text: /*
   * Copyright (c) 2006-2021, RT-Thread Development Team
   *
   * SPDX-License-Identifier: Apache-2.0
   *
   * Change Logs:
   * Date           Author       Notes
   * 2021-03-19     RT-Thread    first version
   */
  
  #include <stdio.h>
  #include <stdarg.h>
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <stdarg.h>
  
  #undef errno
  extern int errno;
  extern int _end;
  extern void print_char(char);
  caddr_t _sbrk(int incr)
  {
      static unsigned char *heap = NULL;
      unsigned char *prev_heap;
  
      if (heap == NULL)
      {
          heap = (unsigned char *) &_end;
      }
      prev_heap = heap;
  
      heap += incr;
  
      return (caddr_t) prev_heap;
  }
  
  int link(char *old, char *new)
  {
      return -1;
  }
  
  int _close(int file)
  {
      return -1;
  }
  
  int _fstat(int file, struct stat *st)
  {
      st->st_mode = S_IFCHR;
      return 0;
  }
  
  int _isatty(int file)
  {
      return 1;
  }
  
  int _lseek(int file, int ptr, int dir)
  {
      return 0;
  }
  
  int _read(int file, char *ptr, int len)
  {
      return 0;
  }
  
  void abort(void)
  {
      /* Abort called */
      while (1)
          ;
  }
  