Updated comments, Makefile and REAMDE.txt

Makefile

+NASM=nasm
+ASFLAGS=-felf64
+LDFLAGS=-s -melf_x86_64
+
+# To build with debugging symbols
+#ASFLAGS=-felf64 -F dwarf -g
+#LDFLAGS=-melf_x86_64
+
 all: wtfstopw
 
 wtfstopw: wtfstopw.o
-	ld -s -melf_x86_64 wtfstopw.o -o wtfstopw
+	ld $(LDFLAGS) wtfstopw.o -o wtfstopw
 wtfstopw.o: wtfstopw.asm
-	nasm -felf64 wtfstopw.asm
+	$(NASM) $(ASFLAGS) wtfstopw.asm
 	
 .PHONY: clean
 

README.txt

 
 Build :
 -------
-
-make
-
+	make
 or
-
-nasm -felf64 wtfstopw.asm && ld -s -melf_x86_64 wtfstopw.o -o wtfstopw
+	nasm -felf64 wtfstopw.asm
+	ld -s -melf_x86_64 wtfstopw.o -o wtfstopw
 
 Usage :
 -------
-./wtfstopw
+	./wtfstopw [-h] [-r NDIGITS]
+Options :
+---------
+	-h print an help message and exit
+	-r number of digits bellow seconds to display, default is 2
 
 Interactions :
 --------------
-- press enter to exit or close stdin
-- send SIGINT (with kill -2 or ctrl + c) for new lap on stdout
-- elapsed time is sent on stderr and laps infos on stdout
+	press enter to exit or close stdin
+	send SIGINT (with kill -2 or ctrl + c) for new lap on stdout
+	elapsed time is sent on stderr and laps infos on stdout
+
 
+Build with debugging symbols :
+------------------------------
+	nasm -g -F dwarf -felf64 -l wtfstopw.lst wtfstopw.asm
+	ld -melf_x86_64 wtfstopw.o -o wtfstopw

wtfstopw.asm

 ;
 ; A simple precise stopwatch
 ; Build : nasm -felf64 wtfstopw.asm && ld -s -melf_x86_64 wtfstopw.o -o wtfstopw
-; Build Debug : nasm -felf64 -l wtfstopw.lst wtfstopw.asm && ld -melf_x86_64 wtfstopw.o -o wtfstopw
-;
-; Usage : ./wtfstopw
-;	press enter to exit
-;	send SIGINT (with kill -2 or ctrl + c) for new lap on stdout
+; Build Debug : nasm -g -F dwarf -felf64 -l wtfstopw.lst wtfstopw.asm && ld -melf_x86_64 wtfstopw.o -o wtfstopw
 ;
+; ./wtfstopw [-h] [-r NDIGITS]
+; Options :
+; 	-h print this help and exit
+; 	-r number of digits bellow seconds to display, default is 2
+; Interact :
+; 	press enter to exit
+; 	send SIGINT (with kill -2 ir ctrl + c) for a new lap
+
+
 
 [bits 64]
 
 		db 0x9, "-h print this help and exit", 0xA
 		db 0x9, "-r Number of digits bellow seconds, between [1..8]"
 		db 0xA
+		db "Interactions :", 0xA
+		db 0x9, "Press enter or close stdin to exit", 0xA
+		db 0x9, "Send SIGINT (with kill -2 or ctrl + c) for a new lap"
+		db 0xA
+		db 0x9, "Elapsed time is sent on stderr and laps infos on stdout"
+		db 0xA
 	usage_postlen: equ $ - usage_post
 
 	badarg_msg: db "Unexpected argument : "