Fix incorrect CRC in IDAT chunk. Examples PNGs passed pngcheck.

Author: miloyip

rgb.png

@@ -30,7 +30,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 /*! \file
     \brief      svpng() is a minimalistic C function for saving RGB/RGBA image into uncompressed PNG.
     \author     Milo Yip
-    \version    0.1.0
+    \version    0.1.1
     \copyright  MIT license
     \sa         http://github.com/miloyip/svpng
 */
@@ -82,7 +82,7 @@ SVPNG_LINKAGE void svpng(SVPNG_OUTPUT, unsigned w, unsigned h, const unsigned ch
 #define SVPNG_U32(u) do { SVPNG_PUT((u) >> 24); SVPNG_PUT(((u) >> 16) & 255); SVPNG_PUT(((u) >> 8) & 255); SVPNG_PUT((u) & 255); } while(0)
 #define SVPNG_U8C(u) do { SVPNG_PUT(u); c ^= (u); c = (c >> 4) ^ t[c & 15]; c = (c >> 4) ^ t[c & 15]; } while(0)
 #define SVPNG_U8AC(ua, l) for (i = 0; i < l; i++) SVPNG_U8C((ua)[i])
-#define SVPNG_U16LC(u) do { SVPNG_U8C(u); SVPNG_U8C(((u) >> 8) & 255); } while(0)
+#define SVPNG_U16LC(u) do { SVPNG_U8C((u) & 255); SVPNG_U8C(((u) >> 8) & 255); } while(0)
 #define SVPNG_U32C(u) do { SVPNG_U8C((u) >> 24); SVPNG_U8C(((u) >> 16) & 255); SVPNG_U8C(((u) >> 8) & 255); SVPNG_U8C((u) & 255); } while(0)
 #define SVPNG_U8ADLER(u) do { SVPNG_U8C(u); a = (a + (u)) % 65521; b = (b + a) % 65521; } while(0)
 #define SVPNG_BEGIN(s, l) do { SVPNG_U32(l); c = ~0U; SVPNG_U8AC(s, 4); } while(0)