typedef struct Line	Line;typedef struct Cand	Cand;typedef struct Diff	Diff;typedef struct Change	Change; struct Line {	int	serial;	int	value;}; struct Cand {	int x;	int y;	int pred;}; struct Change{	int oldx;	int oldy;	int newx;	int newy;}; struct Diff {	Cand cand;	Line *file[2], line;	int len[2];	int binary;	int bindiff;	Line *sfile[2];	/*shortened by pruning common prefix and suffix*/	int slen[2];	int pref, suff;	/*length of prefix and suffix*/	int *class;	/*will be overlaid on file[0]*/	int *member;	/*will be overlaid on file[1]*/	int *klist;	/*will be overlaid on file[0] after class*/	Cand *clist;	/* merely a free storage pot for candidates */	int clen;	int *J;		/*will be overlaid on class*/	long *ixold;	/*will be overlaid on klist*/	long *ixnew;	/*will be overlaid on file[1]*/	char *file1;	char *file2;	Biobuf *input[2];	Biobuf *b0;	Biobuf *b1;	int firstchange;	Change *changes;	int nchanges;}; extern char mode;extern char bflag;extern char rflag;extern char mflag;extern int anychange;extern Biobuf	stdout; #define MAXPATHLEN	1024#define MAXLINELEN	4096 #define	DIRECTORY(s)		((s)->qid.type&QTDIR)#define	REGULAR_FILE(s)		((s)->type == 'M' && !DIRECTORY(s)) int mkpathname(char *, char *, char *);char *mktmpfile(int, Dir **);char *statfile(char *, Dir **);void *emalloc(unsigned);void *erealloc(void *, unsigned);void diff(char *, char *, int);void diffreg(char*, char*, char*, char*);void diffdir(char *, char *, int);void calcdiff(Diff *, char *, char *, char *, char *);Biobuf *prepare(Diff*, int, char *, char *);void check(Diff *, Biobuf *, Biobuf *);void change(Diff *, int, int, int, int);void freediff(Diff *);void flushchanges(Diff *);void fetch(Diff *d, long *f, int a, int b, Biobuf *bp, char *s);int readline(Biobuf*, char*, int);