lib/libc/src/printf.c

/*
 * SPDX-License-Identifier: MIT
 * SPDX-FileCopyrightText: Copyright Marco Paland (info@paland.com), PALANDesign Hannover, Germany
 * SPDX-FileCopyrightText: Copyright TF-RMM Contributors.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * \brief Tiny printf, sprintf and (v)snprintf implementation, optimized for
 * speed on
 *   embedded systems with a very limited resources. These routines are thread
 *   safe and reentrant!
 *   Use this instead of the bloated standard/newlib printf cause these use
 *   malloc for printf (and may not be thread safe).
 */

/*
 * fine this globally (e.g. gcc -DPRINTF_INCLUDE_CONFIG_H ...) to include the
 * printf_config.h header file
 * default: undefined
 */
/*
 * support for the floating point type (%f)
 * default: activated
 */
#ifndef PRINTF_DISABLE_SUPPORT_FLOAT
#define PRINTF_SUPPORT_FLOAT
#endif

/* import float.h for DBL_MAX */
#if defined(PRINTF_SUPPORT_FLOAT)
#include <float.h>
#endif

#ifdef PRINTF_INCLUDE_CONFIG_H
#include "printf_config.h"
#endif

#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>

/*
 * 'ntoa' conversion buffer size, this must be big enough to hold one converted
 * numeric number including padded zeros (dynamically created on stack)
 * default: 32 byte
 */
#ifndef PRINTF_NTOA_BUFFER_SIZE
#define PRINTF_NTOA_BUFFER_SIZE    32U
#endif

/*
 *'ftoa' conversion buffer size, this must be big enough to hold one converted
 * float number including padded zeros (dynamically created on stack)
 * default: 32 byte
 */
#ifndef PRINTF_FTOA_BUFFER_SIZE
#define PRINTF_FTOA_BUFFER_SIZE    32U
#endif

/*
 * support for exponential floating point notation (%e/%g)
 * default: activated
 */
#ifndef PRINTF_DISABLE_SUPPORT_EXPONENTIAL
#define PRINTF_SUPPORT_EXPONENTIAL
#endif

/*
 * define the default floating point precision
 * default: 6 digits
 */
#ifndef PRINTF_DEFAULT_FLOAT_PRECISION
#define PRINTF_DEFAULT_FLOAT_PRECISION  6U
#endif

/*
 * define the largest float suitable to print with %f
 * default: 1e9
 */
#ifndef PRINTF_MAX_FLOAT
#define PRINTF_MAX_FLOAT  1e9
#endif

/*
 * support for the long long types (%llu or %p)
 * default: activated
 */
#ifndef PRINTF_DISABLE_SUPPORT_LONG_LONG
#define PRINTF_SUPPORT_LONG_LONG
#endif

/*
 * support for the ptrdiff_t type (%t)
 * ptrdiff_t is normally defined in <stddef.h> as long or long long type
 * default: activated
 */
#ifndef PRINTF_DISABLE_SUPPORT_PTRDIFF_T
#define PRINTF_SUPPORT_PTRDIFF_T
#endif

/******************************************************************************/

/* internal flag definitions */
#define FLAGS_ZEROPAD   (1U <<  0U)
#define FLAGS_LEFT      (1U <<  1U)
#define FLAGS_PLUS      (1U <<  2U)
#define FLAGS_SPACE     (1U <<  3U)
#define FLAGS_HASH      (1U <<  4U)
#define FLAGS_UPPERCASE (1U <<  5U)
#define FLAGS_CHAR      (1U <<  6U)
#define FLAGS_SHORT     (1U <<  7U)
#define FLAGS_LONG      (1U <<  8U)
#define FLAGS_LONG_LONG (1U <<  9U)
#define FLAGS_PRECISION (1U << 10U)
#define FLAGS_ADAPT_EXP (1U << 11U)

/* output function type */
typedef void (*out_fct_type)(char character, void *buffer, size_t idx,
			     size_t maxlen);


/* wrapper (used as buffer) for output function type */
typedef struct {
	void (*fct)(char character, void *arg);
	void *arg;
} out_fct_wrap_type;


/* internal buffer output */
static inline void _out_buffer(char character, void *buffer, size_t idx,
			       size_t maxlen)
{
	if (idx < maxlen) {
		((char *)buffer)[idx] = character;
	}
}


/* internal null output */
static inline void _out_null(char character, void *buffer, size_t idx,
			     size_t maxlen)
{
	(void)character; (void)buffer; (void)idx; (void)maxlen;
}


/* internal _putchar wrapper */
static inline void _out_char(char character, void *buffer, size_t idx,
			     size_t maxlen)
{
	(void)buffer; (void)idx; (void)maxlen;
	if (character) {
		_putchar(character);
	}
}


/* internal output function wrapper */
static inline void _out_fct(char character, void *buffer, size_t idx,
			    size_t maxlen)
{
	(void)idx; (void)maxlen;
	if (character) {
		/* buffer is the output fct pointer */
		((out_fct_wrap_type *)buffer)->fct(character,
						  ((out_fct_wrap_type *)buffer)->arg);
	}
}


/*
 * internal secure strlen
 * \return The length of the string (excluding the terminating 0) limited by
 * 'maxsize'
 */
static inline unsigned int _strnlen_s(const char *str, size_t maxsize)
{
	const char *s;

	for (s = str; *s && maxsize--; ++s) {
		;
	}

	return (unsigned int)(s - str);
}

/*
 * internal test if char is a digit (0-9)
 * \return true if char is a digit
 */
static inline bool _is_digit(char ch)
{
	return (ch >= '0') && (ch <= '9');
}


/* internal ASCII string to unsigned int conversion */
static unsigned int _atoi(const char **str)
{
	unsigned int i = 0U;

	while (_is_digit(**str)) {
		i = i * 10U + (unsigned int)(*((*str)++) - '0');
	}
	return i;
}


/* output the specified string in reverse, taking care of any zero-padding */
static size_t _out_rev(out_fct_type out, char *buffer, size_t idx, size_t maxlen, const char *buf, size_t len, unsigned int width, unsigned int flags)
{
	const size_t start_idx = idx;

	/* pad spaces up to given width */
	if (!(flags & FLAGS_LEFT) && !(flags & FLAGS_ZEROPAD)) {
		for (size_t i = len; i < width; i++) {
			out(' ', buffer, idx++, maxlen);
		}
	}

	/* reverse string */
	while (len) {
		out(buf[--len], buffer, idx++, maxlen);
	}

	/* append pad spaces up to given width */
	if (flags & FLAGS_LEFT) {
		while (idx - start_idx < width) {
			out(' ', buffer, idx++, maxlen);
		}
	}

	return idx;
}


/* internal itoa format */
static size_t _ntoa_format(out_fct_type out, char *buffer, size_t idx, size_t maxlen, char *buf, size_t len, bool negative, unsigned int base, unsigned int prec, unsigned int width, unsigned int flags)
{
	/* pad leading zeros */
	if (!(flags & FLAGS_LEFT)) {
		if (width && (flags & FLAGS_ZEROPAD) && (negative || (flags & (FLAGS_PLUS | FLAGS_SPACE)))) {
			width--;
		}
		while ((len < prec) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
			buf[len++] = '0';
		}
		while ((flags & FLAGS_ZEROPAD) && (len < width) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
			buf[len++] = '0';
		}
	}

	/* handle hash */
	if (flags & FLAGS_HASH) {
		if (!(flags & FLAGS_PRECISION) && len && ((len == prec) || (len == width))) {
			len--;
			if (len && (base == 16U)) {
				len--;
			}
		}
		if ((base == 16U) && !(flags & FLAGS_UPPERCASE) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
			buf[len++] = 'x';
		} else if ((base == 16U) && (flags & FLAGS_UPPERCASE) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
			buf[len++] = 'X';
		} else if ((base == 2U) && (len < PRINTF_NTOA_BUFFER_SIZE)) {
			buf[len++] = 'b';
		}
		if (len < PRINTF_NTOA_BUFFER_SIZE) {
			buf[len++] = '0';
		}
	}

	if (len < PRINTF_NTOA_BUFFER_SIZE) {
		if (negative) {
			buf[len++] = '-';
		} else if (flags & FLAGS_PLUS) {
			/* ignore the space if the '+' exists */
			buf[len++] = '+';
		} else if (flags & FLAGS_SPACE) {
			buf[len++] = ' ';
		}
	}

	return _out_rev(out, buffer, idx, maxlen, buf, len, width, flags);
}


/* internal itoa for 'long' type */
static size_t _ntoa_long(out_fct_type out, char *buffer, size_t idx,
			 size_t maxlen, unsigned long value, bool negative,
			 unsigned long base, unsigned int prec,
			 unsigned int width, unsigned int flags)
{
	char buf[PRINTF_NTOA_BUFFER_SIZE];
	size_t len = 0U;

	/* no hash for 0 values */
	if (!value) {
		flags &= ~FLAGS_HASH;
	}

	/* write if precision != 0 and value is != 0 */
	if (!(flags & FLAGS_PRECISION) || value) {
		do {
			const char digit = (char)(value % base);

			buf[len++] = digit < 10 ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - 10;
			value /= base;
		} while (value && (len < PRINTF_NTOA_BUFFER_SIZE));
	}

	return _ntoa_format(out, buffer, idx, maxlen, buf, len, negative,
			    (unsigned int)base, prec, width, flags);
}


/* internal itoa for 'long long' type */
#if defined(PRINTF_SUPPORT_LONG_LONG)
static size_t _ntoa_long_long(out_fct_type out, char *buffer, size_t idx,
			      size_t maxlen, unsigned long long value,
			      bool negative, unsigned long long base,
			      unsigned int prec, unsigned int width,
			      unsigned int flags)
{
	char buf[PRINTF_NTOA_BUFFER_SIZE];
	size_t len = 0U;

	/* no hash for 0 values */
	if (!value) {
		flags &= ~FLAGS_HASH;
	}

	/* write if precision != 0 and value is != 0 */
	if (!(flags & FLAGS_PRECISION) || value) {
		do {
			const char digit = (char)(value % base);

			buf[len++] = digit < 10 ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - 10;
			value /= base;
		} while (value && (len < PRINTF_NTOA_BUFFER_SIZE));
	}

	return _ntoa_format(out, buffer, idx, maxlen, buf, len, negative,
			    (unsigned int)base, prec, width, flags);
}
#endif  /* PRINTF_SUPPORT_LONG_LONG */


#if defined(PRINTF_SUPPORT_FLOAT)

#if defined(PRINTF_SUPPORT_EXPONENTIAL)
/*
 * forward declaration so that _ftoa can switch to exp notation for
 * values > PRINTF_MAX_FLOAT
 */
static size_t _etoa(out_fct_type out, char *buffer, size_t idx, size_t maxlen,
		    double value, unsigned int prec, unsigned int width,
		    unsigned int flags);
#endif


/* internal ftoa for fixed decimal floating point */
static size_t _ftoa(out_fct_type out, char *buffer, size_t idx, size_t maxlen,
		    double value, unsigned int prec, unsigned int width,
		    unsigned int flags)
{
	char buf[PRINTF_FTOA_BUFFER_SIZE];
	size_t len  = 0U;
	double diff = 0.0;

	/* powers of 10 */
	static const double pow10[] = { 1, 10, 100, 1000, 10000, 100000,
		1000000, 10000000, 100000000, 1000000000 };

	/* test for special values */
	if (value != value) {
		return _out_rev(out, buffer, idx, maxlen, "nan", 3, width,
				flags);
	}

	if (value < -DBL_MAX) {
		return _out_rev(out, buffer, idx, maxlen, "fni-", 4, width,
				flags);
	}

	if (value > DBL_MAX) {
		return _out_rev(out, buffer, idx, maxlen,
				(flags & FLAGS_PLUS) ? "fni+" : "fni",
				(flags & FLAGS_PLUS) ? 4U : 3U, width, flags);
	}

	/*
	 * test for very large values
	 * standard printf behavior is to print EVERY whole number digit --
	 * which could be 100s of characters overflowing your buffers == bad
	 */
	if ((value > PRINTF_MAX_FLOAT) || (value < -PRINTF_MAX_FLOAT)) {
#if defined(PRINTF_SUPPORT_EXPONENTIAL)
		return _etoa(out, buffer, idx, maxlen, value, prec, width,
			     flags);
#else
		return 0U;
#endif
	}

	/* test for negative */
	bool negative = false;

	if (value < 0) {
		negative = true;
		value = 0 - value;
	}

	/* set default precision, if not set explicitly */
	if (!(flags & FLAGS_PRECISION)) {
		prec = PRINTF_DEFAULT_FLOAT_PRECISION;
	}
	/*
	 * limit precision to 9, cause a prec >= 10 can lead to overflow
	 * errors
	 */
	while ((len < PRINTF_FTOA_BUFFER_SIZE) && (prec > 9U)) {
		buf[len++] = '0';
		prec--;
	}

	int whole = (int)value;
	double tmp = (value - whole) * pow10[prec];
	unsigned long frac = (unsigned long)tmp;

	diff = tmp - frac;

	if (diff > 0.5) {
		++frac;
		/* handle rollover, e.g. case 0.99 with prec 1 is 1.0 */
		if (frac >= pow10[prec]) {
			frac = 0;
			++whole;
		}
	} else if (diff < 0.5) {
		/* skip */
	} else if ((frac == 0U) || (frac & 1U)) {
		/* if halfway, round up if odd OR if last digit is 0 */
		++frac;
	}

	if (prec == 0U) {
		diff = value - (double)whole;
		if ((!(diff < 0.5) || (diff > 0.5)) && (whole & 1)) {
			/*
			 * exactly 0.5 and ODD, then round up
			 * 1.5 -> 2, but 2.5 -> 2
			 */
			++whole;
		}
	} else {
		unsigned int count = prec;

		/* now do fractional part, as an unsigned number */
		while (len < PRINTF_FTOA_BUFFER_SIZE) {
			--count;
			buf[len++] = (char)(48U + (frac % 10U));
			frac /= 10U;
			if (!frac) {
				break;
			}
		}
		/* add extra 0s */
		while ((len < PRINTF_FTOA_BUFFER_SIZE) && (count-- > 0U)) {
			buf[len++] = '0';
		}
		if (len < PRINTF_FTOA_BUFFER_SIZE) {
			/* add decimal */
			buf[len++] = '.';
		}
	}

	/* do whole part, number is reversed */
	while (len < PRINTF_FTOA_BUFFER_SIZE) {
		buf[len++] = (char)(48 + (whole % 10));
		whole /= 10;
		if (!whole) {
			break;
		}
	}

	/* pad leading zeros */
	if (!(flags & FLAGS_LEFT) && (flags & FLAGS_ZEROPAD)) {
		if (width && (negative || (flags & (FLAGS_PLUS | FLAGS_SPACE)))) {
			width--;
		}
		while ((len < width) && (len < PRINTF_FTOA_BUFFER_SIZE)) {
			buf[len++] = '0';
		}
	}

	if (len < PRINTF_FTOA_BUFFER_SIZE) {
		if (negative) {
			buf[len++] = '-';
		} else if (flags & FLAGS_PLUS) {
			/* ignore the space if the '+' exists */
			buf[len++] = '+';
		} else if (flags & FLAGS_SPACE) {
			buf[len++] = ' ';
		}
	}

	return _out_rev(out, buffer, idx, maxlen, buf, len, width, flags);
}


#if defined(PRINTF_SUPPORT_EXPONENTIAL)
/*
 * internal ftoa variant for exponential floating-point type, contributed by
 * Martijn Jasperse <m.jasperse@gmail.com>
 */
static size_t _etoa(out_fct_type out, char *buffer, size_t idx, size_t maxlen,
		    double value, unsigned int prec, unsigned int width,
		    unsigned int flags)
{
	/* check for NaN and special values */
	if ((value != value) || (value > DBL_MAX) || (value < -DBL_MAX)) {
		return _ftoa(out, buffer, idx, maxlen, value, prec, width,
			     flags);
	}

	/* determine the sign */
	const bool negative = value < 0;

	if (negative) {
		value = -value;
	}

	/* default precision */
	if (!(flags & FLAGS_PRECISION)) {
		prec = PRINTF_DEFAULT_FLOAT_PRECISION;
	}

	/*
	 * determine the decimal exponent
	 * based on the algorithm by David Gay
	 * (https://www.ampl.com/netlib/fp/dtoa.c)
	 */
	union {
		uint64_t U;
		double   F;
	} conv;

	conv.F = value;
	/* effectively log2 */
	int exp2 = (int)((conv.U >> 52U) & 0x07FFU) - 1023;

	/* drop the exponent so conv.F is now in [1,2) */
	conv.U = (conv.U & ((1ULL << 52U) - 1U)) | (1023ULL << 52U);

	/*
	 * now approximate log10 from the log2 integer part and an expansion
	 * of ln around 1.5
	 */
	int expval = (int)(0.1760912590558 + exp2 * 0.301029995663981 + (conv.F - 1.5) * 0.289529654602168);
	/*
	 * now we want to compute 10^expval but we want to be sure it won't
	 * overflow
	 */
	exp2 = (int)(expval * 3.321928094887362 + 0.5);
	const double z  = expval * 2.302585092994046 - exp2 * 0.6931471805599453;
	const double z2 = z * z;

	conv.U = (uint64_t)(exp2 + 1023) << 52U;
	/*
	 * compute exp(z) using continued fractions, see
	 * https://en.wikipedia.org/wiki/Exponential_function#Continued_fractions_for_ex
	 */
	conv.F *= 1 + 2 * z / (2 - z + (z2 / (6 + (z2 / (10 + z2 / 14)))));
	/* correct for rounding errors */
	if (value < conv.F) {
		expval--;
		conv.F /= 10;
	}

	/*
	 * the exponent format is "%+03d" and largest value is "307", so set
	 * aside 4-5 characters
	 */
	unsigned int minwidth = ((expval < 100) && (expval > -100)) ? 4U : 5U;

	/*
	 * in "%g" mode, "prec" is the number of *significant figures* not
	 * decimals
	 */
	if (flags & FLAGS_ADAPT_EXP) {
		/* do we want to fall-back to "%f" mode? */
		if ((value >= 1e-4) && (value < 1e6)) {
			if ((int)prec > expval) {
				prec = (unsigned int)((int)prec - expval - 1);
			} else {
				prec = 0;
			}
			/* make sure _ftoa respects precision */
			flags |= FLAGS_PRECISION;
			/* no characters in exponent */
			minwidth = 0U;
			expval   = 0;
		} else {
			/* we use one sigfig for the whole part */
			if ((prec > 0) && (flags & FLAGS_PRECISION)) {
				--prec;
			}
		}
	}

	/* will everything fit? */
	unsigned int fwidth = width;

	if (width > minwidth) {
		/*
		 * we didn't fall-back so subtract the characters required for
		 * the exponent
		 */
		fwidth -= minwidth;
	} else {
		/* not enough characters, so go back to default sizing */
		fwidth = 0U;
	}
	if ((flags & FLAGS_LEFT) && minwidth) {
		/* if we're padding on the right, DON'T pad the floating part */
		fwidth = 0U;
	}

	/* rescale the float value */
	if (expval) {
		value /= conv.F;
	}

	/* output the floating part */
	const size_t start_idx = idx;

	idx = _ftoa(out, buffer, idx, maxlen, negative ? -value : value, prec, fwidth, flags & ~FLAGS_ADAPT_EXP);

	/* output the exponent part */
	if (minwidth) {
		/* output the exponential symbol */
		out((flags & FLAGS_UPPERCASE) ? 'E' : 'e', buffer, idx++,
		    maxlen);
		/* output the exponent value */
		idx = _ntoa_long(out, buffer, idx, maxlen, (expval < 0) ? -expval : expval, expval < 0, 10, 0, minwidth-1, FLAGS_ZEROPAD | FLAGS_PLUS);
		/* might need to right-pad spaces */
		if (flags & FLAGS_LEFT) {
			while (idx - start_idx < width) {
				out(' ', buffer, idx++, maxlen);
			}
		}
	}
	return idx;
}
#endif  /* PRINTF_SUPPORT_EXPONENTIAL */
#endif  /* PRINTF_SUPPORT_FLOAT */


/* internal vsnprintf */
static int _vsnprintf(out_fct_type out, char *buffer, const size_t maxlen,
		      const char *format, va_list va)
{
	unsigned int flags, width, precision, n;
	size_t idx = 0U;

	if (!buffer) {
		/* use null output function */
		out = _out_null;
	}

	while (*format) {
		/* format specifier?  %[flags][width][.precision][length] */
		if (*format != '%') {
			/* no */
			out(*format, buffer, idx++, maxlen);
			format++;
			continue;
		} else {
			/* yes, evaluate it */
			format++;
		}

		/* evaluate flags */
		flags = 0U;
		do {
			switch (*format) {
			case '0':
				flags |= FLAGS_ZEROPAD; format++; n = 1U;
				break;
			case '-':
				flags |= FLAGS_LEFT;    format++; n = 1U;
				break;
			case '+':
				flags |= FLAGS_PLUS;    format++; n = 1U;
				break;
			case ' ':
				flags |= FLAGS_SPACE;   format++; n = 1U;
				break;
			case '#':
				flags |= FLAGS_HASH;    format++; n = 1U;
				break;
			default:
				n = 0U;
				break;
			}
		} while (n);

		/* evaluate width field */
		width = 0U;
		if (_is_digit(*format)) {
			width = _atoi(&format);
		} else if (*format == '*') {
			const int w = va_arg(va, int);

			if (w < 0) {
				flags |= FLAGS_LEFT; /* reverse padding */
				width = (unsigned int)-w;
			} else {
				width = (unsigned int)w;
			}
			format++;
		}

		/* evaluate precision field */
		precision = 0U;
		if (*format == '.') {
			flags |= FLAGS_PRECISION;
			format++;
			if (_is_digit(*format)) {
				precision = _atoi(&format);
			} else if (*format == '*') {
				const int prec = (int)va_arg(va, int);

				precision = prec > 0 ? (unsigned int)prec : 0U;
				format++;
			}
		}

		/* evaluate length field */
		switch (*format) {
		case 'l':
			flags |= FLAGS_LONG;
			format++;
			if (*format == 'l') {
				flags |= FLAGS_LONG_LONG;
				format++;
			}
			break;
		case 'h':
			flags |= FLAGS_SHORT;
			format++;
			if (*format == 'h') {
				flags |= FLAGS_CHAR;
				format++;
			}
			break;
#if defined(PRINTF_SUPPORT_PTRDIFF_T)
		case 't':
			flags |= (sizeof(ptrdiff_t) == sizeof(long) ? FLAGS_LONG : FLAGS_LONG_LONG);
			format++;
			break;
#endif
		case 'j':
			flags |= (sizeof(intmax_t) == sizeof(long) ? FLAGS_LONG : FLAGS_LONG_LONG);
			format++;
			break;
		case 'z':
			flags |= (sizeof(size_t) == sizeof(long) ? FLAGS_LONG : FLAGS_LONG_LONG);
			format++;
			break;
		default:
			break;
		}

		/* evaluate specifier */
		switch (*format) {
		case 'd':
		case 'i':
		case 'u':
		case 'x':
		case 'X':
		case 'o':
		case 'b': {
			/* set the base */
			unsigned int base;

			if (*format == 'x' || *format == 'X') {
				base = 16U;
			} else if (*format == 'o') {
				base =  8U;
			} else if (*format == 'b') {
				base =  2U;
			} else {
				base = 10U;
				/* no hash for dec format */
				flags &= ~FLAGS_HASH;
			}
			/* uppercase */
			if (*format == 'X') {
				flags |= FLAGS_UPPERCASE;
			}

			/* no plus or space flag for u, x, X, o, b */
			if ((*format != 'i') && (*format != 'd')) {
				flags &= ~(FLAGS_PLUS | FLAGS_SPACE);
			}

			/* ignore '0' flag when precision is given */
			if (flags & FLAGS_PRECISION) {
				flags &= ~FLAGS_ZEROPAD;
			}

			/* convert the integer */
			if ((*format == 'i') || (*format == 'd')) {
				/* signed */
				if (flags & FLAGS_LONG_LONG) {
#if defined(PRINTF_SUPPORT_LONG_LONG)
					const long long value = va_arg(va, long long);

					idx = _ntoa_long_long(out, buffer, idx, maxlen, (unsigned long long)(value > 0 ? value : 0 - value), value < 0, base, precision, width, flags);
#endif
				} else if (flags & FLAGS_LONG) {
					const long value = va_arg(va, long);

					idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned long)(value > 0 ? value : 0 - value), value < 0, base, precision, width, flags);
				} else {
					const int value = (flags & FLAGS_CHAR) ? (char)va_arg(va, int) : (flags & FLAGS_SHORT) ? (short int)va_arg(va, int) : va_arg(va, int);

					idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned int)(value > 0 ? value : 0 - value), value < 0, base, precision, width, flags);
				}
			} else {
				/* unsigned */
				if (flags & FLAGS_LONG_LONG) {
#if defined(PRINTF_SUPPORT_LONG_LONG)
					idx = _ntoa_long_long(out, buffer, idx, maxlen, va_arg(va, unsigned long long), false, base, precision, width, flags);
#endif
				} else if (flags & FLAGS_LONG) {
					idx = _ntoa_long(out, buffer, idx, maxlen, va_arg(va, unsigned long), false, base, precision, width, flags);
				} else {
					const unsigned int value = (flags & FLAGS_CHAR) ? (unsigned char)va_arg(va, unsigned int) : (flags & FLAGS_SHORT) ? (unsigned short int)va_arg(va, unsigned int) : va_arg(va, unsigned int);

					idx = _ntoa_long(out, buffer, idx, maxlen, value, false, base, precision, width, flags);
				}
			}
			format++;
			break;
		}
#if defined(PRINTF_SUPPORT_FLOAT)
		case 'f':
		case 'F':
			if (*format == 'F') {
				flags |= FLAGS_UPPERCASE;
			}

			idx = _ftoa(out, buffer, idx, maxlen,
				    va_arg(va, double), precision, width, flags);
			format++;
			break;
#if defined(PRINTF_SUPPORT_EXPONENTIAL)
		case 'e':
		case 'E':
		case 'g':
		case 'G':
			if ((*format == 'g') || (*format == 'G')) {
				flags |= FLAGS_ADAPT_EXP;
			}

			if ((*format == 'E') || (*format == 'G')) {
				flags |= FLAGS_UPPERCASE;
			}

			idx = _etoa(out, buffer, idx, maxlen,
				    va_arg(va, double), precision, width, flags);
			format++;
			break;
#endif  /* PRINTF_SUPPORT_EXPONENTIAL */
#endif  /* PRINTF_SUPPORT_FLOAT */
		case 'c': {
			unsigned int l = 1U;
			/* pre padding */
			if (!(flags & FLAGS_LEFT)) {
				while (l++ < width) {
					out(' ', buffer, idx++, maxlen);
				}
			}
			/* char output */
			out((char)va_arg(va, int), buffer, idx++, maxlen);
			/* post padding */
			if (flags & FLAGS_LEFT) {
				while (l++ < width) {
					out(' ', buffer, idx++, maxlen);
				}
			}
			format++;
			break;
		}

		case 's': {
			const char *p = va_arg(va, char*);
			unsigned int l = _strnlen_s(p, precision ? precision : (size_t)-1);
			/* pre padding */
			if (flags & FLAGS_PRECISION) {
				l = (l < precision ? l : precision);
			}
			if (!(flags & FLAGS_LEFT)) {
				while (l++ < width) {
					out(' ', buffer, idx++, maxlen);
				}
			}
			/* string output */
			while ((*p != 0) && (!(flags & FLAGS_PRECISION) || precision--)) {
				out(*(p++), buffer, idx++, maxlen);
			}
			/* post padding */
			if (flags & FLAGS_LEFT) {
				while (l++ < width) {
					out(' ', buffer, idx++, maxlen);
				}
			}
			format++;
			break;
		}

		case 'p': {
			width = sizeof(void *) * 2U;
			flags |= FLAGS_ZEROPAD | FLAGS_UPPERCASE;
#if defined(PRINTF_SUPPORT_LONG_LONG)
			const bool is_ll = sizeof(uintptr_t) == sizeof(long long);

			if (is_ll) {
				idx = _ntoa_long_long(out, buffer, idx, maxlen, (uintptr_t)va_arg(va, void *), false, 16U, precision, width, flags);
			} else {
#endif
				idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned long)((uintptr_t)va_arg(va, void *)), false, 16U, precision, width, flags);
#if defined(PRINTF_SUPPORT_LONG_LONG)
			}
#endif
			format++;
			break;
		}

		case '%':
			out('%', buffer, idx++, maxlen);
			format++;
			break;

		default:
			out(*format, buffer, idx++, maxlen);
			format++;
			break;
		}
	}

	/* termination */
	out((char)0, buffer, idx < maxlen ? idx : maxlen - 1U, maxlen);

	/* return written chars without terminating \0 */
	return (int)idx;
}


/*****************************************************************************/

int printf_(const char *format, ...)
{
	va_list va;

	va_start(va, format);
	char buffer[1];
	const int ret = _vsnprintf(_out_char, buffer, (size_t)-1, format, va);

	va_end(va);
	return ret;
}


int sprintf_(char *buffer, const char *format, ...)
{
	va_list va;

	va_start(va, format);
	const int ret = _vsnprintf(_out_buffer, buffer, (size_t)-1, format, va);

	va_end(va);
	return ret;
}


int snprintf_(char *buffer, size_t count, const char *format, ...)
{
	va_list va;

	va_start(va, format);
	const int ret = _vsnprintf(_out_buffer, buffer, count, format, va);

	va_end(va);
	return ret;
}


int vprintf_(const char *format, va_list va)
{
	char buffer[1];

	return _vsnprintf(_out_char, buffer, (size_t)-1, format, va);
}


int vsnprintf_(char *buffer, size_t count, const char *format, va_list va)
{
	return _vsnprintf(_out_buffer, buffer, count, format, va);
}


int fctprintf(void (*out)(char character, void *arg), void *arg,
	      const char *format, ...)
{
	va_list va;

	va_start(va, format);
	const out_fct_wrap_type out_fct_wrap = { out, arg };
	const int ret = _vsnprintf(_out_fct, (char *)(uintptr_t)&out_fct_wrap, (size_t)-1, format, va);

	va_end(va);
	return ret;
}