ack/lang/cem/libcc/gen/gcvt.c

/* $Header$ */
#ifndef NOFLOAT
extern char	*ecvt();

#define NDIGINEXP	2

char *
gcvt(value, ndigit, buf)
	double value;
	char *buf;
	register int ndigit;
{
	int sign, dp;
	register char *s1, *s2;
	register int i;

	s1 = ecvt(value, ndigit, &dp, &sign);
	s2 = buf;
	if (sign) *s2++ = '-';
	for (i = ndigit - 1; i > 0 && s1[i] == '0'; i--) ndigit--;
	if (dp - ndigit > NDIGINEXP + 2 || dp < -NDIGINEXP - 1) {
		/* Use E format, otherwise we need too many '0''s */
		dp--;
		*s2++ = *s1++;
		*s2++ = '.';
		while (--ndigit > 0) *s2++ = *s1++;
		*s2++ = 'e';
		if (dp < 0) {
			*s2++ = '-';
			dp = -dp;
		}
		else	 *s2++ = '+';
		s2 += NDIGINEXP;
		for (i = NDIGINEXP; i > 0; i--) {
			*--s2 = dp % 10 + '0';
			dp /= 10;
		}
		return buf;
	}
	if (dp <= 0) {
		if (*s1 != '0')	{
			/* otherwise the whole number is 0 */
			*s2++ = '.';
		}
		while (dp < 0) {
			dp++;
			*s2++ = '0';
		}
	}
	for (i = 1; i <= ndigit; i++) {
		*s2++ = *s1++;
		if (i == dp) *s2++ = '.';
	}
	if (i <= dp) {
		while (i++ <= dp) *s2++ = '0';
		*s2++ = '.';
	}
	if (s2[-1]=='.') s2--;
	*s2 = '\0';
	return buf;
}
#endif