anchor.diff:    ;; Read & save SPSR_EL1
     (mezzano.lap.arm64:mrs :x9 :spsr-el1)
     (mezzano.lap.arm64:str :x9 (:sp #x88))
  +  ;; Save x30.
  +  (mezzano.lap.arm64:str :x30 (:sp #x80))
     ;; Set up for call to handler.
     (mezzano.lap.arm64:orr :x7 :xzr :x29)
     (mezzano.lap.arm64:movz :x5 #.(ash 2 sys.int::+n-fixnum-bits+)) ; 2 args
  
positive.code:   ;; +40 pad (ss on x86-64)
    ;; +32 sp (not set)
    ;; +24 cspr (not set)
    ;; +16 pad (cs on x86-64)
    ;; +8 pc (not set)
    ;; +0 x29 (frame pointer)
    ;; x29 contains function to branch to.
  
negative.code:   ;; +40 pad (ss on x86-64)
    ;; +32 sp (not set)
    ;; +24 cspr (not set)
    ;; +16 x30 (cs on x86-64)
    ;; +8 pc (not set)
    ;; +0 x29 (frame pointer)
    ;; x29 contains function to branch to.
  