flate

commit cb7adc2901ab8582b02d3a77e9139c3fb70c6a49
parent 144b062df1777a3fe05588e5c62d5e4aed9f4c13
Author: nsz@tpx <unknown>
Date:   Fri,  7 Aug 2009 10:50:26 +0200

deflate match: let it overflow
Diffstat:
deflate.c
 | 
16
+++++++---------
flate.h
 | 
2
+-

2 files changed, 8 insertions(+), 10 deletions(-)
diff --git a/deflate.c b/deflate.c
@@ -509,30 +509,28 @@ static Match getmatch(State *s, ushort pos, ushort mpos) {
 	ushort chainlen = MaxChainLen;
 	uchar *q;
 	uchar *p = s->win + pos;
-	uchar *end = p + maxlen;
+	uchar *end = p + MaxMatch; /* out of bound if avail < MaxMatch */
 
 	do {
 		q = s->win + mpos;
 		/* at least m.len+1 long */
 		if (q[m.len] != p[m.len] || q[0] != p[0])
 			continue;
-		/* loop unroll: MaxMatch % 10 == 8 */
-/* TODO: if maxlen == MaxMatch
+		/* loop unroll: MaxMatch % 10 == 8, overflow if avail < MaxMatch */
 		while (*++q == *++p && *++q == *++p
 		    && *++q == *++p && *++q == *++p
 		    && *++q == *++p && *++q == *++p
 		    && *++q == *++p && ++p != end && *++q == *p
 		    && *++q == *++p && *++q == *++p);
 		len = MaxMatch - (end - p);
-*/
-		while (++p != end && *++q == *p);
-		len = maxlen - (end - p);
 		p -= len;
 		if (len > m.len) {
 			m.dist = pos - mpos;
-			m.len = len;
-			if (len == maxlen)
+			if (len >= maxlen) {
+				m.len = maxlen;
 				return m;
+			}
+			m.len = len;
 		}
 	} while ((mpos = s->chain[mpos % WinSize]) > limit && --chainlen);
 	if (m.len < MinMatch || (m.len == MinMatch && m.dist > BigDist))
@@ -577,7 +575,7 @@ static int fillwin(State *s) {
 static int deflate_state(State *s) {
 	Match m;
 	Match prevm = {0, 0};
-	int pos = s->pos;
+	int pos;
 	int head;
 
 	/* messy.. */
diff --git a/flate.h b/flate.h
@@ -7,7 +7,7 @@ enum {
 	FlateOk  = 0,
 	FlateErr = -1,
 	FlateIn  = -2,
-	FlateOut = -3,
+	FlateOut = -3
 };
 /* TODO inflate assume Flate* < 0 */