88 lines
1.8 KiB
Plaintext
88 lines
1.8 KiB
Plaintext
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#
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mes 2,EM_WSIZE,EM_PSIZE
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;
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; layout of a setjmp buffer:
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;
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; -----------------
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; | signal mask | (only for Berkeley 4.[2-])
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; -----------------
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; | |
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; | GTO descriptor |
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; | (SP, LB, PC) |
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; | |
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; -----------------
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;
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; setjmp saves the signalmask, PC, SP, and LB of caller, and creates a
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; GTO descriptor from this.
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; The big problem here is how to get the return address, i.e. the PC of
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; the caller; This problem is solved by the front-end, which must pass
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; it as an extra parameter to setjmp.
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; a GTO descriptor must be in the global data area
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gtobuf
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bss 3*EM_PSIZE,0,0
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inp $fill_ret_area
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exp $setjmp
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pro $setjmp,0
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#ifdef __BSD4_2
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; save mask of currently blocked signals.
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; longjmp must restore this mask
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loc 0
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cal $sigblock
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asp EM_WSIZE
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lfr EM_WSIZE
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lal 0
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loi EM_PSIZE
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stf 3*EM_PSIZE
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#endif
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; create GTO descriptor for longjmp
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lxl 0
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dch ; Local Base of caller
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lxa 0 ; Stackpointer of caller
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lal EM_PSIZE
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loi EM_PSIZE ; Return address of caller
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lal 0
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loi EM_PSIZE ; address of jmpbuf
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sti 3*EM_PSIZE ; LB, SP, and PC stored in jmpbuf
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loc 0
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ret EM_WSIZE ; setjmp must return 0
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end 0
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pro $fill_ret_area,0
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; put argument in function result area
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lol 0
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ret EM_WSIZE
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end 0
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exp $longjmp
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pro $longjmp,?
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#ifdef __BSD4_2
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; restore signal mask
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lal 0
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loi EM_PSIZE
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lof 3*EM_PSIZE
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cal $sigsetmask
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asp EM_WSIZE
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lfr EM_WSIZE
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asp EM_WSIZE
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#endif
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lal 0
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loi EM_PSIZE ; address of jmpbuf
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lae gtobuf
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blm 3*EM_PSIZE ; fill GTO descriptor from jmpbuf
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lol EM_PSIZE ; second parameter of longjmp: the return value
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dup EM_WSIZE
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zne *3
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; of course, longjmp may not return 0!
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asp EM_WSIZE
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loc 1
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3
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; put return value in function result area
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cal $fill_ret_area
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asp EM_WSIZE
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gto gtobuf ; there we go ...
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; ASP and GTO do not damage function result area
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end 0
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