platform/system/printf.c

/*
 * Copyright (c) 2022 FuZhou Lockzhiner Electronic Co., Ltd. All rights reserved.
 */
///////////////////////////////////////////////////////////////////////////////
// \author (c) Marco Paland (info@paland.com)
//             2014-2019, PALANDesign Hannover, Germany
//
// \license The MIT License (MIT)
//
// 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).
//
///////////////////////////////////////////////////////////////////////////////

#include <stdbool.h>
#include <stdint.h>
#include "uart_debug.h"
#include "printf.h"

// define this globally (e.g. gcc -DPRINTF_INCLUDE_CONFIG_H ...) to include the
// printf_config.h header file
// default: undefined
#ifdef PRINTF_INCLUDE_CONFIG_H
#include "printf_config.h"
#endif

// '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 the floating point type (%f)
// default: activated
#ifndef PRINTF_DISABLE_SUPPORT_FLOAT
#define PRINTF_SUPPORT_FLOAT
#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)

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

// 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;
}

enum HAL_UART_ID_T {
    HAL_UART_ID_0 = 0
};


// 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) {
        uart_debug_putc(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)
{
    size_t str_maxsize = maxsize;
    const char* s;
    for (s = str; *s && str_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 buffer_idx, size_t maxlen,
    const char* buf, size_t buf_len, unsigned int buf_width, unsigned int flags)
{
    const size_t start_idx = buffer_idx;
    size_t idx = buffer_idx;
    size_t len = buf_len;
    unsigned int width = buf_width;

    // 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 buf_len, bool negative, unsigned int base,
                           unsigned int prec, unsigned int prec_width, unsigned int flags)
{
    size_t len = buf_len;
    unsigned int width = prec_width;

    // 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) {
            buf[len++] = '+';  // ignore the space if the '+' exists
        } 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 l_value, bool negative,
    unsigned long base, unsigned int prec,
    unsigned int width, unsigned int l_flags)
{
    unsigned long value = l_value;
    unsigned int flags = l_flags;
    char buf[PRINTF_NTOA_BUFFER_SIZE];
    size_t len = 0U;
    char num_count = 10;

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

    // write if precision != 0 and value is != 0
    if (!(flags & FLAGS_PRECISION) || value) {
        do {
            if (base == 0) {
                return 0;
            }

            const char digit = (char)(value % base);
            buf[len++] = digit < num_count ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - num_count;
            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 l_value, bool negative,
                              unsigned long long base, unsigned int prec,
                              unsigned int width, unsigned int l_flags)
{
    unsigned int flags = l_flags;
    unsigned long long value = l_value;
    char buf[PRINTF_NTOA_BUFFER_SIZE];
    size_t len = 0U;
    char num_count = 10;

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

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

            if (base == 0) {
                digit = 0;
            } else {
                digit = (char)(value % base);
            }
            buf[len++] = digit < num_count ? '0' + digit : (flags & FLAGS_UPPERCASE ? 'A' : 'a') + digit - num_count;
            if (base == 0) {
                value = 0;
            } else {
                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 d_value, unsigned int i_prec,
                    unsigned int i_width, unsigned int flags)
{
    double value = d_value;
    unsigned int prec = i_prec;
    unsigned int width = i_width;
    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
    };
    double half = 0.5;
    size_t limit_precision = 9U;
    int ascii_0 = (int)('0');
    int num_count = 10;

    // test for special values
    if (value != value) {
        return _out_rev(out, buffer, idx, maxlen, "nan", strlen("nan"), width, flags);
    }
    if (value < -DBL_MAX) {
        return _out_rev(out, buffer, idx, maxlen, "fni-", strlen("fni-"), width, flags);
    }
    if (value > DBL_MAX) {
        return _out_rev(out, buffer, idx, maxlen,
                        (flags & FLAGS_PLUS) ? "fni+" : "fni",
                        (flags & FLAGS_PLUS) ? strlen("fni-") : strlen("fni"),
                        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 > limit_precision)) {
        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 > half) {
        ++frac;
        // handle rollover, e.g. case 0.99 with prec 1 is 1.0
        if (frac >= pow10[prec]) {
            frac = 0;
            ++whole;
        }
    } else if (diff < half) {
    } 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 < half) || (diff > half)) && (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)(ascii_0 + (frac % num_count));
            if (!(frac /= 10U)) {
                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)(ascii_0 + (whole % num_count));
        if (!(whole /= num_count)) {
            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) {
            buf[len++] = '+';  // ignore the space if the '+' exists
        } 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)
{
#define CONV_F_RATE             10
#define NTOA_LONG_BASE_MAX      10
    size_t s_idx = idx;
    unsigned int i_prec = prec;
    unsigned int i_flags = flags;
    double d_value = value;
    double half = 0.5;
    double exp_base = 2.0;
    double exp_six = 6.0;
    double exp_ten = 10.0;
    double exp_fourteen = 14.0;
    uint64_t exp2_eff1 = 52U;
    uint64_t exp2_eff2 = 0x7FFU;
    uint64_t exp2_eff3 = 1023U;
    double exp2_eff4 = 3.321928094887362;
    int exp2_eff3_int = 1023;
    double expval_eff1 = 0.1760912590558;
    double expval_eff2 = 0.301029995663981;
    double expval_eff3 = 1.5;
    double expval_eff4 = 0.289529654602168;
    int expval_eff5_int = 100;
    double z_eff1 = 2.302585092994046;
    double z_eff2 = 0.6931471805599453;
    unsigned int minwidth_four = 4U;
    unsigned int minwidth_five = 5U;
    double fall_back_min = 1e-4;
    double fall_back_max = 1e6;

    // check for NaN and special values
    if ((d_value != d_value) || (d_value > DBL_MAX) || (d_value < -DBL_MAX)) {
        return _ftoa(out, buffer, s_idx, maxlen, value, i_prec, width, i_flags);
    }

    // determine the sign
    const bool negative = d_value < 0;
    if (negative) {
        d_value = -d_value;
    }

    // default precision
    if (!(i_flags & FLAGS_PRECISION)) {
        i_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 = d_value;
    int exp2 = (int)((conv.U >> exp2_eff1) & exp2_eff2) - exp2_eff3_int; // effectively log2
    // drop the exponent so conv.F is now in [1,2)
    conv.U = (conv.U & ((1ULL << exp2_eff1) - 1U)) | (exp2_eff3 << exp2_eff1);
    // now approximate log10 from the log2 integer part and an expansion of ln around 1.5
    int expval = (int)(expval_eff1 + exp2 * expval_eff2 + (conv.F - expval_eff3) * expval_eff4);
    // now we want to compute 10^expval but we want to be sure it won't overflow
    exp2 = (int)(expval * exp2_eff4 + half);
    const double z  = expval * z_eff1 - exp2 * z_eff2;
    const double z2 = z * z;
    conv.U = (uint64_t)(exp2 + exp2_eff3_int) << exp2_eff1;
    // compute exp(z) using continued fractions,
    // see https://en.wikipedia.org/wiki/Exponential_function#Continued_fractions_for_ex
    conv.F *= 1 + exp_base * z / (exp_base - z + (z2 / (exp_six + (z2 / (exp_ten + z2 / exp_fourteen)))));
    // correct for rounding errors
    if (d_value < conv.F) {
        expval--;
        conv.F /= CONV_F_RATE;
    }

    // the exponent format is "%+03d" and largest value is "307", so set aside 4-5 characters
    unsigned int minwidth = ((expval < expval_eff5_int) && (expval > -expval_eff5_int)) ? minwidth_four : minwidth_five;

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

    // output the floating part
    const size_t start_idx = s_idx;
    s_idx = _ftoa(out, buffer, s_idx, maxlen,
                  negative ? -d_value : d_value,
                  i_prec, fwidth, i_flags & ~FLAGS_ADAPT_EXP);

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


// internal vsnprintf
static int vsnprintf_s(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;
    out_fct_type out_tmp = out;
    char *format_tmp = format;

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

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

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

        // evaluate width field
        width = 0U;
        if (_is_digit(*format_tmp)) {
            width = _atoi(&format_tmp);
        } else if (*format_tmp == '*') {
            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_tmp++;
        }

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

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

        // evaluate specifier
        switch (*format_tmp) {
            case 'd' :
            case 'i' :
            case 'u' :
            case 'x' :
            case 'X' :
            case 'o' :
            case 'b' :
                {
                    // set the base
                    unsigned int base;
                    if (*format_tmp == 'x' || *format_tmp == 'X') {
                        base = 16U;
                    } else if (*format_tmp == 'o') {
                        base =  8U;
                    } else if (*format_tmp == 'b') {
                        base =  2U;
                    } else {
                        base = 10U;
                        flags &= ~FLAGS_HASH;   // no hash for dec format_tmp
                    }
                    // uppercase
                    if (*format_tmp == 'X') {
                        flags |= FLAGS_UPPERCASE;
                    }

                    // no plus or space flag for u, x, X, o, b
                    if ((*format_tmp != 'i') && (*format_tmp != '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_tmp == 'i') || (*format_tmp == '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_tmp, 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_tmp, 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_tmp, 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_tmp, buffer, idx, maxlen,
                                                  va_arg(va, unsigned long long),
                                                  false, base, precision, width, flags);
#endif
                        } else if (flags & FLAGS_LONG) {
                            idx = _ntoa_long(out_tmp, 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_tmp, buffer, idx, maxlen, value, false, base, precision, width, flags);
                        }
                    }
                    format_tmp++;
                    break;
                }
#if defined(PRINTF_SUPPORT_FLOAT)
            case 'f' :
            case 'F' :
                if (*format_tmp == 'F') {
                    flags |= FLAGS_UPPERCASE;
                }
                idx = _ftoa(out_tmp, buffer, idx, maxlen, va_arg(va, double), precision, width, flags);
                format_tmp++;
                break;
#if defined(PRINTF_SUPPORT_EXPONENTIAL)
            case 'e':
            case 'E':
            case 'g':
            case 'G':
                if ((*format_tmp == 'g') || (*format_tmp == 'G')) {
                    flags |= FLAGS_ADAPT_EXP;
                }
                if ((*format_tmp == 'E') || (*format_tmp == 'G')) {
                    flags |= FLAGS_UPPERCASE;
                }
                idx = _etoa(out_tmp, buffer, idx, maxlen, va_arg(va, double), precision, width, flags);
                format_tmp++;
                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_tmp(' ', buffer, idx++, maxlen);
                        }
                    }
                    // char output
                    out_tmp((char)va_arg(va, int), buffer, idx++, maxlen);
                    // post padding
                    if (flags & FLAGS_LEFT) {
                        while (l++ < width) {
                            out_tmp(' ', buffer, idx++, maxlen);
                        }
                    }
                    format_tmp++;
                    break;
                }

            case 's' :
                {
                    const char* p = va_arg(va, char*);
                    if (!p) {
                        p = '(null)';
                    }
                    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_tmp(' ', buffer, idx++, maxlen);
                        }
                    }
                    // string output
                    while ((*p != 0) && (!(flags & FLAGS_PRECISION) || precision--)) {
                        out_tmp(*(p++), buffer, idx++, maxlen);
                    }
                    // post padding
                    if (flags & FLAGS_LEFT) {
                        while (l++ < width) {
                            out_tmp(' ', buffer, idx++, maxlen);
                        }
                    }
                    format_tmp++;
                    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_tmp, buffer, idx, maxlen,
                                              (uintptr_t)va_arg(va, void*), false, 16U, precision,
                                              width, flags);
                    } else {
#endif
                        idx = _ntoa_long(out_tmp, buffer, idx, maxlen,
                                         (unsigned long)((uintptr_t)va_arg(va, void*)),
                                         false, 16U, precision, width, flags);
#if defined(PRINTF_SUPPORT_LONG_LONG)
                    }
#endif
                    format_tmp++;
                    break;
                }

            case '%' :
                out_tmp('%', buffer, idx++, maxlen);
                format_tmp++;
                break;

            default :
                out_tmp(*format_tmp, buffer, idx++, maxlen);
                format_tmp++;
                break;
        }
    }

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

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


int __wrap_printf(const char* format, ...)
{
    va_list va;
    va_start(va, format);
    char buffer[1];
    int ret = vsnprintf_s(_out_char, buffer, (size_t) -1, format, va);
    if (ret < 0) {
        return 0;
    }
    va_end(va);
    return ret;
}

int __wrap_snprintf(char* buffer, size_t count, const char* format, ...)
{
    va_list va;
    va_start(va, format);
    const int ret = vsnprintf_s(_out_buffer, buffer, count, format, va);
    va_end(va);
    return ret;
}

int __wrap_vsnprintf(char* buffer, size_t count, const char* format, va_list va)
{
    return vsnprintf_s(_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 };
    int ret = vsnprintf_s(_out_fct, (char*)(uintptr_t)&out_fct_wrap, (size_t) -1, format, va);
    if (ret < 0) {
        return 0;
    }
    va_end(va);
    return ret;
}