shithub: ips

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ipsdiff refactor

--- a/ipsdiff.c

+++ b/ipsdiff.c

@@ -10,7 +10,7 @@

 struct Bin{

 	int fd;

 	long dot;

-	long n, off;

+	long n;

 	uchar data[0xFFFF];

 };

@@ -20,13 +20,10 @@

 static long

 slurp(Bin *b)

 {

-	long n;

-

-	n = readn(b->fd, b->data + b->off, sizeof b->data - b->off);

-	if(n < 0)

+	b->n = readn(b->fd, b->data, sizeof b->data);

+	if(b->n < 0)

 		sysfatal("read: %r");

-	b->n = b->off + n;

-	return n;

+	return b->n;

 }

 static void

@@ -33,17 +30,35 @@

 emit(u32int off, uchar *data, u16int size)

 {

 	uchar buf[3 + 2];

+	uchar buf2[2 + 1];

+	uchar v, *p, *e;

 	if(size == 0)

 		return;

+

 	PUT3(buf, off);

+	if(size > 3 && data[0] == data[1]){

+		p = data + 2;

+		e = data + size;

+		v = data[0];

+		while(p < e && *p == v)

+			p++;

+		PUT2(buf2, size);

+		if(p == e)

+			size = 0;

+		buf2[2] = v;

+	}

+

 	PUT2(buf+3, size);

 	if(dump)

 		fprint(2, "%ud %ud\n", off, size);

 	if(Bwrite(ips, buf, sizeof buf) != sizeof buf)

 		sysfatal("Bwrite: %r");

-	if(Bwrite(ips, data, size) != size)

+

+	if(size == 0 && Bwrite(ips, buf2, sizeof buf2) != sizeof buf2)

 		sysfatal("Bwrite: %r");

+	if(size != 0 && Bwrite(ips, data, size) != size)

+		sysfatal("Bwrite: %r");

 }

 static void

@@ -62,21 +77,22 @@

 	if(a->n != b->n)

 		sysfatal("desync: %ld %ld", a->n, a->n);

-	while(ap < ae && bp < be){

+	for(; ap < ae && bp < be; ap = ac, bp = bc){

 		if(*ap == *bp){

-			ap++;

-			bp++;

+			ac = ap+1;

+			bc = bp+1;

 			continue;

 		}

-		// FIXME: better way of expanding diff context

-		x = 32;

+		x = 2;

 		for(ac = ap, bc = bp; ac < ae && bc < be; ac++, bc++){

-			if(--x <= 0 && *ac == *bc)

+			if(*ac == *bc)

+				x--;

+			else

+				x = 2;

+			if(x == 0)

 				break;

 		}

 		emit(a->dot + (ap - a->data), bp, bc - bp);

-		ap = ac;

-		bp = bc;

 	}

 	a->dot += a->n;

 	b->dot += b->n;