V8/usr/src/cmd/PDP11/fpp/aux/rhftoa.c

/* ftoa from portable c library, modified to use faster multiply 
   up and down. */

ftoa (x, str, prec, format)
float x;
char *str;
{
	/* converts a floating point number to an ascii string */
	/* x is stored into str, which should be at least 30 chars long */
	int ie, i, k, ndig, fstyle;
	double y;
	ndig =  ( prec<0) ? 7 : (prec > 22 ? 23 : prec+1);
	if  (format == 'f' || format == 'F')
		fstyle = 1;
	else
		fstyle = 0;
	/* print in e format unless last arg is 'f' */
	ie = 0;
	/* if x negative, write minus and reverse */
	if ( x < 0.0)
	{
		*str++ = '-';
		x = -x;
	}

	/* put x in range 1 <= x < 10 */
	if(x > 0.0) {
		if(x<1e-32){
			x=x* 1e33; 
			ie -= 33;
		}
		if(x<1e-16){
			x=x* 1e17; 
			ie -= 17;
		}
		if(x<1e-8){
			x=x* 1e9; 
			ie -= 9;
		}
		if(x<1e-4){
			x=x* 1e5; 
			ie -= 5;
		}
		if(x<1e-2){
			x=x* 1e3; 
			ie -= 3;
		}
		if(x<1e-1){
			x=x* 1e2; 
			ie -= 2;
		}
		while(x<1.0){ 
			x=x* 10.; 
			ie -= 1;
		}
	}
	if(x>=1e32){
		x=x/1e32; 
		ie += 32;
	}
	if(x>=1e16){
		x=x/1e16; 
		ie += 16;
	}
	if(x>=1e8){
		x=x/1e8; 
		ie += 8;
	}
	if(x>=1e4){
		x=x/1e4; 
		ie += 4;
	}
	if(x>=1e2){
		x=x/1e2; 
		ie += 2;
	}
	while(x>=10.){
		x=x/10.;
		ie++;
	}

	/* in f format, number of digits is related to size */
	if (fstyle) ndig += ie;

	/* round. x is between 1 and 10 and ndig will be printed to
	   right of decimal point so rounding is ... */
	y = 10.0;
	for (i = 0; i < ndig; i++)
		y=y/10.0;
	x=x+.5*y;
	if (x >= 10.0) /* repair rounding disasters */
	{
		x = 1.0;
		ie++;
		if (fstyle) ndig++;
	}
	/* now loop.  put out a digit (obtain by multiplying by
	  10, truncating, subtracting) until enough digits out */
	/* if fstyle, and leading zeros, they go out special */
	if (fstyle && ie < 0)
	{
		*str++ = '0';
		i = (ndig > 0) ? -1 : (ndig-1);
		i -= ie;
		if (i > 0)
		{
			*str++ = '.';
			while (i--)
				*str++ = '0';
		}
	}
	for (i=0; i < ndig; i++)
	{
		if (i == (fstyle ? ie+1 : 1)) /* where is decimal point */
			*str++ = '.';
		k = x;
		*str++ = k + '0';
		x -= (y=k);
		x=x*10.;
	}

	/* now, in estyle,  put out exponent if not zero */
	if (!fstyle && ie != 0)
	{
		*str++ = 'E';
		if (ie < 0)
		{
			ie = -ie;
			*str++ = '-';
		}
		for (k=100; k > ie; k /=10);
		for (; k > 0; k /=10)
		{
			*str++ = ie/k + '0';
			ie = ie%k;
		}
	}
	*str = '\0';
	return;
}

/* printf here to force loading of pfloat is printf is called. */

printf(arg0)
char *arg0;
{
	extern int putchar();
	return(format(putchar,"%r",&arg0));
}

__dummy() {
	extern pfloat(); /* force pfloat and pscien to be loaded */
	pfloat();
}