anchor.diff:    (sys.lap-x86:sar64 :rcx 3)
     (sys.lap-x86:rep)
     (sys.lap-x86:movs8)
  -  (sys.lap-x86:mov64 :rbx :lsp)
  +  (sys.lap-x86:mov32 :ecx 8)
  +  (sys.lap-x86:mov64 :rbx :lsp)
  +  (sys.lap-x86:ret))
  +
  +;; (to-storage from-storage bytes-per-col to-stride from-stride nrows)
  +(define-lap-function %%bitblt ()
  +  (sys.lap-x86:mov64 :rdi :r8) ; to-storage
  +  (sys.lap-x86:mov64 :rsi :r9) ; from-storage
  +  (sys.lap-x86:sar64 :rsi 3)
  +  (sys.lap-x86:sar64 :rdi 3)
  +  (sys.lap-x86:mov64 :r8 (:lsp)) ; nrows
  +  (sys.lap-x86:sub64 :r11 :r10)
  +  (sys.lap-x86:sub64 :r12 :r10)
  +  (sys.lap-x86:jmp loop-test)
  +  loop-head
  +  (sys.lap-x86:mov64 :rcx :r10) ; bytes-per-col
  +  (sys.lap-x86:sar64 :rcx 3)
  +  (sys.lap-x86:rep)
  +  (sys.lap-x86:movs8)
  +  (sys.lap-x86:mov64 :rax :r11) ; to-stride
  +  (sys.lap-x86:sar64 :rax 3)
  +  (sys.lap-x86:add64 :rdi :rax)
  +  (sys.lap-x86:mov64 :rax :r12) ; from-stride
  +  (sys.lap-x86:sar64 :rax 3)
  +  (sys.lap-x86:add64 :rsi :rax)
  +  loop-test
  +  (sys.lap-x86:sub64 :r8 8)
  +  (sys.lap-x86:jge loop-head)
  +  (sys.lap-x86:mov32 :ecx 8)
  +  (sys.lap-x86:lea64 :rbx (:lsp 8))
     (sys.lap-x86:ret))
   
   (defun %bitblt (nrows ncols from-array from-row from-col to-array to-row to-col)
  
positive.code:         (setf from-storage (+ (lisp-object-address from-storage) 1)))
        (incf to-storage (* (+ (* to-row to-width) to-col to-offset) stride))
        (incf from-storage (* (+ (* from-row from-width) from-col from-offset) stride))
        (dotimes (i nrows)
          (%fast-copy to-storage from-storage bytes-per-col)
          (incf to-storage to-stride)
          (incf from-storage from-stride)))))
  
  ;;; (value destination count)
  (define-lap-function %fast-set-8 ()
  
negative.code:         ((equal type '(unsigned-byte 64))
           (incf to-storage (* to-offset 8))
           (dotimes (i nrows)
             (%fast-set-64 val to-storage ncols)
             (incf to-storage (* to-width 8))))))))
  