/* the guts of printf - this implementation came from 4.3BSD-Tahoe */

#include <sys/types.h>
#include <ctype.h>
#include <stdarg.h>

#define	PUTC(ch)	(*(*outptrp)++ = (ch))

#define	ARG() \
	_ulong = flags&LONGINT ? va_arg(argp, long) : va_arg(argp, int);

#define	BUF	256

#define	todigit(c)	((c) - '0')
#define	tochar(n)	((n) + '0')

/* have to deal with the negative buffer count kludge */
#define	NEGATIVE_COUNT_KLUDGE

#define	LONGINT		0x01		/* long integer */
#define	LONGDBL		0x02		/* long double; unimplemented */
#define	SHORTINT	0x04		/* short integer */
#define	ALT		0x08		/* alternate form */
#define	LADJUST		0x10		/* left adjustment */
#define	ZEROPAD		0x20		/* zero (as opposed to blank) pad */
#define	HEXPREFIX	0x40		/* add 0x or 0X prefix */

_doprnt(fmt0, argp, outptrp)
	u_char *fmt0;
	va_list argp;
	char **outptrp;
{
	register u_char *fmt;	/* format string */
	register int ch;	/* character from fmt */
	register int cnt;	/* return value accumulator */
	register int n;		/* random handy integer */
	register char *t;	/* buffer pointer */
	u_long _ulong;		/* integer arguments %[diouxX] */
	int base;		/* base for [diouxX] conversion */
	int dprec;		/* decimal precision in [diouxX] */
	int fieldsz;		/* field size expanded by sign, etc */
	int flags;		/* flags as above */
	int prec;		/* precision from format (%.3d), or -1 */
	int realsz;		/* field size expanded by decimal precision */
	int size;		/* size of converted field or string */
	int width;		/* width from format (%8d), or 0 */
	char sign;		/* sign prefix (' ', '+', '-', or \0) */
	char softsign;		/* temporary negative sign for floats */
	char *digs;		/* digits for [diouxX] conversion */
	char buf[BUF];		/* space for %c, %[diouxX], %[eEfgG] */

	fmt = fmt0;
	digs = "0123456789abcdef";
	for (cnt = 0;; ++fmt) {
		for (; (ch = *fmt) && ch != '%'; ++cnt, ++fmt)
			PUTC(ch);
		if (!ch)
			return (cnt);

		flags = 0; dprec = 0; width = 0;
		prec = -1;
		sign = '\0';

rflag:		switch (*++fmt) {
		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 '*':
			/*
			 * ``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.
			 */
			if ((width = va_arg(argp, int)) >= 0)
				goto rflag;
			width = -width;
			/* FALLTHROUGH */
		case '-':
			flags |= LADJUST;
			goto rflag;
		case '+':
			sign = '+';
			goto rflag;
		case '.':
			if (*++fmt == '*')
				n = va_arg(argp, int);
			else {
				n = 0;
				while (isascii(*fmt) && isdigit(*fmt))
					n = 10 * n + todigit(*fmt++);
				--fmt;
			}
			prec = n < 0 ? -1 : n;
			goto rflag;
		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 + todigit(*fmt);
			} while (isascii(*++fmt) && isdigit(*fmt));
			width = n;
			--fmt;
			goto rflag;
		case 'L':
			flags |= LONGDBL;
			goto rflag;
		case 'h':
			flags |= SHORTINT;
			goto rflag;
		case 'l':
			flags |= LONGINT;
			goto rflag;
		case 'c':
			*(t = buf) = va_arg(argp, int);
			size = 1;
			sign = '\0';
			goto pforw;
		case 'D':
			flags |= LONGINT;
			/*FALLTHROUGH*/
		case 'd':
		case 'i':
			ARG();
			if ((long)_ulong < 0) {
				_ulong = -_ulong;
				sign = '-';
			}
			base = 10;
			goto number;
		case 'n':
			if (flags & LONGINT)
				*va_arg(argp, long *) = cnt;
			else if (flags & SHORTINT)
				*va_arg(argp, short *) = cnt;
			else
				*va_arg(argp, int *) = cnt;
			break;
		case 'O':
			flags |= LONGINT;
			/*FALLTHROUGH*/
		case 'o':
			ARG();
			base = 8;
			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 */
			_ulong = (u_long)va_arg(argp, void *);
			base = 16;
			goto nosign;
		case 's':
			if (!(t = va_arg(argp, char *)))
				t = "(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;

				for (p = t, size = 0; size < prec; p++, size++)
					if (*p == '\0')
						break;
			} else
				size = strlen(t);
			sign = '\0';
			goto pforw;
		case 'U':
			flags |= LONGINT;
			/*FALLTHROUGH*/
		case 'u':
			ARG();
			base = 10;
			goto nosign;
		case 'X':
			digs = "0123456789ABCDEF";
			/* FALLTHROUGH */
		case 'x':
			ARG();
			base = 16;
			/* 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
			 */
			t = buf + BUF;
			if (_ulong != 0 || prec != 0) {
				do {
					*--t = digs[_ulong % base];
					_ulong /= base;
				} while (_ulong);
				digs = "0123456789abcdef";
				if (flags & ALT && base == 8 && *t != '0')
					*--t = '0'; /* octal leading 0 */
			}
			size = buf + BUF - t;

pforw:
			/*
			 * All reasonable formats wind up here.  At this point,
			 * `t' 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
			 * fieldsz excludes decimal prec; realsz includes it
			 */
			fieldsz = size;
			if (sign)
				fieldsz++;
			if (flags & HEXPREFIX)
				fieldsz += 2;
			realsz = dprec > fieldsz ? dprec : fieldsz;

			/* right-adjusting blank padding */
			if ((flags & (LADJUST|ZEROPAD)) == 0 && width)
				for (n = realsz; n < width; n++)
					PUTC(' ');
			/* prefix */
			if (sign)
				PUTC(sign);
			if (flags & HEXPREFIX) {
				PUTC('0');
				PUTC((char)*fmt);
			}
			/* right-adjusting zero padding */
			if ((flags & (LADJUST|ZEROPAD)) == ZEROPAD)
				for (n = realsz; n < width; n++)
					PUTC('0');
			/* leading zeroes from decimal precision */
			for (n = fieldsz; n < dprec; n++)
				PUTC('0');

			for (n = size; --n >= 0; )
				PUTC(*t++);
			/* left-adjusting padding (always blank) */
			if (flags & LADJUST)
				for (n = realsz; n < width; n++)
					PUTC(' ');
			/* finally, adjust cnt */
			cnt += width > realsz ? width : realsz;
			break;
		case '\0':	/* "%?" prints ?, unless ? is NULL */
			return (cnt);
		default:
			PUTC((char)*fmt);
			cnt++;
		}
	}
	/* NOTREACHED */
}