#define NULL 0
#define EOF (-1)
#define BUFSIZ 1024
#define OPEN_MAX 20 /* max #files open at once */

typedef struct _iobuf {
     int cnt; /* characters left */
     char *ptr; /* next character position */
     char *base; /* location of buffer */
     int flag; /* mode of file access */
     int fd; /* file descriptor */
} FILE;

extern FILE _iob[OPEN_MAX];

#define stdin (&_iob[0])
#define stdout (&_iob[1])
#define stderr (&_iob[2])

enum _flags {
     _READ = 01, /* file open for reading */
     _WRITE = 02, /* file open for writing */
     _UNBUF = 04, /* file is ubuffered */
     _EOF = 010, /* EOF has occured on this file */
     _ERR = 020 /* error occurred on this file */
};

int _fillbuf(FILE *);
int _flushbuf(int, FILE *);

#define feof(p) (((p)->flag & _EOF) != 0)
#define ferror(p) (((p)->flag & _ERR) != 0)
#define fileno(p) ((p)->fd)

#define getc(p) (--(p)->cnt >= 0 \
                ? (unsigned char) *(p)->ptr++ : _fillbuf(p))
/*#define putc(x,p) (--(p)->cnt >= 0 \
  ? *(p)->ptr++ = (x) : _flushbuf((x),p)*/

#define getchar() getc(stdin)
/*#define putchar(x) putc(x, stdout)*/

FILE *fopen(char *name, char *mode);