arch/.unmaintained/dummy/stackswap.c

   1 |*****************************************************************************
   2 |
   3 |   NAME
   4 |
   5 |       __AROS_LH1(void, StackSwap,
   6 |
   7 |   SYNOPSIS
   8 |       __AROS_LA(struct StackSwapStruct *, newStack, A0),
   9 |
  10 |   LOCATION
  11 |       struct ExecBase *, SysBase, 122, Exec)
  12 |
  13 |   FUNCTION
  14 |       This function switches to the new stack given by the parameters in the
  15 |       stackswapstruct structure. The old stack parameters are returned in
  16 |       the same structure so that the stack can be restored later
  17 |
  18 |   INPUTS
  19 |       newStack - parameters for the new stack
  20 |
  21 |   RESULT
  22 |
  23 |   NOTES
  24 |
  25 |   EXAMPLE
  26 |
  27 |   BUGS
  28 |
  29 |   SEE ALSO
  30 |
  31 |   INTERNALS
  32 |
  33 |   HISTORY
  34 |
  35 |******************************************************************************
  36
  37         Disable     =   -0x78
  38         Enable      =   -0x7e
  39         ThisTask    =   0x114
  40         tc_SPLower  =   0x3a
  41
  42         .globl  _Exec_StackSwap
  43 _Exec_StackSwap:
  44         | Preserve returnaddress and fix sp
  45         movel   sp@+,d0
  46
  47         | Get pointer to tc_SPLower in a1 (tc_SPUpper is next)
  48         movel   a6@(ThisTask),a1
  49         leal    a1@(tc_SPLower),a1
  50
  51         | Just to be sure interrupts always find a good stackframe
  52         jsr     a6@(Disable)
  53
  54         | Swap Lower boundaries
  55         movel   a1@,d1
  56         movel   a0@,a1@+
  57         movel   d1,a0@+
  58
  59         | Swap higher boundaries
  60         movel   a1@,d1
  61         movel   a0@,a1@
  62         movel   d1,a0@+
  63
  64         | Swap stackpointers
  65         movel   sp,d1
  66         movel   a0@,sp
  67         movel   d1,a0@
  68
  69         | Reenable interrupts.
  70         jsr     a6@(Enable)
  71
  72         | Restore returnaddress and return
  73         movel   d1,sp@-
  74         rts
  75