/*

 * Integer functions

 *

 * Copyright (C) 2011-2024, Joachim Metz <joachim.metz@gmail.com>

 *

 * Refer to AUTHORS for acknowledgements.

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU Lesser General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public License

 * along with this program.  If not, see <https://www.gnu.org/licenses/>.

 */

#include <common.h>

#include <types.h>

#include "libfwevt_integer.h"

#include "libfwevt_libcerror.h"

/* Copies an integer from an UTF-16 stream

 * Returns 1 if successful or -1 on error

 */

int libfwevt_integer_copy_from_utf16_stream(

     uint64_t *integer_value,

     const uint8_t *utf16_stream,

     size_t utf16_stream_size,

     libcerror_error_t **error )

{

  static char *function       = "libfwevt_integer_copy_from_utf16_stream";

  size_t utf16_stream_offset  = 0;

  uint64_t safe_integer_value = 0;

  uint8_t digit               = 0;

  if( integer_value == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid integer value.",

     function );

    return( -1 );

  }

  if( utf16_stream == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-16 stream.",

     function );

    return( -1 );

  }

  if( ( utf16_stream_size < 2 )

   || ( utf16_stream_size > SSIZE_MAX )

   || ( ( utf16_stream_size % 2 ) != 0 ) )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_OUT_OF_BOUNDS,

     "%s: UTF-16 stream size value out of bounds.",

     function );

    return( -1 );

  }

  for( utf16_stream_offset = 0;

       utf16_stream_offset < utf16_stream_size;

       utf16_stream_offset += 2 )

  {

    if( utf16_stream_offset >= 42 )

    {

      libcerror_error_set(

       error,

       LIBCERROR_ERROR_DOMAIN_RUNTIME,

       LIBCERROR_RUNTIME_ERROR_UNSUPPORTED_VALUE,

       "%s: unsupported UTF-16 stream.",

       function );

      return( -1 );

    }

    if( utf16_stream[ utf16_stream_offset + 1 ] != 0 )

    {

      libcerror_error_set(

       error,

       LIBCERROR_ERROR_DOMAIN_RUNTIME,

       LIBCERROR_RUNTIME_ERROR_UNSUPPORTED_VALUE,

       "%s: unsupported integer string.",

       function );

      return( -1 );

    }

    digit = utf16_stream[ utf16_stream_offset ];

    if( digit == 0 )

    {

      break;

    }

    if( ( digit < (uint8_t) '0' )

     || ( digit > (uint8_t) '9' ) )

    {

      libcerror_error_set(

       error,

       LIBCERROR_ERROR_DOMAIN_RUNTIME,

       LIBCERROR_RUNTIME_ERROR_UNSUPPORTED_VALUE,

       "%s: invalid integer string.",

       function );

      return( -1 );

    }

    safe_integer_value *= 10;

    safe_integer_value += digit - (uint8_t) '0';

  }

  if( ( utf16_stream[ utf16_stream_offset ] != 0 )

   || ( utf16_stream[ utf16_stream_offset + 1 ] != 0 ) )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_RUNTIME,

     LIBCERROR_RUNTIME_ERROR_UNSUPPORTED_VALUE,

     "%s: unsupported integer string.",

     function );

    return( -1 );

  }

  *integer_value = safe_integer_value;

  return( 1 );

}

/* Deterimes the size of the string of the integer as a signed decimal

 * The string size includes the end of string character

 * Returns 1 if successful or -1 on error

 */

int libfwevt_integer_as_signed_decimal_get_string_size(

     uint64_t integer_value,

     uint8_t integer_size,

     size_t *string_size,

     libcerror_error_t **error )

{

  static char *function        = "libfwevt_integer_as_signed_decimal_get_string_size";

  uint64_t divider             = 0;

  uint8_t is_negative          = 0;

  uint8_t number_of_characters = 0;

  int8_t bit_shift             = integer_size - 1;

  if( string_size == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid string size.",

     function );

    return( -1 );

  }

  /* The string is at least a single digit with an end of string character

   */

  number_of_characters = 2;

  is_negative = (uint8_t) ( integer_value >> bit_shift );

  if( is_negative != 0 )

  {

    number_of_characters += 1;

    integer_value &= ~( (uint64_t) 1 << bit_shift );

    if( integer_value == 0 )

    {

      integer_value |= (uint64_t) 1 << bit_shift;

    }

  }

  divider = 1;

  while( ( integer_value / divider ) >= 10 )

  {

    divider *= 10;

    number_of_characters += 1;

  }

  *string_size = number_of_characters;

  return( 1 );

}

/* Copies an integer as an unsigned decimal to an UTF-8 string

 * The string size should include the end of string character

 * Returns 1 if successful or -1 on error

 */

int libfwevt_integer_as_signed_decimal_copy_to_utf8_string_with_index(

     uint64_t integer_value,

     uint8_t integer_size,

     uint8_t *utf8_string,

     size_t utf8_string_size,

     size_t *utf8_string_index,

     libcerror_error_t **error )

{

  static char *function         = "libfwevt_integer_as_signed_decimal_copy_to_utf8_string_with_index";

  size_t safe_utf8_string_index = 0;

  uint64_t divider              = 0;

  uint8_t is_negative           = 0;

  uint8_t number_of_characters  = 0;

  int8_t bit_shift              = integer_size - 1;

  if( utf8_string == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-8 string.",

     function );

    return( -1 );

  }

  if( utf8_string_size > (size_t) SSIZE_MAX )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_EXCEEDS_MAXIMUM,

     "%s: invalid UTF-8 string size value exceeds maximum.",

     function );

    return( -1 );

  }

  if( utf8_string_index == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-8 string index.",

     function );

    return( -1 );

  }

  safe_utf8_string_index = *utf8_string_index;

  /* The string is at least a single digit with an end of string character

   */

  number_of_characters = 2;

  is_negative = (uint8_t) ( integer_value >> bit_shift );

  if( is_negative != 0 )

  {

    number_of_characters += 1;

    integer_value &= ~( (uint64_t) 1 << bit_shift );

    if( integer_value == 0 )

    {

      integer_value |= (uint64_t) 1 << bit_shift;

    }

  }

  divider = 1;

  while( ( integer_value / divider ) >= 10 )

  {

    divider *= 10;

    number_of_characters += 1;

  }

  if( ( number_of_characters > utf8_string_size )

   || ( safe_utf8_string_index > ( utf8_string_size - number_of_characters ) ) )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_TOO_SMALL,

     "%s: invalid UTF-8 string size value too small.",

     function );

    return( -1 );

  }

  if( is_negative != 0 )

  {

    utf8_string[ safe_utf8_string_index++ ] = (uint8_t) '-';

  }

  while( divider > 1 )

  {

    utf8_string[ safe_utf8_string_index++ ] = (uint8_t) '0' + (uint8_t) ( integer_value / divider );

    integer_value %= divider;

    divider /= 10;

  }

  utf8_string[ safe_utf8_string_index++ ] = (uint8_t) '0' + (uint8_t) ( integer_value / divider );

  utf8_string[ safe_utf8_string_index++ ] = 0;

  *utf8_string_index = safe_utf8_string_index;

  return( 1 );

}

/* Copies an integer as an unsigned decimal to an UTF-16 string

 * The string size should include the end of string character

 * Returns 1 if successful or -1 on error

 */

int libfwevt_integer_as_signed_decimal_copy_to_utf16_string_with_index(

     uint64_t integer_value,

     uint8_t integer_size,

     uint16_t *utf16_string,

     size_t utf16_string_size,

     size_t *utf16_string_index,

     libcerror_error_t **error )

{

  static char *function          = "libfwevt_integer_as_signed_decimal_copy_to_utf16_string_with_index";

  size_t safe_utf16_string_index = 0;

  uint64_t divider               = 0;

  uint8_t is_negative            = 0;

  uint8_t number_of_characters   = 0;

  int8_t bit_shift               = integer_size - 1;

  if( utf16_string == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-16 string.",

     function );

    return( -1 );

  }

  if( utf16_string_size > (size_t) SSIZE_MAX )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_EXCEEDS_MAXIMUM,

     "%s: invalid UTF-16 string size value exceeds maximum.",

     function );

    return( -1 );

  }

  if( utf16_string_index == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-16 string index.",

     function );

    return( -1 );

  }

  safe_utf16_string_index = *utf16_string_index;

  /* The string is at least a single digit with an end of string character

   */

  number_of_characters = 2;

  is_negative = (uint8_t) ( integer_value >> bit_shift );

  if( is_negative != 0 )

  {

    number_of_characters += 1;

    integer_value &= ~( (uint64_t) 1 << bit_shift );

    if( integer_value == 0 )

    {

      integer_value |= (uint64_t) 1 << bit_shift;

    }

  }

  divider = 1;

  while( ( integer_value / divider ) >= 10 )

  {

    divider *= 10;

    number_of_characters += 1;

  }

  if( ( number_of_characters > utf16_string_size )

   || ( safe_utf16_string_index > ( utf16_string_size - number_of_characters ) ) )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_TOO_SMALL,

     "%s: invalid UTF-16 string size value too small.",

     function );

    return( -1 );

  }

  if( is_negative != 0 )

  {

    utf16_string[ safe_utf16_string_index++ ] = (uint16_t) '-';

  }

  while( divider > 1 )

  {

    utf16_string[ safe_utf16_string_index++ ] = (uint16_t) '0' + (uint16_t) ( integer_value / divider );

    integer_value %= divider;

    divider /= 10;

  }

  utf16_string[ safe_utf16_string_index++ ] = (uint16_t) '0' + (uint16_t) ( integer_value / divider );

  utf16_string[ safe_utf16_string_index++ ] = 0;

  *utf16_string_index = safe_utf16_string_index;

  return( 1 );

}

/* Deterimes the size of the string of the integer as an unsigned decimal

 * The string size includes the end of string character

 * Returns 1 if successful or -1 on error

 */

int libfwevt_integer_as_unsigned_decimal_get_string_size(

     uint64_t integer_value,

     size_t *string_size,

     libcerror_error_t **error )

{

  static char *function        = "libfwevt_integer_as_decimal_get_string_size";

  uint64_t divider             = 0;

  uint8_t number_of_characters = 0;

  if( string_size == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid string size.",

     function );

    return( -1 );

  }

  /* The string is at least a single digit with an end of string character

   */

  number_of_characters = 2;

  divider = 1;

  while( ( integer_value / divider ) >= 10 )

  {

    divider *= 10;

    number_of_characters += 1;

  }

  *string_size = number_of_characters;

  return( 1 );

}

/* Copies an integer as an unsigned decimal to an UTF-8 string

 * The string size should include the end of string character

 * Returns 1 if successful or -1 on error

 */

int libfwevt_integer_as_unsigned_decimal_copy_to_utf8_string_with_index(

     uint64_t integer_value,

     uint8_t *utf8_string,

     size_t utf8_string_size,

     size_t *utf8_string_index,

     libcerror_error_t **error )

{

  static char *function         = "libfwevt_integer_as_unsigned_decimal_copy_to_utf8_string_with_index";

  size_t safe_utf8_string_index = 0;

  uint64_t divider              = 0;

  uint8_t number_of_characters  = 0;

  if( utf8_string == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-8 string.",

     function );

    return( -1 );

  }

  if( utf8_string_size > (size_t) SSIZE_MAX )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_EXCEEDS_MAXIMUM,

     "%s: invalid UTF-8 string size value exceeds maximum.",

     function );

    return( -1 );

  }

  if( utf8_string_index == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-8 string index.",

     function );

    return( -1 );

  }

  safe_utf8_string_index = *utf8_string_index;

  /* The string is at least a single digit with an end of string character

   */

  number_of_characters = 2;

  divider = 1;

  while( ( integer_value / divider ) >= 10 )

  {

    divider *= 10;

    number_of_characters += 1;

  }

  if( ( number_of_characters > utf8_string_size )

   || ( safe_utf8_string_index > ( utf8_string_size - number_of_characters ) ) )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_TOO_SMALL,

     "%s: invalid UTF-8 string size value too small.",

     function );

    return( -1 );

  }

  while( divider > 1 )

  {

    utf8_string[ safe_utf8_string_index++ ] = (uint8_t) '0' + (uint8_t) ( integer_value / divider );

    integer_value %= divider;

    divider /= 10;

  }

  utf8_string[ safe_utf8_string_index++ ] = (uint8_t) '0' + (uint8_t) ( integer_value / divider );

  utf8_string[ safe_utf8_string_index++ ] = 0;

  *utf8_string_index = safe_utf8_string_index;

  return( 1 );

}

/* Copies an integer as an unsigned decimal to an UTF-16 string

 * The string size should include the end of string character

 * Returns 1 if successful or -1 on error

 */

int libfwevt_integer_as_unsigned_decimal_copy_to_utf16_string_with_index(

     uint64_t integer_value,

     uint16_t *utf16_string,

     size_t utf16_string_size,

     size_t *utf16_string_index,

     libcerror_error_t **error )

{

  static char *function          = "libfwevt_integer_as_unsigned_decimal_copy_to_utf16_string_with_index";

  size_t safe_utf16_string_index = 0;

  uint64_t divider               = 0;

  uint8_t number_of_characters   = 0;

  if( utf16_string == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-16 string.",

     function );

    return( -1 );

  }

  if( utf16_string_size > (size_t) SSIZE_MAX )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_EXCEEDS_MAXIMUM,

     "%s: invalid UTF-16 string size value exceeds maximum.",

     function );

    return( -1 );

  }

  if( utf16_string_index == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-16 string index.",

     function );

    return( -1 );

  }

  safe_utf16_string_index = *utf16_string_index;

  /* The string is at least a single digit with an end of string character

   */

  number_of_characters = 2;

  divider = 1;

  while( ( integer_value / divider ) >= 10 )

  {

    divider *= 10;

    number_of_characters += 1;

  }

  if( ( number_of_characters > utf16_string_size )

   || ( safe_utf16_string_index > ( utf16_string_size - number_of_characters ) ) )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_TOO_SMALL,

     "%s: invalid UTF-16 string size value too small.",

     function );

    return( -1 );

  }

  while( divider > 1 )

  {

    utf16_string[ safe_utf16_string_index++ ] = (uint16_t) '0' + (uint16_t) ( integer_value / divider );

    integer_value %= divider;

    divider /= 10;

  }

  utf16_string[ safe_utf16_string_index++ ] = (uint16_t) '0' + (uint16_t) ( integer_value / divider );

  utf16_string[ safe_utf16_string_index++ ] = 0;

  *utf16_string_index = safe_utf16_string_index;

  return( 1 );

}

/* Copies an integer as hexadecimal to an UTF-8 string

 * The string size should include the end of string character

 * Returns 1 if successful or -1 on error

 */

int libfwevt_integer_as_hexadecimal_copy_to_utf8_string_with_index(

     uint64_t integer_value,

     uint8_t integer_size,

     uint8_t *utf8_string,

     size_t utf8_string_size,

     size_t *utf8_string_index,

     libcerror_error_t **error )

{

  static char *function         = "libfwevt_integer_as_hexadecimal_copy_to_utf8_string_with_index";

  size_t safe_utf8_string_index = 0;

  uint8_t number_of_characters  = 0;

  uint8_t byte_value            = 0;

  int8_t bit_shift              = 0;

  if( integer_size == 32 )

  {

    number_of_characters = 11;

  }

  else if( integer_size == 64 )

  {

    number_of_characters = 19;

  }

  else

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_RUNTIME,

     LIBCERROR_RUNTIME_ERROR_UNSUPPORTED_VALUE,

     "%s: unsupported integer size.",

     function );

    return( -1 );

  }

  if( utf8_string == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-8 string.",

     function );

    return( -1 );

  }

  if( utf8_string_size > (size_t) SSIZE_MAX )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_EXCEEDS_MAXIMUM,

     "%s: invalid UTF-8 string size value exceeds maximum.",

     function );

    return( -1 );

  }

  if( utf8_string_index == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-8 string index.",

     function );

    return( -1 );

  }

  safe_utf8_string_index = *utf8_string_index;

  if( ( number_of_characters > utf8_string_size )

   || ( safe_utf8_string_index > ( utf8_string_size - number_of_characters ) ) )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_TOO_SMALL,

     "%s: invalid UTF-8 string size value too small.",

     function );

    return( -1 );

  }

  utf8_string[ safe_utf8_string_index++ ] = (uint8_t) '0';

  utf8_string[ safe_utf8_string_index++ ] = (uint8_t) 'x';

  bit_shift = (uint8_t) ( integer_size - 4 );

  do

  {

    byte_value = (uint8_t) ( ( integer_value >> bit_shift ) & 0x0f );

    if( byte_value <= 9 )

    {

      utf8_string[ safe_utf8_string_index++ ] = (uint8_t) '0' + byte_value;

    }

    else

    {

      utf8_string[ safe_utf8_string_index++ ] = (uint8_t) 'a' + byte_value - 10;

    }

    bit_shift -= 4;

  }

  while( bit_shift >= 0 );

  utf8_string[ safe_utf8_string_index++ ] = 0;

  *utf8_string_index = safe_utf8_string_index;

  return( 1 );

}

/* Copies an integer as hexadecimal to an UTF-16 string

 * The string size should include the end of string character

 * Returns 1 if successful or -1 on error

 */

int libfwevt_integer_as_hexadecimal_copy_to_utf16_string_with_index(

     uint64_t integer_value,

     uint8_t integer_size,

     uint16_t *utf16_string,

     size_t utf16_string_size,

     size_t *utf16_string_index,

     libcerror_error_t **error )

{

  static char *function          = "libfwevt_integer_as_hexadecimal_copy_to_utf16_string_with_index";

  size_t safe_utf16_string_index = 0;

  uint8_t number_of_characters   = 0;

  uint8_t byte_value             = 0;

  int8_t bit_shift               = 0;

  if( integer_size == 32 )

  {

    number_of_characters = 11;

  }

  else if( integer_size == 64 )

  {

    number_of_characters = 19;

  }

  else

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_RUNTIME,

     LIBCERROR_RUNTIME_ERROR_UNSUPPORTED_VALUE,

     "%s: unsupported integer size.",

     function );

    return( -1 );

  }

  if( utf16_string == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-16 string.",

     function );

    return( -1 );

  }

  if( utf16_string_size > (size_t) SSIZE_MAX )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_EXCEEDS_MAXIMUM,

     "%s: invalid UTF-16 string size value exceeds maximum.",

     function );

    return( -1 );

  }

  if( utf16_string_index == NULL )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_INVALID_VALUE,

     "%s: invalid UTF-16 string index.",

     function );

    return( -1 );

  }

  safe_utf16_string_index = *utf16_string_index;

  if( ( number_of_characters > utf16_string_size )

   || ( safe_utf16_string_index > ( utf16_string_size - number_of_characters ) ) )

  {

    libcerror_error_set(

     error,

     LIBCERROR_ERROR_DOMAIN_ARGUMENTS,

     LIBCERROR_ARGUMENT_ERROR_VALUE_TOO_SMALL,

     "%s: invalid UTF-16 string size value too small.",

     function );

    return( -1 );

  }

  utf16_string[ safe_utf16_string_index++ ] = (uint16_t) '0';

  utf16_string[ safe_utf16_string_index++ ] = (uint16_t) 'x';

  bit_shift = (uint16_t) ( integer_size - 4 );

  do

  {

    byte_value = (uint16_t) ( ( integer_value >> bit_shift ) & 0x0f );

    if( byte_value <= 9 )

    {

      utf16_string[ safe_utf16_string_index++ ] = (uint16_t) '0' + byte_value;

    }

    else

    {

      utf16_string[ safe_utf16_string_index++ ] = (uint16_t) 'a' + byte_value - 10;

    }

    bit_shift -= 4;

  }

  while( bit_shift >= 0 );

  utf16_string[ safe_utf16_string_index++ ] = 0;

  *utf16_string_index = safe_utf16_string_index;

  return( 1 );

}