/**
 Copyright (C) 2002 Michael Ringgaard. All rights reserved.
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:

 1. Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the
    documentation and/or other materials provided with the distribution.
 3. Neither the name of the project nor the names of its contributors
    may be used to endorse or promote products derived from this software
    without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
 FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 SUCH DAMAGE.
*/
/**
  ******************************************************************************
  * @file    stm32_tiny_vsnprintf.c
  * @author  MCD Application Team
  * @brief   Tiny implementation of vsnprintf like function
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2019 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/*
 * Following implementation is adapted from original one
 *   https://github.com/jpbonn/coremark_lm32/blob/master/ee_printf.c
 */

/* Includes ------------------------------------------------------------------*/
#include "stm32_tiny_vsnprintf.h"

/* Private typedef -----------------------------------------------------------*/
/* Private defines -----------------------------------------------------------*/
#define TINY_PRINTF

#define ZEROPAD    (1<<0)  /* Pad with zero */
#define SIGN      (1<<1)  /* Unsigned/signed long */
#define UPPERCASE   (1<<6)  /* 'ABCDEF' */
#ifdef TINY_PRINTF
#else
#define PLUS      (1<<2)  /* Show plus */
#define HEX_PREP   (1<<5)  /* 0x */
#define SPACE     (1<<3)  /* Spacer */
#define LEFT      (1<<4)  /* Left justified */
#endif

#define is_digit(c) ((c) >= '0' && (c) <= '9')

/* Private macros ------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
/* Global variables ----------------------------------------------------------*/
/* Private function prototypes -----------------------------------------------*/

static char *lower_digits = "0123456789abcdefghijklmnopqrstuvwxyz";
static char *upper_digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

/* Functions Definition ------------------------------------------------------*/
#ifdef TINY_PRINTF
#else
static size_t strnlen(const char *s, size_t count);

static size_t strnlen(const char *s, size_t count)
{
  const char *sc;
  for (sc = s; *sc != '\0' && count--; ++sc);
  return sc - s;
}
#endif

static int ee_skip_atoi(const char **s)
{
  int i = 0;
  while (is_digit(**s)) i = i*10 + *((*s)++) - '0';
  return i;
}

#define ASSIGN_STR(_c)  do { *str++ = (_c); max_size--; if (max_size == 0) return str; } while (0)

static char *ee_number(char *str, int max_size, long num, int base, int size, int precision, int type)
{
  char c;
  char sign, tmp[66];
  char *dig = lower_digits;
  int i;

  if (type & UPPERCASE)  dig = upper_digits;
#ifdef TINY_PRINTF
#else
  if (type & LEFT) type &= ~ZEROPAD;
#endif
  if (base < 2 || base > 36) return 0;

  c = (type & ZEROPAD) ? '0' : ' ';
  sign = 0;
  if (type & SIGN)
  {
    if (num < 0)
    {
      sign = '-';
      num = -num;
      size--;
    }
#ifdef TINY_PRINTF
#else
    else if (type & PLUS)
    {
      sign = '+';
      size--;
    }
    else if (type & SPACE)
    {
      sign = ' ';
      size--;
    }
#endif
  }

#ifdef TINY_PRINTF
#else
  if (type & HEX_PREP)
  {
    if (base == 16)
      size -= 2;
    else if (base == 8)
      size--;
  }
#endif

  i = 0;

  if (num == 0)
    tmp[i++] = '0';
  else
  {
    while (num != 0)
    {
      tmp[i++] = dig[((unsigned long) num) % (unsigned) base];
      num = ((unsigned long) num) / (unsigned) base;
    }
  }

  if (i > precision) precision = i;
  size -= precision;
  if (!(type & (ZEROPAD /* TINY option   | LEFT */))) while (size-- > 0) ASSIGN_STR(' ');
  if (sign) ASSIGN_STR(sign);

#ifdef TINY_PRINTF
#else
  if (type & HEX_PREP)
  {
    if (base == 8)
      ASSIGN_STR('0');
    else if (base == 16)
    {
      ASSIGN_STR('0');
      ASSIGN_STR(lower_digits[33]);
    }
  }
#endif

#ifdef TINY_PRINTF
  while (size-- > 0) ASSIGN_STR(c);
#else
  if (!(type & LEFT)) while (size-- > 0) ASSIGN_STR(c);
#endif
  while (i < precision--) ASSIGN_STR('0');
  while (i-- > 0) ASSIGN_STR(tmp[i]);
  while (size-- > 0) ASSIGN_STR(' ');

  return str;
}

#ifdef TINY_PRINTF
#else
static char *eaddr(char *str, unsigned char *addr, int size, int precision, int type)
{
  char tmp[24];
  char *dig = lower_digits;
  int i, len;

  if (type & UPPERCASE)  dig = upper_digits;
  len = 0;
  for (i = 0; i < 6; i++)
  {
    if (i != 0) tmp[len++] = ':';
    tmp[len++] = dig[addr[i] >> 4];
    tmp[len++] = dig[addr[i] & 0x0F];
  }

  if (!(type & LEFT)) while (len < size--) *str++ = ' ';
  for (i = 0; i < len; ++i) *str++ = tmp[i];
  while (len < size--) *str++ = ' ';

  return str;
}

static char *iaddr(char *str, unsigned char *addr, int size, int precision, int type)
{
  char tmp[24];
  int i, n, len;

  len = 0;
  for (i = 0; i < 4; i++)
  {
    if (i != 0) tmp[len++] = '.';
    n = addr[i];

    if (n == 0)
      tmp[len++] = lower_digits[0];
    else
    {
      if (n >= 100)
      {
        tmp[len++] = lower_digits[n / 100];
        n = n % 100;
        tmp[len++] = lower_digits[n / 10];
        n = n % 10;
      }
      else if (n >= 10)
      {
        tmp[len++] = lower_digits[n / 10];
        n = n % 10;
      }

      tmp[len++] = lower_digits[n];
    }
  }

  if (!(type & LEFT)) while (len < size--) *str++ = ' ';
  for (i = 0; i < len; ++i) *str++ = tmp[i];
  while (len < size--) *str++ = ' ';

  return str;
}
#endif

#ifdef HAS_FLOAT

char *ecvtbuf(double arg, int ndigits, int *decpt, int *sign, char *buf);
char *fcvtbuf(double arg, int ndigits, int *decpt, int *sign, char *buf);
static void ee_bufcpy(char *d, char *s, int count);

void ee_bufcpy(char *pd, char *ps, int count) {
  char *pe=ps+count;
  while (ps!=pe)
    *pd++=*ps++;
}

static void parse_float(double value, char *buffer, char fmt, int precision)
{
  int decpt, sign, exp, pos;
  char *fdigits = NULL;
  char cvtbuf[80];
  int capexp = 0;
  int magnitude;

  if (fmt == 'G' || fmt == 'E')
  {
    capexp = 1;
    fmt += 'a' - 'A';
  }

  if (fmt == 'g')
  {
    fdigits = ecvtbuf(value, precision, &decpt, &sign, cvtbuf);
    magnitude = decpt - 1;
    if (magnitude < -4  ||  magnitude > precision - 1)
    {
      fmt = 'e';
      precision -= 1;
    }
    else
    {
      fmt = 'f';
      precision -= decpt;
    }
  }

  if (fmt == 'e')
  {
    fdigits = ecvtbuf(value, precision + 1, &decpt, &sign, cvtbuf);

    if (sign) *buffer++ = '-';
    *buffer++ = *fdigits;
    if (precision > 0) *buffer++ = '.';
    ee_bufcpy(buffer, fdigits + 1, precision);
    buffer += precision;
    *buffer++ = capexp ? 'E' : 'e';

    if (decpt == 0)
    {
      if (value == 0.0)
        exp = 0;
      else
        exp = -1;
    }
    else
      exp = decpt - 1;

    if (exp < 0)
    {
      *buffer++ = '-';
      exp = -exp;
    }
    else
      *buffer++ = '+';

    buffer[2] = (exp % 10) + '0';
    exp = exp / 10;
    buffer[1] = (exp % 10) + '0';
    exp = exp / 10;
    buffer[0] = (exp % 10) + '0';
    buffer += 3;
  }
  else if (fmt == 'f')
  {
    fdigits = fcvtbuf(value, precision, &decpt, &sign, cvtbuf);
    if (sign) *buffer++ = '-';
    if (*fdigits)
    {
      if (decpt <= 0)
      {
        *buffer++ = '0';
        *buffer++ = '.';
        for (pos = 0; pos < -decpt; pos++) *buffer++ = '0';
        while (*fdigits) *buffer++ = *fdigits++;
      }
      else
      {
        pos = 0;
        while (*fdigits)
        {
          if (pos++ == decpt) *buffer++ = '.';
          *buffer++ = *fdigits++;
        }
      }
    }
    else
    {
      *buffer++ = '0';
      if (precision > 0)
      {
        *buffer++ = '.';
        for (pos = 0; pos < precision; pos++) *buffer++ = '0';
      }
    }
  }

  *buffer = '\0';
}

static void decimal_point(char *buffer)
{
  while (*buffer)
  {
    if (*buffer == '.') return;
    if (*buffer == 'e' || *buffer == 'E') break;
    buffer++;
  }

  if (*buffer)
  {
    int n = strnlen(buffer,256);
    while (n > 0)
    {
      buffer[n + 1] = buffer[n];
      n--;
    }

    *buffer = '.';
  }
  else
  {
    *buffer++ = '.';
    *buffer = '\0';
  }
}

static void cropzeros(char *buffer)
{
  char *stop;

  while (*buffer && *buffer != '.') buffer++;
  if (*buffer++)
  {
    while (*buffer && *buffer != 'e' && *buffer != 'E') buffer++;
    stop = buffer--;
    while (*buffer == '0') buffer--;
    if (*buffer == '.') buffer--;
    while (buffer!=stop)
    *++buffer=0;
  }
}

static char *flt(char *str, double num, int size, int precision, char fmt, int flags)
{
  char tmp[80];
  char c, sign;
  int n, i;

  // Left align means no zero padding
#ifdef TINY_PRINTF
#else
  if (flags & LEFT) flags &= ~ZEROPAD;
#endif

  // Determine padding and sign char
  c = (flags & ZEROPAD) ? '0' : ' ';
  sign = 0;
  if (flags & SIGN)
  {
    if (num < 0.0)
    {
      sign = '-';
      num = -num;
      size--;
    }
#ifdef TINY_PRINTF
#else
    else if (flags & PLUS)
    {
      sign = '+';
      size--;
    }
    else if (flags & SPACE)
    {
      sign = ' ';
      size--;
    }
#endif
  }

  // Compute the precision value
  if (precision < 0)
    precision = 6; // Default precision: 6

  // Convert floating point number to text
  parse_float(num, tmp, fmt, precision);

#ifdef TINY_PRINTF
#else
  if ((flags & HEX_PREP) && precision == 0) decimal_point(tmp);
#endif
  if (fmt == 'g' && !(flags & HEX_PREP)) cropzeros(tmp);

  n = strnlen(tmp,256);

  // Output number with alignment and padding
  size -= n;
  if (!(flags & (ZEROPAD | LEFT))) while (size-- > 0) *str++ = ' ';
  if (sign) *str++ = sign;
  if (!(flags & LEFT)) while (size-- > 0) *str++ = c;
  for (i = 0; i < n; i++) *str++ = tmp[i];
  while (size-- > 0) *str++ = ' ';

  return str;
}

#endif

#define CHECK_STR_SIZE(_buf, _str, _size) \
  if ((((_str) - (_buf)) >= ((_size)-1))) { break; }

int tiny_vsnprintf_like(char *buf, const int size, const char *fmt, va_list args)
{
  unsigned long num;
  int base;
  char *str;
  int len;
  int i;
  char *s;

  int flags;            // Flags to number()

  int field_width;      // Width of output field
  int precision;        // Min. # of digits for integers; max number of chars for from string
  int qualifier;        // 'h', 'l', or 'L' for integer fields

  if (size <= 0)
  {
    return 0;
  }

  for (str = buf; *fmt || ((str - buf) >= size-1); fmt++)
  {
    CHECK_STR_SIZE(buf, str, size);

    if (*fmt != '%')
    {
      *str++ = *fmt;
      continue;
    }

    // Process flags
    flags = 0;
#ifdef TINY_PRINTF
    /* Support %0, but not %-, %+, %space and %# */
    fmt++;
    if (*fmt == '0')
    {
      flags |= ZEROPAD;
    }
#else
repeat:
    fmt++; // This also skips first '%'
    switch (*fmt)
    {
      case '-': flags |= LEFT; goto repeat;
      case '+': flags |= PLUS; goto repeat;
      case ' ': flags |= SPACE; goto repeat;
      case '#': flags |= HEX_PREP; goto repeat;
      case '0': flags |= ZEROPAD; goto repeat;
    }
#endif

    // Get field width
    field_width = -1;
    if (is_digit(*fmt))
      field_width = ee_skip_atoi(&fmt);
#ifdef TINY_PRINTF
    /* Does not support %* */
#else
    else if (*fmt == '*')
    {
      fmt++;
      field_width = va_arg(args, int);
      if (field_width < 0)
      {
        field_width = -field_width;
        flags |= LEFT;
      }
    }
#endif

    // Get the precision
    precision = -1;
#ifdef TINY_PRINTF
    /* Does not support %. */
#else
    if (*fmt == '.')
    {
      ++fmt;
      if (is_digit(*fmt))
        precision = ee_skip_atoi(&fmt);
      else if (*fmt == '*')
      {
        ++fmt;
        precision = va_arg(args, int);
      }
      if (precision < 0) precision = 0;
    }
#endif

    // Get the conversion qualifier
    qualifier = -1;
#ifdef TINY_PRINTF
      /* Does not support %l and %L */
#else
    if (*fmt == 'l' || *fmt == 'L')
    {
      qualifier = *fmt;
      fmt++;
    }
#endif

    // Default base
    base = 10;

    switch (*fmt)
    {
      case 'c':
#ifdef TINY_PRINTF
#else
        if (!(flags & LEFT))
#endif
          while (--field_width > 0) *str++ = ' ';
        *str++ = (unsigned char) va_arg(args, int);
#ifdef TINY_PRINTF
#else
        while (--field_width > 0) *str++ = ' ';
#endif
        continue;

      case 's':
        s = va_arg(args, char *);
        if (!s) s = "<NULL>";
#ifdef TINY_PRINTF
        len = strlen(s);
#else
        len = strnlen(s, precision);
        if (!(flags & LEFT))
#endif
          while (len < field_width--) *str++ = ' ';
        for (i = 0; i < len; ++i) *str++ = *s++;
#ifdef TINY_PRINTF
#else
        while (len < field_width--) *str++ = ' ';
#endif
        continue;

#ifdef TINY_PRINTF
      /* Does not support %p, %A, %a, %o */
#else
      case 'p':
        if (field_width == -1)
        {
          field_width = 2 * sizeof(void *);
          flags |= ZEROPAD;
        }
        str = ee_number(str, (size - (str - buf)), (unsigned long) va_arg(args, void *), 16, field_width, precision, flags);
        continue;

      case 'A':
        flags |= UPPERCASE;

      case 'a':
        if (qualifier == 'l')
          str = eaddr(str, va_arg(args, unsigned char *), field_width, precision, flags);
        else
          str = iaddr(str, va_arg(args, unsigned char *), field_width, precision, flags);
        continue;

      // Integer number formats - set up the flags and "break"
      case 'o':
        base = 8;
        break;
#endif

      case 'X':
        flags |= UPPERCASE;

      case 'x':
        base = 16;
        break;

      case 'd':
      case 'i':
        flags |= SIGN;

      case 'u':
        break;

#ifdef HAS_FLOAT

      case 'f':
        str = flt(str, va_arg(args, double), field_width, precision, *fmt, flags | SIGN);
        continue;

#endif

      default:
        if (*fmt != '%') *str++ = '%';
        CHECK_STR_SIZE(buf, str, size);
        if (*fmt)
          *str++ = *fmt;
        else
          --fmt;
        CHECK_STR_SIZE(buf, str, size);
        continue;
    }

    if (qualifier == 'l')
      num = va_arg(args, unsigned long);
    else if (flags & SIGN)
      num = va_arg(args, int);
    else
      num = va_arg(args, unsigned int);

    str = ee_number(str, ((size - 1) - (str - buf)), num, base, field_width, precision, flags);
  }

  *str = '\0';
  return str - buf;
}
