/*	minimal printf-like function
 *	printf(fmt, arg, ...)
 *		acceptable formats are %d, %o, %x, %c, %s
 *		no precision, width, or modifier
 *  the inernal buffer is only MAXCHAR long, there is no check to make sure
 *  it fits.
 *
 *	It calls a function putchar(char a) to output each character.
 */
#define MAXCHARS	512

static void itoa(char **buf, int i, int base);

int printf(char *fmt, int arg, ...)
	{
	int *p = &arg;
	char *bp, *s;
	int i;
	char buf[MAXCHARS];

	bp = buf;
	*bp = 0;
	while (*fmt)
		if (*fmt != '%')
			*bp++ = *fmt++;
		else
			{
			switch (*++fmt)
				{
			case 'd':
				i = *p++;
				if (i < 0)
					{
					*bp++ = '-';
					i = -i;
					}
				itoa(&bp, i, 10);
				break;
			case 'o':
				i = *p++;
				if (i < 0)
					{
					*bp++ = '-';
					i = -i;
					}
				*bp++ = '0';
				itoa(&bp, i, 8);
				break;
			case 'x':
				i = *p++;
				if (i < 0)
					{
					*bp++ = '-';
					i = -i;
					}
				*bp++ = '0';
				*bp++ = 'x';
				itoa(&bp, i, 16);
				break;
			case 'c':
				*bp++ = *p++;
				break;
			case 's':
				s = *(char **)p;
				p += sizeof (char **) / sizeof (int);
				if (!s)
					s = "(null)";
				while (*s)
					*bp++ = *s++;
				break;
				}
			fmt++;
			}
	*bp = 0;
	for (bp = buf; *bp; bp++)
		putchar(*bp);
	}

static void itoa(char **buf, int i, int base)
	{
	char *s;
#define LEN	20
	int rem;
	static char rev[LEN+1];

	rev[LEN] = 0;
	if (i == 0)
		{
		(*buf)[0] = '0';
		++(*buf);
		return;
		}
	s = &rev[LEN];
	while (i)
		{
		rem = i % base;
		if (rem <= 10)
			*--s = rem + '0';
		else if (base == 16)
			*--s = "abcdef"[rem - 10];
		i /= base;
		}
	while (*s)
		{
		(*buf)[0] = *s++;
		++(*buf);
		}
	}