From f7643ada270fb9a788f0abf2c55e5ed6d9c35abb Mon Sep 17 00:00:00 2001
From: doodspav <doodspav@gmail.com>
Date: Sat, 11 Mar 2023 04:10:36 +0000
Subject: [PATCH] GHI #11 Setup CMake for building project

---
 CMakeLists.txt                         | 73 ++++++++++++++++++++++++++
 cmake/util/OptionVariables.cmake       | 30 +++++++++++
 cmake/util/PreventInSourceBuilds.cmake |  9 ++++
 cmake/util/ProjectIsTopLevel.cmake     |  6 +++
 include/patomic/patomic.h              | 22 ++++++++
 src/patomic.c                          | 11 ++++
 6 files changed, 151 insertions(+)
 create mode 100644 CMakeLists.txt
 create mode 100644 cmake/util/OptionVariables.cmake
 create mode 100644 cmake/util/PreventInSourceBuilds.cmake
 create mode 100644 cmake/util/ProjectIsTopLevel.cmake
 create mode 100644 include/patomic/patomic.h
 create mode 100644 src/patomic.c

diff --git a/CMakeLists.txt b/CMakeLists.txt
new file mode 100644
index 000000000..9acfaa22d
--- /dev/null
+++ b/CMakeLists.txt
@@ -0,0 +1,73 @@
+cmake_minimum_required(VERSION 3.14)
+
+include(cmake/util/PreventInSourceBuilds.cmake)
+
+project(
+    patomic
+    VERSION 0.5.1
+    DESCRIPTION "Portable C90 Atomics Library"
+    HOMEPAGE_URL "https://github.com/doodspav/patomic"
+    LANGUAGES C
+)
+
+# don't change include order, OptionVariables checks if project is top level
+include(cmake/util/ProjectIsTopLevel.cmake)
+include(cmake/util/OptionVariables.cmake)
+
+
+# ---- Declare Library ----
+
+add_library(
+    patomic_patomic
+    # include
+    include/patomic/patomic.h
+    # src
+    src/patomic.c
+)
+
+# alias to cause error at configuration time instead of link time if target is missing
+add_library(patomic::patomic ALIAS patomic_patomic)
+
+
+# ---- Generate Build Info Headers ----
+
+# used in export header generated below
+if(NOT BUILD_SHARED_LIBS)
+    target_compile_definitions(patomic_patomic PUBLIC PATOMIC_STATIC_DEFINE)
+endif()
+
+include(GenerateExportHeader)
+generate_export_header(
+    patomic_patomic
+    BASE_NAME patomic
+    EXPORT_FILE_NAME include/patomic/patomic_export.h
+)
+
+
+# ---- Library Properties ----
+
+set_target_properties(
+    patomic_patomic PROPERTIES
+    C_VISIBILITY_PRESET hidden
+    VISIBILITY_INLINES_HIDDEN YES
+    VERSION "${PROJECT_VERSION}"
+    SOVERSION "${PROJECT_VERSION_MAJOR}"
+    EXPORT_NAME patomic
+    OUTPUT_NAME patomic
+)
+
+# header files generated by CMake
+target_include_directories(
+    patomic_patomic SYSTEM
+    PUBLIC
+    "$<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>"
+)
+
+# header files from /include
+target_include_directories(
+    patomic_patomic ${warning_guard}
+    PUBLIC
+    "$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>"
+)
+
+target_compile_features(patomic_patomic PUBLIC c_std_90)
diff --git a/cmake/util/OptionVariables.cmake b/cmake/util/OptionVariables.cmake
new file mode 100644
index 000000000..0a81c559d
--- /dev/null
+++ b/cmake/util/OptionVariables.cmake
@@ -0,0 +1,30 @@
+# ---- Developer Mode ----
+
+# Developer mode enables targets and code paths in the CMake scripts that are
+# only relevant for the developer(s) of patomic.
+# Targets necessary to build the project must be provided unconditionally, so
+# that consumers can trivially build and package the project.
+if(PROJECT_IS_TOP_LEVEL)
+    option(patomic_DEVELOPER_MODE "Enable developer mode" OFF)
+    option(BUILD_SHARED_LIBS "Build shared libs" OFF)
+endif()
+
+
+# ---- Warning Guard ----
+
+# target_include_directories with SYSTEM modifier will request the compiler to
+# omit warnings from the provided paths, if the compiler supports that.
+# This is to provide a user experience similar to find_package when
+# add_subdirectory or FetchContent is used to consume this project.
+set(warning_guard "")
+if(NOT PROJECT_IS_TOP_LEVEL)
+    option(
+        patomic_INCLUDES_WITH_SYSTEM
+        "Use SYSTEM modifier for patomic's includes, disabling warnings"
+        ON
+    )
+    mark_as_advanced(patomic_INCLUDES_WITH_SYSTEM)
+    if(patomic_INCLUDES_WITH_SYSTEM)
+        set(warning_guard SYSTEM)
+    endif()
+endif()
diff --git a/cmake/util/PreventInSourceBuilds.cmake b/cmake/util/PreventInSourceBuilds.cmake
new file mode 100644
index 000000000..c78f18825
--- /dev/null
+++ b/cmake/util/PreventInSourceBuilds.cmake
@@ -0,0 +1,9 @@
+# in-source build guard
+if(CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR)
+    message(
+        FATAL_ERROR
+        "In-source builds are not supported. "
+        "Please read the BUILDING document before trying to build this project. "
+        "You may need to delete 'CMakeCache.txt' and 'CMakeFiles/' first."
+    )
+endif()
diff --git a/cmake/util/ProjectIsTopLevel.cmake b/cmake/util/ProjectIsTopLevel.cmake
new file mode 100644
index 000000000..fc2ef6c9f
--- /dev/null
+++ b/cmake/util/ProjectIsTopLevel.cmake
@@ -0,0 +1,6 @@
+# this variable is set by project() in CMake 3.21+
+string(
+    COMPARE EQUAL
+    "${CMAKE_SOURCE_DIR}" "${PROJECT_SOURCE_DIR}"
+    PROJECT_IS_TOP_LEVEL
+)
diff --git a/include/patomic/patomic.h b/include/patomic/patomic.h
new file mode 100644
index 000000000..2ce79ea60
--- /dev/null
+++ b/include/patomic/patomic.h
@@ -0,0 +1,22 @@
+#ifndef PATOMIC_PATOMIC_H
+#define PATOMIC_PATOMIC_H
+
+#include <patomic/patomic_export.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+PATOMIC_EXPORT int
+patomic_example_add(
+    int a,
+    int b
+);
+
+
+#ifdef __cplusplus
+}  /* extern "C" */
+#endif
+
+#endif  /* PATOMIC_PATOMIC_H */
diff --git a/src/patomic.c b/src/patomic.c
new file mode 100644
index 000000000..404519e55
--- /dev/null
+++ b/src/patomic.c
@@ -0,0 +1,11 @@
+#include <patomic/patomic.h>
+
+
+PATOMIC_EXPORT int
+patomic_example_add(
+    int a,
+    int b
+)
+{
+    return a + b;
+}