flate

commit e6de1ab18b761e304518e0b3bb50c39b8ad83452
parent 62cef5aaa820f7de3a20d9c7f641f2326047ad4e
Author: nsz@tpx <unknown>
Date:   Sun,  9 Aug 2009 15:25:43 +0200

deflate optimization: do while(), s/ushort/int/
Diffstat:
Makefile
 | 
18
+++++++++---------
deflate.c
 | 
42
+++++++++++++++++++++---------------------

2 files changed, 30 insertions(+), 30 deletions(-)
diff --git a/Makefile b/Makefile
@@ -1,5 +1,5 @@
-CFLAGS=-g -Wall -ansi -pedantic
-#CFLAGS=-O3 -Wall -ansi -pedantic
+#CFLAGS=-g -Wall -ansi -pedantic
+CFLAGS=-O3 -Wall -ansi -pedantic
 LDFLAGS=
 SRC=inflate.c inflate_simple.c inflate_example.c inflate_callback.c \
     deflate.c deflate_simple.c deflate_example.c
@@ -25,10 +25,10 @@ clean:
 
 prof: profinf profdef
 
-profinf: inflate.c
-	gcc -O3 -fprofile-arcs -ftest-coverage -pg -g -Wall $<
+profinf: inflate_example.c inflate.c
+	gcc -O3 -fprofile-arcs -ftest-coverage -pg -g -Wall $+
 	./a.out <a.dat >/dev/null
-	gcov -b $< >/dev/null
+	gcov -b $+ >/dev/null
 	gprof a.out >$<.gprof
 #	gcc -g -Wall $<
 #	valgrind -v --leak-check=yes ./a.out <a.dat >/dev/null 2>a.valgrind
@@ -36,9 +36,9 @@ profinf: inflate.c
 #	grep alloc a.valgrind
 	rm -f a.out a.valgrind *.gcno *.gcda gmon.out
 
-profdef: deflate.c
-	gcc -O0 -fprofile-arcs -ftest-coverage -pg -g -Wall $<
-	./a.out <a.pdf >/dev/null
-	gcov -b $< >/dev/null
+profdef: deflate_example.c deflate.c
+	gcc -O3 -fprofile-arcs -ftest-coverage -pg -g -Wall $+
+	./a.out <g.tar >/dev/null
+	gcov -b $+ >/dev/null
 	gprof a.out >$<.gprof
 	rm -f a.out *.gcno *.gcda gmon.out
diff --git a/deflate.c b/deflate.c
@@ -500,15 +500,15 @@ static ushort addtochain(State *s, ushort pos) {
 	return i;
 }
 
-static Match getmatch(State *s, ushort pos, ushort mpos) {
+static Match getmatch(State *s, int pos, int mpos) {
 	Match m = {0, MinMatch-1};
-	ushort len;
-	ushort maxlen = s->avail < MaxMatch ? s->avail : MaxMatch;
-	ushort limit = pos - MaxDist;
-	ushort chainlen = MaxChainLen;
+	int len;
+	int maxlen = s->avail < MaxMatch ? s->avail : MaxMatch;
+	int limit = pos - MaxDist;
+	int chainlen = MaxChainLen;
 	uchar *q;
 	uchar *p = s->win + pos;
-	uchar *end = p + MaxMatch; /* out of bound if avail < MaxMatch */
+	uchar *end = p + MaxMatch;
 
 	do {
 		q = s->win + mpos;
@@ -516,11 +516,12 @@ static Match getmatch(State *s, ushort pos, ushort mpos) {
 		if (q[m.len] != p[m.len] || q[0] != p[0])
 			continue;
 		/* 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);
+		/* only small gain over while (++p != end && *++q == *p); */
+		do; 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);
 		p -= len;
 		if (len > m.len) {
@@ -548,8 +549,7 @@ static void newblock(State *s) {
 }
 
 static int fillwin(State *s) {
-	int n;
-	int need, have;
+	int n, k;
 
 	if (s->pos >= 2*MaxDist) {
 		/* shift win */
@@ -563,15 +563,15 @@ static int fillwin(State *s) {
 	}
 	if (s->avail < MaxMatch) {
 		/* fill win */
-		need = WinSize - s->pos - s->avail;
-		have = s->srcend - s->src;
-		if (have > need)
-			have = need;
-		if (have == 0)
+		n = WinSize - s->pos - s->avail;
+		k = s->srcend - s->src;
+		if (k > n)
+			k = n;
+		if (k == 0)
 			return FlateIn;
-		memcpy(s->win + s->pos + s->avail, s->src, have);
-		s->src += have;
-		s->avail += have;
+		memcpy(s->win + s->pos + s->avail, s->src, k);
+		s->src += k;
+		s->avail += k;
 	}
 	return FlateOk;
 }