sprintf.c

编译后直接运行的ＭＰ３播放器全部Ｃ语言源代码 一个包含FAT文件系统、系统引导 Boot、FLASH Driver等内容的

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id: sprintf.c,v 1.11 2003/05/24 00:19:27 linusnielsen Exp $
 *
 * Copyright (C) 2002 by Gary Czvitkovicz
 *
 * All files in this archive are subject to the GNU General Public License.
 * See the file COPYING in the source tree root for full license agreement.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

/*
 * Minimal printf and snprintf formatting functions
 *
 * These support %c %s %d and %x
 * Field width and zero-padding flag only
 */

#include <stdarg.h>
#include <string.h>
#include <stdbool.h>

#include "file.h" /* for write(), used in fprintf() */
#include "sprintf.h" /* to allow the simulator magic */

static const char hexdigit[] = "0123456789ABCDEF";

static int format(
    /* call 'push()' for each output letter */
    int (*push)(void *userp, unsigned char data),
    void *userp,
    const char *fmt,
    va_list ap)
{
    char *str;
    char tmpbuf[12], pad;
    int ch, width, val, sign;
    unsigned int uval;
    bool ok = true;

    tmpbuf[sizeof tmpbuf - 1] = '\0';

    while ((ch = *fmt++) != '\0' && ok)
    {
	if (ch == '%')
	{
	    ch = *fmt++;
	    pad = ' ';
	    if (ch == '0')
		pad = '0';

	    width = 0;
	    while (ch >= '0' && ch <= '9')
	    {
		width = 10*width + ch - '0';
		ch = *fmt++;
	    }

	    str = tmpbuf + sizeof tmpbuf - 1;
	    switch (ch)
	    {
		case 'c':
		    *--str = va_arg (ap, int);
		    break;

		case 's':
		    str = va_arg (ap, char*);
		    break;

		case 'd':
		    val = sign = va_arg (ap, int);
		    if (val < 0)
			val = -val;
		    do
		    {
			*--str = (val % 10) + '0';
			val /= 10;
		    }
		    while (val > 0);
		    if (sign < 0)
			*--str = '-';
		    break;

		case 'x':
		case 'X':
		    uval = va_arg (ap, int);
		    do
		    {
			*--str = hexdigit[uval & 0xf];
			uval >>= 4;
		    }
		    while (uval);
		    break;

		default:
		    *--str = ch;
		    break;
	    }

	    if (width > 0)
	    {
		width -= strlen (str);
		while (width-- > 0 && ok)
		    ok=push(userp, pad);
	    }
	    while (*str != '\0' && ok)
                ok=push(userp, *str++);
	}
	else
	    ok=push(userp, ch);
    }
    return ok; /* true means good */
}

struct for_snprintf {
    unsigned char *ptr; /* where to store it */
    int bytes; /* amount already stored */
    int max;   /* max amount to store */
};

static int sprfunc(void *ptr, unsigned char letter)
{
    struct for_snprintf *pr = (struct for_snprintf *)ptr;
    if(pr->bytes < pr->max) {
        *pr->ptr = letter;
        pr->ptr++;
        pr->bytes++;
        return true;
    }
    return false; /* filled buffer */
}


int snprintf(char *buf, size_t size, const char *fmt, ...)
{
    bool ok;
    va_list ap;
    struct for_snprintf pr;

    pr.ptr = buf;
    pr.bytes = 0;
    pr.max = size;

    va_start(ap, fmt);
    ok = format(sprfunc, &pr, fmt, ap);
    va_end(ap);

    /* make sure it ends with a trailing zero */
    pr.ptr[ok?0:-1]='\0';
    
    return pr.bytes;
}

int vsnprintf(char *buf, int size, const char *fmt, va_list ap)
{
    bool ok;
    struct for_snprintf pr;

    pr.ptr = buf;
    pr.bytes = 0;
    pr.max = size;

    ok = format(sprfunc, &pr, fmt, ap);

    /* make sure it ends with a trailing zero */
    pr.ptr[ok?0:-1]='\0';
    
    return pr.bytes;
}

struct for_fprintf {
    int fd;    /* where to store it */
    int bytes; /* amount stored */
};

static int fprfunc(void *pr, unsigned char letter)
{
    struct for_fprintf *fpr  = (struct for_fprintf *)pr;
    int rc = write(fpr->fd, &letter, 1);
    
    if(rc > 0) {
        fpr->bytes++; /* count them */
        return true;  /* we are ok */
    }

    return false; /* failure */
}


int fprintf(int fd, const char *fmt, ...)
{
    bool ok;
    va_list ap;
    struct for_fprintf fpr;

    fpr.fd=fd;
    fpr.bytes=0;

    va_start(ap, fmt);
    ok = format(fprfunc, &fpr, fmt, ap);
    va_end(ap);

    return fpr.bytes; /* return 0 on error */
}