Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!ncar!boulder!ccncsu!haines
From: haines@debussy.cs.colostate.edu (Matt Haines)
Newsgroups: comp.sys.hp
Subject: HPPA Context switching code - still having problems
Message-ID: <7748@ccncsu.ColoState.EDU>
Date: 29 Jun 90 21:28:32 GMT
Sender: news@ccncsu.ColoState.EDU
Organization: Colorado State Computer Science Department
Lines: 122

Hi again.

I'm still working on the HPPA context-switching code, and I'm still
having some problems.  I fixed my problem with doubles (the dynamic
storage allocator wasn't aligning things on full word boundaries),
but it still core dumps sometimes.  I say sometimes because for some
programs it seems to work fine.

Anyway, I have included the crux of the code.  There are two routines,
Save and Restore.  They both take an argument of an integer array
whose elements are used to save arguments 1 & 2, the PC and the SP, in
that order.  Two external variables are also used to save/restore the
SP and PC.

If there are any obvious errors in my assembly, please let me know.  I'm
having a helluva time getting this thing to run.  (BTW, I did the 
Decstation - Sparc - code in about a day and it worked fine; if anyone
needs that stuff, let me know).

Thanks in advance,
Matt.

-------------------------------------------------------------------------

		.CODE
Save
		.PROC				; declare a procedure
		.CALLINFO CALLER,FRAME=48
		.ENTRY
		LDO	96(30),30		; make room on the stack
						; for saved registers.
		;
		; save gr registers %gr19 .. %gr22
		;
		STW	19,-52(0,30)
		STW	20,-56(0,30)
		STW	21,-60(0,30)
		STW	22,-64(0,30)
		;
		; save fp registers %fr8 .. %fr11
		;
		LDO	-72(30),3
		FSTDS	%fr8,0(0,3)
		LDO	-80(30),3
		FSTDS	%fr9,0(0,3)
		LDO	-88(30),3
		FSTDS	%fr10,0(0,3)
		LDO	-96(30),3
		FSTDS	%fr11,0(0,3)
		;
		; Store the pc and sp to the argment array, elements 2 & 3.
		;
		STW	2,8(0,26)		; save the pc
		STW	30,12(0,26)		; save the sp
		;
		; Get new values for sp and pc from external variables
		;
		ADDIL	L%WorkerSP-$global$,27
		LDW	R%WorkerSP-$global$(0,1),30 ; restore the sp
		ADDIL	L%WorkerPC-$global$,27
		LDW	R%WorkerPC-$global$(0,1),2  ; restore the pc
		;
		; Ok, now go ...
		;
		BE	0(0,2)
		NOP
		.EXIT
		.PROCEND
		.IMPORT WorkerPC,DATA
		.IMPORT WorkerSP,DATA
		.IMPORT $global$,DATA
		.EXPORT Save

; *****************************************************************************

		.CODE
Restore
		.PROC				; declare a procedure
		.CALLINFO CALLER,FRAME=0
		.ENTRY
		;
		; Restore the pc and sp from the argument array, elements 2 & 3
		;
		LDW	8(0,26),2		; reset the pc
		LDW	12(0,26),30		; reset the sp
		;
		; restore gr registers %gr19 .. %gr22
		;
		LDW	-52(30),19
		LDW	-56(30),20
		LDW	-60(30),21
		LDW	-64(30),22
		;
		; restore fp registers %fr4 .. %fr11
		;
		LDO	-72(30),3
		FLDDS	0(0,3),%fr8
		LDO	-80(30),3
		FLDDS	0(0,3),%fr9
		LDO	-88(30),3
		FLDDS	0(0,3),%fr10
		LDO	-96(30),3
		FLDDS	0(0,3),%fr11
		;
		; Re-adjust the sp
		;
		LDO	-96(30),30
		;
		; Go ...
		;
		BE	0(0,2)			; start thread
		NOP
		.EXIT
		.PROCEND
		.EXPORT Restore

-----------------------------------------------------------------------------
--
Matt Haines <haines@cs.colostate.edu>   | "Don't take life too seriously ...
Colorado State University, CS Dept.     |     nobody gets out of here alive!"
503 University Services Center          |                     - Jim Morrison 
Ft. Collins, CO  80523 | (303) 491-1943 |