From 3c41ad5479be9991c2e30351a973b9e078b0e716 Mon Sep 17 00:00:00 2001
From: Tristan Gingold <tgingold@free.fr>
Date: Fri, 10 Feb 2017 22:24:11 +0100
Subject: Add Makefile to build ghdl as a yosys module.

---
 Makefile  | 11 +++++++++++
 README.md | 24 ++++++++++++++++++++++--
 2 files changed, 33 insertions(+), 2 deletions(-)
 create mode 100644 Makefile

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..6acc130
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,11 @@
+# Build ghdl module for yosys
+
+# Prefix where ghdl has been installed
+GHDL_PREFIX=
+
+ifeq ($(GHDL_PREFIX),)
+$(error GHDL_PREFIX not defined)
+endif
+
+ghdl.so: ghdl/ghdl.cc
+	yosys-config --exec --cxx --cxxflags --ldflags -o $@ -shared $< -DYOSYS_ENABLE_GHDL -I$(GHDL_PREFIX)/include $(GHDL_PREFIX)/lib/libghdlsynth.so -Wl,-rpath,$(GHDL_PREFIX)/lib --ldlibs
diff --git a/README.md b/README.md
index 4ef0883..48efb0f 100644
--- a/README.md
+++ b/README.md
@@ -3,9 +3,29 @@ VHDL synthesis (based on ghdl)
 
 This is awfully experimental and work in progress!
 
-## How to build
+## How to build as a module
 
-FIXME: should provide an easy way to build as a module!
+Get and install yosys.
+
+Get ghdl from github,
+build and install
+build and install libghdlsynth.so:
+```sh
+$ make libghdlsynth.so
+$ make install.libghdlsynth.shared
+```
+
+From ghdlsynth-beta:
+
+make GHDL_PREFIX=prefix-used-to-configure-ghdl
+
+This generates ghdl.so, which can be used directly:
+
+```sh
+$ yosys -m ghdl.so
+```
+
+## How to build (not recommended)
 
 Get ghdl from github,
 build and install
-- 
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