add migen tutorial link

diff --git a/3d_gpu.mdwn b/3d_gpu.mdwn
index 97b0b18284c5d2915b20d7bd4b7acdc6e0b3dbc5..6476468f13b0cb65cb41320adf4b0b06432c3001 100644 (file)
--- a/3d_gpu.mdwn
+++ b/3d_gpu.mdwn
@@ -59,3 +59,4 @@ Progress:
 * <http://lists.libre-riscv.org/pipermail/libre-riscv-dev/2019-March/000705.html>
 * <https://chisel.eecs.berkeley.edu/api/latest/chisel3/util/DecoupledIO.html>
 * <http://www.clifford.at/papers/2016/yosys-synth-formal/slides.pdf>
+* <http://blog.lambdaconcept.com/doku.php?id=migen:tutorial>