git.sur5r.net Git - cc65/blob - libsrc/common/stkcheck.s

   1 ;
   2 ; Ullrich von Bassewitz, 18.08.1998
   3 ;
   4 ; Stack checker
   5 ;
   6
   7
   8         .export         _stkcheck, __stksafety
   9         .import         pushax, exit
  10         .import         __hend
  11         .importzp       sp
  12
  13 .data
  14 __stksafety:
  15         .word   64                      ;
  16
  17 .code
  18 _stkcheck:
  19         clc
  20         lda     __hend
  21         adc     __stksafety
  22         tax                             ; Remember low byte
  23         lda     __hend+1
  24         adc     __stksafety+1
  25
  26         cmp     sp+1
  27         bcc     Ok
  28         bne     L1
  29         cpx     sp
  30         bcc     Ok
  31
  32 ; Stack overflow
  33
  34 L1:     inc     sp+1                    ; Create 256 bytes of space
  35         ldx     #0
  36         lda     #4
  37         jsr     pushax
  38         jmp     exit
  39
  40 ; All is well
  41
  42 Ok:     rts
  43
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  48