(v != 0.)
		v = frexpl(v,&exp);
	else	exp = 0;

	/* code the sign of v and exp */
	if((w = exp) < 0)
	{	n |= 02;
		w = -w;
	}

	/* write out the signs and the exp */
	SFOPEN(f,0);
	if(sfputc(f,n) < 0 || (w = sfputu(f,w)) < 0)
		SFMTXRETURN(f, -1);
	SFLOCK(f,0);
	w += 1;

	s = (ends = &c[0])+sizeof(c);
	while(s > ends)
	{	/* get 2^SF_PRECIS precision at a time */
		n = (int)(x = ldexpl(v,SF_PRECIS));
		*--s = n|SF_MORE;
		v = x-n;
		if(v <= 0.)
			break;
	}

	/* last byte is not SF_MORE */
	ends = &c[0] + sizeof(c) -1;
	*ends &= ~SF_MORE;

	/* write out coded bytes */
	n = ends - s + 1;
	w = SFWRITE(f,(Void_t*)s,n) == n ? w+n : -1;

	SFOPEN(f,0);
	SFMTXRETURN(f,w);
}
