Have CMAKE parse conditional lines in KERNEL files

Supports ifeq and ifneq, but requires both to have an else branch

cmake/utils.cmake

@@ -15,10 +15,33 @@ endfunction ()
 # Reads a Makefile into CMake vars.
 macro(ParseMakefileVars MAKEFILE_IN)
   message(STATUS "Reading vars from ${MAKEFILE_IN}...")
+        set (IfElse 0)
+        set (ElseSeen 0)
   file(STRINGS ${MAKEFILE_IN} makefile_contents)
   foreach (makefile_line ${makefile_contents})
+#message(STATUS "parsing ${makefile_line}")
+    if (${IfElse} GREATER 0)
+      string(REGEX MATCH "endif[ \t]*" line_match "${makefile_line}")
+      if (NOT "${line_match}" STREQUAL "")
+#           message(STATUS "ENDIF ${makefile_line}")
+        set (IfElse 0)
+        set (ElseSeen 0)
+        continue ()
+      endif ()
+      string(REGEX MATCH "else[ \t]*" line_match "${makefile_line}")
+        if (NOT "${line_match}" STREQUAL "") 
+#           message(STATUS "ELSE ${makefile_line}")
+           set (ElseSeen 1)        
+           continue ()  
+        endif()
+      if ( (${IfElse} EQUAL 2 AND ${ElseSeen} EQUAL 0) OR ( ${IfElse} EQUAL 1 AND ${ElseSeen} EQUAL 1))
+#           message(STATUS "skipping ${makefile_line}")
+         continue ()
+      endif ()    
+    endif ()    
     string(REGEX MATCH "([0-9_a-zA-Z]+)[ \t]*=[ \t]*(.+)$" line_match "${makefile_line}")
     if (NOT "${line_match}" STREQUAL "")
+#message(STATUS "match on ${line_match}")
       set(var_name ${CMAKE_MATCH_1})
       set(var_value ${CMAKE_MATCH_2})
       # check for Makefile variables in the string, e.g. $(TSUFFIX)
@@ -33,7 +56,31 @@ macro(ParseMakefileVars MAKEFILE_IN)
     else ()
       string(REGEX MATCH "include \\$\\(KERNELDIR\\)/(.+)$" line_match "${makefile_line}")
       if (NOT "${line_match}" STREQUAL "")
+#message(STATUS "match on include ${line_match}")
         ParseMakefileVars(${KERNELDIR}/${CMAKE_MATCH_1})
+      else ()
+#        message(STATUS "unmatched line ${line_match}")
+        string(REGEX MATCH "ifeq \\(\\$\\(([_A-Z]+)\\),[ \t]*([0-9_A-Z]+)\\)" line_match "${makefile_line}")
+        if (NOT "${line_match}" STREQUAL "")
+#          message(STATUS "IFEQ: ${line_match} first: ${CMAKE_MATCH_1} second: ${CMAKE_MATCH_2}")
+          if (${${CMAKE_MATCH_1}} STREQUAL ${CMAKE_MATCH_2})
+#            message (STATUS "condition is true")
+            set (IfElse 1)
+          else ()
+            set (IfElse 2)
+          endif ()
+        else ()
+          string(REGEX MATCH "ifneq \\(\\$\\(([_A-Z]+)\\),[ \t]*([0-9_A-Z]+)\\)" line_match "${makefile_line}")
+          if (NOT "${line_match}" STREQUAL "")
+#            message(STATUS "IFNEQ: ${line_match} first: ${CMAKE_MATCH_1} second: ${CMAKE_MATCH_2}")
+            if (NOT ( ${${CMAKE_MATCH_1}} STREQUAL ${CMAKE_MATCH_2}))
+              message (STATUS "condition is true")
+              set (IfElse 1)
+            else ()
+              set (IfElse 2)
+            endif ()
+          endif ()
+        endif ()
       endif ()
     endif ()
   endforeach ()