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improved comments; should now be understandable for anyone who knows EM

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This commit is contained in:
ceriel 1988-04-21 10:08:56 +00:00
parent e41fd6d8a9
commit 5f4707b280
1 changed files with 19 additions and 12 deletions
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31
lang/cem/libcc/gen/setjmp.e
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@ -5,7 +5,7 @@
; layout of a setjmp buffer:
;
; -----------------
; | signal mask | (only for Berkeley 4.2)
; | signal mask | (only for Berkeley 4.[2-])
; -----------------
; | |
; | GTO descriptor |
@ -19,14 +19,16 @@
; the caller; This problem is solved by the front-end, which must pass
; it as an extra parameter to setjmp.
; a GTO descriptor must be in the global data area
gtobuf
bss 3*EM_PSIZE,0,0
inp $fill_ret_area
exp $setjmp
pro $setjmp,0
mes 11
#ifdef __BSD4_2
; save mask of currently blocked signals.
; longjmp must restore this mask
loc 0
cal $sigblock
asp EM_WSIZE
@ -35,46 +37,51 @@ gtobuf
loi EM_PSIZE
stf 3*EM_PSIZE
#endif
; create GTO descriptor for longjmp
; create GTO descriptor for longjmp
lxl 0
dch ; Local Base of caller
lxa 0 ; Stackpointer of caller
lal EM_PSIZE
loi EM_PSIZE
loi EM_PSIZE ; Return address of caller
lal 0
loi EM_PSIZE
sti 3*EM_PSIZE ; stored in jmpbuf
loi EM_PSIZE ; address of jmpbuf
sti 3*EM_PSIZE ; LB, SP, and PC stored in jmpbuf
loc 0
ret EM_WSIZE
ret EM_WSIZE ; setjmp must return 0
end 0
pro $fill_ret_area,0
; put argument in function result area
lol 0
ret EM_WSIZE
end 0
exp $longjmp
pro $longjmp,?
#ifdef __BSD4_2
; restore signal mask
lal 0
loi EM_PSIZE
#ifdef __BSD4_2
dup EM_PSIZE
lof 3*EM_PSIZE
cal $sigsetmask
asp EM_WSIZE
lfr EM_WSIZE
asp EM_WSIZE
#endif
lal 0
loi EM_PSIZE ; address of jmpbuf
lae gtobuf
blm 3*EM_PSIZE
lol EM_PSIZE
blm 3*EM_PSIZE ; fill GTO descriptor from jmpbuf
lol EM_PSIZE ; second parameter of longjmp: the return value
dup EM_WSIZE
zne *3
; of course, longjmp may not return 0!
; of course, longjmp may not return 0!
asp EM_WSIZE
loc 1
3
; put return value in function result area
cal $fill_ret_area
asp EM_WSIZE
gto gtobuf ; there we go ...
; ASP and GTO do not damage function result area
end 0