262  *  	xxxfb_setcolreg - Optional function. Sets a color register.
270  *  	Set a single color register. The values supplied have a 16 bit
272  *	Things to take into consideration are how many color registers, if
273  *	any, are supported with the current color visual. With truecolor mode
274  *	no color palettes are supported. Here a pseudo palette is created
276  *	pseudocolor mode we have a limited color palette. To deal with this
277  *	we can program what color is displayed for a particular pixel value.
278  *	DirectColor is similar in that we can program each color field. If
300      *   var->{color}.offset contains start of bitfield  in xxxfb_setcolreg()
301      *   var->{color}.length contains length of bitfield  in xxxfb_setcolreg()
307      *   color depth = SUM(var->{color}.length)  in xxxfb_setcolreg()
310      *    var->{color}.offset is 0 unless the palette index takes less than  in xxxfb_setcolreg()
313      *    var->{color}.length is set so that 1 << length is the number of  in xxxfb_setcolreg()
317      *    color depth = var->{color}.length  in xxxfb_setcolreg()
324      *    var->{color}.offset is 0  in xxxfb_setcolreg()
325      *    white = (1 << var->{color}.length) - 1, black = 0  in xxxfb_setcolreg()
328      *    color depth is always 2  in xxxfb_setcolreg()
332      *    var->{color}.offset contains start of bitfield  in xxxfb_setcolreg()
333      *    var->{color}.length contains length of bitfield  in xxxfb_setcolreg()
339      *    color depth = SUM(var->{color}.length})  in xxxfb_setcolreg()
341      *  The color depth is used by fbcon for choosing the logo and also  in xxxfb_setcolreg()
342      *  for color palette transformation if color depth < 4  in xxxfb_setcolreg()
345      *  a criteria for describing the color visual.  in xxxfb_setcolreg()
351      *  Another common mistake is using bits_per_pixel to calculate the color  in xxxfb_setcolreg()
352      *  depth.  The bits_per_pixel field does not directly translate to color  in xxxfb_setcolreg()
353      *  depth. You have to compute for the color depth (using the color  in xxxfb_setcolreg()
358      * This is the point where the color is converted to something that  in xxxfb_setcolreg()
368      * This is the point where the function feeds the color to the hardware  in xxxfb_setcolreg()
489  *	depending on the rastering operation with the value of color which
490  *	is in the current color depth format.
500  *	@color:	The color to fill in the rectangle with.  in xxxfb_fillrect()
540  *	mono image (needed for font handling) or a color image (needed for
550  *      @fg_color: For mono bitmap images this is color data for  in xxxfb_imageblit()
555  *	@cmap: The colormap used for color images.  in xxxfb_imageblit()
608  *      - fbcon only supports a 2-color cursor (cursor->image.depth = 1)  in xxxfb_cursor()
710      * FBINFO_HWACCEL_IMAGEBLIT - hardware mono->color expansion  in xxxfb_probe()
714      * FBINFO_READS_FAST - if set, prefer moves over mono->color expansion  in xxxfb_probe()