ack/lang/m2/libm2/par_misc.e
1991-03-11 16:21:13 +00:00

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#
;
; (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
; See the copyright notice in the ACK home directory, in the file "Copyright".
;
;
; Module: coroutine primitives
; Author: Kees Bot, Edwin Scheffer, Ceriel Jacobs
; Version: $Header$
;
mes 2,EM_WSIZE,EM_PSIZE
; topsize takes care of two things:
; - given a stack-break,
; it computes the size of the chunk of memory needed to save the stack;
; - also, if this stack-break = 0, it creates one, assuming that caller is
; the stack-break.
;
; This implementation assumes a continuous stack growing downwards
exp $topsize
pro $topsize, 3*EM_WSIZE+3*EM_PSIZE
; local space for line-number, ignoremask, filename, stack-break, size,
; and stack-pointer (see the topsave routine)
mes 11
lal 0
loi EM_PSIZE
loi EM_PSIZE ; stack-break or 0
zer EM_PSIZE
cmp
zne *1
lxl 0
dch ; local base of caller
lal 0
loi EM_PSIZE
sti EM_PSIZE
1
lal 0
loi EM_PSIZE
loi EM_PSIZE
lpb ; convert this local base to an argument base.
; An implementation of a sort of "topsize" EM
; instruction should take a local base, and save
; the whole frame.
lor 1 ; stack-break SP
sbs EM_WSIZE ; stack-break-SP
ret EM_WSIZE ; return size of block to be saved
end 3*EM_WSIZE+3*EM_PSIZE
exp $topsave
pro $topsave, 0
mes 11
loe 0
lae 4 ; load line number and file name
loi EM_PSIZE
lim ; ignore mask
lor 0 ; LB
lal 0
loi EM_PSIZE ; stack-break
lpb
lor 1
sbs EM_WSIZE
loc EM_WSIZE
adu EM_WSIZE ; gives size
dup EM_WSIZE
stl 0 ; save size
lor 1 ; SP (the SP BEFORE pushing)
lor 1 ; SP (address of stack top to save)
lal EM_PSIZE ; area
loi EM_PSIZE
lol 0 ; size
bls EM_WSIZE ; move whole block
asp 3*EM_PSIZE+3*EM_WSIZE ; remove the lot from the stack
loc 1
ret EM_WSIZE ; return 1
end 0
sv
bss EM_PSIZE,0,0
exp $topload
pro $topload, 0
mes 11
lal 0
loi EM_PSIZE
lae sv
sti EM_PSIZE ; saved parameter
lxl 0
2
dup EM_PSIZE
lal 0
loi EM_PSIZE ; compare target SP with current LB to see if we must
loi EM_PSIZE
cmp ; find another LB first
zgt *1
dch ; just follow dinamic chain to make sure we find
; a legal one
bra *2
1
str 0
lae sv
loi EM_PSIZE
loi EM_PSIZE ; load indirect to
str 1 ; restore SP
asp -EM_PSIZE ; to stop int from complaining about non-existent memory
lae sv
loi EM_PSIZE ; source address
lor 1
adp EM_PSIZE ; destimation address
lae sv
loi EM_PSIZE
adp EM_PSIZE
loi EM_WSIZE ; size of block
bls EM_WSIZE ; move block back (SP becomes the SP AFTER again,
; because of the asp -EM_PSIZE!)
asp EM_PSIZE+EM_WSIZE ; drop size + SP
str 0 ; restore local base
sim ; ignore mask
lae 4
sti EM_PSIZE
ste 0 ; line and file
loc 0
ret EM_WSIZE ; return 0
end 0