add libflate

src/libflate/deflatezlib.c

@@ -0,0 +1,60 @@
+#include <u.h>
+#include <libc.h>
+#include <flate.h>
+#include "zlib.h"
+
+typedef struct ZRead	ZRead;
+
+struct ZRead
+{
+	ulong	adler;
+	void	*rr;
+	int	(*r)(void*, void*, int);
+};
+
+static int
+zlread(void *vzr, void *buf, int n)
+{
+	ZRead *zr;
+
+	zr = vzr;
+	n = (*zr->r)(zr->rr, buf, n);
+	if(n <= 0)
+		return n;
+	zr->adler = adler32(zr->adler, buf, n);
+	return n;
+}
+
+int
+deflatezlib(void *wr, int (*w)(void*, void*, int), void *rr, int (*r)(void*, void*, int), int level, int debug)
+{
+	ZRead zr;
+	uchar buf[4];
+	int ok;
+
+	buf[0] = ZlibDeflate | ZlibWin32k;
+
+	/* bogus zlib encoding of compression level */
+	buf[1] = ((level > 2) + (level > 5) + (level > 8)) << 6;
+
+	/* header check field */
+	buf[1] |= 31 - ((buf[0] << 8) | buf[1]) % 31;
+	if((*w)(wr, buf, 2) != 2)
+		return FlateOutputFail;
+
+	zr.rr = rr;
+	zr.r = r;
+	zr.adler = 1;
+	ok = deflate(wr, w, &zr, zlread, level, debug);
+	if(ok != FlateOk)
+		return ok;
+
+	buf[0] = zr.adler >> 24;
+	buf[1] = zr.adler >> 16;
+	buf[2] = zr.adler >> 8;
+	buf[3] = zr.adler;
+	if((*w)(wr, buf, 4) != 4)
+		return FlateOutputFail;
+
+	return FlateOk;
+}