changed so the linkerscript is passed through the preprocessor

Author: itzandroidtab

project/CMakeLists.txt

@@ -1,3 +1,6 @@
+# include the linkerscript generator needed to preprocess the linkerscripts
+include (${CMAKE_SOURCE_DIR}/targets/arm/linkerscript/linkerscript.cmake)
+
 # set the sources
 set(SOURCES
     ${CMAKE_CURRENT_SOURCE_DIR}/main.cpp
@@ -40,8 +43,7 @@ target_link_libraries(klib_project PUBLIC target_cpu)
 target_link_libraries(klib_project PUBLIC m)
 
 # link to the linkerscript of the target cpu
-target_link_options(klib_project PUBLIC "-T${TARGET_LINKERSCRIPT}")
-set_target_properties(klib_project PROPERTIES LINK_DEPENDS ${TARGET_LINKERSCRIPT})
+add_linkerscript(klib_project ${TARGET_LINKERSCRIPT})
 
 # add the project directory to the include directories
 include_directories(${CMAKE_CURRENT_SOURCE_DIR})

targets/arm/linkerscript/linkerscript.cmake

@@ -0,0 +1,26 @@
+# helper function to preprocess a linker script. This allows 
+# using C preprocessor in the linkerscript files (including 
+# macroes, conditionals, etc)
+function(add_linkerscript target linkerscript options)
+    set(output "${CMAKE_BINARY_DIR}/linkerscript.ld")
+    set(CURRENT_DIR "${CMAKE_SOURCE_DIR}/targets/arm/linkerscript")
+
+    # run the preprocessor on the linkerscript
+    add_custom_command(
+        OUTPUT ${output}
+        # run the linkerscript through the C preprocessor. Force include the base linkerscript template.
+        COMMAND ${CMAKE_C_COMPILER} -E -P -x c ${linkerscript} -o ${output} -include ${CURRENT_DIR}/linkerscript.ld ${options}
+        DEPENDS ${linkerscript} ${CURRENT_DIR}/linkerscript.ld
+        COMMENT "Preprocessing linker script ${linkerscript}"
+        VERBATIM
+    )
+
+    # create a custom target to generate the linkerscript
+    add_custom_target(generate_linkerscript DEPENDS "${output}")
+    add_dependencies(${target} generate_linkerscript)
+
+    # add the linkerscript to the target
+    target_link_options(${target} PUBLIC "-T${output}")
+    set_target_properties(${target} PROPERTIES LINK_DEPENDS ${output})
+endfunction()
+

targets/arm/linkerscript/linkerscript.ld

@@ -0,0 +1,9 @@
+/* macro to define the vectors section. Should be pointed to the correct memory region */
+#define VECTORS() \
+    .vectors (READONLY) : \
+    { \
+        . = ALIGN(4); \
+        /* vector table */ \
+        KEEP(*(.vectors .vectors.*)); \
+        . = ALIGN(4); \
+    }