From 36c08c89eb7d23b2a33df48f40d96441422292a1 Mon Sep 17 00:00:00 2001
From: Robert Bradshaw <robertwb@math.washington.edu>
Date: Thu, 21 Jan 2010 22:31:20 -0800
Subject: [PATCH] Library linking demo.

---
 Demos/libraries/call_mymath.pyx |  5 +++++
 Demos/libraries/mymath.c        |  5 +++++
 Demos/libraries/mymath.h        |  1 +
 Demos/libraries/setup.py        | 31 +++++++++++++++++++++++++++++++
 4 files changed, 42 insertions(+)
 create mode 100644 Demos/libraries/call_mymath.pyx
 create mode 100644 Demos/libraries/mymath.c
 create mode 100644 Demos/libraries/mymath.h
 create mode 100644 Demos/libraries/setup.py

diff --git a/Demos/libraries/call_mymath.pyx b/Demos/libraries/call_mymath.pyx
new file mode 100644
index 00000000..1b45f804
--- /dev/null
+++ b/Demos/libraries/call_mymath.pyx
@@ -0,0 +1,5 @@
+cdef extern from "mymath.h":
+    double sinc(double)
+
+def call_sinc(x):
+    return sinc(x)
diff --git a/Demos/libraries/mymath.c b/Demos/libraries/mymath.c
new file mode 100644
index 00000000..b16ed5ae
--- /dev/null
+++ b/Demos/libraries/mymath.c
@@ -0,0 +1,5 @@
+#include "math.h"
+
+double sinc(double x) {
+    return x == 0 ? 1 : sin(x)/x;
+}
\ No newline at end of file
diff --git a/Demos/libraries/mymath.h b/Demos/libraries/mymath.h
new file mode 100644
index 00000000..4f2bb4b7
--- /dev/null
+++ b/Demos/libraries/mymath.h
@@ -0,0 +1 @@
+double sinc(double);
diff --git a/Demos/libraries/setup.py b/Demos/libraries/setup.py
new file mode 100644
index 00000000..b4a3659a
--- /dev/null
+++ b/Demos/libraries/setup.py
@@ -0,0 +1,31 @@
+import os
+
+from distutils.core import setup
+from distutils.extension import Extension
+from Cython.Distutils import build_ext
+
+
+# For demo purposes, we build our own tiny library.
+try:
+    print "building libmymath.a"
+    assert os.system("gcc -c mymath.c -o mymath.o") == 0
+    assert os.system("ar rcs libmymath.a mymath.o") == 0
+except:
+    if not os.path.exists("libmymath.a"):
+        print "Error building external library, please create libmymath.a manually."
+        sys.exit(1)
+
+# Here is how to use the library built above. 
+ext_modules=[ 
+    Extension("call_mymath",
+              sources = ["call_mymath.pyx"],
+              include_dirs = [os.getcwd()],  # path to .h file(s)
+              library_dirs = [os.getcwd()],  # path to .a or .so file(s)
+              libraries = ['mymath'])
+]
+
+setup(
+  name = 'Demos',
+  cmdclass = {'build_ext': build_ext},
+  ext_modules = ext_modules,
+)
-- 
2.26.2