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-rw-r--r--src/emu/video.h478
1 files changed, 334 insertions, 144 deletions
diff --git a/src/emu/video.h b/src/emu/video.h
index 774cb9f16c1..ef66e2a0309 100644
--- a/src/emu/video.h
+++ b/src/emu/video.h
@@ -4,8 +4,36 @@
Core MAME video routines.
- Copyright Nicola Salmoria and the MAME Team.
- Visit http://mamedev.org for licensing and usage restrictions.
+****************************************************************************
+
+ Copyright Aaron Giles
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are
+ met:
+
+ * Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in
+ the documentation and/or other materials provided with the
+ distribution.
+ * Neither the name 'MAME' nor the names of its contributors may be
+ used to endorse or promote products derived from this software
+ without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY AARON GILES ''AS IS'' AND ANY EXPRESS OR
+ IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED. IN NO EVENT SHALL AARON GILES BE LIABLE FOR ANY DIRECT,
+ INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ POSSIBILITY OF SUCH DAMAGE.
***************************************************************************/
@@ -19,16 +47,16 @@
#define __VIDEO_H__
-/***************************************************************************
- CONSTANTS
-***************************************************************************/
+//**************************************************************************
+// CONSTANTS
+//**************************************************************************
-/* number of levels of frameskipping supported */
-#define FRAMESKIP_LEVELS 12
-#define MAX_FRAMESKIP (FRAMESKIP_LEVELS - 2)
+// number of levels of frameskipping supported
+const int FRAMESKIP_LEVELS = 12;
+const int MAX_FRAMESKIP = FRAMESKIP_LEVELS - 2;
-/* screen types */
-enum
+// screen types
+enum screen_type_enum
{
SCREEN_TYPE_INVALID = 0,
SCREEN_TYPE_RASTER,
@@ -38,117 +66,271 @@ enum
-/***************************************************************************
- MACROS
-***************************************************************************/
-
-/* these functions are macros primarily due to include file ordering */
-/* plus, they are very simple */
-#define video_screen_count(config) (config)->devicelist.count(VIDEO_SCREEN)
-#define video_screen_first(config) (config)->devicelist.first(VIDEO_SCREEN)
-#define video_screen_next(previous) (previous)->typenext()
+//**************************************************************************
+// TYPE DEFINITIONS
+//**************************************************************************
-#define video_screen_get_format(screen) (((screen_config *)(screen)->baseconfig().inline_config)->format)
+// forward references
+class render_target;
+struct render_texture;
+class screen_device;
-/* allocates a bitmap that has the same dimensions and format as the passed in screen */
-#define video_screen_auto_bitmap_alloc(screen) auto_bitmap_alloc(screen->machine, video_screen_get_width(screen), video_screen_get_height(screen), video_screen_get_format(screen))
+// callback that is called to notify of a change in the VBLANK state
+typedef void (*vblank_state_changed_func)(screen_device &device, void *param, bool vblank_state);
+// ======================> screen_device_config
-/***************************************************************************
- TYPE DEFINITIONS
-***************************************************************************/
+class screen_device_config : public device_config
+{
+ friend class screen_device;
+
+ // construction/destruction
+ screen_device_config(const machine_config &mconfig, const char *tag, const device_config *owner, UINT32 clock);
+
+public:
+ // allocators
+ static device_config *static_alloc_device_config(const machine_config &mconfig, const char *tag, const device_config *owner, UINT32 clock);
+ virtual device_t *alloc_device(running_machine &machine) const;
+
+ // basic information getters
+ virtual const char *name() const { return "Video Screen"; }
+
+ // configuration readers
+ screen_type_enum screen_type() const { return m_type; }
+ int width() const { return m_width; }
+ int height() const { return m_height; }
+ const rectangle &visible_area() const { return m_visarea; }
+ bool oldstyle_vblank_supplied() const { return m_oldstyle_vblank_supplied; }
+ attoseconds_t refresh() const { return m_refresh; }
+ attoseconds_t vblank() const { return m_vblank; }
+ bitmap_format format() const { return m_format; }
+ float xoffset() const { return m_xoffset; }
+ float yoffset() const { return m_yoffset; }
+ float xscale() const { return m_xscale; }
+ float yscale() const { return m_yscale; }
+
+ // indexes to inline data
+ enum
+ {
+ INLINE_TYPE,
+ INLINE_FORMAT,
+ INLINE_REFRESH,
+ INLINE_VBLANK,
+ INLINE_WIDTH,
+ INLINE_HEIGHT,
+ INLINE_VIS_MINX,
+ INLINE_VIS_MAXX,
+ INLINE_VIS_MINY,
+ INLINE_VIS_MAXY,
+ INLINE_XOFFSET,
+ INLINE_XSCALE,
+ INLINE_YOFFSET,
+ INLINE_YSCALE,
+ INLINE_OLDVBLANK
+ };
+
+private:
+ // device_config overrides
+ virtual void device_config_complete();
+ virtual bool device_validity_check(const game_driver &driver) const;
+
+ // configuration data
+ screen_type_enum m_type; // type of screen
+ int m_width, m_height; // default total width/height (HTOTAL, VTOTAL)
+ rectangle m_visarea; // default visible area (HBLANK end/start, VBLANK end/start)
+ bool m_oldstyle_vblank_supplied; // MDRV_SCREEN_VBLANK_TIME macro used
+ attoseconds_t m_refresh; // default refresh period
+ attoseconds_t m_vblank; // duration of a VBLANK
+ bitmap_format m_format; // bitmap format
+ float m_xoffset, m_yoffset; // default X/Y offsets
+ float m_xscale, m_yscale; // default X/Y scale factor
+};
-// forward references
-class render_target;
-/*-------------------------------------------------
- screen_config - configuration of a single
- screen
--------------------------------------------------*/
+// ======================> screen_device
-typedef struct _screen_config screen_config;
-struct _screen_config
+class screen_device : public device_t
{
- int type; /* type of screen */
- int width, height; /* default total width/height (HTOTAL, VTOTAL) */
- rectangle visarea; /* default visible area (HBLANK end/start, VBLANK end/start) */
- UINT8 oldstyle_vblank_supplied; /* MDRV_SCREEN_VBLANK_TIME macro used */
- attoseconds_t refresh; /* default refresh period */
- attoseconds_t vblank; /* duration of a VBLANK */
- bitmap_format format; /* bitmap format */
- float xoffset, yoffset; /* default X/Y offsets */
- float xscale, yscale; /* default X/Y scale factor */
+ friend class screen_device_config;
+ friend resource_pool_object<screen_device>::~resource_pool_object();
+
+ // construction/destruction
+ screen_device(running_machine &_machine, const screen_device_config &config);
+ virtual ~screen_device();
+
+public:
+ // information getters
+ const screen_device_config &config() const { return m_config; }
+ screen_type_enum screen_type() const { return m_config.m_type; }
+ int width() const { return m_width; }
+ int height() const { return m_height; }
+ const rectangle &visible_area() const { return m_visarea; }
+ bitmap_format format() const { return m_config.m_format; }
+
+ // dynamic configuration
+ void configure(int width, int height, const rectangle &visarea, attoseconds_t frame_period);
+ void set_visible_area(int min_x, int max_x, int min_y, int max_y);
+
+ // beam positioning and state
+ int vpos() const;
+ int hpos() const;
+ bool vblank() const { return attotime_compare(timer_get_time(machine), m_vblank_end_time) < 0; }
+ bool hblank() const { int curpos = hpos(); return (curpos < m_visarea.min_x || curpos > m_visarea.max_x); }
+
+ // timing
+ attotime time_until_pos(int vpos, int hpos = 0) const;
+ attotime time_until_vblank_start() const { return time_until_pos(m_visarea.max_y + 1); }
+ attotime time_until_vblank_end() const;
+ attotime time_until_update() const { return (machine->config->video_attributes & VIDEO_UPDATE_AFTER_VBLANK) ? time_until_vblank_end() : time_until_vblank_start(); }
+ attotime scan_period() const { return attotime_make(0, m_scantime); }
+ attotime frame_period() const { return (this == NULL || !started()) ? k_default_frame_period : attotime_make(0, m_frame_period); };
+ UINT64 frame_number() const { return m_frame_number; }
+
+ // updating
+ bool update_partial(int scanline);
+ void update_now();
+
+ // additional helpers
+ void save_snapshot(mame_file *fp);
+ void register_vblank_callback(vblank_state_changed_func vblank_callback, void *param);
+ bitmap_t *alloc_compatible_bitmap(int width = 0, int height = 0) { return auto_bitmap_alloc(machine, (width == 0) ? m_width : width, (height == 0) ? m_height : height, m_config.m_format); }
+
+ // internal to the video system
+ bool update_quads();
+ void update_burnin();
+
+ // globally accessible constants
+ static const int k_default_frame_rate = 60;
+ static const attotime k_default_frame_period;
+
+private:
+ // device-level overrides
+ virtual void device_start();
+ virtual void device_post_load();
+
+ // internal helpers
+ void realloc_screen_bitmaps();
+
+ static TIMER_CALLBACK( static_vblank_begin_callback ) { reinterpret_cast<screen_device *>(ptr)->vblank_begin_callback(); }
+ void vblank_begin_callback();
+
+ static TIMER_CALLBACK( static_vblank_end_callback ) { reinterpret_cast<screen_device *>(ptr)->vblank_end_callback(); }
+ void vblank_end_callback();
+
+ static TIMER_CALLBACK( static_scanline0_callback ) { reinterpret_cast<screen_device *>(ptr)->scanline0_callback(); }
+public: // temporary
+ void scanline0_callback();
+private:
+
+ static TIMER_CALLBACK( static_scanline_update_callback ) { reinterpret_cast<screen_device *>(ptr)->scanline_update_callback(param); }
+ void scanline_update_callback(int scanline);
+
+ void finalize_burnin();
+
+ // internal state
+ const screen_device_config &m_config;
+
+ // dimensions
+ int m_width; // current width (HTOTAL)
+ int m_height; // current height (VTOTAL)
+ rectangle m_visarea; // current visible area (HBLANK end/start, VBLANK end/start)
+
+ // textures and bitmaps
+ render_texture * m_texture[2]; // 2x textures for the screen bitmap
+ bitmap_t * m_bitmap[2]; // 2x bitmaps for rendering
+ bitmap_t * m_burnin; // burn-in bitmap
+ UINT8 m_curbitmap; // current bitmap index
+ UINT8 m_curtexture; // current texture index
+ INT32 m_texture_format; // texture format of bitmap for this screen
+ bool m_changed; // has this bitmap changed?
+ INT32 m_last_partial_scan; // scanline of last partial update
+
+ // screen timing
+ attoseconds_t m_frame_period; // attoseconds per frame
+ attoseconds_t m_scantime; // attoseconds per scanline
+ attoseconds_t m_pixeltime; // attoseconds per pixel
+ attoseconds_t m_vblank_period; // attoseconds per VBLANK period
+ attotime m_vblank_start_time; // time of last VBLANK start
+ attotime m_vblank_end_time; // time of last VBLANK end
+ emu_timer * m_vblank_begin_timer; // timer to signal VBLANK start
+ emu_timer * m_vblank_end_timer; // timer to signal VBLANK end
+ emu_timer * m_scanline0_timer; // scanline 0 timer
+ emu_timer * m_scanline_timer; // scanline timer
+ UINT64 m_frame_number; // the current frame number
+
+ struct callback_item
+ {
+ callback_item * m_next;
+ vblank_state_changed_func m_callback;
+ void * m_param;
+ };
+ callback_item * m_callback_list; // list of VBLANK callbacks
};
-/*-------------------------------------------------
- vblank_state_changed_func -
- callback that is called to notify of a change
- in the VBLANK state
--------------------------------------------------*/
+// device type definition
+const device_type SCREEN = screen_device_config::static_alloc_device_config;
-typedef void (*vblank_state_changed_func)(running_device *device, void *param, int vblank_state);
-
-/***************************************************************************
- SCREEN DEVICE CONFIGURATION MACROS
-***************************************************************************/
+//**************************************************************************
+// SCREEN DEVICE CONFIGURATION MACROS
+//**************************************************************************
#define MDRV_SCREEN_ADD(_tag, _type) \
- MDRV_DEVICE_ADD(_tag, VIDEO_SCREEN, 0) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, type, SCREEN_TYPE_##_type)
+ MDRV_DEVICE_ADD(_tag, SCREEN, 0) \
+ MDRV_SCREEN_TYPE(_type)
#define MDRV_SCREEN_MODIFY(_tag) \
MDRV_DEVICE_MODIFY(_tag)
#define MDRV_SCREEN_FORMAT(_format) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, format, _format)
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_FORMAT, _format)
#define MDRV_SCREEN_TYPE(_type) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, type, SCREEN_TYPE_##_type)
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_TYPE, SCREEN_TYPE_##_type)
#define MDRV_SCREEN_RAW_PARAMS(_pixclock, _htotal, _hbend, _hbstart, _vtotal, _vbend, _vbstart) \
- MDRV_DEVICE_CONFIG_DATA64(screen_config, refresh, HZ_TO_ATTOSECONDS(_pixclock) * (_htotal) * (_vtotal)) \
- MDRV_DEVICE_CONFIG_DATA64(screen_config, vblank, ((HZ_TO_ATTOSECONDS(_pixclock) * (_htotal) * (_vtotal)) / (_vtotal)) * ((_vtotal) - ((_vbstart) - (_vbend)))) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, width, _htotal) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, height, _vtotal) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, visarea.min_x, _hbend) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, visarea.max_x, (_hbstart) - 1) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, visarea.min_y, _vbend) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, visarea.max_y, (_vbstart) - 1)
+ MDRV_DEVICE_INLINE_DATA64(screen_device_config::INLINE_REFRESH, HZ_TO_ATTOSECONDS(_pixclock) * (_htotal) * (_vtotal)) \
+ MDRV_DEVICE_INLINE_DATA64(screen_device_config::INLINE_VBLANK, ((HZ_TO_ATTOSECONDS(_pixclock) * (_htotal) * (_vtotal)) / (_vtotal)) * ((_vtotal) - ((_vbstart) - (_vbend)))) \
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_WIDTH, _htotal) \
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_HEIGHT, _vtotal) \
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_VIS_MINX, _hbend) \
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_VIS_MAXX, (_hbstart) - 1) \
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_VIS_MINY, _vbend) \
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_VIS_MAXY, (_vbstart) - 1)
#define MDRV_SCREEN_REFRESH_RATE(_rate) \
- MDRV_DEVICE_CONFIG_DATA64(screen_config, refresh, HZ_TO_ATTOSECONDS(_rate))
+ MDRV_DEVICE_INLINE_DATA64(screen_device_config::INLINE_REFRESH, HZ_TO_ATTOSECONDS(_rate))
#define MDRV_SCREEN_VBLANK_TIME(_time) \
- MDRV_DEVICE_CONFIG_DATA64(screen_config, vblank, _time) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, oldstyle_vblank_supplied, TRUE)
+ MDRV_DEVICE_INLINE_DATA64(screen_device_config::INLINE_VBLANK, _time) \
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_OLDVBLANK, true)
#define MDRV_SCREEN_SIZE(_width, _height) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, width, _width) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, height, _height)
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_WIDTH, _width) \
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_HEIGHT, _height)
#define MDRV_SCREEN_VISIBLE_AREA(_minx, _maxx, _miny, _maxy) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, visarea.min_x, _minx) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, visarea.max_x, _maxx) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, visarea.min_y, _miny) \
- MDRV_DEVICE_CONFIG_DATA32(screen_config, visarea.max_y, _maxy)
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_VIS_MINX, _minx) \
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_VIS_MAXX, _maxx) \
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_VIS_MINY, _miny) \
+ MDRV_DEVICE_INLINE_DATA16(screen_device_config::INLINE_VIS_MAXY, _maxy)
#define MDRV_SCREEN_DEFAULT_POSITION(_xscale, _xoffs, _yscale, _yoffs) \
- MDRV_DEVICE_CONFIG_DATAFP32(screen_config, xoffset, _xoffs, 24) \
- MDRV_DEVICE_CONFIG_DATAFP32(screen_config, xscale, _xscale, 24) \
- MDRV_DEVICE_CONFIG_DATAFP32(screen_config, yoffset, _yoffs, 24) \
- MDRV_DEVICE_CONFIG_DATAFP32(screen_config, yscale, _yscale, 24)
+ MDRV_DEVICE_INLINE_DATA32(screen_device_config::INLINE_XOFFSET, (_xoffs) * (double)(1 << 24)) \
+ MDRV_DEVICE_INLINE_DATA32(screen_device_config::INLINE_XSCALE, (_xscale) * (double)(1 << 24)) \
+ MDRV_DEVICE_INLINE_DATA32(screen_device_config::INLINE_YOFFSET, (_yoffs) * (double)(1 << 24)) \
+ MDRV_DEVICE_INLINE_DATA32(screen_device_config::INLINE_YSCALE, (_yscale) * (double)(1 << 24))
-/***************************************************************************
- FUNCTION PROTOTYPES
-***************************************************************************/
+//**************************************************************************
+// FUNCTION PROTOTYPES
+//**************************************************************************
/* ----- core implementation ----- */
@@ -156,69 +338,6 @@ typedef void (*vblank_state_changed_func)(running_device *device, void *param, i
void video_init(running_machine *machine);
-/* ----- screen management ----- */
-
-/* set the resolution of a screen */
-void video_screen_configure(running_device *screen, int width, int height, const rectangle *visarea, attoseconds_t refresh);
-
-/* set the visible area of a screen; this is a subset of video_screen_configure */
-void video_screen_set_visarea(running_device *screen, int min_x, int max_x, int min_y, int max_y);
-
-/* force a partial update of the screen up to and including the requested scanline */
-int video_screen_update_partial(running_device *screen, int scanline);
-
-/* force an update from the last beam position up to the current beam position */
-void video_screen_update_now(running_device *screen);
-
-/* return the current vertical or horizontal position of the beam for a screen */
-int video_screen_get_vpos(running_device *screen);
-int video_screen_get_hpos(running_device *screen);
-
-/* return the current vertical or horizontal blanking state for a screen */
-int video_screen_get_vblank(running_device *screen);
-int video_screen_get_hblank(running_device *screen);
-
-/* return the current width for a screen */
-int video_screen_get_width(running_device *screen);
-
-/* return the current height for a screen */
-int video_screen_get_height(running_device *screen);
-
-/* return the current visible area for a screen */
-const rectangle *video_screen_get_visible_area(running_device *screen);
-
-/* return the time when the beam will reach a particular H,V position */
-attotime video_screen_get_time_until_pos(running_device *screen, int vpos, int hpos);
-
-/* return the time when the beam will reach the start of VBLANK */
-attotime video_screen_get_time_until_vblank_start(running_device *screen);
-
-/* return the time when the beam will reach the end of VBLANK */
-attotime video_screen_get_time_until_vblank_end(running_device *screen);
-
-/* return the time when the VIDEO_UPDATE function will be called */
-attotime video_screen_get_time_until_update(running_device *screen);
-
-/* return the amount of time the beam takes to draw one scan line */
-attotime video_screen_get_scan_period(running_device *screen);
-
-/* return the amount of time the beam takes to draw one complete frame */
-attotime video_screen_get_frame_period(running_device *screen);
-
-/* return the current frame number -- this is always increasing */
-UINT64 video_screen_get_frame_number(running_device *screen);
-
-/* registers a VBLANK callback for the given screen */
-void video_screen_register_vblank_callback(running_device *screen, vblank_state_changed_func vblank_callback, void *param);
-
-
-/* ----- video screen device interface ----- */
-
-/* device get info callback */
-#define VIDEO_SCREEN DEVICE_GET_INFO_NAME(video_screen)
-DEVICE_GET_INFO( video_screen );
-
-
/* ----- global rendering ----- */
/* update the screen, handling frame skipping and rendering */
@@ -256,7 +375,7 @@ void video_set_fastforward(int fastforward);
/* ----- snapshots ----- */
/* save a snapshot of a given screen */
-void video_screen_save_snapshot(running_machine *machine, running_device *screen, mame_file *fp);
+void screen_save_snapshot(running_machine *machine, device_t *screen, mame_file *fp);
/* save a snapshot of all the active screens */
void video_save_active_screen_snapshots(running_machine *machine);
@@ -285,4 +404,75 @@ int video_get_view_for_target(running_machine *machine, render_target *target, c
void video_assert_out_of_range_pixels(running_machine *machine, bitmap_t *bitmap);
+
+//**************************************************************************
+// INLINE HELPERS
+//**************************************************************************
+
+//-------------------------------------------------
+// screen_count - return the number of
+// video screen devices in a machine_config
+//-------------------------------------------------
+
+inline int screen_count(const machine_config &config)
+{
+ return config.devicelist.count(SCREEN);
+}
+
+
+//-------------------------------------------------
+// screen_first - return the first
+// video screen device config in a machine_config
+//-------------------------------------------------
+
+inline const screen_device_config *screen_first(const machine_config &config)
+{
+ return downcast<screen_device_config *>(config.devicelist.first(SCREEN));
+}
+
+
+//-------------------------------------------------
+// screen_next - return the next
+// video screen device config in a machine_config
+//-------------------------------------------------
+
+inline const screen_device_config *screen_next(const screen_device_config *previous)
+{
+ return downcast<screen_device_config *>(previous->typenext());
+}
+
+
+//-------------------------------------------------
+// screen_count - return the number of
+// video screen devices in a machine
+//-------------------------------------------------
+
+inline int screen_count(running_machine &machine)
+{
+ return machine.devicelist.count(SCREEN);
+}
+
+
+//-------------------------------------------------
+// screen_first - return the first
+// video screen device in a machine
+//-------------------------------------------------
+
+inline screen_device *screen_first(running_machine &machine)
+{
+ return downcast<screen_device *>(machine.devicelist.first(SCREEN));
+}
+
+
+//-------------------------------------------------
+// screen_next - return the next
+// video screen device in a machine
+//-------------------------------------------------
+
+inline screen_device *screen_next(screen_device *previous)
+{
+ return downcast<screen_device *>(previous->typenext());
+}
+
+
#endif /* __VIDEO_H__ */