From c6c59383ddb97c0b3ecf733174b31a2b28fd1ebd Mon Sep 17 00:00:00 2001
From: Phillip Johnston <phillip@embeddedartistry.com>
Date: Tue, 4 Aug 2020 10:57:58 -0700
Subject: [PATCH] Add a refactoring example

---
 examples/c/meson.build               |   4 +
 examples/c/refactoring_global_data.c | 132 +++++++++++++++++++++++++++
 2 files changed, 136 insertions(+)
 create mode 100644 examples/c/refactoring_global_data.c

diff --git a/examples/c/meson.build b/examples/c/meson.build
index 347087f..9cb6800 100644
--- a/examples/c/meson.build
+++ b/examples/c/meson.build
@@ -4,6 +4,10 @@ static_library('interrupt_latency',
 	'interrupt_latency.c'
 )
 
+executable('refactoring_global_data',
+	'refactoring_global_data.c'
+)
+
 executable('circular_buffer',
 	[
 		'circular_buffer_test.c',
diff --git a/examples/c/refactoring_global_data.c b/examples/c/refactoring_global_data.c
new file mode 100644
index 0000000..9a77a4f
--- /dev/null
+++ b/examples/c/refactoring_global_data.c
@@ -0,0 +1,132 @@
+//#define USE_EXAMPLE_1 // Legacy code example
+//#define USE_EXAMPLE_2 // Intermediate refactoring example
+#define USE_EXAMPLE_3 // Full refactoring
+
+#ifdef USE_EXAMPLE_1
+#include <stdio.h>
+
+int data_0 = 1;
+int data_1 = 2;
+int data_2 = 3;
+int data_3 = 4;
+
+int func0(void)
+{
+	return data_0 + data_1;
+}
+
+int func1(void)
+{
+	return data_2 + data_3;
+}
+
+int main(void)
+{
+	int a = func0();
+	int b = func1();
+	int calculated = a + b;
+	printf("Calculated value: %d\n", calculated);
+
+	return 0;
+}
+#elif defined(USE_EXAMPLE_2)
+#include <stdio.h>
+
+typedef struct {
+	int data_0;
+	int data_1;
+	int data_2;
+	int data_3;
+} global_data_t;
+
+global_data_t instance_1 = {
+	.data_0 = 1,
+	.data_1 = 2,
+	.data_2 = 3,
+	.data_3 = 4
+};
+
+global_data_t* g_data_ptr;
+#define data_0 (g_data_ptr->data_0)
+#define data_1 (g_data_ptr->data_1)
+#define data_2 (g_data_ptr->data_2)
+#define data_3 (g_data_ptr->data_3)
+
+int func0(void)
+{
+	return data_0 + data_1;
+}
+
+int func1(void)
+{
+	return data_2 + data_3;
+}
+
+int main(void)
+{
+	g_data_ptr = &instance_1;
+
+	int a = func0();
+	int b = func1();
+	int calculated = a + b;
+	printf("Calculated value: %d\n", calculated);
+
+	return 0;
+}
+#elif defined(USE_EXAMPLE_3)
+#include <stdio.h>
+
+typedef struct {
+	int data_0;
+	int data_1;
+	int data_2;
+	int data_3;
+} global_data_t;
+
+global_data_t instance_1 = {
+	.data_0 = 1,
+	.data_1 = 2,
+	.data_2 = 3,
+	.data_3 = 4
+};
+
+global_data_t instance_2 = {
+	.data_0 = 5,
+	.data_1 = 6,
+	.data_2 = 7,
+	.data_3 = 8
+};
+
+global_data_t* g_data_ptr;
+#define data_0 (g_data_ptr->data_0)
+#define data_1 (g_data_ptr->data_1)
+#define data_2 (g_data_ptr->data_2)
+#define data_3 (g_data_ptr->data_3)
+
+int func0(global_data_t* g_data_ptr)
+{
+	return data_0 + data_1;
+}
+
+int func1(global_data_t* g_data_ptr)
+{
+	return data_2 + data_3;
+}
+
+int main(void)
+{
+	int a = func0(&instance_1);
+	int b = func1(&instance_1);
+	int calculated = a + b;
+	printf("Calculated value for instance_1: %d\n", calculated);
+
+	a = func0(&instance_2);
+	b = func1(&instance_2);
+	calculated = a + b;
+	printf("Calculated value for instance_2: %d\n", calculated);
+
+	return 0;
+}
+#else
+#error Please enable an example using one of the macros shown above.
+#endif