iovfprintf.c

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			/* NOSTRICT */
			_ulong = (unsigned long)va_arg(ap, void *);
			base = HEX;
			flags |= HEXPREFIX;
			ch = 'x';
			goto nosign;
		case 's':
			if ((cp = va_arg(ap, char *)) == NULL)
				cp = "(null)";
			if (prec >= 0) {
				/*
				 * can't use strlen; can only look for the
				 * NUL in the first `prec' characters, and
				 * strlen() will go further.
				 */
				char *p = (char*)memchr(cp, 0, prec);

				if (p != NULL) {
					size = p - cp;
					if (size > prec)
						size = prec;
				} else
					size = prec;
			} else
				size = strlen(cp);
			sign = '\0';
			break;
		case 'U':
			flags |= LONGINT;
			/*FALLTHROUGH*/
		case 'u':
			_ulong = UARG();
			base = DEC;
			goto nosign;
		case 'X':
		case 'x':
			_ulong = UARG();
			base = HEX;
			/* leading 0x/X only if non-zero */
			if (flags & ALT && _ulong != 0)
				flags |= HEXPREFIX;

			/* unsigned conversions */
nosign:			sign = '\0';
			/*
			 * ``... diouXx conversions ... if a precision is
			 * specified, the 0 flag will be ignored.''
			 *	-- ANSI X3J11
			 */
number:			if ((dprec = prec) >= 0)
				flags &= ~ZEROPAD;

			/*
			 * ``The result of converting a zero value with an
			 * explicit precision of zero is no characters.''
			 *	-- ANSI X3J11
			 */
			cp = buf + BUF;
			if (_ulong != 0 || prec != 0) {
			        char *xdigs; /* digits for [xX] conversion */
				/*
				 * unsigned mod is hard, and unsigned mod
				 * by a constant is easier than that by
				 * a variable; hence this switch.
				 */
				switch (base) {
				case OCT:
					do {
						*--cp = to_char(_ulong & 7);
						_ulong >>= 3;
					} while (_ulong);
					/* handle octal leading 0 */
					if (flags & ALT && *cp != '0')
						*--cp = '0';
					break;

				case DEC:
					/* many numbers are 1 digit */
					while (_ulong >= 10) {
						*--cp = to_char(_ulong % 10);
						_ulong /= 10;
					}
					*--cp = to_char(_ulong);
					break;

				case HEX:
					if (ch == 'X')
					    xdigs = "0123456789ABCDEF";
					else /* ch == 'x' || ch == 'p' */
					    xdigs = "0123456789abcdef";
					do {
						*--cp = xdigs[_ulong & 15];
						_ulong >>= 4;
					} while (_ulong);
					break;

				default:
					cp = "bug in vform: bad base";
					goto skipsize;
				}
			}
			size = buf + BUF - cp;
		skipsize:
			break;
		default:	/* "%?" prints ?, unless ? is NUL */
			if (ch == '\0')
				goto done;
			/* pretend it was %c with argument ch */
			cp = buf;
			*cp = ch;
			size = 1;
			sign = '\0';
			break;
		}

		/*
		 * All reasonable formats wind up here.  At this point,
		 * `cp' points to a string which (if not flags&LADJUST)
		 * should be padded out to `width' places.  If
		 * flags&ZEROPAD, it should first be prefixed by any
		 * sign or other prefix; otherwise, it should be blank
		 * padded before the prefix is emitted.  After any
		 * left-hand padding and prefixing, emit zeroes
		 * required by a decimal [diouxX] precision, then print
		 * the string proper, then emit zeroes required by any
		 * leftover floating precision; finally, if LADJUST,
		 * pad with blanks.
		 */

		/*
		 * compute actual size, so we know how much to pad.
		 */
#if defined(FLOATING_POINT) && !defined (_IO_USE_DTOA)
		fieldsz = size + fpprec;
#else
		fieldsz = size;
#endif
		dpad = dprec - size;
		if (dpad < 0)
		    dpad = 0;

		if (sign)
			fieldsz++;
		else if (flags & HEXPREFIX)
			fieldsz += 2;
		fieldsz += dpad;

		/* right-adjusting blank padding */
		if ((flags & (LADJUST|ZEROPAD)) == 0)
			PAD_SP(width - fieldsz);

		/* prefix */
		if (sign) {
			PRINT(&sign, 1);
		} else if (flags & HEXPREFIX) {
			ox[0] = '0';
			ox[1] = ch;
			PRINT(ox, 2);
		}

		/* right-adjusting zero padding */
		if ((flags & (LADJUST|ZEROPAD)) == ZEROPAD)
			PAD_0(width - fieldsz);

		/* leading zeroes from decimal precision */
		PAD_0(dpad);

		/* the string or number proper */
		PRINT(cp, size);

#if defined(FLOATING_POINT) && !defined (_IO_USE_DTOA)
		/* trailing f.p. zeroes */
		PAD_0(fpprec);
#endif

		/* left-adjusting padding (always blank) */
		if (flags & LADJUST)
			PAD_SP(width - fieldsz);

		/* finally, adjust ret */
		ret += width > fieldsz ? width : fieldsz;

	}
done:
	return ret;
error:
	return EOF;
	/* NOTREACHED */
}

#if defined(FLOATING_POINT) && !defined(_IO_USE_DTOA)

static char *exponent(register char *p, register int exp, int fmtch)
{
	register char *t;
	char expbuf[MAXEXP];

	*p++ = fmtch;
	if (exp < 0) {
		exp = -exp;
		*p++ = '-';
	}
	else
		*p++ = '+';
	t = expbuf + MAXEXP;
	if (exp > 9) {
		do {
			*--t = to_char(exp % 10);
		} while ((exp /= 10) > 9);
		*--t = to_char(exp);
		for (; t < expbuf + MAXEXP; *p++ = *t++);
	}
	else {
		*p++ = '0';
		*p++ = to_char(exp);
	}
	return (p);
}

static char * round(double fract, int *exp,
		    register char *start, register char *end,
		    char ch, int *signp)
{
	double tmp;

	if (fract)
	(void)modf(fract * 10, &tmp);
	else
		tmp = to_digit(ch);
	if (tmp > 4)
		for (;; --end) {
			if (*end == '.')
				--end;
			if (++*end <= '9')
				break;
			*end = '0';
			if (end == start) {
				if (exp) {	/* e/E; increment exponent */
					*end = '1';
					++*exp;
				}
				else {		/* f; add extra digit */
				*--end = '1';
				--start;
				}
				break;
			}
		}
	/* ``"%.3f", (double)-0.0004'' gives you a negative 0. */
	else if (*signp == '-')
		for (;; --end) {
			if (*end == '.')
				--end;
			if (*end != '0')
				break;
			if (end == start)
				*signp = 0;
		}
	return (start);
}

int __cvt_double(double number, register int prec, int flags, int *signp,
		 int fmtch, char *startp, char *endp)
{
	register char *p, *t;
	register double fract;
	int dotrim = 0, expcnt, gformat = 0;
	double integer, tmp;

	expcnt = 0;
	if (number < 0) {
		number = -number;
		*signp = '-';
	} else
		*signp = 0;

	fract = modf(number, &integer);

	/* get an extra slot for rounding. */
	t = ++startp;

	/*
	 * get integer portion of number; put into the end of the buffer; the
	 * .01 is added for modf(356.0 / 10, &integer) returning .59999999...
	 */
	for (p = endp - 1; p >= startp && integer; ++expcnt) {
		tmp = modf(integer / 10, &integer);
		*p-- = to_char((int)((tmp + .01) * 10));
	}
	switch (fmtch) {
	case 'f':
	case 'F':
		/* reverse integer into beginning of buffer */
		if (expcnt)
			for (; ++p < endp; *t++ = *p);
		else
			*t++ = '0';
		/*
		 * if precision required or alternate flag set, add in a
		 * decimal point.
		 */
		if (prec || flags&ALT)
			*t++ = '.';
		/* if requires more precision and some fraction left */
		if (fract) {
			if (prec)
				do {
					fract = modf(fract * 10, &tmp);
					*t++ = to_char((int)tmp);
				} while (--prec && fract);
			if (fract)
				startp = round(fract, (int *)NULL, startp,
				    t - 1, (char)0, signp);
		}
		for (; prec--; *t++ = '0');
		break;
	case 'e':
	case 'E':
eformat:	if (expcnt) {
			*t++ = *++p;
			if (prec || flags&ALT)
				*t++ = '.';
			/* if requires more precision and some integer left */
			for (; prec && ++p < endp; --prec)
				*t++ = *p;
			/*
			 * if done precision and more of the integer component,
			 * round using it; adjust fract so we don't re-round
			 * later.
			 */
			if (!prec && ++p < endp) {
				fract = 0;
				startp = round((double)0, &expcnt, startp,
				    t - 1, *p, signp);
			}
			/* adjust expcnt for digit in front of decimal */
			--expcnt;
		}
		/* until first fractional digit, decrement exponent */
		else if (fract) {
			/* adjust expcnt for digit in front of decimal */
			for (expcnt = -1;; --expcnt) {
				fract = modf(fract * 10, &tmp);
				if (tmp)
					break;
			}
			*t++ = to_char((int)tmp);
			if (prec || flags&ALT)
				*t++ = '.';
		}
		else {
			*t++ = '0';
			if (prec || flags&ALT)
				*t++ = '.';
		}
		/* if requires more precision and some fraction left */
		if (fract) {
			if (prec)
				do {
					fract = modf(fract * 10, &tmp);
					*t++ = to_char((int)tmp);
				} while (--prec && fract);
			if (fract)
				startp = round(fract, &expcnt, startp,
				    t - 1, (char)0, signp);
		}
		/* if requires more precision */
		for (; prec--; *t++ = '0');

		/* unless alternate flag, trim any g/G format trailing 0's */
		if (gformat && !(flags&ALT)) {
			while (t > startp && *--t == '0');
			if (*t == '.')
				--t;
			++t;
		}
		t = exponent(t, expcnt, fmtch);
		break;
	case 'g':
	case 'G':
		/* a precision of 0 is treated as a precision of 1. */
		if (!prec)
			++prec;
		/*
		 * ``The style used depends on the value converted; style e
		 * will be used only if the exponent resulting from the
		 * conversion is less than -4 or greater than the precision.''
		 *	-- ANSI X3J11
		 */
		if (expcnt > prec || (!expcnt && fract && fract < .0001)) {
			/*
			 * g/G format counts "significant digits, not digits of
			 * precision; for the e/E format, this just causes an
			 * off-by-one problem, i.e. g/G considers the digit
			 * before the decimal point significant and e/E doesn't
			 * count it as precision.
			 */
			--prec;
			fmtch -= 2;		/* G->E, g->e */
			gformat = 1;
			goto eformat;
		}
		/*
		 * reverse integer into beginning of buffer,
		 * note, decrement precision
		 */
		if (expcnt)
			for (; ++p < endp; *t++ = *p, --prec);
		else
			*t++ = '0';
		/*
		 * if precision required or alternate flag set, add in a
		 * decimal point.  If no digits yet, add in leading 0.
		 */
		if (prec || flags&ALT) {
			dotrim = 1;
			*t++ = '.';
		}
		else
			dotrim = 0;
		/* if requires more precision and some fraction left */
		if (fract) {
			if (prec) {
				/* If no integer part, don't count initial
				 * zeros as significant digits. */
				do {
					fract = modf(fract * 10, &tmp);
					*t++ = to_char((int)tmp);
				} while(!tmp && !expcnt);
				while (--prec && fract) {
					fract = modf(fract * 10, &tmp);
					*t++ = to_char((int)tmp);
				}
			}
			if (fract)
				startp = round(fract, (int *)NULL, startp,
				    t - 1, (char)0, signp);
		}
		/* alternate format, adds 0's for precision, else trim 0's */
		if (flags&ALT)
			for (; prec--; *t++ = '0');
		else if (dotrim) {
			while (t > startp && *--t == '0');
			if (*t != '.')
				++t;
		}
	}
	return (t - startp);
}

#endif /* defined(FLOATING_POINT) && !defined(_IO_USE_DTOA) */