add orig_prog_diff and alt_prog_diff rules to Makefiles

1993/plummer/Makefile

@@ -124,9 +124,9 @@ ALT_TARGET= ${PROG}.alt
 all: data ${TARGET}
 	@${TRUE}
 
-.PHONY: all alt data everything clean clobber install \
-	love haste waste maker easter_egg sandwich \
-	supernova deep_magic magic charon pluto
+.PHONY: all alt data everything orig_prog_diff alt_prog_diff \
+	clean clobber install love haste waste maker easter_egg \
+	sandwich supernova deep_magic magic charon pluto
 
 ${PROG}: ${PROG}.c
 	@echo "NOTE: this program will likely crash or do something else without enough args."
@@ -150,6 +150,18 @@ data: ${DATA}
 everything: all alt
 	@${TRUE}
 
+# diff orig source and source
+#
+orig_prog_diff: ${PROG}.orig.c ${PROG}.c
+	@-${DIFF} -u ${PROG}.orig.c ${PROG}.c
+
+# diff alt source and source
+#
+alt_prog_diff: ${PROG}.c
+	@-if [[ -e ${PROG}.alt.c ]]; then \
+	    ${DIFF} -u ${PROG}.alt.c ${PROG}.c; \
+	fi
+
 
 ###############
 # utility rules