linux/drivers/video/fbdev/aty/mach64_cursor.c

// SPDX-License-Identifier: GPL-2.0
/*
 *  ATI Mach64 CT/VT/GT/LT Cursor Support
 */

#include <linux/fb.h>
#include <linux/init.h>
#include <linux/string.h>
#include "../core/fb_draw.h"

#include <asm/io.h>

#ifdef __sparc__
#include <asm/fbio.h>
#endif

#include <video/mach64.h>
#include "atyfb.h"

/*
 * The hardware cursor definition requires 2 bits per pixel. The
 * Cursor size reguardless of the visible cursor size is 64 pixels
 * by 64 lines. The total memory required to define the cursor is
 * 16 bytes / line for 64 lines or 1024 bytes of data. The data
 * must be in a contigiuos format. The 2 bit cursor code values are
 * as follows:
 *
 *	00 - pixel colour = CURSOR_CLR_0
 *	01 - pixel colour = CURSOR_CLR_1
 *	10 - pixel colour = transparent (current display pixel)
 *	11 - pixel colour = 1's complement of current display pixel
 *
 *	Cursor Offset        64 pixels		 Actual Displayed Area
 *            \_________________________/
 *	      |			|	|	|
 *	      |<--------------->|	|	|
 *	      | CURS_HORZ_OFFSET|	|	|
 *	      |			|_______|	|  64 Lines
 *	      |			   ^	|	|
 *	      |			   |	|	|
 *	      |		CURS_VERT_OFFSET|	|
 *	      |			   |	|	|
 *	      |____________________|____|	|
 *
 *
 * The Screen position of the top left corner of the displayed
 * cursor is specificed by CURS_HORZ_VERT_POSN. Care must be taken
 * when the cursor hot spot is not the top left corner and the
 * physical cursor position becomes negative. It will be displayed
 * if either the horizontal or vertical cursor position is negative
 *
 * If x becomes negative the cursor manager must adjust the CURS_HORZ_OFFSET
 * to a larger number and saturate CUR_HORZ_POSN to zero.
 *
 * if Y becomes negative, CUR_VERT_OFFSET must be adjusted to a larger number,
 * CUR_OFFSET must be adjusted to a point to the appropriate line in the cursor
 * definitation and CUR_VERT_POSN must be saturated to zero.
 */

    /*
     *  Hardware Cursor support.
     */
static const u8 cursor_bits_lookup[16] = …;

static int atyfb_cursor(struct fb_info *info, struct fb_cursor *cursor)
{ … }

int aty_init_cursor(struct fb_info *info, struct fb_ops *atyfb_ops)
{ … }