PNG_u2             94 contrib/libtests/pngunknown.c #define PNG_U16(b1, b2) ((png_uint_16)PNG_u2(b1, b2))
PNG_u2             96 contrib/libtests/pngunknown.c    (((png_uint_32)PNG_u2(b1, b2) << 16) + PNG_u2(b3, b4))