# mes 2,EM_WSIZE,EM_PSIZE exp $setjmp pro $setjmp,3*EM_WSIZE ; setjmp saves the StackPointer and the LocalBase, and the chunk of ; memory between the StackPointer and the ArgumentBase, + its size in a ; buffer, pointed to by the parameter. ; longjump can then restore this buffer and return. ; Notice that this does not work on EM implementations in which every ; procedure frame has a different fragment in memory, because in this case ; the ArgumentBase will point into the fragment of the caller. ; What really is needed is a way to find out the size of the return ; status block. ; On EM-implementations in which the stack grows upwards it is untested, ; as there are no such implementations available now. ; This implementation of setjmp/longjmp ; depends on the assumption that the routine calling ; setjmp does not have register variables, and that it saves all registers ; that are available for variables. #ifdef __BSD4_2 loc 0 cal $sigblock asp EM_WSIZE lfr EM_WSIZE stl -3*EM_WSIZE #endif loc 0 stl -2*EM_WSIZE lor 1 ; load StackPointer lal 0 loi EM_PSIZE sti EM_PSIZE ; save it lxl 0 ; load LocalBase lal 0 loi EM_PSIZE adp EM_PSIZE sti EM_PSIZE ; save it lxa 0 ; load ArgumentBase lal 0 loi EM_PSIZE loi EM_PSIZE ; load saved StackPointer sbs EM_WSIZE ; gives size of block that is to be saved, or negative size dup EM_WSIZE zgt *5 ngi EM_WSIZE loc 1 stl -2*EM_WSIZE; one if the stack grows upwards 5 stl -EM_WSIZE ; save size of block in local lol -EM_WSIZE lal 0 loi EM_PSIZE adp 2*EM_PSIZE sti EM_WSIZE ; and also in the buffer lal 0 loi EM_PSIZE loi EM_PSIZE ; load saved StackPointer lol -2*EM_WSIZE; positive if the stack grows upwards zle *6 asp EM_PSIZE lxa 0 adp EM_WSIZE ; in this case the source address = ArgumentBase+EM_WSIZE 6 lal 0 loi EM_PSIZE adp 2*EM_PSIZE+EM_WSIZE ; destination address lol -EM_WSIZE ; count bls EM_WSIZE ; block copy loc 0 ret EM_WSIZE end 3*EM_WSIZE exp $longjmp pro $longjmp,3*EM_WSIZE ; first, find out wether the stack grows upwards loc 0 stl -2*EM_WSIZE lxa 0 lxl 0 cmp zge *7 loc 1 stl -2*EM_WSIZE; this local contains 1 if it does, otherwise it contains 0 7 ; then, adjust StackPointer until it is below the saved StackPointer (or ; above if it grows upwards) ; then push parameters ; then copy the saved block in its proper place ; notice that the parameters can not be used anymore now ; then restore the LocalBase and the Stackpointer and return. 1 loc 0 2 lor 1 lal 0 loi EM_PSIZE loi EM_PSIZE ; saved StackPointer cmp ; compare with current one lol -2*EM_WSIZE zle *8 zlt *1 bra *10 8 zgt *1 10 lal 0 loi EM_PSIZE loi EM_PSIZE ; push saved StackPointer lol EM_PSIZE ; push value to be returned by longjmp lal 0 loi EM_PSIZE adp EM_PSIZE loi EM_PSIZE ; push saved LocalBase lal 0 loi EM_PSIZE adp 2*EM_PSIZE+EM_WSIZE ; source address lal 0 loi EM_PSIZE loi EM_PSIZE ; saved stackpointer lol -2*EM_WSIZE zle *9 ; if not positive, this is the destination address, ; otherwise subtract the size of the saved area and add EM_WSIZE adp EM_WSIZE lal 0 loi EM_PSIZE adp 2*EM_PSIZE loi EM_WSIZE ngi EM_WSIZE ads EM_WSIZE 9 ; destination address lal 0 loi EM_PSIZE adp 2*EM_PSIZE loi EM_WSIZE ; size bls EM_WSIZE ; now we have a frame exactly as it was in setjmp, ; and exactly at the same place str 0 ; restore LocalBase stl -EM_WSIZE ; saves the return value str 1 ; restores the StackPointer #ifdef __BSD4_2 lol -3*EM_WSIZE cal $sigsetmask asp EM_WSIZE lfr EM_WSIZE asp EM_WSIZE #endif lol -EM_WSIZE dup EM_WSIZE zne *3 ; of course, longjmp may not return 0! asp EM_WSIZE loc 1 3 ret EM_WSIZE end 3*EM_WSIZE