anchor.diff:    (sys.lap-x86:stos32)
     (sys.lap-x86:ret))
   
  +#+x86-64
  +(sys.int::define-lap-function %%bitset-row-r8g8b8 ((to-base colour ncols))
  +  (sys.lap-x86:test64 :r10 :r10) ; ncols
  +  (sys.lap-x86:jz OUT)
  +  (sys.lap-x86:mov64 :rdi :r8) ; to-storage
  +  (sys.lap-x86:mov64 :rax :r9) ; colour
  +  (sys.lap-x86:sar64 :rdi #.sys.int::+n-fixnum-bits+)
  +  (sys.lap-x86:sar64 :rax #.sys.int::+n-fixnum-bits+)
  +  ;; Extract colour components
  +  (sys.lap-x86:mov32 :ecx :eax)
  +  (sys.lap-x86:shr32 :ecx 8)
  +  (sys.lap-x86:mov32 :edx :ecx)
  +  (sys.lap-x86:shr32 :edx 8)
  +  LOOP
  +  (sys.lap-x86:mov8 (:rdi 0) :al)
  +  (sys.lap-x86:mov8 (:rdi 1) :cl)
  +  (sys.lap-x86:mov8 (:rdi 2) :dl)
  +  (sys.lap-x86:add64 :rdi 3)
  +  (sys.lap-x86:sub64 :r10 #.(ash 1 sys.int::+n-fixnum-bits+))
  +  (sys.lap-x86:jnz LOOP)
  +  OUT
  +  (sys.lap-x86:ret))
  +
   #+arm64
  -(sys.int::define-lap-function %%bitset-row ((to-base colour ncols))
  +(sys.int::define-lap-function %%bitset-row-x8r8g8b8 ((to-base colour ncols))
     (mezzano.lap.arm64:add :x12 :xzr :x0 :asr #.sys.int::+n-fixnum-bits+) ; to-storage
     (mezzano.lap.arm64:add :x9 :xzr :x1 :asr #.sys.int::+n-fixnum-bits+) ; colour
     (mezzano.lap.arm64:add :x5 :xzr :x2 :asr #.sys.int::+n-fixnum-bits+) ; ncols
  
positive.code:     t))
  
  #+x86-64
  (sys.int::define-lap-function %%bitblt-row ((to-base from-base ncols))
    (sys.lap-x86:mov64 :rdi :r8) ; to-storage
    (sys.lap-x86:mov64 :rsi :r9) ; from-storage
    (sys.lap-x86:mov64 :rcx :r10) ; ncols
  
negative.code:                            (* (1- (framebuffer-height *current-framebuffer*))
                                (framebuffer-pitch *current-framebuffer*))
                             0)
                         (* light-offset (framebuffer-bytes-per-pixel *current-framebuffer*)))))
        (when (<= (+ light-offset 32) (framebuffer-width *current-framebuffer*))
          (funcall (framebuffer-fill-fn *current-framebuffer*)
                   (convert-to-pmap-address fb-addr)
                   #xFF000000
                   32)
          (funcall (framebuffer-damage-fn *current-framebuffer*)
                   0 0
                   (framebuffer-width *current-framebuffer*) 1
  