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ncsldiff.c

by Michael L Powell last modified 2007-01-26 03:24

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/*

 *      Copyright (c) 1984 AT&T
 *      All Rights Reserved

 *      THIS IS UNPUBLISHED PROPRIETARY SOURCE 
 *      CODE OF AT&T.
 *      The copyright notice above does not 
 *      evidence any actual or intended
 *      publication of such source code.

 */
/**
ncsldiff - report number of changed source lines in a file

Synopsis:	ncsldiff  oldfile  newfile

Compares the two files,
and reports on the standard output the number of lines in the
current file, lines in the old file, the difference of the two,
the number of deleted or changed lines, the number of new or changed lines,
and the number of unchanged lines.

The changes from diff(1) are: modifying output() to report counts
instead of printing changed lines.  Also e, f, and h options deleted.
A c option was added to suppress printing of headers.
NOTE: IBM version compiled with -DIBM370 does not have capability
to specify directories in place of file names and does not
allow input from a terminal.

ncsldiff.c 1.2 of 10/16/82 this modification by G. Patton
*/

static char	*sccs = "@(#)ncsldiff.c	1.2";

/*	diff - differential file comparison
*
*	Uses an algorithm due to Harold Stone, which finds
*	a pair of longest identical subsequences in the two
*	files.
*
*	The major goal is to generate the match vector J.
*	J[i] is the index of the line in file1 corresponding
*	to line i file0. J[i] = 0 if there is no
*	such line in file1.
*
*	Lines are hashed so as to work in core. All potential
*	matches are located by sorting the lines of each file
*	on the hash (called value_____). In particular, this
*	collects the equivalence classes in file1 together.
*	Subroutine equiv____  replaces the value of each line in
*	file0 by the index of the first element of its 
*	matching equivalence in (the reordered) file1.
*	To save space equiv_____ squeezes file1 into a single
*	array member______ in which the equivalence classes
*	are simply concatenated, except that their first
*	members are flagged by changing sign.
*
*	Next the indices that point into member______ are unsorted_______   into
*	array class_____ according to the original order of file0.
*
*	The cleverness lies in routine stone______. This marches
*	through the lines of file0, developing a vector klist_____
*	of "k-candidates". At step i a k-candidate is a matched
*	pair of lines x,y (x in file0 y in file1) such that
*	there is a common subsequence of lenght k
*	between the first i lines of file0 and the first y 
*	lines of file1, but there is no such subsequence for
*	any smaller y. x is the earliest possible mate to y
*	that occurs in such a subsequence.
*
*	Whenever any of the members of the equivalence class of
*	lines in file1 matable to a line in file0 has serial number 
*	less than the y of some k-candidate, that k-candidate 
*	with the smallest such y is replaced. The new 
*	k-candidate is chained (via pred____) to the current
*	k-1 candidate so that the actual subsequence can
*	be recovered. When a member has serial number greater
*	that the y of all k-candidates, the klist is extended.
*	At the end, the longest subsequence is pulled out
*	and placed in the array J by unravel_______.
*
*	With J in hand, the matches there recorded are
*	check_____ed against reality to assure that no spurious
*	matches have crept in due to hashing. If they have,
*	they are broken, and "jackpot " is recorded--a harmless
*	matter except that a true match for a spuriously
*	mated line may now be unnecessarily reported as a change.
*
*	Much of the complexity of the program comes simply
*	from trying to minimize core utilization and
*	maximize the range of doable problems by dynamically
*	allocating what is needed and reusing what is not.
*	The core requirements for problems larger than somewhat
*	are (in words) 2*length(file0) + length(file1) +
*	3*(number of k-candidates installed),  typically about
*	6n words for files of length n. 
*/
#include <stdio.h>
#if IBM370
/* signal and stat are not used in the IBM version.  sys/types.h is
  used by sys/stat.h and is not required.    
  ctype.h has been included in stdio.h on the ibm machine.  */
#else
#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>
#endif
#include <signal.h>
#define	prints(s)	fputs(s,stdout)

#define HALFLONG 16
#define low(x)	(x&((1L<<HALFLONG)-1))
#define high(x)	(x>>HALFLONG)
FILE *input[2];
FILE *fopen();

struct cand {
	int x;
	int y;
	int pred;
} cand;
struct line {
	int serial;
	int value;
} *file[2], line;
int len[2];
struct 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*/
struct cand *clist;	/* merely a free storage pot for candidates */
int clen = 0;
int *J;		/*will be overlaid on class*/
long *ixold;	/*will be overlaid on klist*/
long *ixnew;	/*will be overlaid on file[1]*/
int opt;	/* -1,0,1 = -e,normal,-f */
int ncom = 0;   /* -1,0 = -c,normal = noheadings,headings */
int status = 2;
int anychange = 0;
char *empty = "";
int bflag;

char *tempfile;	/*used when comparing against std input*/
char *mktemp();
char *dummy;	/*used in resetting storage search ptr*/

extern char *malloc();

void done()
{
#if IBM370
/* unlink of tempfile not done for IBM implementation */
#else
	if(tempfile)
		unlink(tempfile);
#endif
	exit(status);
}

char *talloc(n)
{
	register char *p;
	p = malloc((unsigned)n);
	if(p!=NULL)
		return(p);
	noroom();
}

char *ralloc(p,n)	/*compacting reallocation */
char *p;
{
	register char *q;
	char *realloc();
#if IBM370
/* freeing memory is not done in ibm implementation */
#else
	free(p);
	free(dummy);
	dummy = malloc(1);
#endif
	q = realloc(p, (unsigned)n);
	if(q==NULL)
		noroom();
	return(q);
}

noroom()
{
	mesg("files too big, try -h\n",empty);
	done();
}

sort(a,n)	/*shellsort CACM #201*/
struct line *a;
{
	struct line w;
	register int j,m;
	struct line *ai;
	register struct line *aim;
	int k;
	for(j=1;j<=n;j*= 2)
		m = 2*j - 1;
	for(m/=2;m!=0;m/=2) {
		k = n-m;
		for(j=1;j<=k;j++) {
			for(ai = &a[j]; ai > a; ai -= m) {
				aim = &ai[m];
				if(aim < ai)
					break;	/*wraparound*/
				if(aim->value > ai[0].value ||
				   aim->value == ai[0].value &&
				   aim->serial > ai[0].serial)
					break;
				w.value = ai[0].value;
				ai[0].value = aim->value;
				aim->value = w.value;
				w.serial = ai[0].serial;
				ai[0].serial = aim->serial;
				aim->serial = w.serial;
			}
		}
	}
}

unsort(f, l, b)
struct line *f;
int *b;
{
	register int *a;
	register int i;
	a = (int *)talloc((l+1)*sizeof(int));
	for(i=1;i<=l;i++)
		a[f[i].serial] = f[i].value;
	for(i=1;i<=l;i++)
		b[i] = a[i];
	free((char *)a);
}

#if IBM370
/* the IBM implementation does not allow only specifying directories */
#else
filename(pa1, pa2)
char **pa1, **pa2;
{
	register char *a1, *b1, *a2;
	char buf[512];
	struct stat stbuf;
	int i, f;
	a1 = *pa1;
	a2 = *pa2;
	if(stat(a1,&stbuf)!=-1 && ((stbuf.st_mode&S_IFMT)==S_IFDIR)) {
		b1 = *pa1 = malloc(100);
		while(*b1++ = *a1++) ;
		b1[-1] = '/';
		a1 = b1;
		while(*a1++ = *a2++)
			if(*a2 && *a2!='/' && a2[-1]=='/')
				a1 = b1;
	}
	else if(a1[0]=='-'&&a1[1]==0&&tempfile==0) {
		signal(SIGHUP,done);
		signal(SIGINT,done);
		signal(SIGPIPE,done);
		signal(SIGTERM,done);
		*pa1 = tempfile = mktemp("/tmp/dXXXXX");
		if((f=creat(tempfile,0600)) < 0) {
			mesg("cannot create ",tempfile);
			done();
		}
		while((i=read(0,buf,512))>0)
			write(f,buf,i);
		close(f);
	}
}
#endif

prepare(i, arg)
char *arg;
{
	register struct line *p;
	register j,h;
	if((input[i] = fopen(arg,"r")) == NULL){
		mesg("cannot open ", arg);
		done();
	}
	p = (struct line *)talloc(3*sizeof(line));
	for(j=0; h=readhash(input[i]);) {
		p = (struct line *)ralloc((char *)p,(++j+3)*sizeof(line));
		p[j].value = h;
	}
	len[i] = j;
	file[i] = p;
	fclose(input[i]);
}

prune()
{
	register i,j;
	for(pref=0;pref<len[0]&&pref<len[1]&&
		file[0][pref+1].value==file[1][pref+1].value;
		pref++ ) ;
	for(suff=0;suff<len[0]-pref&&suff<len[1]-pref&&
		file[0][len[0]-suff].value==file[1][len[1]-suff].value;
		suff++) ;
	for(j=0;j<2;j++) {
		sfile[j] = file[j]+pref;
		slen[j] = len[j]-pref-suff;
		for(i=0;i<=slen[j];i++)
			sfile[j][i].serial = i;
	}
}

equiv(a,n,b,m,c)
struct line *a, *b;
int *c;
{
	register int i, j;
	i = j = 1;
	while(i<=n && j<=m) {
		if(a[i].value <b[j].value)
			a[i++].value = 0;
		else if(a[i].value == b[j].value)
			a[i++].value = j;
		else
			j++;
	}
	while(i <= n)
		a[i++].value = 0;
	b[m+1].value = 0;
	j = 0;
	while(++j <= m) {
		c[j] = -b[j].serial;
		while(b[j+1].value == b[j].value) {
			j++;
			c[j] = b[j].serial;
		}
	}
	c[j] = -1;
}

main(argc, argv)
char **argv;
{
	register int k;
	char **args;

	args = argv;
	if(argc>3 && *argv[1]=='-') {
		argc--;
		argv++;
		for(k=1;argv[0][k];k++) {
			switch(argv[0][k]) {
			case 'e':
				mesg("e option invalid",empty);
				done();
			case 'f':
				mesg("f option invalid",empty);
				done();
			case 'b':
				bflag = 1;
				break;
			case 'h':
				mesg("h option invalid",empty);
				done();
			case 'c':
				ncom = -1;  /* no headings */
				break;
			}
		}
	}
	if(argc!=3) {
		mesg("arg count",empty);
		done();
	}
	dummy = malloc(1);

#if IBM370
/* the IBM implementation does not allow only specifying directories
   or reading input from a terminal */
#else
	filename(&argv[1], &argv[2]);
	filename(&argv[2], &argv[1]);
#endif
	prepare(0, argv[1]);
	prepare(1, argv[2]);
	prune();
	sort(sfile[0],slen[0]);
	sort(sfile[1],slen[1]);

	member = (int *)file[1];
	equiv(sfile[0], slen[0], sfile[1], slen[1], member);
	member = (int *)ralloc((char *)member,(slen[1]+2)*sizeof(int));

	class = (int *)file[0];
	unsort(sfile[0], slen[0], class);
	class = (int *)ralloc((char *)class,(slen[0]+2)*sizeof(int));

	klist = (int *)talloc((slen[0]+2)*sizeof(int));
	clist = (struct cand *)talloc(sizeof(cand));
	k = stone(class, slen[0], member, klist);
	free((char *)member);
	free((char *)class);

	J = (int *)talloc((len[0]+2)*sizeof(int));
	unravel(klist[k]);
	free((char *)clist);
	free((char *)klist);

	ixold = (long *)talloc((len[0]+2)*sizeof(long));
	ixnew = (long *)talloc((len[1]+2)*sizeof(long));
	check(argv);
	output(argv);
	status = anychange;
	done();
}

stone(a,n,b,c)
int *a;
int *b;
int *c;
{
	register int i, k,y;
	int j, l;
	int oldc, tc;
	int oldl;
	k = 0;
	c[0] = newcand(0,0,0);
	for(i=1; i<=n; i++) {
		j = a[i];
		if(j==0)
			continue;
		y = -b[j];
		oldl = 0;
		oldc = c[0];
		do {
			if(y <= clist[oldc].y)
				continue;
			l = search(c, k, y);
			if(l!=oldl+1)
				oldc = c[l-1];
			if(l<=k) {
				if(clist[c[l]].y <= y)
					continue;
				tc = c[l];
				c[l] = newcand(i,y,oldc);
				oldc = tc;
				oldl = l;
			} else {
				c[l] = newcand(i,y,oldc);
				k++;
				break;
			}
		} while((y=b[++j]) > 0);
	}
	return(k);
}

newcand(x,y,pred)
{
	register struct cand *q;
	clist = (struct cand *)ralloc((char *)clist,++clen*sizeof(cand));
	q = clist + clen -1;
	q->x = x;
	q->y = y;
	q->pred = pred;
	return(clen-1);
}

search(c, k, y)
int *c;
{
	register int i, j, l;
	int t;
	if(clist[c[k]].y<y)	/*quick look for typical case*/
		return(k+1);
	i = 0;
	j = k+1;
	while((l=(i+j)/2) > i) {
		t = clist[c[l]].y;
		if(t > y)
			j = l;
		else if(t < y)
			i = l;
		else
			return(l);
	}
	return(l+1);
}

unravel(p)
{
	register int i;
	register struct cand *q;
	for(i=0; i<=len[0]; i++)
		J[i] =	i<=pref ? i:
			i>len[0]-suff ? i+len[1]-len[0]:
			0;
	for(q=clist+p;q->y!=0;q=clist+q->pred)
		J[q->x+pref] = q->y+pref;
}

/* check does double duty:
1.  ferret out any fortuitous correspondences due
to confounding by hashing (which result in "jackpot")
2.  collect random access indexes to the two files */

check(argv)
char **argv;
{
	register int i, j;
	int jackpot;
	long ctold, ctnew;
	char c,d;
	input[0] = fopen(argv[1],"r");
	input[1] = fopen(argv[2],"r");
	j = 1;
	ixold[0] = ixnew[0] = 0;
	jackpot = 0;
	ctold = ctnew = 0;
	for(i=1;i<=len[0];i++) {
		if(J[i]==0) {
			ixold[i] = ctold += skipline(0);
			continue;
		}
		while(j<J[i]) {
			ixnew[j] = ctnew += skipline(1);
			j++;
		}
		for(;;) {
			c = getc(input[0]);
			d = getc(input[1]);
			ctold++;
			ctnew++;
			if(bflag && isspace(c) && isspace(d)) {
				do {
					if(c=='\n') break;
					ctold++;
				} while(isspace(c=getc(input[0])));
				do {
					if(d=='\n') break;
					ctnew++;
				} while(isspace(d=getc(input[1])));
			}
			if(c!=d) {
				jackpot++;
				J[i] = 0;
				if(c!='\n')
					ctold += skipline(0);
				if(d!='\n')
					ctnew += skipline(1);
				break;
			}
			if(c=='\n')
				break;
		}
		ixold[i] = ctold;
		ixnew[j] = ctnew;
		j++;
	}
	for(;j<=len[1];j++) {
		ixnew[j] = ctnew += skipline(1);
	}
	fclose(input[0]);
	fclose(input[1]);
/*
	if(jackpot)
		mesg("jackpot",empty);
*/
}

skipline(f)
{
	register i;
	for(i=1;getc(input[f])!='\n';i++) ;
	return(i);
}

int	Added, Deleted;

output(argv)
char **argv;
{
	int m;
	register int i0, i1, j1;
	int j0;
	int unchanged;
	int Delta;

	input[0] = fopen(argv[1],"r");
	input[1] = fopen(argv[2],"r");
	m = len[0];
	J[0] = 0;
	J[m+1] = len[1]+1;
	if(opt!=-1) for(i0=1;i0<=m;i0=i1+1) {
		while(i0<=m&&J[i0]==J[i0-1]+1) i0++;
		j0 = J[i0-1]+1;
		i1 = i0-1;
		while(i1<m&&J[i1+1]==0) i1++;
		j1 = J[i1+1]-1;
		J[i1] = j1;
		change(i0,i1,j0,j1);
	} else for(i0=m;i0>=1;i0=i1-1) {
		while(i0>=1&&J[i0]==J[i0+1]-1&&J[i0]!=0) i0--;
		j0 = J[i0+1]-1;
		i1 = i0+1;
		while(i1>1&&J[i1-1]==0) i1--;
		j1 = J[i1-1]+1;
		J[i1] = j1;
		change(i1,i0,j1,j0);
	}
	if(m==0)
		change(1,0,1,len[1]);
	unchanged = len[0] - Deleted;
	Delta = len[1] - len[0];
	if( ncom == 0 ) {
		printf("Count	Count	Size	Del.	New    	\n");
		printf("Curr.	Prev.	Delta	or Chg.	or Chg.	Unchg.\n");
	}
	printf("%-8d%-8d%-8d%-8d%-8d%-8d\n",
		len[1], len[0], Delta, Deleted, Added, unchanged);
}

change(a,b,c,d)
{
	if (a <= b)
		Deleted += b - a + 1;
	if (c <= d)
		Added += d - c + 1;
}



/* hashing has the effect of
 * arranging line in 7-bit bytes and then
 * summing 1-s complement in 16-bit hunks 
*/

readhash(f)
FILE *f;
{
	long sum;
	register unsigned shift;
	register space;
	register t;
	sum = 1;
	space = 0;
	if(!bflag) for(shift=0;(t=getc(f))!='\n';shift+=7) {
		if(t==-1)
			return(0);
		sum += (long)t << (shift%=HALFLONG);
	}
	else for(shift=0;;) {
		switch(t=getc(f)) {
		case -1:
			return(0);
		case '\t':
		case ' ':
			space++;
			continue;
		default:
			if(space) {
				shift += 7;
				space = 0;
			}
			sum += (long)t << (shift%=HALFLONG);
			shift += 7;
			continue;
		case '\n':
			break;
		}
		break;
	}
	sum = low(sum) + high(sum);
	return((short)low(sum) + (short)high(sum));
}

mesg(s,t)
char *s, *t;
{
	fprintf(stderr,"ncsldiff: %s%s\n",s,t);
}
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