///////////////////////////////////////////////////////////////////////////////
// \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 "acpi_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;
}

// 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)
    {
      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 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)
  {
  }
  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));
      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)(48 + (whole % 10));
    if (!(whole /= 10))
    {
      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)
{
  // 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;
  int exp2 = (int)((conv.U >> 52U) & 0x07FFU) - 1023;          // effectively log2
  conv.U = (conv.U & ((1ULL << 52U) - 1U)) | (1023ULL << 52U); // drop the exponent so conv.F is now in [1,2)
  // 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)prec - expval - 1);
      }
      else
      {
        prec = 0;
      }
      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 ((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;
        flags &= ~FLAGS_HASH; // no hash for dec format
      }
      // 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 *);
      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(' ', 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;
      uintptr_t value = (uintptr_t)va_arg(va, void *);

      if (value == 0)
      {
        idx = _out_rev(out, buffer, idx, maxlen, ")lin(", 5, width, flags);
      }
      else
      {
#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, value, false, 16U, precision, width, flags);
        }
        else
        {
#endif
          idx = _ntoa_long(out, buffer, idx, maxlen, (unsigned long)(value), false, 16U, precision, width, flags);
#if defined(PRINTF_SUPPORT_LONG_LONG)
        }
#endif
      }
      format++;
      break;
    }
      __attribute__((fallthrough));
    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;
}

// acpica needs this to print stuff to stdout, but I don't know why exactly.
// Maybe some unsetting some configuration options ACPI_LIBRARY /
// APCI_APPLICATION would make sure this is no longer called..
size_t fwrite(const void *ptr, size_t size, size_t nmemb, void *stream)
{
  printf_("acpi called fwrite, probably shouldn't happen or just print this to stdout...");
  return 0;
}