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]
 
 ENDSTRUC
 
 
-%macro TIMESPEC 1
+%macro TIMESPEC 3
 	%1: ISTRUC TIMESPEC_STRUC
-		at TIMESPEC_STRUC.tv_sec, dq 0
-		at TIMESPEC_STRUC.tv_nsec, dq 0
+		at TIMESPEC_STRUC.tv_sec, dq %2
+		at TIMESPEC_STRUC.tv_nsec, dq %3
 	IEND
 	%define %1.tv_sec %1+TIMESPEC_STRUC.tv_sec
 	%define %1.tv_nsec %1+TIMESPEC_STRUC.tv_nsec
 	%define sigaction.sa_restorer sigaction+SIGACTION_STRUC.sa_restorer
 	%define sigaction.sa_mask sigaction+SIGACTION_STRUC.sa_mask
 
-	TIMESPEC ts_start
-	TIMESPEC ts_cur
-
-	ts_sleep:
-		tv_sleep_s dq 0
-		tv_sleep_us dq 10000000
-
-	;; 1/2s sleep
-	;ts_sleep:
-	;	tv_sleep_s dq 0
-	;	tv_sleep_us dq 500000000
+	TIMESPEC ts_start, 0, 0
+	TIMESPEC ts_cur, 0, 0
+	TIMESPEC ts_sleep, 0, 100000000 ; set before mainloop
 
 
 	faultmsg: db "Fault !", 0xA
 	db 0xA
 	startmsglen: equ $ - startmsg
 
+	usage_pre: db "Usage : "
+	usage_prelen: equ $ - usage_pre
+
+	usage_post: db " [-h] [-r NDIGITS]", 0xA
+		db "Options :", 0xA
+		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 : "
+	badarg_msglen: equ $ - badarg_msg
+
+	badval_msg: db "Value for -r should be in [1..8] but got "
+	badval_msglen: equ $ - badval_msg
+
 	hours: db "000000000"
-	timestr: db ":00:00.0000    ", 0x0a
+	timestr: db ":00:00.0           ", 0x0a
 	timestrlen: equ $ - timestr
 
+	time_res: dq 2 ; 2 digits bellow seconds can grow to 8
+
 	nl: db 0x0A
 	buf: db 0
 
 global _start
 _start:
 
+; parse arguments and set time_res value
+jmp arg_parse
+arg_ok:
+
 ; set stdin non blocking
 xor rdx, rdx
 xor rdi, rdi
 mov rdx, startmsglen
 syscall
 
+; set value for ts_sleep.tv_nsec given time_res
+; div sleep time by 10 for each digits added bellow seconds
+mov rax, 100000000
+mov r8, [time_res]
+mov r9, 10
+xor rdx, rdx
+setsleep_loop:
+	cmp r8, 1
+	jle setsleep_endloop
+	div r9
+	sub r8, 1
+	jmp setsleep_loop
+setsleep_endloop:
+mov [ts_sleep.tv_nsec], rax
+
 main_loop:
 	push 2 ; stderr
 	push 0x0D ; \r
 	sub rbx, 1
 	mov [ts_cur.tv_sec], rbx
 	print_time_us_cont:
+	
+	; Divide result given time_res
+	mov r10, rax
+	mov rax, 1000000000
+	mov r9, [time_res]
+	mov r8, 10
+	xor rdx, rdx
+	print_time_respow:
+		div r8
+		sub r9, 1
+		cmp r9, 0
+		jg print_time_respow
+	mov rcx, rax
+	mov rax, r10
 	xor rdx, rdx
-	mov rcx, 100000
 	div rcx
+
 	; set the us char in timestr
 	mov r8, timestr
-	add r8, 10 ; r8 points on last char before \r
-	mov r9, 4 ; r9 count the number of digits
+	mov r9, [time_res] ; r9 count the number of digits
+	add r8, 6 ; first digits after seconds
+	add r8, r9 ; r8 points on last char before \r
 	print_time_us_loop:
 		xor rdx, rdx
 		mov rcx, 10
 	xor rdi, rdi
 	syscall
 
+;
+;	Argument parsing
+;
+arg_parse:
+	; Checking argument count
+	mov rax, [rsp]
+	cmp rax, 1
+	je arg_ok
+	cmp rax, 3
+	jle parse_r
+	arg_err: ; badval & badarg jmp here too
+		mov rax, [rsp+8] ; argv[0] program name
+		mov rdi, -1 ; return status
+		jmp usage
+	parse_r:
+	mov rax, [rsp+16] ; 1st arg should be "-r"
+	mov bl, [rax]
+	cmp bl, '-'
+	jne badarg
+	mov bl, [rax+1]
+	cmp bl, 'h' ; -h
+	je arg_err
+	cmp bl, 'r'
+	jne badarg
+	mov bl, [rax+2]
+	cmp bl, 0
+	jne arg_nxt ; the value seems to be just after the -r like -r2
+	nxt_arg:
+		; the 1st argument is -r the second must be the time_res
+		; check that the arg exists
+		mov rax, [rsp]
+		cmp rax, 3
+		jne arg_err
+		mov rax, [rsp+24]
+		jmp arg_cont
+	arg_nxt:
+		; check that there is no more args
+		mov rbx, [rsp]
+		cmp rbx, 2
+		jne arg_err
+		add rax, 2
+	arg_cont:
+	; rax should point on the value
+	mov bl, [rax+1]
+	cmp bl, 0
+	jne badval
+	xor rbx, rbx
+	mov bl, [rax]
+	cmp bl, '1'
+	jl badval
+	cmp bl, '8'
+	jg badval
+	sub bl, '0'
+	mov [time_res], rbx
+	jmp arg_ok
+
+; print an error message, usage and exit with rax pointing the value
+badval:
+	mov rsi, badval_msg
+	mov rdx, badval_msglen
+	jmp arg_strerr
+
+; print an error message, usage and exit
+badarg:
+	mov rsi, badarg_msg
+	mov rdx, badarg_msglen
+	mov rax, [rsp+16]
+	jmp arg_strerr
+
+; rsi msg ptr, rdx msg len, rax arg ptr
+arg_strerr:
+	mov r8, rax
+	mov rax, 1
+	mov rdi, 1
+	syscall
+	mov rsi, r8
+	mov rax, r8
+	call proc_strlen
+	mov rax, 1
+	syscall
+	mov rax, 1
+	mov rsi, nl
+	mov rdx, 1
+	syscall
+	syscall
+	jmp arg_err
+
+;
+; Print usage and exit
+; 	Except rax to point on programm name and rdi to be the return code
+;
+usage:
+	push rdi
+	push rax
+
+	mov rax, 1 ; write
+	mov rdi, 1 ; stdout
+	mov rsi, usage_pre
+	mov rdx, usage_prelen
+	syscall
+
+	pop rsi
+	mov rax, rsi
+	call proc_strlen
+	mov rax, 1
+	syscall
+
+	mov rax, 1
+	mov rsi, usage_post
+	mov rdx, usage_postlen
+	syscall
+
+	mov rax, 60
+	pop rdi
+	syscall
+
+; With rax pointing on the string, the result will be in rdx
+proc_strlen:
+	mov r8, rax
+	mov r9, r8
+	sub r9, 1
+	strlen_loop:
+		add r9, 1
+		mov al, [r9]
+		cmp al, 0
+		jne strlen_loop
+	sub r9, r8
+	mov rdx, r9
+	ret
+
 .end: