#include <errno.h>
#include <stddef.h>
#include <sys/types.h>

extern char _end;

static char *heap_end;

caddr_t _sbrk(int incr)
{
  extern char _estack;
  char *prev;

  if (heap_end == NULL)
  {
    heap_end = &_end;
  }

  prev = heap_end;
  if ((heap_end + incr) >= (&_estack - 0x800))
  {
    errno = ENOMEM;
    return (caddr_t)-1;
  }

  heap_end += incr;
  return (caddr_t)prev;
}

int _write(int file, char *ptr, int len)
{
  (void)file;
  (void)ptr;
  return len;
}

int _read(int file, char *ptr, int len)
{
  (void)file;
  (void)ptr;
  (void)len;
  return 0;
}

int _close(int file)
{
  (void)file;
  return -1;
}

int _fstat(int file, void *st)
{
  (void)file;
  (void)st;
  return 0;
}

int _isatty(int file)
{
  (void)file;
  return 1;
}

int _lseek(int file, int ptr, int dir)
{
  (void)file;
  (void)ptr;
  (void)dir;
  return 0;
}

void _exit(int status)
{
  (void)status;
  while (1)
  {
  }
}

int _kill(int pid, int sig)
{
  (void)pid;
  (void)sig;
  errno = EINVAL;
  return -1;
}

int _getpid(void)
{
  return 1;
}