int2str.cc

/* Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

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   Without limiting anything contained in the foregoing, this file,
   which is part of C Driver for MySQL (Connector/C), is also subject to the
   Universal FOSS Exception, version 1.0, a copy of which can be found at
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   This program is distributed in the hope that it will be useful,
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

#include <stdlib.h>
#include <sys/types.h>

#include "m_string.h"  // IWYU pragma: keep
#include "my_inttypes.h"

/*
  _dig_vec arrays are public because they are used in several outer places.
*/
char _dig_vec_upper[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
char _dig_vec_lower[] = "0123456789abcdefghijklmnopqrstuvwxyz";

/*
  Convert integer to its string representation in given scale of notation.

  SYNOPSIS
    int2str()
      val     - value to convert
      dst     - points to buffer where string representation should be stored
      radix   - radix of scale of notation
      upcase  - set to 1 if we should use upper-case digits

  DESCRIPTION
    Converts the (long) integer value to its character form and moves it to
    the destination buffer followed by a terminating NUL.
    If radix is -2..-36, val is taken to be SIGNED, if radix is  2..36, val is
    taken to be UNSIGNED. That is, val is signed if and only if radix is.
    All other radixes treated as bad and nothing will be changed in this case.

    For conversion to decimal representation (radix is -10 or 10) one can use
    optimized int10_to_str() function.

  RETURN VALUE
    Pointer to ending NUL character or NullS if radix is bad.
*/

char *int2str(long int val, char *dst, int radix, int upcase) {
  char buffer[65];
  char *p;
  long int new_val;
  char *dig_vec = upcase ? _dig_vec_upper : _dig_vec_lower;
  ulong uval = (ulong)val;

  if (radix < 0) {
    if (radix < -36 || radix > -2) return NullS;
    if (val < 0) {
      *dst++ = '-';
      /* Avoid integer overflow in (-val) for LLONG_MIN (BUG#31799). */
      uval = (ulong)0 - uval;
    }
    radix = -radix;
  } else if (radix > 36 || radix < 2)
    return NullS;

  /*
    The slightly contorted code which follows is due to the fact that
    few machines directly support unsigned long / and %.  Certainly
    the VAX C compiler generates a subroutine call.  In the interests
    of efficiency (hollow laugh) I let this happen for the first digit
    only; after that "val" will be in range so that signed integer
    division will do.  Sorry 'bout that.  CHECK THE CODE PRODUCED BY
    YOUR C COMPILER.  The first % and / should be unsigned, the second
    % and / signed, but C compilers tend to be extraordinarily
    sensitive to minor details of style.  This works on a VAX, that's
    all I claim for it.
  */
  p = &buffer[sizeof(buffer) - 1];
  *p = '\0';
  new_val = uval / (ulong)radix;
  *--p = dig_vec[(uchar)(uval - (ulong)new_val * (ulong)radix)];
  val = new_val;
  while (val != 0) {
    ldiv_t res;
    res = ldiv(val, radix);
    *--p = dig_vec[res.rem];
    val = res.quot;
  }
  while ((*dst++ = *p++) != 0)
    ;
  return dst - 1;
}

/*
  Converts integer to its string representation in decimal notation.

  SYNOPSIS
    int10_to_str()
      val     - value to convert
      dst     - points to buffer where string representation should be stored
      radix   - flag that shows whenever val should be taken as signed or not

  DESCRIPTION
    This is version of int2str() function which is optimized for normal case
    of radix 10/-10. It takes only sign of radix parameter into account and
    not its absolute value.

  RETURN VALUE
    Pointer to ending NUL character.
*/

char *int10_to_str(long int val, char *dst, int radix) {
  char buffer[65];
  char *p;
  long int new_val;
  unsigned long int uval = (unsigned long int)val;

  if (radix < 0) /* -10 */
  {
    if (val < 0) {
      *dst++ = '-';
      /* Avoid integer overflow in (-val) for LLONG_MIN (BUG#31799). */
      uval = (unsigned long int)0 - uval;
    }
  }

  p = &buffer[sizeof(buffer) - 1];
  *p = '\0';
  new_val = (long)(uval / 10);
  *--p = '0' + (char)(uval - (unsigned long)new_val * 10);
  val = new_val;

  while (val != 0) {
    new_val = val / 10;
    *--p = '0' + (char)(val - new_val * 10);
    val = new_val;
  }
  while ((*dst++ = *p++) != 0)
    ;
  return dst - 1;
}