HAGL graphics library speed tests for GD32V based boards. See the accompanying blog post.
$ git clone git@github.com:tuupola/gd32v_gfx.git --recursive
$ cd gd32v_gfx
$ make SOC=gd32vf103 BOARD=gd32vf103c_longan_nano all
$ make SOC=gd32vf103 BOARD=gd32vf103c_longan_nano upload