From fc58dab96f27624435a1c08480234a7c03071e27 Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Wed, 30 Oct 2019 19:40:56 +0100
Subject: Extract settings into config file, add documentation

---
 ldc_2d/cpp/CMakeLists.txt |  2 +-
 ldc_2d/cpp/README.md      | 18 ++++++++++++++++++
 ldc_2d/cpp/config.py      | 13 +++++++++++++
 ldc_2d/cpp/generate.py    | 20 ++++++++++----------
 4 files changed, 42 insertions(+), 11 deletions(-)
 create mode 100644 ldc_2d/cpp/README.md
 create mode 100644 ldc_2d/cpp/config.py

diff --git a/ldc_2d/cpp/CMakeLists.txt b/ldc_2d/cpp/CMakeLists.txt
index e00af90..5b5fb90 100644
--- a/ldc_2d/cpp/CMakeLists.txt
+++ b/ldc_2d/cpp/CMakeLists.txt
@@ -16,7 +16,7 @@ add_custom_command(
 	WORKING_DIRECTORY
 		${CMAKE_CURRENT_SOURCE_DIR}
 	DEPENDS
-		generate.py ldc.cpp.mako
+		generate.py config.py ldc.cpp.mako
 )
 
 include_directories(
diff --git a/ldc_2d/cpp/README.md b/ldc_2d/cpp/README.md
new file mode 100644
index 0000000..8e84c83
--- /dev/null
+++ b/ldc_2d/cpp/README.md
@@ -0,0 +1,18 @@
+# Lid driven cavity
+
+This example models the common lid driven cavity example.
+Note that the actual optimized C++ implementation is generated using the _boltzgen_ library.
+
+See `config.py` for various configuration options. Both 2D and 3D are supported.
+
+## Build instructions
+
+```
+mkdir build
+cd build
+cmake ..
+make
+./ldc
+```
+
+This should result in some summarizing CLI output in addition to a `test.vtk` file for visualization in Paraview.
diff --git a/ldc_2d/cpp/config.py b/ldc_2d/cpp/config.py
new file mode 100644
index 0000000..3ed8bd5
--- /dev/null
+++ b/ldc_2d/cpp/config.py
@@ -0,0 +1,13 @@
+from boltzgen.lbm.model import *
+from boltzgen import Geometry
+
+descriptor = D2Q9
+geometry   = Geometry(512, 512)
+tau        = 0.52
+precision  = 'single'
+
+## 3D LDC
+#descriptor = D3Q19
+#geometry   = Geometry(64, 64, 64)
+#tau        = 0.52
+#precision  = 'single'
diff --git a/ldc_2d/cpp/generate.py b/ldc_2d/cpp/generate.py
index 167cc1b..4222e98 100755
--- a/ldc_2d/cpp/generate.py
+++ b/ldc_2d/cpp/generate.py
@@ -5,6 +5,8 @@ import argparse
 from boltzgen import LBM, Generator, Geometry
 from boltzgen.lbm.model import D2Q9
 
+import config
+
 argparser = argparse.ArgumentParser(
     description = 'Generate a C++ implementation of a lid driven cavity simulation using LBM')
 argparser.add_argument(
@@ -12,29 +14,27 @@ argparser.add_argument(
 
 args = argparser.parse_args()
 
-geometry = Geometry(128, 128)
-
-functions = ['collide_and_stream', 'equilibrilize', 'collect_moments', 'momenta_boundary']
-
-lbm = LBM(D2Q9)
+lbm = LBM(config.descriptor)
 generator = Generator(
-    descriptor = D2Q9,
+    descriptor = config.descriptor,
     moments    = lbm.moments(),
-    collision  = lbm.bgk(f_eq = lbm.equilibrium(), tau = 0.52),
+    collision  = lbm.bgk(f_eq = lbm.equilibrium(), tau = config.tau),
     target     = 'cpp',
-    precision  = 'double',
+    precision  = config.precision,
     index      = 'XYZ',
     layout     = 'AOS')
 
 if args.output is None:
     args.output = '.'
 
+functions = ['collide_and_stream', 'equilibrilize', 'collect_moments', 'momenta_boundary']
+
 with open('%s/kernel.h' % args.output, 'w') as kernel:
-    kernel.write(generator.kernel(geometry, functions))
+    kernel.write(generator.kernel(config.geometry, functions))
 
 ldc_src = ''
 with open('ldc.cpp.mako', 'r') as template:
     ldc_src = template.read()
 
 with open('%s/ldc.cpp' % args.output, 'w') as app:
-    app.write(generator.custom(geometry, ldc_src))
+    app.write(generator.custom(config.geometry, ldc_src))
-- 
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