PDP-10.its/src/mits_s/uuo.3

	.title	System call support
	.sbttl	EMT handling (system calls)

;;; ;;; General info:
;;; ;;; 	Emulator trap setup and dispatch.  Also contains some of the system
;;; ;;; 	wide traps.
;;; ;;; Known bugs:
;;; ;;; 	$CHINT is not defined (should probably be flushed).
;;; ;;; 	$CNSGE is not defined if there are no terminals.

.macro .args a,b,c,d,e,f
 .irp arg,<a,b,c,d,e,f>
  .irp num,\.irpcnt
   .lif nb arg
     mov arg,r'num
  .endm
 .endm
.endm

.macro	systrp num,name
.'name=emt+<<num>&<377>>
.word $'name
.endm

emttb1:
	systrp	-34,makchn	;make a channel from a device at user level
	systrp	-32,ioctl	;other I/O control
	systrp	-30,dup		;duplicate an I/O channel
	systrp	-26,link	;link channels together
	systrp	-24,unlink	;unlink channel
	systrp	-22,chint	;set channel interrupt
	systrp	-20,close	;close a channel
	systrp	-16,status	;get channel status
	systrp	-14,count	;get character count
	systrp	-12,soutz	;asciz string output
	systrp	-10,sout	;string output
	systrp	-06,sin		;string input
	systrp	-04,bout	;byte output
	systrp	-02,bin		;byte input
emttbl:	systrp	000,hang	;comparison hang
	systrp	002,rti		;software interrupt return
	systrp	004,sleep	;process sleep
	systrp	006,open	;device open
	systrp	010,uall	;user allocate
	systrp	012,udall	;user deallocate
	systrp	014,logout	;logout user
	systrp	016,usrgo	;start up a job
	systrp	020,cnsget	;get tty index
	systrp	022,ccnmks	;chaos:make-connection

uuoini:	mov #emtbrk,@#030
	mov #pr7,@#030+2
	mov #trpbrk,@#034
	mov #pr7,@#034+2
	return

emtbrk:	mtps 2(sp)		;reset priority level
	push r5,r4		;save a couple regs
	mov usrnow,r5		;get the current user
	bis #%pclok,ustop(r5)	;job can be pclsr'd
	clr usrerr(r5)		;no error yet
	mov 4(sp),r4		;get return address
	movb -2(r4),r4		;get low byte of emt instruction
	call @emttbl(r4)	;call the routine
	bic #%pclok,ustop(r5)	;can no longer pclsr job
	ifpclsr <
	  bic #%pclsr,ustop(r5)
	  pop r4,r5
	  sub #2,(sp)		;backup over the emt
	  jcall schslp		;put this process to sleep and wake up
				;somebody
	  >
	bic #psw.c,6(sp)	;no error yet
	tst usrerr(r5)
	if ne,<bis #psw.c,6(sp)>
	pop r4,r5
	rti



;;; 	psw at software interrupt time
;;; 	pc  at software interrupt time
;;; 	saved r0
;;; 	psw of .rti
;;; 	pc  of .rti
;;; 	r5
;;; 	r4
;;; sp/	return address

$rti:	pop *,r4,r5,*,*
	tst r0
	if ne,<mov r0,2(sp)>
	pop r0
	rti

;;; When the hang function is true (skips) the process is eligible
$hang:	mov r0,usrhng(r5)
	mov r1,hngpt1(r5)
	mov r2,hngpt2(r5)
	bis #%ishng,ustop(r5)	;declare hanging
	.deshed
	bic #%ishng,ustop(5)	;declare not hanging
	return


.macro hng.fn name,instr,test
hng.'name:
	instr @hngpt1(r5),@hngpt2(r5)
	if test,<add #2,(sp)>
	return
.endm

hng.fn eq,cmp,eq
hng.fn ne,cmp,ne
hng.fn le,cmp,le
hng.fn lt,cmp,lt
hng.fn pl,cmp,pl
hng.fn lo,cmp,lo
hng.fn gt,cmp,gt
hng.fn be,bit,eq
hng.fn bn,bit,ne

hng.or:	tst @hngpt1(r5)
	if eq,<
	  tst @hngpt2(r5)
	  if eq,<return>
	  >
	add #2,(sp)
	return

hng.and:tst @hngpt1(r5)
	if ne,<
	  tst @hngpt2(r5)
	  if ne,<add #2,(sp)>
	  >
	return


$sleep:	tst r1
	if eq,<			;if r1=0, then r0 is delta
	  add time,r0		;compute absolute
	  com r1		;and make r1<>0
	  >
	push r2,r1,r0		;save registers
	.args #hng.pl,#time,sp
	call $hang		;hang until when time>r0
	pop r0,r1,r2		;restore
	return


$uall:	tst usrvrs(r5)		;does the jobs variables already exist?
	if ne,<
	  mov usrvrs(r5),r0
	  return
	  >
	loop <
	  push r0,r0		;on stack: r0 r0
	  call fsmall
	  call fsmclr		;zero them
	  pop r0		;on stack: r0
	  if ne,<
	    mov r0,usrvrs(r5)
	    pop *
	    return
	    >
	  call $fsmhng		;wait for a block to get freed
	  pop r0		;get back the r0 on the stack
	  ifpclsr <return>
	  rptl
	  >

$udall:	push usrvrs(r5)
	if eq,<pop *>
	else <
	  call fsmfre
	  clr usrvrs(r5)
	  >
	return


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