fix comparison of unsigned chars
fix comparison of unsigned chars
ycaihua/skim-app,ycaihua/skim-app,ycaihua/skim-app,WoLpH/skim,ycaihua/skim-app,WoLpH/skim,ycaihua/skim-app,WoLpH/skim,WoLpH/skim,WoLpH/skim