1 files changed, 66 insertions, 0 deletions
diff --git a/circuitpython/lib/uzlib/tinfzlib.c b/circuitpython/lib/uzlib/tinfzlib.c
new file mode 100644
index 0000000..5cb8852
--- /dev/null
+++ b/circuitpython/lib/uzlib/tinfzlib.c
@@ -0,0 +1,66 @@
+/*
+ * uzlib  -  tiny deflate/inflate library (deflate, gzip, zlib)
+ *
+ * Copyright (c) 2003 by Joergen Ibsen / Jibz
+ * All Rights Reserved
+ *
+ * http://www.ibsensoftware.com/
+ *
+ * Copyright (c) 2014-2018 by Paul Sokolovsky
+ *
+ * This software is provided 'as-is', without any express
+ * or implied warranty.  In no event will the authors be
+ * held liable for any damages arising from the use of
+ * this software.
+ *
+ * Permission is granted to anyone to use this software
+ * for any purpose, including commercial applications,
+ * and to alter it and redistribute it freely, subject to
+ * the following restrictions:
+ *
+ * 1. The origin of this software must not be
+ *    misrepresented; you must not claim that you
+ *    wrote the original software. If you use this
+ *    software in a product, an acknowledgment in
+ *    the product documentation would be appreciated
+ *    but is not required.
+ *
+ * 2. Altered source versions must be plainly marked
+ *    as such, and must not be misrepresented as
+ *    being the original software.
+ *
+ * 3. This notice may not be removed or altered from
+ *    any source distribution.
+ */
+
+#include "tinf.h"
+
+int uzlib_zlib_parse_header(TINF_DATA *d)
+{
+   unsigned char cmf, flg;
+
+   /* -- get header bytes -- */
+
+   cmf = uzlib_get_byte(d);
+   flg = uzlib_get_byte(d);
+
+   /* -- check format -- */
+
+   /* check checksum */
+   if ((256*cmf + flg) % 31) return TINF_DATA_ERROR;
+
+   /* check method is deflate */
+   if ((cmf & 0x0f) != 8) return TINF_DATA_ERROR;
+
+   /* check window size is valid */
+   if ((cmf >> 4) > 7) return TINF_DATA_ERROR;
+
+   /* check there is no preset dictionary */
+   if (flg & 0x20) return TINF_DATA_ERROR;
+
+   /* initialize for adler32 checksum */
+   d->checksum_type = TINF_CHKSUM_ADLER;
+   d->checksum = 1;
+
+   return cmf >> 4;
+}