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faster deltas: remove sha1sum

The cryptographic hash wasn't helping: may as well just
compare the bytes directly. Our block size is small, and
we don't need to minimize network bandwidth.

--- a/delta.c

+++ b/delta.c

@@ -18,7 +18,6 @@

 	int	len;

 	int	off;

 	u64int	rhash;

-	Hash	chash;

 };

 struct Dtab {

@@ -51,7 +50,6 @@

 	dt->b[probe].off = off;

 	dt->b[probe].rhash = rh;

 	dt->nb++;

-	sha1(buf, len, dt->b[probe].chash.h, nil);

 	if(dt->sz < 2*dt->nb){

 		sz = dt->sz;

 		db = dt->b;

@@ -95,11 +93,11 @@

 }

 static int

-sameblk(Dblock *b, Hash h, uchar *s, uchar *e)

+sameblk(Dblock *b, uchar *s, uchar *e)

 {

 	if(b->len != e - s)

 		return 0;

-	return hasheq(&b->chash, &h) && memcmp(b->buf, s, b->len) == 0;

+	return memcmp(b->buf, s, b->len) == 0;

 }

 static int

@@ -122,7 +120,6 @@

 Delta*

 deltify(void *targ, int ntarg, void *base, int nbase, int *pnd)

 {

-	Hash h;

 	Dblock *k;

 	Delta *d;

 	Dtab dt;

@@ -134,9 +131,9 @@

 	tp = targ;

 	s = bp;

 	e = bp;

-	dt.b = emalloc(16*sizeof(Dblock));

 	dt.nb = 0;

-	dt.sz = 16;

+	dt.sz = 128;

+	dt.b = emalloc(dt.sz*sizeof(Dblock));

 	while(e != bp + nbase){

 		e += nextblk(s, bp + nbase, &rh);

 		addblk(&dt, s, e - s, s - bp, rh);

@@ -151,8 +148,7 @@

 	e += nextblk(s, tp + ntarg, &rh);

 	while(1){

 		if((k = findrough(&dt, rh)) != nil){

-			sha1(s, e - s, h.h, nil);

-			if(sameblk(k, h, s, e)){

+			if(sameblk(k, s, e)){

 				nb = k->len;

 				eb = k->buf + k->len;

 				/* stretch the block as far as it'll go */