flate

commit 2a4423264be4b26a110c77a07ccd7e108e90c22d
parent d695e2aaa37ee9a3f7b05fe5e23cb3c6fbb7d3e2
Author: nsz <nszabolcs@gmail.com>
Date:   Wed, 15 Jul 2009 23:42:08 +0200

dont finish block until we have a lazy match
Diffstat:
deflate_simple.c
 | 
61
++++++++++++++++++++++++++++++++++---------------------------

1 file changed, 34 insertions(+), 27 deletions(-)
diff --git a/deflate_simple.c b/deflate_simple.c
@@ -244,7 +244,7 @@ static void hufflens(uchar *lens, int *freqs, int nsym, int limit) {
 		}
 }
 
-/* adding n (<= 16) bits to dst */
+/* output n (<= 16) bits */
 static void putbits(State *s, uint bits, int n) {
 	s->bits |= bits << s->nbits;
 	s->nbits += n;
@@ -258,7 +258,6 @@ static void putbits(State *s, uint bits, int n) {
 static int clencodes(int *codes, int *extra, uchar *llen, int nlit, uchar *dlen, int ndist) {
 	int i, c, r, rr;
 	int n = 0;
-/*	int exbits = 0;*/
 
 	for (i = 0; i < nlit; i++)
 		codes[i] = llen[i];
@@ -275,13 +274,11 @@ static int clencodes(int *codes, int *extra, uchar *llen, int nlit, uchar *dlen,
 				codes[n] = 18;
 				extra[n++] = rr - 11;
 				r -= rr;
-/*				exbits += 7;*/
 			}
 			if (r >= 3) {
 				codes[n] = 17;
 				extra[n++] = r - 3;
 				r = 0;
-/*				exbits += 3;*/
 			}
 		}
 		while (r--) {
@@ -291,7 +288,6 @@ static int clencodes(int *codes, int *extra, uchar *llen, int nlit, uchar *dlen,
 				codes[n] = 16;
 				extra[n++] = rr - 3;
 				r -= rr;
-/*				exbits += 2;*/
 			}
 		}
 	}
@@ -325,7 +321,7 @@ static void putblock(State *s, ushort *lcode, uchar *llen, ushort *dcode, uchar 
 	putbits(s, lcode[256], llen[256]);
 }
 
-static void emitblock(State *s, int blocklen) {
+static void deflate_block(State *s, int blocklen) {
 	int cfreq[Nclen];
 	uchar llen[Nlitlen], dlen[Ndist], clen[Nclen];
 	ushort lcode[Nlitlen], dcode[Ndist], ccode[Nclen];
@@ -351,7 +347,7 @@ static void emitblock(State *s, int blocklen) {
 	for (nclen = Nclen; nclen > 4 && clen[clenorder[nclen-1]] == 0; nclen--);
 
 	/* calc size */
-	uncsize = 3 + 4 + 8*blocklen; /* +byte alignment (8-nbits+3)%8 */
+	uncsize = 3 + 4 + 8*blocklen + (16 - 3 - s->nbits)%8; /* byte aligned */
 	fixsize = 3;
 	dynsize = 3 + 5 + 5 + 4;
 	dynsize += 3 * nclen;
@@ -365,6 +361,7 @@ static void emitblock(State *s, int blocklen) {
 		if (c == 18)
 			dynsize += 7;
 	}
+/* TODO: */
 	for (p = s->lzbuf, plit = s->src; p != s->lzp;) {
 		c = *p++;
 		if (c >= LzRunlen) {
@@ -498,19 +495,6 @@ static Match getmatch(State *s, uchar *src, int len) {
 	return m;
 }
 
-static void newblock(State *s, uchar *src) {
-	int i;
-
-	s->src = src;
-	s->lzp = s->lzbuf;
-	s->runlen = 0;
-	for (i = 0; i < Nlitlen; i++)
-		s->lfreq[i] = 0;
-	for (i = 0; i < Ndist; i++)
-		s->dfreq[i] = 0;
-	s->lfreq[256]++; /* EOB */
-}
-
 static void lzinit(State *s) {
 	int i;
 
@@ -536,19 +520,41 @@ static void lzinit(State *s) {
 	s->lastblock = 0;
 }
 
+static void newblock(State *s) {
+	int i;
+
+	s->lzp = s->lzbuf;
+	s->runlen = 0;
+	for (i = 0; i < Nlitlen; i++)
+		s->lfreq[i] = 0;
+	for (i = 0; i < Ndist; i++)
+		s->dfreq[i] = 0;
+	s->lfreq[256]++; /* EOB */
+}
+
 int deflate(uchar *src, int len, uchar *dst) {
 	State s;
 	int step;
 	int hash;
 	Match m;
 	Match prevm = {0, 0};
-	uchar prevc = '\0';
+	uchar prevc = 0;
 
 	lzinit(&s);
-	newblock(&s, src);
+	newblock(&s);
 	s.dst = dst;
+	s.src = src;
 	while (len > 0) {
 		m = getmatch(&s, src, len);
+/*
+		if (m.len >= MinMatch) {
+			recordmatch(&s, m);
+			step = m.len;
+		} else {
+			recordlit(&s, *src);
+			step = 1;
+		}
+*/
 		if (m.len >= MinMatch)
 			if (m.len <= prevm.len) {
 				recordmatch(&s, prevm);
@@ -570,6 +576,7 @@ int deflate(uchar *src, int len, uchar *dst) {
 				recordlit(&s, *src);
 				step = 1;
 			}
+
 		while (step > 0) {
 			if (len >= MinMatch) {
 				hash = gethash(src);
@@ -581,18 +588,18 @@ int deflate(uchar *src, int len, uchar *dst) {
 			len--;
 			step--;
 		}
-		if (src - s.src > 1 << 15) {
+		if (prevm.len == 0 && src - s.src > 1<<15) {
 			if (s.runlen)
 				*s.lzp++ = s.runlen | LzRunlen;
-			emitblock(&s, src - s.src);
-			newblock(&s, src);
+			deflate_block(&s, src - s.src);
+			newblock(&s);
+			s.src = src;
 		}
 	}
-
 	if (s.runlen)
 		*s.lzp++ = s.runlen | LzRunlen;
 	s.lastblock = 1;
-	emitblock(&s, src - s.src);
+	deflate_block(&s, src - s.src);
 	putbits(&s, 0, 7);
 	return s.dst - dst;
 }