Skip to content

Instantly share code, notes, and snippets.

@tiqwab

tiqwab/diff.c Secret

Last active December 11, 2022 02:09
Show Gist options
  • Save tiqwab/7cb46ad3d8c44dd9eccf030bc14d643d to your computer and use it in GitHub Desktop.
Save tiqwab/7cb46ad3d8c44dd9eccf030bc14d643d to your computer and use it in GitHub Desktop.
#
/* 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>
#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <signal.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.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 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*/
void done()
{
unlink(tempfile);
exit(status);
}
void mesg(char *s, char *t)
{
fprintf(stderr,"diff: %s%s\n",s,t);
}
void noroom()
{
mesg("files too big, try -h\n",empty);
done();
}
char * talloc(int n)
{
char *p;
p = (char *) malloc((unsigned)n);
if(p!=NULL)
return p;
noroom();
}
char * ralloc(char *p, int n) /*compacting reallocation */
{
char *q;
free(p);
free(dummy);
dummy = malloc(1);
q = realloc(p, (unsigned)n);
if(q==NULL)
noroom();
return q;
}
/* hashing has the effect of
* arranging line in 7-bit bytes and then
* summing 1-s complement in 16-bit hunks
*/
short readhash(FILE *f)
{
long sum;
unsigned int shift;
int space;
int 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);
}
void sort(struct line *a, int n) /*shellsort CACM #201*/
{
struct line w;
int j,m;
struct line *ai;
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;
}
}
}
}
void unsort(struct line *f, int l, int *b)
{
int *a;
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);
}
void filename(char **pa1, char **pa2)
{
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);
}
}
void prepare(int i, char *arg)
{
struct line *p;
int 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]);
}
void prune()
{
int 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;
}
}
void equiv(struct line *a, int n, struct line *b, int m, int *c)
{
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;
}
int newcand(int x, int y, int pred)
{
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;
}
int search(int *c, int k, int y)
{
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;
}
int stone(int *a, int n, int *b, int *c)
{
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;
}
void unravel(int p)
{
int i;
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;
}
int skipline(int f)
{
int i;
for(i=1;getc(input[f])!='\n';i++) ;
return i;
}
/* 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 */
void check(char **argv)
{
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);
*/
}
void range(int a, int b, char *separator)
{
printf("%d", a>b?b:a);
if(a<b) {
printf("%s%d", separator, b);
}
}
void fetch(long *f, int a, int b, FILE *lb, char *s)
{
int i, j;
int nc;
for(i=a;i<=b;i++) {
fseek(lb,f[i-1],0);
nc = f[i]-f[i-1];
prints(s);
for(j=0;j<nc;j++)
putchar(getc(lb));
}
}
void change(int a, int b, int c, int d)
{
if(a>b&&c>d) return;
anychange = 1;
if(opt!=1) {
range(a,b,",");
putchar(a>b?'a':c>d?'d':'c');
if(opt!=-1) range(c,d,",");
} else {
putchar(a>b?'a':c>d?'d':'c');
range(a,b," ");
}
putchar('\n');
if(opt==0) {
fetch(ixold,a,b,input[0],"< ");
if(a<=b&&c<=d) prints("---\n");
}
fetch(ixnew,c,d,input[1],opt==0?"> ":empty);
if(opt!=0&&c<=d) prints(".\n");
}
void output(char **argv)
{
int m;
int i0, i1, j1;
int j0;
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]);
}
void main(int argc, char **argv)
{
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':
opt = -1;
break;
case 'f':
opt = 1;
break;
case 'b':
bflag = 1;
break;
case 'h':
execv("/usr/lib/diffh",args);
mesg("cannot find diffh",empty);
done();
}
}
}
if(argc!=3) {
mesg("arg count",empty);
done();
}
dummy = malloc(1);
filename(&argv[1], &argv[2]);
filename(&argv[2], &argv[1]);
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();
}
@tiqwab
Copy link
Author

tiqwab commented Dec 1, 2022

Add some fix to run on Linux.

/*	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>
#include <ctype.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <signal.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.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 status = 2;
int anychange = 0;
char *empty = "";
int bflag;

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

void done()
{
	// unlink(tempfile);
	exit(status);
}

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

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

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

char * ralloc(char *p, int n)	/*compacting reallocation */
{
	char *q;
	// free(p);
	free(dummy);
	dummy = malloc(1);
	q = realloc(p, (unsigned)n);
	if(q==NULL)
		noroom();
	return q;
}

/* hashing has the effect of
 * arranging line in 7-bit bytes and then
 * summing 1-s complement in 16-bit hunks 
*/
short readhash(FILE *f)
{
	long sum;
	unsigned int shift;
	int space;
	int 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);
}

void sort(struct line *a, int n)	/*shellsort CACM #201*/
{
	struct line w;
	int j,m;
	struct line *ai;
	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;
			}
		}
	}
}

void unsort(struct line *f, int l, int *b)
{
	int *a;
	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);
}

void filename(char **pa1, char **pa2)
{
	char *a1, *b1, *a2;
	char buf[512];
	struct stat stbuf;
	int i;
    FILE *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) {
		signal(SIGHUP,done);
		signal(SIGINT,done);
		signal(SIGPIPE,done);
		signal(SIGTERM,done);
		f = tmpfile();
		// *pa1 = tempfile = mkstemp("/tmp/dXXXXX");
		// if((f=creat(tempfile,0600)) < 0) {
		// 	mesg("cannot create ",tempfile);
		// 	done();
		// }
		while((i=read(0,buf,512))>0)
            fwrite(buf, 1, i, f);
			// write(f,buf,i);
		// close(f);
	}
}

void prepare(int i, char *arg)
{
	struct line *p;
	int 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]);
}

void prune()
{
	int 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;
	}
}

void equiv(struct line *a, int n, struct line *b, int m, int *c)
{
	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;
}

int newcand(int x, int y, int pred)
{
	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;
}

int search(int *c, int k,  int y)
{
	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;
}

int stone(int *a, int n, int *b, int *c)
{
	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;
}

void unravel(int p)
{
	int i;
	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;
}

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

/* 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 */

void check(char **argv)
{
	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);
*/
}

void range(int a, int b, char *separator)
{
	printf("%d", a>b?b:a);
	if(a<b) {
		printf("%s%d", separator, b);
	}
}

void fetch(long *f, int a, int b, FILE *lb, char *s)
{
	int i, j;
	int nc;
	for(i=a;i<=b;i++) {
		fseek(lb,f[i-1],0);
		nc = f[i]-f[i-1];
		prints(s);
		for(j=0;j<nc;j++)
			putchar(getc(lb));
	}
}

void change(int a, int b, int c, int d)
{
	if(a>b&&c>d) return;
	anychange = 1;
	if(opt!=1) {
		range(a,b,",");
		putchar(a>b?'a':c>d?'d':'c');
		if(opt!=-1) range(c,d,",");
	} else {
		putchar(a>b?'a':c>d?'d':'c');
		range(a,b," ");
	}
	putchar('\n');
	if(opt==0) {
		fetch(ixold,a,b,input[0],"< ");
		if(a<=b&&c<=d) prints("---\n");
	}
	fetch(ixnew,c,d,input[1],opt==0?"> ":empty);
	if(opt!=0&&c<=d) prints(".\n");
}

void output(char **argv)
{
	int m;
	int i0, i1, j1;
	int j0;
	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]);
}

void main(int argc, char **argv)
{
	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':
				opt = -1;
				break;
			case 'f':
				opt = 1;
				break;
			case 'b':
				bflag = 1;
				break;
			case 'h':
				execv("/usr/lib/diffh",args);
				mesg("cannot find diffh",empty);
				done();
			}
		}
	}
	if(argc!=3) {
		mesg("arg count",empty);
		done();
	}
	dummy = malloc(1);

	filename(&argv[1], &argv[2]);
	filename(&argv[2], &argv[1]);
	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();
}

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment