vfprintf.c

cygwin, 著名的在win32下模拟unix操作系统的东东

	arg_type[0] = -1;
	numargs = 0;
	is_pos_arg = 0;
#endif

	/*
	 * Scan the format for conversions (`%' character).
	 */
	for (;;) {
	        cp = fmt;
	        while ((n = _mbtowc_r(_REENT, &wc, fmt, MB_CUR_MAX, &state)) > 0) {
			fmt += n;
			if (wc == '%') {
				fmt--;
				break;
			}
		}
		if ((m = fmt - cp) != 0) {
			PRINT(cp, m);
			ret += m;
		}
		if (n <= 0)
			goto done;

		fmt_anchor = fmt;
		fmt++;		/* skip over '%' */

		flags = 0;
		dprec = 0;
		width = 0;
		prec = -1;
		sign = '\0';
		N = arg_index;
#ifndef _NO_POS_ARGS
		is_pos_arg = 0;
#endif

rflag:		ch = *fmt++;
reswitch:	switch (ch) {
		case ' ':
			/*
			 * ``If the space and + flags both appear, the space
			 * flag will be ignored.''
			 *	-- ANSI X3J11
			 */
			if (!sign)
				sign = ' ';
			goto rflag;
		case '#':
			flags |= ALT;
			goto rflag;
		case '*':
			n = N;
#ifndef _NO_POS_ARGS
			/* we must check for positional arg used for dynamic width */
			old_is_pos_arg = is_pos_arg;
			is_pos_arg = 0;
			if (is_digit(*fmt)) {
				char *old_fmt = fmt;

				n = 0;
				ch = *fmt++;
				do {
					n = 10 * n + to_digit(ch);
					ch = *fmt++;
				} while (is_digit(ch));

				if (ch == '$') {
					if (n <= MAX_POS_ARGS) {
						n -= 1;
						is_pos_arg = 1;
					}
					else
						goto error;
				}
				else {
					fmt = old_fmt;
					goto rflag;
				}
			}
#endif /* !_NO_POS_ARGS */

			/*
			 * ``A negative field width argument is taken as a
			 * - flag followed by a positive field width.''
			 *	-- ANSI X3J11
			 * They don't exclude field widths read from args.
			 */
			width = GET_ARG(n, ap, int);
#ifndef _NO_POS_ARGS
			is_pos_arg = old_is_pos_arg;
#endif
			if (width >= 0)
				goto rflag;
			width = -width;
			/* FALLTHROUGH */
		case '-':
			flags |= LADJUST;
			goto rflag;
		case '+':
			sign = '+';
			goto rflag;
		case '.':
			if ((ch = *fmt++) == '*') {
				n = N;
#ifndef _NO_POS_ARGS
				/* we must check for positional arg used for dynamic width */
				old_is_pos_arg = is_pos_arg;
				is_pos_arg = 0;
				if (is_digit(*fmt)) {
					char *old_fmt = fmt;

					n = 0;
					ch = *fmt++;
					do {
						n = 10 * n + to_digit(ch);
						ch = *fmt++;
					} while (is_digit(ch));

					if (ch == '$') {
						if (n <= MAX_POS_ARGS) {
							n -= 1;
							is_pos_arg = 1;
						}
						else
							goto error;
					}
					else {
						fmt = old_fmt;
						goto rflag;
					}
				}
#endif /* !_NO_POS_ARGS */
				prec = GET_ARG(n, ap, int);
#ifndef _NO_POS_ARGS
				is_pos_arg = old_is_pos_arg;
#endif
				if (prec < 0)
					prec = -1;
				goto rflag;
			}
			n = 0;
			while (is_digit(ch)) {
				n = 10 * n + to_digit(ch);
				ch = *fmt++;
			}
			prec = n < 0 ? -1 : n;
			goto reswitch;
		case '0':
			/*
			 * ``Note that 0 is taken as a flag, not as the
			 * beginning of a field width.''
			 *	-- ANSI X3J11
			 */
			flags |= ZEROPAD;
			goto rflag;
		case '1': case '2': case '3': case '4':
		case '5': case '6': case '7': case '8': case '9':
			n = 0;
			do {
				n = 10 * n + to_digit(ch);
				ch = *fmt++;
			} while (is_digit(ch));
#ifndef _NO_POS_ARGS
			if (ch == '$') {
				if (n <= MAX_POS_ARGS) {
					N = n - 1;
					is_pos_arg = 1;
					goto rflag;
				}
				else
					goto error;
			}
#endif /* !_NO_POS_ARGS */
			width = n;
			goto reswitch;
#ifdef FLOATING_POINT
		case 'L':
			flags |= LONGDBL;
			goto rflag;
#endif
		case 'h':
			flags |= SHORTINT;
			goto rflag;
		case 'l':
			if (*fmt == 'l') {
				fmt++;
				flags |= QUADINT;
			} else {
				flags |= LONGINT;
			}
			goto rflag;
		case 'q':
			flags |= QUADINT;
			goto rflag;
		case 'c':
			*(cp = buf) = GET_ARG(N, ap, int);
			size = 1;
			sign = '\0';
			break;
		case 'D':
			flags |= LONGINT;
			/*FALLTHROUGH*/
		case 'd':
		case 'i':
			_uquad = SARG();
#ifndef _NO_LONGLONG
			if ((quad_t)_uquad < 0)
#else
			if ((long) _uquad < 0)
#endif
			{

				_uquad = -_uquad;
				sign = '-';
			}
			base = DEC;
			goto number;
#ifdef FLOATING_POINT
		case 'e':
		case 'E':
		case 'f':
		case 'g':
		case 'G':
			if (prec == -1) {
				prec = DEFPREC;
			} else if ((ch == 'g' || ch == 'G') && prec == 0) {
				prec = 1;
			}

#ifdef _NO_LONGDBL
			if (flags & LONGDBL) {
				_fpvalue = (double) GET_ARG(N, ap, _LONG_DOUBLE);
			} else {
				_fpvalue = GET_ARG(N, ap, double);
			}

			/* do this before tricky precision changes */
			if (isinf(_fpvalue)) {
				if (_fpvalue < 0)
					sign = '-';
				cp = "Inf";
				size = 3;
				break;
			}
			if (isnan(_fpvalue)) {
				cp = "NaN";
				size = 3;
				break;
			}

#else /* !_NO_LONGDBL */
			
			if (flags & LONGDBL) {
				_fpvalue = GET_ARG(N, ap, _LONG_DOUBLE);
			} else {
				_fpvalue = (_LONG_DOUBLE)GET_ARG(N, ap, double);
			}

			/* do this before tricky precision changes */
			tmp = _ldcheck (&_fpvalue);
			if (tmp == 2) {
				if (_fpvalue < 0)
					sign = '-';
				cp = "Inf";
				size = 3;
				break;
			}
			if (tmp == 1) {
				cp = "NaN";
				size = 3;
				break;
			}
#endif /* !_NO_LONGDBL */

			flags |= FPT;

			cp = cvt(data, _fpvalue, prec, flags, &softsign,
				&expt, ch, &ndig);

			if (ch == 'g' || ch == 'G') {
				if (expt <= -4 || expt > prec)
					ch = (ch == 'g') ? 'e' : 'E';
				else
					ch = 'g';
			} 
			if (ch <= 'e') {	/* 'e' or 'E' fmt */
				--expt;
				expsize = exponent(expstr, expt, ch);
				size = expsize + ndig;
				if (ndig > 1 || flags & ALT)
					++size;
			} else if (ch == 'f') {		/* f fmt */
				if (expt > 0) {
					size = expt;
					if (prec || flags & ALT)
						size += prec + 1;
				} else	/* "0.X" */
					size = prec + 2;
			} else if (expt >= ndig) {	/* fixed g fmt */
				size = expt;
				if (flags & ALT)
					++size;
			} else
				size = ndig + (expt > 0 ?
					1 : 2 - expt);

			if (softsign)
				sign = '-';
			break;
#endif /* FLOATING_POINT */
		case 'n':
#ifndef _NO_LONGLONG
			if (flags & QUADINT)
				*GET_ARG(N, ap, quad_ptr_t *) = ret;
			else 
#endif
			if (flags & LONGINT)
				*GET_ARG(N, ap, long_ptr_t) = ret;
			else if (flags & SHORTINT)
				*GET_ARG(N, ap, short_ptr_t) = ret;
			else
				*GET_ARG(N, ap, int_ptr_t) = ret;
			continue;	/* no output */
		case 'O':
			flags |= LONGINT;
			/*FALLTHROUGH*/
		case 'o':
			_uquad = UARG();
			base = OCT;
			goto nosign;
		case 'p':
			/*
			 * ``The argument shall be a pointer to void.  The
			 * value of the pointer is converted to a sequence
			 * of printable characters, in an implementation-
			 * defined manner.''
			 *	-- ANSI X3J11
			 */
			/* NOSTRICT */
			_uquad = (u_long)(unsigned _POINTER_INT)GET_ARG(N, ap, void_ptr_t);
			base = HEX;
			xdigs = "0123456789abcdef";
			flags |= HEXPREFIX;
			ch = 'x';
			goto nosign;
		case 's':
			if ((cp = GET_ARG(N, ap, char_ptr_t)) == 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 = 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':
			_uquad = UARG();
			base = DEC;
			goto nosign;
		case 'X':
			xdigs = "0123456789ABCDEF";
			goto hex;
		case 'x':
			xdigs = "0123456789abcdef";
hex:			_uquad = UARG();
			base = HEX;
			/* leading 0x/X only if non-zero */
			if (flags & ALT && _uquad != 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 (_uquad != 0 || prec != 0) {
				/*
				 * 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(_uquad & 7);
						_uquad >>= 3;
					} while (_uquad);
					/* handle octal leading 0 */
					if (flags & ALT && *cp != '0')
						*--cp = '0';
					break;

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

				case HEX:
					do {
						*--cp = xdigs[_uquad & 15];
						_uquad >>= 4;
					} while (_uquad);
					break;

				default:
					cp = "bug in vfprintf: bad base";
					size = strlen(cp);
					goto skipsize;
				}
			}
                       /*
			* ...result is to be converted to an 'alternate form'.
			* For o conversion, it increases the precision to force
			* the first digit of the result to be a zero."
			*     -- ANSI X3J11
			*
			* To demonstrate this case, compile and run:
                        *    printf ("%#.0o",0);
			*/
                       else if (base == OCT && (flags & ALT))
                         *--cp = '0';

			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.
		 * size excludes decimal prec; realsz includes it.
		 */
		realsz = dprec > size ? dprec : size;
		if (sign)
			realsz++;
		else if (flags & HEXPREFIX)
			realsz+= 2;

		/* right-adjusting blank padding */
		if ((flags & (LADJUST|ZEROPAD)) == 0)
			PAD(width - realsz, blanks);

		/* 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(width - realsz, zeroes);

		/* leading zeroes from decimal precision */
		PAD(dprec - size, zeroes);

		/* the string or number proper */
#ifdef FLOATING_POINT
		if ((flags & FPT) == 0) {
			PRINT(cp, size);
		} else {	/* glue together f_p fragments */
			if (ch >= 'f') {	/* 'f' or 'g' */
				if (_fpvalue == 0) {
					/* kludge for __dtoa irregularity */
					PRINT("0", 1);
					if (expt < ndig || (flags & ALT) != 0) {
						PRINT(decimal_point, 1);
						PAD(ndig - 1, zeroes);
					}
				} else if (expt <= 0) {
					PRINT("0", 1);
					if(expt || ndig) {
						PRINT(decimal_point, 1);
						PAD(-expt, zeroes);
						PRINT(cp, ndig);
					}
				} else if (expt >= ndig) {
					PRINT(cp, ndig);
					PAD(expt - ndig, zeroes);
					if (flags & ALT)
						PRINT(".", 1);
				} else {
					PRINT(cp, expt);
					cp += expt;