#include <u.h>#include <libc.h>#include <bio.h>#include "diff.h" struct line {	int	serial;	int	value;};extern struct line *file[2];extern int len[2];extern long *ixold, *ixnew;extern int *J; static Biobuf *input[2];static char *file1, *file2;static int firstchange; #define MAXLINELEN	4096#define MIN(x, y)	((x) < (y) ? (x): (y)) static intreadline(Biobuf *bp, char *buf){	int c;	char *p, *e; 	p = buf;	e = p + MAXLINELEN-1;	do {		c = Bgetc(bp);		if (c < 0) {			if (p == buf)				return -1;			break;		}		if (c == '\n')			break;		*p++ = c;	} while (p < e);	*p = 0;	if (c != '\n' && c >= 0) {		do c = Bgetc(bp);		while (c >= 0 && c != '\n');	}	return p - buf;} #define HALFLONG 16#define low(x)	(x&((1L<<HALFLONG)-1))#define high(x)	(x>>HALFLONG) /* * hashing has the effect of * arranging line in 7-bit bytes and then * summing 1-s complement in 16-bit hunks  */static intreadhash(Biobuf *bp, char *buf){	long sum;	unsigned shift;	char *p;	int len, space; 	sum = 1;	shift = 0;	if ((len = readline(bp, buf)) == -1)		return 0;	p = buf;	switch(bflag)	/* various types of white space handling */	{	case 0:		while (len--) {			sum += (long)*p++ << (shift &= (HALFLONG-1));			shift += 7;		}		break;	case 1:		/*		 * coalesce multiple white-space		 */		for (space = 0; len--; p++) {			if (isspace(*p)) {				space++;				continue;			}			if (space) {				shift += 7;				space = 0;			}			sum += (long)*p << (shift &= (HALFLONG-1));			shift += 7;		}		break;	default:		/*		 * strip all white-space		 */		while (len--) {			if (isspace(*p)) {				p++;				continue;			}			sum += (long)*p++ << (shift &= (HALFLONG-1));			shift += 7;		}		break;	}	sum = low(sum) + high(sum);	return ((short)low(sum) + (short)high(sum));} Biobuf *prepare(int i, char *arg){	struct line *p;	int j, h;	Biobuf *bp;	char *cp, buf[MAXLINELEN];	int nbytes;	Rune r; 	bp = Bopen(arg, OREAD);	if (!bp) {		panic(mflag ? 0: 2, "cannot open %s: %r\n", arg);		return 0;	}	nbytes = Bread(bp, buf, MIN(1024, MAXLINELEN));	if (nbytes > 0) {		cp = buf;		while (cp < buf+nbytes-UTFmax) {			/*			 * heuristic for a binary file in the			 * brave new UNICODE world			 */			cp += chartorune(&r, cp);			if (r == 0 || (r > 0x7f && r <= 0xa0)) {				Bclose(bp);				panic(mflag ? 0: 2, "binary file %s\n", arg);				return 0;			}		}		Bseek(bp, 0, 0);	}	p = MALLOC(struct line, 3);	for (j = 0; h = readhash(bp, buf); p[j].value = h)		p = REALLOC(p, struct line, (++j+3));	len[i] = j;	file[i] = p;	input[i] = bp;			/*fix*/	if (i == 0) {			/*fix*/		file1 = arg;		firstchange = 0;	}	else		file2 = arg;	return bp;} static intsquishspace(char *buf){	char *p, *q;	int space; 	for (space = 0, q = p = buf; *q; q++) {		if (isspace(*q)) {			space++;			continue;		}		if (space && bflag == 1) {			*p++ = ' ';			space = 0;		}		*p++ = *q;	}	*p = 0;	return p - buf;} /* * need to fix up for unexpected EOF's */voidcheck(Biobuf *bf, Biobuf *bt){	int f, t, flen, tlen;	char fbuf[MAXLINELEN], tbuf[MAXLINELEN]; 	ixold[0] = ixnew[0] = 0;	for (f = t = 1; f < len[0]; f++) {		flen = readline(bf, fbuf);		ixold[f] = ixold[f-1] + flen + 1;		/* ftell(bf) */		if (J[f] == 0)			continue;		do {			tlen = readline(bt, tbuf);			ixnew[t] = ixnew[t-1] + tlen + 1;	/* ftell(bt) */		} while (t++ < J[f]);		if (bflag) {			flen = squishspace(fbuf);			tlen = squishspace(tbuf);		}		if (flen != tlen || strcmp(fbuf, tbuf))			J[f] = 0;	}	while (t < len[1]) {		tlen = readline(bt, tbuf);		ixnew[t] = ixnew[t-1] + tlen + 1;	/* fseek(bt) */		t++;	}} static voidrange(int a, int b, char *separator){	Bprint(&stdout, "%d", a > b ? b: a);	if (a < b)		Bprint(&stdout, "%s%d", separator, b);} static voidfetch(long *f, int a, int b, Biobuf *bp, char *s){	char buf[MAXLINELEN]; 	Bseek(bp, f[a-1], 0);	while (a++ <= b) {		readline(bp, buf);		Bprint(&stdout, "%s%s\n", s, buf);	}} voidchange(int a, int b, int c, int d){	if (a > b && c > d)		return;	anychange = 1;	if (mflag && firstchange == 0) {		Bprint(&stdout, "diff %s %s\n", file1, file2);		firstchange = 1;	}	if (mode != 'f') {		range(a, b, ",");		Bputc(&stdout, a > b ? 'a': c > d ? 'd': 'c');		if (mode != 'e')			range(c, d, ",");	}	else {		Bputc(&stdout, a > b ? 'a': c > d ? 'd': 'c');		range(a, b, " ");	}	Bputc(&stdout, '\n');	if (mode == 0) {		fetch(ixold, a, b, input[0], "< ");		if (a <= b && c <= d)			Bprint(&stdout, "---\n");	}	fetch(ixnew, c, d, input[1], mode == 0 ? "> ": "");	if (mode != 0 && c <= d)		Bprint(&stdout, ".\n");}