printf.c

这是TFTP 协议的最新源代码 很辛苦的

/*
	Copyright 2001-2004 Georges Menie (www.menie.org)

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

/* this is just for the printf/sprintf prototype checking */
#include "baselib.h"

/*
	putchar is the only external dependency for this file,
	if you have a working putchar, no change needed.
	If the function should be called something else, use
	#define putchar(c) your_function(c)
*/

static void printchar (char **str, int c)
{
	extern int putchar (int c);

	if (str) {
		**str = c;
		++(*str);
	}
	else
		(void) putchar (c);
}

#define PAD_RIGHT 1
#define PAD_ZERO 2

static int prints (char **out, const char *string, int width, int pad)
{
	register int pc = 0, padchar = ' ';

	if (width > 0) {
		register int len = 0;
		register const char *ptr;

		for (ptr = string; *ptr; ++ptr)
			++len;
		if (len >= width)
			width = 0;
		else
			width -= len;
		if (pad & PAD_ZERO)
			padchar = '0';
	}
	if (!(pad & PAD_RIGHT)) {
		for (; width > 0; --width) {
			printchar (out, padchar);
			++pc;
		}
	}
	for (; *string; ++string) {
		printchar (out, *string);
		++pc;
	}
	for (; width > 0; --width) {
		printchar (out, padchar);
		++pc;
	}

	return pc;
}

/* the following should be enough for 32 bit int */
#define PRINT_BUF_LEN 12

static int printi (char **out, int i, int b, int sg, int width, int pad,
				   int letbase)
{
	char print_buf[PRINT_BUF_LEN];
	register char *s;
	register int t, neg = 0, pc = 0;
	register unsigned int u = i;

	if (i == 0) {
		print_buf[0] = '0';
		print_buf[1] = '\0';
		return prints (out, print_buf, width, pad);
	}

	if (sg && b == 10 && i < 0) {
		neg = 1;
		u = -i;
	}

	s = print_buf + PRINT_BUF_LEN - 1;
	*s = '\0';

	while (u) {
		t = u % b;
		if (t >= 10)
			t += letbase - '0' - 10;
		*--s = t + '0';
		u /= b;
	}

	if (neg) {
		if (width && (pad & PAD_ZERO)) {
			printchar (out, '-');
			++pc;
			--width;
		}
		else {
			*--s = '-';
		}
	}

	return pc + prints (out, s, width, pad);
}

static int print (char **out, int *varg)
{
	register int width, pad;
	register int pc = 0;
	register char *format = (char *) (*varg++);
	char scr[2];

	for (; *format != 0; ++format) {
		if (*format == '%') {
			++format;
			width = pad = 0;
			if (*format == '\0')
				break;
			if (*format == '%')
				goto out;
			if (*format == '-') {
				++format;
				pad = PAD_RIGHT;
			}
			while (*format == '0') {
				++format;
				pad |= PAD_ZERO;
			}
			for (; *format >= '0' && *format <= '9'; ++format) {
				width *= 10;
				width += *format - '0';
			}
			if (*format == 's') {
				register char *s = *((char **) varg++);

				pc += prints (out, s ? s : "(null)", width, pad);
				continue;
			}
			if (*format == 'd') {
				pc += printi (out, *varg++, 10, 1, width, pad, 'a');
				continue;
			}
			if (*format == 'x' || *format == 'p') {
				pc += printi (out, *varg++, 16, 0, width, pad, 'a');
				continue;
			}
			if (*format == 'X') {
				pc += printi (out, *varg++, 16, 0, width, pad, 'A');
				continue;
			}
			if (*format == 'u') {
				pc += printi (out, *varg++, 10, 0, width, pad, 'a');
				continue;
			}
			if (*format == 'c') {
				/* char are converted to int then pushed on the stack */
				scr[0] = *varg++;
				scr[1] = '\0';
				pc += prints (out, scr, width, pad);
				continue;
			}
			if (*format == 'l') {
				/* ignored : assuming sizeof(int) == sizeof(long) */
				continue;
			}
		}
		else {
		  out:
			printchar (out, *format);
			++pc;
		}
	}
	if (out)
		**out = '\0';
	return pc;
}

/* assuming sizeof(void *) == sizeof(int) */

int printf (const char *format, ...)
{
	register int *varg = (int *) (&format);

	return print (0, varg);
}

int sprintf (char *out, const char *format, ...)
{
	register int *varg = (int *) (&format);

	return print (&out, varg);
}

#ifdef TEST_PRINTF
int main (void)
{
	char *ptr = "Hello world!";
	char *np = 0;
	int i = 5;
	unsigned int bs = sizeof (int) * 8;
	int mi;
	char buf[80];

	mi = (1 << (bs - 1)) + 1;
	printf ("%s\n", ptr);
	printf ("printf test\n");
	printf ("%s is null pointer\n", np);
	printf ("%d = 5\n", i);
	printf ("%d = - max int\n", mi);
	printf ("char %c = 'a'\n", 'a');
	printf ("hex %x = ff\n", 0xff);
	printf ("hex %02x = 00\n", 0);
	printf ("signed %d = unsigned %u = hex %x\n", -3, -3, -3);
	printf ("%d %s(s)%", 0, "message");
	printf ("\n");
	printf ("%d %s(s) with %%\n", 0, "message");
	sprintf (buf, "justif: \"%-10s\"\n", "left");
	printf ("%s", buf);
	sprintf (buf, "justif: \"%10s\"\n", "right");
	printf ("%s", buf);
	sprintf (buf, " 3: %04d zero padded\n", 3);
	printf ("%s", buf);
	sprintf (buf, " 3: %-4d left justif.\n", 3);
	printf ("%s", buf);
	sprintf (buf, " 3: %4d right justif.\n", 3);
	printf ("%s", buf);
	sprintf (buf, "-3: %04d zero padded\n", -3);
	printf ("%s", buf);
	sprintf (buf, "-3: %-4d left justif.\n", -3);
	printf ("%s", buf);
	sprintf (buf, "-3: %4d right justif.\n", -3);
	printf ("%s", buf);

	return 0;
}

/*
 * if you compile this file with
 *   gcc -Wall $(YOUR_C_OPTIONS) -DTEST_PRINTF -c printf.c
 * you will get a normal warning:
 *   printf.c:214: warning: spurious trailing `%' in format
 * this line is testing an invalid % at the end of the format string.
 *
 * this should display (on 32bit int machine) :
 *
 * Hello world!
 * printf test
 * (null) is null pointer
 * 5 = 5
 * -2147483647 = - max int
 * char a = 'a'
 * hex ff = ff
 * hex 00 = 00
 * signed -3 = unsigned 4294967293 = hex fffffffd
 * 0 message(s)
 * 0 message(s) with %
 * justif: "left      "
 * justif: "     right"
 *  3: 0003 zero padded
 *  3: 3    left justif.
 *  3:    3 right justif.
 * -3: -003 zero padded
 * -3: -3   left justif.
 * -3:   -3 right justif.
 */

#endif