PNG_PASS_ROW_SHIFT   55 contrib/libtests/pngunknown.c #define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
PNG_PASS_ROW_SHIFT   84 contrib/libtests/pngvalid.c #define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)
PNG_PASS_ROW_SHIFT 2604 png.h          #define PNG_PASS_ROW_SHIFT(pass) ((pass)>2?(8-(pass))>>1:3)