anchor.diff:  (declaim (inline bitset-mask-1-whole))
   (defun %bitset-mask-1-whole (setter nrows ncols colour mask mask-offset mask-stride to to-offset to-stride)
     (sys.int::with-deferred-gc ()
  -    (when (sys.int::%array-header-p to)
  -      (setf to (sys.int::%array-header-storage to)))
  -    (unless (integerp to)
  -      (assert (typep to 'simple-array))
  -      (setf to (+ (sys.int::lisp-object-address to) (- sys.int::+tag-array-like+) 8)))
  -    (when (sys.int::%array-header-p mask)
  -      (setf mask (sys.int::%array-header-storage mask)))
  -    (unless (integerp mask)
  -      (assert (typep mask 'simple-array))
  -      (setf mask (+ (sys.int::lisp-object-address mask) (- sys.int::+tag-array-like+) 8)))
  +    (setf to (%simple-array-data-pointer to))
  +    (setf mask (%simple-array-data-pointer mask))
       (dotimes (y nrows)
         (%bitset-mask-1-line setter ncols colour mask mask-offset to to-offset)
         (incf mask-offset mask-stride)
  
positive.code:     (assert (equal (array-element-type from) '(unsigned-byte 32)))
      (assert (equal (array-element-type to) '(unsigned-byte 32)))
      (sys.int::with-deferred-gc ()
        (when (sys.int::%array-header-p from)
          (setf from (sys.int::%array-header-storage from)))
        (unless (integerp from)
          (assert (typep from 'simple-array))
          (setf from (+ (sys.int::lisp-object-address from) (- sys.int::+tag-array-like+) 8)))
        (when (sys.int::%array-header-p to)
          (setf to (sys.int::%array-header-storage to)))
        (unless (integerp to)
          (assert (typep to 'simple-array))
          (setf to (+ (sys.int::lisp-object-address to) (- sys.int::+tag-array-like+) 8)))
        (dotimes (y nrows)
          (%bitblt-argb-xrgb-line ncols from from-offset to to-offset)
          (incf from-offset from-stride)
  
negative.code:             from-array from-offset from-width
              to-array to-offset to-width)))
  
  (defun %simple-array-data-pointer (array)
    "Find the address of ARRAY's first data element."
    (when (sys.int::%array-header-p array)
      (setf array (sys.int::%array-header-storage array)))
    (unless (integerp array)
      (assert (typep array 'simple-array))
      (setf array (+ (sys.int::lisp-object-address array) (- sys.int::+tag-array-like+) 8)))
    array)
  
  ;;; SETTER NCOLS COLOUR MASK MASK-OFFSET TO TO-OFFSET
  (sys.int::define-lap-function %bitset-mask-1-line ()
    (sys.lap-x86:mov64 :rsi :r11)
  