snprintf.c

minicom的源码,linux下常用的串口程序.

/*
 * This version of snprintf() and vsnprintf() is based on Sprint from
 * SIO by Panagiotis Tsirigotis, as included with xidentd-2.2.1.
 *
 * The modifications were made by The XFree86 Project, Inc and are
 * Copyright 1999 by The XFree86 Project, Inc.  These modifications
 * consist of removing the support for writing to file streams,
 * renaming some functions, ansification, and making some adjustments
 * to achieve the semantics for snprintf and vsnprintf() as described
 * in the relevant man page for FreeBSD 2.2.8.
 *
 *
 * The original version carries the following notice:
 *
 * (c) Copyright 1992, 1993 by Panagiotis Tsirigotis
 *
 * The author (Panagiotis Tsirigotis) grants permission to use, copy,
 * and distribute this software and its documentation for any purpose
 * and without fee, provided that a) the above copyright notice extant in
 * files in this distribution is not removed from files included in any
 * redistribution, and b) this file is also included in any redistribution.
 *
 * Modifications to this software may be distributed, either by distributing
 * the modified software or by distributing patches to the original software,
 * under the following additional terms:
 *
 * 1. The version number will be modified as follows:
 *      a. The first 3 components of the version number
 *         (i.e. <number>.<number>.<number>) will remain unchanged.
 *      b. A new component will be appended to the version number to indicate
 *         the modification level. The form of this component is up to the
 *         author of the modifications.
 *
 * 2. The author of the modifications will include his/her name by appending
 *    it along with the new version number to this file and will be
 *    responsible for any wrong behavior of the modified software.
 *
 * The author makes no representations about the suitability of this
 * software for any purpose.  It is provided "as is" without any express
 * or implied warranty.
 *
 * Changes and modifications for: 
 *
 * xinetd Version 2.1.4-bsdi
 * xinetd Version 2.1.4-freebsd
 * xinetd Version 2.1.4-linux
 *
 * are      
 *
 * (c) Copyright 1995 by Charles Murcko
 * All Rights Reserved
 */

/* $XFree86: xc/lib/misc/snprintf.c,v 3.1 1999/04/28 15:04:51 dawes Exp $ */


/*
 * Assumption: systems that don't have snprintf and vsnprintf do have
 * ecvt, fcvt and gcvt.
 */

/* From: Id: sprint.c,v 1.5 1995/09/10 18:35:09 chuck Exp */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#ifndef HAVE_STDARG_H
#error Need stdarg here!
#endif

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

#ifndef SCOPE
#define SCOPE					/**/
#endif

#ifndef WIDE_INT
#define WIDE_INT				long
#endif

typedef WIDE_INT wide_int;
typedef unsigned WIDE_INT u_wide_int;
typedef int bool_int;

#ifndef FALSE
#define FALSE					0
#define TRUE					1
#endif

#define NUL					'\0'

#define S_NULL					"(null)"
#define S_NULL_LEN				6

#define FLOAT_DIGITS				6
#define EXPONENT_LENGTH				10

typedef enum { NO = 0, YES = 1 } boolean_e ;

/*
 * NUM_BUF_SIZE is the size of the buffer used for arithmetic conversions
 *
 * XXX: this is a magic number; do not decrease it
 */
#define NUM_BUF_SIZE				512

/*
 * The INS_CHAR macro inserts a character in the buffer.
 * It uses the char pointers sp and bep:
 *      sp points to the next available character in the buffer
 *      bep points to the end-of-buffer
 * While using this macro, note that the nextb pointer is NOT updated.
 *
 * Excess characters are discarded if the string overflows.
 *
 * NOTE: Evaluation of the c argument should not have any side-effects
 */
#define INS_CHAR( c, sp, bep, cc )					\
	{								\
	    if ( sp < bep )						\
		*sp++ = c ;						\
	    cc++ ;							\
	}

#define NUM( c )			( c - '0' )

#define STR_TO_DEC( str, num )						\
	num = NUM( *str++ ) ;						\
	while ( isdigit( *str ) ) {					\
		num *= 10 ;						\
		num += NUM( *str++ ) ;					\
	}

/*
 * This macro does zero padding so that the precision
 * requirement is satisfied. The padding is done by
 * adding '0's to the left of the string that is going
 * to be printed.
 */
#define FIX_PRECISION( adjust, precision, s, s_len )			\
	if ( adjust )							\
		while ( s_len < precision ) {				\
			*--s = '0' ;					\
			s_len++ ;					\
	}

/*
 * Macro that does padding. The padding is done by printing
 * the character ch.
 */
#define PAD( width, len, ch )						\
	do {								\
		INS_CHAR( ch, sp, bep, cc ) ;				\
		width-- ;						\
	} while ( width > len )

/*
 * Prefix the character ch to the string str
 * Increase length
 * Set the has_prefix flag
 */
#define PREFIX( str, length, ch )					\
	*--str = ch ; length++ ; has_prefix = YES

static char *conv_10(wide_int num, bool_int is_unsigned,
			bool_int * is_negative, char *buf_end, int *len);
SCOPE int vsnprintf(char *str, size_t size, const char *fmt, va_list ap);

/*
 * snprintf is based on SIO's Sprint.
 *
 * Sprint is the equivalent of printf for SIO.
 * It returns the # of chars written
 * Assumptions:
 *     - all floating point arguments are passed as doubles
 */
SCOPE int 
snprintf(char *str, size_t size, const char *fmt, ...)
{
    int cc;
    va_list ap;

    va_start(ap, fmt);
    cc = vsnprintf(str, size, fmt, ap);
    va_end(ap);
    return cc;
}

/*
 * Convert a floating point number to a string formats 'f', 'e' or 'E'.
 * The result is placed in buf, and len denotes the length of the string
 * The sign is returned in the is_negative argument (and is not placed
 * in buf).  Always add decimal point if add_dp is YES.
 */
static char *
conv_fp(char format, double num, boolean_e add_dp, int precision,
	bool_int *is_negative, char buf[], int *len)
{
    char *s = buf;
    char *p;
    int decimal_point;

    if (format == 'f')
	p = fcvt(num, precision, &decimal_point, is_negative);
    else			       /* either e or E format */
	p = ecvt(num, precision + 1, &decimal_point, is_negative);

    /*
     * Check for Infinity and NaN
     */
    if (isalpha(*p)) {
	*len = strlen(strcpy(buf, p));
	*is_negative = FALSE;
	return (buf);
    }
    if (format == 'f')
	if (decimal_point <= 0) {
	    *s++ = '0';
	    if (precision > 0) {
		*s++ = '.';
		while (decimal_point++ < 0)
		    *s++ = '0';
	    } else if (add_dp)
		*s++ = '.';
	} else {
	    while (decimal_point-- > 0)
		*s++ = *p++;
	    if (precision > 0 || add_dp)
		*s++ = '.';
    } else {
	*s++ = *p++;
	if (precision > 0 || add_dp)
	    *s++ = '.';
    }

    /*
     * copy the rest of p, the NUL is NOT copied
     */
    while (*p)
	*s++ = *p++;

    if (format != 'f') {
	char temp[EXPONENT_LENGTH];    /* for exponent conversion */
	int t_len;
	bool_int exponent_is_negative;

	*s++ = format;		       /* either e or E */
	decimal_point--;
	if (decimal_point != 0) {
	    p = conv_10((wide_int) decimal_point, FALSE, &exponent_is_negative,
		&temp[EXPONENT_LENGTH], &t_len);
	    *s++ = exponent_is_negative ? '-' : '+';

	    /*
	     * Make sure the exponent has at least 2 digits
	     */
	    if (t_len == 1)
		*s++ = '0';
	    while (t_len--)
		*s++ = *p++;
	} else {
	    *s++ = '+';
	    *s++ = '0';
	    *s++ = '0';
	}
    }
    *len = s - buf;
    return (buf);
}

/*
 * Convert num to a base X number where X is a power of 2. nbits determines X.
 * For example, if nbits is 3, we do base 8 conversion
 * Return value:
 *           a pointer to a string containing the number
 *
 * The caller provides a buffer for the string: that is the buf_end argument
 * which is a pointer to the END of the buffer + 1 (i.e. if the buffer
 * is declared as buf[ 100 ], buf_end should be &buf[ 100 ])
 */
static char *
conv_p2(u_wide_int num, int nbits, char format, char *buf_end, int *len)
{
    int mask = (1 << nbits) - 1;
    char *p = buf_end;
    static char low_digits[] = "0123456789abcdef";
    static char upper_digits[] = "0123456789ABCDEF";
    char *digits = (format == 'X') ? upper_digits : low_digits;

    do {
	*--p = digits[num & mask];
	num >>= nbits;
    }
    while (num);

    *len = buf_end - p;
    return (p);
}

/*
 * Convert num to its decimal format.
 * Return value:
 *       - a pointer to a string containing the number (no sign)
 *             - len contains the length of the string
 *             - is_negative is set to TRUE or FALSE depending on the sign
 *               of the number (always set to FALSE if is_unsigned is TRUE)
 *
 * The caller provides a buffer for the string: that is the buf_end argument
 * which is a pointer to the END of the buffer + 1 (i.e. if the buffer
 * is declared as buf[ 100 ], buf_end should be &buf[ 100 ])
 */
static char *
conv_10(wide_int num, bool_int is_unsigned, bool_int *is_negative,
	char *buf_end, int *len)
{
    char *p = buf_end;
    u_wide_int magnitude;

    if (is_unsigned) {
	magnitude = (u_wide_int) num;
	*is_negative = FALSE;
    } else {
	*is_negative = (num < 0);

	/*
	 * On a 2's complement machine, negating the most negative integer 
	 * results in a number that cannot be represented as a signed integer.
	 * Here is what we do to obtain the number's magnitude:
	 *              a. add 1 to the number
	 *              b. negate it (becomes positive)
	 *              c. convert it to unsigned
	 *              d. add 1
	 */
	if (*is_negative) {
	    wide_int t = num + 1;

	    magnitude = ((u_wide_int) - t) + 1;
	} else
	    magnitude = (u_wide_int) num;
    }

    /*
     * We use a do-while loop so that we write at least 1 digit 
     */
    do {
	register u_wide_int new_magnitude = magnitude / 10;

	*--p = magnitude - new_magnitude * 10 + '0';
	magnitude = new_magnitude;
    }
    while (magnitude);

    *len = buf_end - p;
    return (p);