diff --git a/2020/Makefile b/2020/Makefile
index 8211a5f..415cdac 100644
--- a/2020/Makefile
+++ b/2020/Makefile
@@ -1,25 +1,87 @@
+# AOC Makefile - GNU make only.
+#
+# Copyright (C) 2021-2022 Bruno Raoult ("br")
+# Licensed under the GNU General Public License v3.0 or later.
+# Some rights reserved. See COPYING.
+#
+# You should have received a copy of the GNU General Public License along with this
+# program. If not, see <https://www.gnu.org/licenses/gpl-3.0-standalone.html>.
+#
+# SPDX-License-Identifier: GPL-3.0-or-later <https://spdx.org/licenses/GPL-3.0-or-later.html>
+#
+
+
 SUBDIRS := $(shell echo day??)
 
-EXCLUDE := --exclude 'cob-01/'
+CC       = gcc
 
-.PHONY: clean $(SUBDIRS)
+#LIBS   = -lreadline -lncurses
+CFLAGS   += -std=gnu11
+
+CFLAGS += -O2
+CFLAGS += -g
+#CFLAGS += -pg
+CFLAGS += -Wall
+CFLAGS += -Wextra
+CFLAGS += -march=native
+
+CFLAGS += -DDEBUG_DEBUG		# activate general debug (debug.c)
+CFLAGS += -DDEBUG_POOL		# memory pools management
+
+INCDIR    := ./include
+LIBSRCDIR := ./libsrc
+LIBDIR    := ./lib
+LIB       := libaoc_$(shell uname -m)
+SLIB      := $(LIBDIR)/$(LIB).a
+DLIB      := $(LIBDIR)/$(LIB).so
+LIBSRC    := $(wildcard $(LIBSRCDIR)/*.c)
+LIBOBJ    := $(patsubst %.c,%.o,$(LIBSRC))
+LDFLAGS   := -L$(LIBDIR)
+LDLIB     := -l$(LIB)
+
+.PHONY: clean cleanlib cleanall all redo output lib $(SUBDIRS)
+
+all: lib $(SUBDIRS)
 
 clean:
-	for dir in $(SUBDIRS) ; do \
-		make -C $$dir clean ; \
+	@for dir in $(SUBDIRS) ; do \
+		$(MAKE) --no-print-directory -C $$dir clean ; \
 	done
 
-all: $(SUBDIRS)
+cleanlib: clean
+	@$(RM) -f $(SLIB) $(DLIB) $(LIBOBJ)
+
+cleanall: clean cleanlib
+
+redo: cleanall all
 
 $(SUBDIRS):
 	@echo "========================================="
 	@echo "================= $@ ================="
 	@echo "========================================="
 	@echo
-	@echo "+++++++++++++++++ ex1"
-	@$(MAKE) --no-print-directory -C $@ ex1 2>&1
-	@echo "+++++++++++++++++ ex2"
-	@$(MAKE) --no-print-directory -C $@ ex2 2>&1
+	@echo "+++++++++++++++++ part 1"
+	+@$(MAKE) --no-print-directory -C $@ ex1 2>&1
+	@echo "+++++++++++++++++ part 2"
+	+@$(MAKE) --no-print-directory -C $@ ex2 2>&1
 
 output:
 	@$(MAKE) --no-print-directory all >OUTPUT 2>&1
+
+lib: $(DLIB) $(SLIB)
+
+$(SLIB): $(LIBOBJ)
+	@echo building $@ static library.
+	@mkdir -p $(LIBDIR)
+	@$(AR) $(ARFLAGS) -o $@ $^
+
+$(DLIB): CFLAGS += -fPIC
+$(DLIB): LDFLAGS += -shared
+$(DLIB): $(LIBOBJ)
+	@echo building $@ shared library.
+	@mkdir -p $(LIBDIR)
+	@$(CC) $(LDFLAGS) $^ -o $@
+
+.c.o:
+	@echo compiling $<.
+	@$(CC) -c $(CFLAGS) $(LDFLAGS) -I $(INCDIR) -o $@ $<
diff --git a/2020/day01/Makefile b/2020/day01/Makefile
index 89b1a9f..9bf7369 100644
--- a/2020/day01/Makefile
+++ b/2020/day01/Makefile
@@ -28,7 +28,7 @@ ex2: ex2-c ex2-sort-cob ex2-pure-sort-cob
 	@$(TIME) ex2-c < $(INPUT)
 
 clean:
-	@rm -f ex1-c ex2-c core ex2-galoisgirl-cob ex2-cob
+	@rm -f ex1-c ex2-c core ex*-cob
 
 output:
 	$(MAKE) --no-print-directory all >OUTPUT 2>&1
diff --git a/2020/day24/Makefile b/2020/day24/Makefile
index b66bb2c..9d4af32 100644
--- a/2020/day24/Makefile
+++ b/2020/day24/Makefile
@@ -1,6 +1,6 @@
 # AOC daily Makefile - GNU make only.
 #
-# Copyright (C) 2022 Bruno Raoult ("br")
+# Copyright (C) 2021-2022 Bruno Raoult ("br")
 # Licensed under the GNU General Public License v3.0 or later.
 # Some rights reserved. See COPYING.
 #
@@ -14,17 +14,15 @@ INPUT   := INPUT.txt
 SHELL   := /bin/bash
 
 CC      := gcc
-BEAR    := bear
 
-#LIB     := aoc_$(shell uname -m)
-#INCDIR  := ../include
-INCDIR  := .
-#LIBDIR  := ../lib
-#LDFLAGS := -L$(LIBDIR)
+LIB     := aoc_$(shell uname -m)
+INCDIR  := ../include
+LIBDIR  := ../lib
+LDFLAGS := -L$(LIBDIR)
 #LDLIB   := -l$(LIB) -lm
-#LDLIB   := -l$(LIB)
+LDLIB   := -l$(LIB)
 
-#export LD_LIBRARY_PATH = $(LIBDIR)
+export LD_LIBRARY_PATH = $(LIBDIR)
 
 CFLAGS  += -std=gnu11
 CFLAGS  += -O2
@@ -39,42 +37,46 @@ CFLAGS  += -march=native
 CFLAGS  += -Wmissing-declarations
 CFLAGS  += -Wno-unused-result
 
-#CFLAGS  += -DDEBUG_DEBUG 	# activate general debug (debug.c)
-#CFLAGS  += -DDEBUG_POOL		# memory pools management
+CFLAGS  += -DDEBUG_DEBUG 	# activate general debug (debug.c)
+CFLAGS  += -DDEBUG_POOL		# memory pools management
+
+VALGRIND := valgrind
+VALGRINDFLAGS := --leak-check=full --show-leak-kinds=all --track-origins=yes \
+	--sigill-diagnostics=yes --quiet --show-error-list=yes
+
 
 TIME    := \time -f "\ttime: %E real, %U user, %S sys\n\tcontext-switch:\t%c+%w, page-faults: %F+%R\n"
 export PATH := .:$(PATH)
 
-.PHONY: clean all compile assembly memcheck memcheck1 memcheck2 ex1 ex2 bear
+.PHONY: clean all compile assembly memcheck memcheck1 memcheck2 ex1 ex2
 
-all: ex1 ex2
+all: README.org ex1 ex2
 
 memcheck: memcheck1 memcheck2
 
 memcheck1: aoc-c
-	@valgrind -q -s --track-origins=yes aoc-c -p 1 < $(INPUT)
+	@$(VALGRIND) $(VALGRINDFLAGS) aoc-c -p 1 < $(INPUT)
 
 memcheck2: aoc-c
-	@valgrind -q -s --track-origins=yes aoc-c -p 2 < $(INPUT)
+	@$(VALGRIND) $(VALGRINDFLAGS) aoc-c -p 2 < $(INPUT)
+	@#@valgrind -s --track-origins=yes aoc-c -p 2 < $(INPUT)
 
 compile: aoc-c
 
 assembly: aoc-c.s
 
 ex1: aoc-c
-	@$(TIME) ex1.bash < $(INPUT) 2>&1
-	@$(TIME) aoc-c -p 1 < $(INPUT) 2>&1
+	@$(TIME) aoc-c -p 1 < $(INPUT)
 
 ex2: aoc-c
-	@$(TIME) ex2.bash < $(INPUT) 2>&1
-	@$(TIME) aoc-c -p 2 < $(INPUT) 2>&1
+	@$(TIME) aoc-c -p 2 < $(INPUT)
 
 clean:
-	@rm -f aoc-c core* vgcore* gmon.out aoc-c.s compile_commands.json
+	@rm -f aoc-c core* vgcore* gmon.out aoc-c.s aoc-c.i README.html compile_commands.json
 
 .c:
 	@echo compiling $<
-	$(CC) $(CFLAGS) $(LDFLAGS) -I $(INCDIR) $< $(LDLIB) -o $@
+	@$(CC) $(CFLAGS) $(LDFLAGS) -I $(INCDIR) $< $(LDLIB) -o $@
 
 # generate pre-processed file (.i) and assembler (.s)
 %.i: %.c
@@ -85,6 +87,7 @@ clean:
 	@echo generating $@
 	@$(CC) -S -fverbose-asm $(CFLAGS) -I $(INCDIR) $< -o $@
 
-bear: clean
-	@$(BEAR) -- make compile
-	@touch .ccls-root
+# generate README.org from README.html (must cleanup !)
+%.org: %.html
+	@echo generating $@. Cleanup before commit !
+	@pandoc $< -o $@