lib/libc/ack/rts/setjmp.e

   1 #
   2  mes 2,_EM_WSIZE,_EM_PSIZE
   3 ;
   4 ; layout of a setjmp buffer:
   5 ;
   6 ;  -----------------
   7 ; |      flag       |           (!0 when blocked signals saved (POSIX))
   8 ;  -----------------
   9 ; | signal mask/set |           (for Berkeley 4.[2-] / POSIX)
  10 ;  -----------------
  11 ; |                 |
  12 ; |  GTO descriptor |
  13 ; |   (SP, LB, PC)  |
  14 ; |                 |
  15 ;  -----------------
  16 ;
  17 ; setjmp saves the signalmask, PC, SP, and LB of caller, and creates a
  18 ; GTO descriptor from this.
  19 ; The big problem here is how to get the return address, i.e. the PC of
  20 ; the caller; This problem is solved by the front-end, which must pass
  21 ; it as an extra parameter to setjmp.
  22
  23 ; a GTO descriptor must be in the global data area
  24 gtobuf
  25  bss 3*_EM_PSIZE,0,0
  26
  27  inp $fill_ret_area
  28  exp $__setjmp
  29  pro $__setjmp,0
  30 #if     defined(_POSIX_SOURCE)
  31 ; save mask of currently blocked signals.
  32 ; longjmp must restore this mask
  33  lol _EM_PSIZE                  ; the flag integer at offset _EM_PSIZE
  34  lal 0
  35  loi _EM_PSIZE
  36  stf 3*_EM_PSIZE+_EM_LSIZE
  37  lol _EM_PSIZE                  ; the flag integer at offset _EM_PSIZE
  38  zeq *1
  39  lal 0
  40  loi _EM_PSIZE
  41  adp 3*_EM_PSIZE
  42  cal $__newsigset
  43  asp _EM_PSIZE
  44 1
  45 #elif   defined(__BSD4_2)
  46  loc 0
  47  cal $sigblock
  48  asp _EM_WSIZE
  49  lfr _EM_WSIZE
  50  lal 0
  51  loi _EM_PSIZE
  52  stf 3*_EM_PSIZE
  53 #endif
  54 ; create GTO descriptor for longjmp
  55  lxl 0
  56  dch            ; Local Base of caller
  57  lxa 0          ; Stackpointer of caller
  58  lal _EM_PSIZE+_EM_WSIZE
  59  loi _EM_PSIZE  ; Return address of caller
  60  lal 0
  61  loi _EM_PSIZE  ; address of jmpbuf
  62  sti 3*_EM_PSIZE        ; LB, SP, and PC stored in jmpbuf
  63  loc 0
  64  ret _EM_WSIZE  ; setjmp must return 0
  65  end 0
  66
  67  pro $fill_ret_area,0
  68 ; put argument in function result area
  69  lol 0
  70  ret _EM_WSIZE
  71  end 0
  72
  73  exp $longjmp
  74  pro $longjmp,?
  75 #if     defined(_POSIX_SOURCE)
  76 ; restore blocked mask
  77  lal 0
  78  loi _EM_PSIZE
  79  lof 3*_EM_PSIZE+_EM_LSIZE
  80  zeq *2
  81  lal 0
  82  loi _EM_PSIZE
  83  adp 3*_EM_PSIZE
  84  cal $__oldsigset
  85  asp _EM_PSIZE
  86 2
  87 #elif   defined(__BSD4_2)
  88 ; restore signal mask
  89  lal 0
  90  loi _EM_PSIZE
  91  lof 3*_EM_PSIZE
  92  cal $_sigsetmask
  93  asp _EM_WSIZE
  94  lfr _EM_WSIZE
  95  asp _EM_WSIZE
  96 #endif
  97  lal 0
  98  loi _EM_PSIZE  ; address of jmpbuf
  99  lae gtobuf
 100  blm 3*_EM_PSIZE        ; fill GTO descriptor from jmpbuf
 101  lol _EM_PSIZE  ; second parameter of longjmp: the return value
 102  dup _EM_WSIZE
 103  zne *3
 104 ; of course, longjmp may not return 0!
 105  inc
 106 3
 107 ; put return value in function result area
 108  cal $fill_ret_area
 109  asp _EM_WSIZE
 110  gto gtobuf     ; there we go ...
 111 ; ASP and GTO do not damage function result area
 112  end 0