add openpiton link

diff --git a/3d_gpu.mdwn b/3d_gpu.mdwn
index 09854d205aa8c6c0091bc9a24bc72cd50e5ac590..5ac25349c67822d4b8b6bf0fcb4d98d937e02059 100644 (file)
--- a/3d_gpu.mdwn
+++ b/3d_gpu.mdwn
@@ -179,5 +179,6 @@ algorithm themselves just like Google did very recently [6]
 * [9] libre-riscv.org/simple_v_extension/
 * [10] https://jbush001.github.io/2016/03/02/videocore-qpu-pipeline.html
 * [11] https://jbush001.github.io/2016/02/27/life-of-triangle.html
+* OpenPiton https://openpiton-blog.princeton.edu/2018/11/announcing-openpiton-with-ariane/