; INIT.ASM - process control initialization  (Retro Unix 8086 v1 - /etc/init)
; ----------------------------------------------------------------------------
;
; RETRO UNIX 8086 (Retro Unix == Turkish Rational Unix)
; Operating System Project (v0.1) by ERDOGAN TAN (Beginning: 11/07/2012) 
; 1.44 MB Floppy Disk 
;
; [ Last Modification: 04/11/2013 ]
;
; Derivation from UNIX Operating System (v1.0 for PDP-11) 
; (Original) Source Code by Ken Thompson (1971-1972)
; <Bell Laboratories (17/3/1972)>
; <Preliminary Release of UNIX Implementation Document> (Section E.12)
;
; ****************************************************************************

; Derived from 'init.s' file of original UNIX v1

; INIT08.ASM, 24/10/2013

.8086

; UNIX v1 system calls
_rele 	equ 0
_exit 	equ 1
_fork 	equ 2
_read 	equ 3
_write	equ 4
_open	equ 5
_close 	equ 6
_wait 	equ 7
_creat 	equ 8
_link 	equ 9
_unlink	equ 10
_exec	equ 11
_chdir	equ 12
_time 	equ 13
_mkdir 	equ 14
_chmod	equ 15
_chown	equ 16
_break	equ 17
_stat	equ 18
_seek	equ 19
_tell 	equ 20
_mount	equ 21
_umount	equ 22
_setuid	equ 23
_getuid	equ 24
_stime	equ 25
_quit	equ 26	
_intr	equ 27
_fstat	equ 28
_emt 	equ 29
_mdate 	equ 30
_stty 	equ 31
_gtty	equ 32
_ilgins	equ 33

;;;
ESCKey equ 1Bh
EnterKey equ 0Dh

sys macro syscallnumber, arg1, arg2, arg3

    ; Retro UNIX 8086 v1 system call.

    ifnb <arg1> 	
      mov bx, arg1
    endif
    
    ifnb <arg2> 	
      mov cx, arg2
    endif

    ifnb <arg3> 	
      mov dx, arg3
    endif
     			
    mov ax, syscallnumber	
    int 20h	
   
    endm

; Retro UNIX 8086 v1 system call format:
; sys systemcall (ax) <arg1 (bx)>, <arg2 (cx)>, <arg3 (dx)>


UNIX   	SEGMENT PUBLIC 'CODE'
        assume cs:UNIX,ds:UNIX,es:UNIX,ss:UNIX

START_CODE:
	;sys _intr, 0  ; disable time-out function 
	;sys _quit, 0  ; disable quit (ctrl+brk) signal
	;
        sys _open, ctty, 0 ; open tty0
	jc error
        sys _open, ctty, 1 ; for read and write
	jc error
	;
	sys _write, 1, msg_te, sizeof_mte
	;jc error
@@:
	sys _read, 0, tchar, 1
	;jc error

	mov al, byte ptr [tchar]

	cmp al, ENTERKey
	je short multiuser

	cmp al, ESCKey
	jne short @b	


singleuser:
help:
 	sys _close, 0 ; close input file/tty
	;jc error
        sys _close, 1 ; close output file/tty
	;jc error
        sys _open, ctty, 0 ; open control tty
	;jc error
        sys _open, ctty, 1 ; for read an write
	;jc error

	sys _exec, shell, shellp

        jmp short singleuser


multiuser:
	sys _close, 0 ; close input file/tty
	;jc error
        sys _close, 1 ; close output file/tty
	;jc error
	;
	sys _mount, fd1, usr  ; root directory on mounted fd1
			      ; disk is /usr
	sys _creat, utmp, 14  ; truncate /tmp/utmp
	;jc error
	sys _close, ax        ; close it
	mov byte ptr [zero]+8, 0 ; put identifier 
				    ; in output buffer
	call wtmprec	      ; go to write acting info
	jc error

	mov si, offset itab   ; address of table to SI

; create shell processes
@@:
	lodsw 		      ; 'x', x=0, 1... to AX
	and ax, ax
	jz short pwait	      ; branch if table end
	mov byte ptr [ttyx]+8, al ; put symbol in ttyx
	mov di, si	
	call dfork            ; go to make new init for this ttyx
	stosw		      ; save child id in word offer
	 		      ;	'0', '1',...etc.
	mov si, di
	jmp short @b          ; set up next child

; wait for process to die
pwait:
        sys _wait       ; wait for user to terminate process
	mov si, offset itab ; initialize for search
	mov dx, ax

; search for process id
@@:
	lodsw		; bump SI to child id location
	or ax, ax
	jz short pwait 	; ? something silly

	lodsw
	cmp dx, ax      ; which process has terminated
	jne short @b  	; not this one

; take name out of utmp
	sub si, 4       ; process is found, point x to 'x'
		        ; for it
	;push si	; save address on stack
	mov dx, word ptr [SI] ; move 'x' to DX
	sub dx, '0'	; remove zone bits from character
	shl dx, 1	; generate proper
	shl dx, 1	; offset
	shl dx, 1	; for
	shl dx, 1	; seek
	mov di, offset zero
	xor ax, ax ; 0	; clear	
	mov cx, 8	; output buffer	
	rep stosw	 
	sys _open, utmp, 1 ; open file for writing
	jc short @f	; if can't open, create user anyway
	mov di, ax	; save file desc
	sys _seek, ax, dx, 0 ; move to proper
			     ; pointer position
	sys _write, di, zero, 16 ; zero this position in
	sys _close, di  ; close file

; re-create user process
@@:
	;pop si		; restore 'x' to SI
	lodsw		; move it to AX
	mov di, si 
	mov byte ptr [ttyx]+8, al ; get correct ttyx
	mov byte ptr [zero]+8, al
	 		; move identifier to output buffer
	call wtmprec    ; go to write accting into
	call dfork      ; fork
	stosw		; save id of child
;short olacak
        jmp pwait ; go to wait for next process end


dfork:
	mov bx, offset @f ; return address for new process
	sys _fork
	jc short dfork ; try again
	retn

@@: ; to new copy of init
	;sys _quit, 0  ; disable quit (ctrl+brk) signal
	;sys _intr, 0  ; disable time-out function 
	;sys _chown, ttyx, 0
	;sys _chmod; ttyx, 15
	;
	sys _open, ttyx, 0 ; open this ttyx for reading
	                   ; and wait until someone calls
	jc short help1     ; branch if trouble
	sys _open, ttyx, 1 ; open this ttyx for writing
			   ; after user call
        jc short help1     ; branch if trouble
	sys _exec, getty, gettyp ; getty types <login> and
		           	 ; executes login which logs user
			         ; in and executes sh-
	sys _exit  ; HELP!

help1:
	jmp help


wtmprec:
	sys _time  ; get time
	mov word ptr [zero]+10, ax ; more to output
	mov word ptr [zero]+12, dx ; buffer

	sys _open, wtmp, 1 ; open accounting file
	jc short @f
	mov si, ax ; save file descriptor

	sys _seek, ax, 0, 2 ; move pointer to end of file
	;;push si    ; save file descriptor
	;jc short @f

	sys _write, si, zero, 16 ; write accting info
	;;pop bx	  ; restore file descriptor
	;jc short @f

	sys _close, si ; close file

@@:
	retn

here:
	hlt
	jmp short here

error:
	mov si, offset msg_err
	call print_msg
        jmp short @b
 
print_msg:
	mov     AH,0Eh
	mov	bl, 7
	mov	bh, byte ptr [ttyx]+8
	sub 	bh, '0'                  
@@:
        lodsb                           ; Load byte at DS:SI to AL
        and     AL,AL            
        jz      short @f      
            
        int     10h                     ; BIOS Service func ( ah ) = 0Eh
                                        ; Write char as TTY
                                        ;AL-char BH-page BL-color
	jmp     short @b         
@@:
        retn


EVEN
tchar:  db 0

EVEN
ctty:   db "/dev/tty", 0
EVEN
shell:  db "/bin/sh", 0
shellm: db "-", 0

;EVEN
usr:	db "/usr",0
EVEN
fd1:	db "/dev/fd1", 0

EVEN
utmp:   db "/tmp/utmp", 0
wtmp:   db "/tmp/wtmp", 0
ttyx:   db "/dev/ttyx", 0
getty:  db "/etc/getty",0

EVEN
shellp: dw shellm
        dw 0
gettyp: dw getty
	dw 0
itab:
	db '0',0, 0,0
	db '1',0, 0,0
	db '2',0, 0,0
	db '3',0, 0,0
	db '4',0, 0,0
	db '5',0, 0,0
	db '6',0, 0,0
	db '7',0, 0,0
	dw 0
zero:
	db 8 dup(0)
	db 6 dup(0)
	db 2 dup(0)	 	

msg_te:
        db 0Dh, 0Ah
        db 'Type ENTER to start in multi user mode', 0Dh, 0Ah
        db 'or type ESC to start in single user mode.'
        db 0Dh, 0Ah
sizeof_mte equ $ - offset msg_te 
        db 0

msg_ok:
        db 0Dh, 0Ah
        db 'OK... '
        db 0Dh, 0Ah
sizeof_ok equ $ - offset msg_ok 
        db 0

msg_err:
	db 0Dh, 0Ah 
        db 'Error ! '
nextline:
	db 0Dh, 0Ah, 0

hext:
	db "00"
	db "01"
	db "02"
	db "03"
	db "04"
	db "05"
	db "06"
	db "07"
	db "08"
	db "09"
	db "0A"
	db "0B"
	db "0C"
	db "0D"
	db "0E"
	db "0F"
	db "FF"
	dw 0
chldm:
	db 0Dh, 0Ah
	db '(Return from syswait)'
	db 0Dh, 0Ah
	db 'Child Process No: '
chld:	dw 3030h
	db 'h '
	db 0Dh, 0Ah
sizeofchld equ $ - offset chldm
	db 0

rcu:	db 0Dh, 0Ah
	db "<Re-create user process> is OK!"
	db 0Dh, 0Ah
	db 0		

UNIX   	ends


; / init -- process control initialization
;
;	sys	intr; 0
;	sys	quit; 0
;	sys	38. / get console switches
;	cmp	r0,$173030
;	bne	1f
;help:
;	clr	r0
;	sys	close
;	mov	$1,r0
;	sys	close
;	sys	open; ctty; 0
;	sys	open; ctty; 1
;	sys	exec; shell; shellp
;	br	help
;1:
;	sys	mount; rk1; usr
;	sys	mount; rk2; ssys
;	sys	mount; rk3; crp
;	mov	$'0,r1
;1:
;	movb	r1,tapx+8
;	sys	chmod; tapx; 17
;	inc	r1
;	cmp	r1,$'8
;	blo	1b
;	sys	creat; utmp; 16
;	sys	close
;	sys	unlink; dpdlock
;	sys	fork
;		br daemon
;	sys	fork
;		br dirass
;	sys	fork
;		br dds
;	movb	$'x,zero+8.
;	jsr	pc,wtmprec
;	mov	$itab,r1
;	br	1f
;
;daemon:
;	sys	exec; etcdpd; etcdpdp
;	sys	exit
;
;dirass:
;	sys	chdir; usrmel
;	sys	exec; melda; meldap
;	sys	exit
;
;dds:
;	sys	exec; usrdd; usrddp
;	sys	exit
;
;/ create shell processes
;
;1:
;	mov	(r1)+,r0
;	beq	pwait
;	movb	r0,ttyx+8
;	jsr	pc,dfork
;	mov	r0,(r1)+
;	br	1b
;
;/ wait for process to die
;
;pwait:
;	sys	wait
;	mov	$itab,r1
;
;/ search for process id
;
;2:
;	tst	(r1)+
;	beq	pwait
;	cmp	r0,(r1)+
;	bne	2b
;
;/ take name out of utmp
;
;	sub	$4,r1
;	mov	r1,-(sp)
;	mov	(r1),r1
;	sub	$'0,r1
;	cmp	r1,$'a-'0
;	blo	2f
;	sub	$'a-'0-10.,r1	/ map a-z into 10. on
;2:
;	asl	r1
;	asl	r1
;	asl	r1
;	asl	r1
;	mov	r1,0f
;	mov	$zero,r1
;2:
;	clr	(r1)+
;	cmp	r1,$zero+16.
;	blo	2b
;	sys	open; utmp; 1
;	bes	2f
;	mov	r0,r1
;	sys	seek; 0:..; 0
;	mov	r1,r0
;	sys	write; zero; 16.
;	mov	r1,r0
;	sys	close
;
;/ re-create user process
;
;2:
;	mov	(sp)+,r1
;	mov	(r1)+,r0
;	movb	r0,ttyx+8
;	movb	r0,zero+8.
;	jsr	pc,wtmprec
;	jsr	pc,dfork
;	mov	r0,(r1)+
;	br	pwait
;
;dfork:
;	sys	fork
;		br 1f
;	bes	dfork
;	rts	pc
;1:
;	sys	quit; 0
;	sys	intr; 0
;	sys	chown; ttyx; 0
;	sys	chmod; ttyx; 15
;	sys	open; ttyx; 0
;	bes	help1
;	sys	open; ttyx; 1
;	bes	help1
;	sys	exec; getty; gettyp
;	sys	exit			/ HELP!
;
;help1:
;	jmp	help
;
;wtmprec:
;	mov	r1,-(sp)
;	sys	time
;	mov	r0,zero+10.
;	mov	r1,zero+12.
;	sys	open; wtmp; 1
;	bes	2f
;	mov	r0,r2
;	sys	seek; 0; 2
;	mov	r2,r0
;	sys	write; zero; 16.
;	mov	r2,r0
;	sys	close
;2:
;	mov	(sp)+,r1
;	rts	pc
;
;etcdpdp:
;	etcdpd; 0
;meldap:
;	melda; 0
;usrddp:
;	usrdd; 0
;usrdd:	</usr/demo/dds\0>
;melda:	</usr/mel/da\0>
;usrmel:</usr/mel\0>
;rk1:	</dev/rk1\0>
;rk2:	</dev/rk2\0>
;rk3:	</dev/rk3\0>
;usr:	</usr\0>
;ssys:	</sys\0>
;crp:	</crp\0>
;ctty:	</dev/tty\0>
;shell:	</bin/sh\0>
;shellm:<-\0>
;dpdlock:
;	</usr/dpd/lock\0>
;etcdpd:
;	</etc/dpd\0>
;tapx:	</dev/tapx\0>
;utmp:	</tmp/utmp\0>
;wtmp:	</tmp/wtmp\0>
;ttyx:	</dev/ttyx\0>
;getty:	</etc/getty\0>
;	.even
;
;shellp:shellm
;	0
;gettyp:getty
;	0
;itab:
;	'0; ..
;	'1; ..
;	'2; ..
;	'3; ..
;	'4; ..
;	'5; ..
;	'6; ..
;	'7; ..
;	'8; ..
;	'a; ..
;	'b; ..
;	 0
;
;	.bss
;offset:.=.+2
;zero:	.=.+8.; .=.+6; .=.+2.


        end  START_CODE
