anchor.diff:          (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)))))
  +      (%%bitblt to-storage from-storage bytes-per-col to-stride from-stride nrows))))
   
   ;;; (value destination count)
   (define-lap-function %fast-set-8 ()
  
positive.code:         ((equal type '(unsigned-byte 64))
           (incf to-storage (* to-offset 8))
           (dotimes (i nrows)
             (dotimes (j ncols)
               (setf (memref-unsigned-byte-64 to-storage j) val))
             (incf to-storage (* to-width 8))))))))
  
negative.code:   (sys.lap-x86:sar64 :rcx 3)
    (sys.lap-x86:rep)
    (sys.lap-x86:movs8)
    (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)
  