T: add a tracer: extract

This tracer extracts the content of a buffer field of an event
that was previously saved using the tracer 'record'.

For example, to extract the channel estimation done in
frame 924 and subframe 2 as saved in the file input_record.raw
and to store it in the file output.raw, do:

./extract -d ../T_messages.txt -o output.raw input_record.raw ENB_PHY_UL_CHANNEL_ESTIMATE chest_t -f frame 924 -f subframe 2

common/utils/T/tracer/Makefile

@@ -6,7 +6,7 @@ CFLAGS=-Wall -g -pthread -DT_TRACER -I.
 LIBS=-lX11 -lm -lpng -lXft
 
 all: record replay extract_config textlog enb ue vcd macpdu2wireshark \
-     extract_input_subframe
+     extract_input_subframe extract
 
 record: utils.o record.o database.o config.o
 	$(CC) $(CFLAGS) -o record $^ $(LIBS)
@@ -21,6 +21,9 @@ extract_input_subframe: extract_input_subframe.o database.o event.o utils.o \
     config.o
 	$(CC) $(CFLAGS) -o $@ $^ $(LIBS)
 
+extract: extract.o database.o event.o utils.o config.o
+	$(CC) $(CFLAGS) -o $@ $^ $(LIBS)
+
 textlog: utils.o textlog.o database.o event.o handler.o config.o \
          event_selector.o view/view.a gui/gui.a logger/logger.a \
          filter/filter.a
@@ -64,7 +67,7 @@ filter/filter.a:
 
 clean:
 	rm -f *.o core tracer_remote textlog enb ue vcd record replay
-	rm -f extract_config macpdu2wireshark extract_input_subframe
+	rm -f extract_config macpdu2wireshark extract_input_subframe extract
 	cd gui && make clean
 	cd view && make clean
 	cd logger && make clean