feat(sys): add sys lib

CMakeLists.txt

@@ -17,8 +17,17 @@ target_link_libraries(strings PRIVATE c-libs)
 add_executable(rc ${CMAKE_CURRENT_SOURCE_DIR}/app/rc.c)
 target_link_libraries(rc PRIVATE c-libs)
 
-add_executable(nolibc ${CMAKE_CURRENT_SOURCE_DIR}/app/nolibc.c
-                      ${CMAKE_CURRENT_SOURCE_DIR}/app/entry.s)
+add_library(
+  sys STATIC
+  ${CMAKE_CURRENT_SOURCE_DIR}/src/sys/entry.s
+  ${CMAKE_CURRENT_SOURCE_DIR}/src/sys/syscall.s
+  ${CMAKE_CURRENT_SOURCE_DIR}/src/sys/syscall.c)
+target_include_directories(
+  sys PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
+             $<INSTALL_INTERFACE:include>)
+
+add_executable(nolibc ${CMAKE_CURRENT_SOURCE_DIR}/app/nolibc.c)
+target_link_libraries(nolibc PRIVATE sys)
 target_compile_options(
   nolibc PRIVATE -fno-asynchronous-unwind-tables -fno-unwind-tables
                  -fno-stack-protector -ffunction-sections -fdata-sections)
@@ -50,7 +59,7 @@ include(CMakePackageConfigHelpers)
 include(GNUInstallDirs)
 
 install(
-  TARGETS c-libs
+  TARGETS c-libs sys
   EXPORT c-libs
   ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
   LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}