Add two commonly used modules. First one checks if the function exists, the second one checks the size of type

Modules/CheckFunctionExists.c

@@ -0,0 +1,15 @@
+#ifdef CHECK_FUNCTION_EXISTS
+
+char CHECK_FUNCTION_EXISTS();
+
+int main()
+{
+  CHECK_FUNCTION_EXISTS();
+  return 0;
+}
+
+#else  /* CHECK_FUNCTION_EXISTS */
+
+#  error "CHECK_FUNCTION_EXISTS has to specify the function"
+
+#endif /* CHECK_FUNCTION_EXISTS */

Modules/CheckFunctionExists.cmake

@@ -0,0 +1,22 @@
+#
+# Check if the type exists and determine size of type.  if the type
+# exists, the size will be stored to the variable.
+#
+# CHECK_TYPE_SIZE - macro which checks the size of type
+# VARIABLE - variable to store size if the type exists.
+#
+
+MACRO(CHECK_FUNCTION_EXISTS FUNCTION VARIABLE)
+  TRY_COMPILE(COMPILE_OK
+             ${PROJECT_BINARY_DIR}
+             ${CMAKE_ROOT}/Modules/CheckFunctionExists.c
+             COMPILE_DEFINITIONS -DCHECK_FUNCTION_EXISTS=${FUNCTION} 
+             OUTPUT_VARIABLE OUTPUT)
+  IF(COMPILE_OK)
+    SET(${VARIABLE} ${COMPILE_OK})
+  ELSE(COMPILE_OK)
+    WRITE_FILE(${PROJECT_BINARY_DIR}/CMakeError.log 
+      "Determining if the function ${FUNCTION} exists failed with the following output:\n"
+      "${OUTPUT}\n")
+  ENDIF(COMPILE_OK)
+ENDMACRO(CHECK_FUNCTION_EXISTS)

Modules/CheckSizeOf.c

@@ -0,0 +1,20 @@
+#ifdef CHECK_SIZE_OF
+
+#ifdef HAVE_SYS_TYPES_H
+#  include <sys/types.h>
+#endif /* HAVE_SYS_TYPES_H */
+
+#ifdef HAVE_STDINT_H
+#  include <stdint.h>
+#endif /* HAVE_STDINT_H */
+
+int main()
+{
+  return sizeof(CHECK_SIZE_OF);
+}
+
+#else  /* CHECK_SIZE_OF */
+
+#  error "CHECK_SIZE_OF has to specify the type"
+
+#endif /* CHECK_SIZE_OF */

Modules/CheckSizeOf.cmake

@@ -0,0 +1,21 @@
+#
+# Check if the type exists and determine size of type.  if the type
+# exists, the size will be stored to the variable.
+#
+# CHECK_TYPE_SIZE - macro which checks the size of type
+# VARIABLE - variable to store size if the type exists.
+#
+
+MACRO(CHECK_TYPE_SIZE TYPE VARIABLE)
+  TRY_RUN(RUN_RESULT COMPILE_OK 
+          ${PROJECT_BINARY_DIR}
+          ${CMAKE_ROOT}/Modules/CheckSizeOf.c
+          COMPILE_DEFINITIONS -DCHECK_SIZE_OF="${TYPE}"
+          OUTPUT_VARIABLE OUTPUT)
+  IF(COMPILE_OK)
+    SET(${VARIABLE} ${RUN_RESULT})
+  ELSE(COMPILE_OK)
+    WRITE_FILE(${PROJECT_BINARY_DIR}/CMakeError.log 
+      "Determining size of ${TYPE} failed with the following output:\n${OUTPUT}\n")
+  ENDIF(COMPILE_OK)
+ENDMACRO(CHECK_TYPE_SIZE)