// license:BSD-3-Clause
// copyright-holders:Aaron Giles
/***************************************************************************
Exidy 440 video system
***************************************************************************/
#include "emu.h"
#include "includes/exidy440.h"
#define PIXEL_CLOCK (EXIDY440_MASTER_CLOCK / 2)
#define HTOTAL (0x1a0)
#define HBEND (0x000)
#define HBSTART (0x140)
#define HSEND (0x178)
#define HSSTART (0x160)
#define VTOTAL (0x104)
#define VBEND (0x000)
#define VBSTART (0x0f0)
#define VSEND (0x0f8)
#define VSSTART (0x0f0)
/* Top Secret has a larger VBLANK area */
#define TOPSECEX_VBSTART (0x0ec)
#define SPRITE_COUNT (0x28)
/*************************************
*
* Initialize the video system
*
*************************************/
void exidy440_state::video_start()
{
/* reset the system */
m_firq_enable = 0;
m_firq_select = 0;
m_palettebank_io = 0;
m_palettebank_vis = 0;
m_firq_vblank = 0;
m_firq_beam = 0;
/* allocate a buffer for VRAM */
m_local_videoram = std::make_unique<uint8_t[]>(256 * 256 * 2);
memset(m_local_videoram.get(), 0, 256 * 256 * 2);
/* allocate a buffer for palette RAM */
m_local_paletteram = std::make_unique<uint8_t[]>(512 * 2);
memset(m_local_paletteram.get(), 0, 512 * 2);
m_collide_firq_timer = machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(exidy440_state::collide_firq_callback), this));
}
void topsecex_state::video_start()
{
exidy440_state::video_start();
m_topsecex_yscroll = 0;
}
/*************************************
*
* Video RAM read/write
*
*************************************/
READ8_MEMBER(exidy440_state::exidy440_videoram_r)
{
uint8_t *base = &m_local_videoram[(*m_scanline * 256 + offset) * 2];
/* combine the two pixel values into one byte */
return (base[0] << 4) | base[1];
}
WRITE8_MEMBER(exidy440_state::exidy440_videoram_w)
{
uint8_t *base = &m_local_videoram[(*m_scanline * 256 + offset) * 2];
/* expand the two pixel values into two bytes */
base[0] = (data >> 4) & 15;
base[1] = data & 15;
}
/*************************************
*
* Palette RAM read/write
*
*************************************/
READ8_MEMBER(exidy440_state::exidy440_paletteram_r)
{
return m_local_paletteram[m_palettebank_io * 512 + offset];
}
WRITE8_MEMBER(exidy440_state::exidy440_paletteram_w)
{
/* update palette ram in the I/O bank */
m_local_paletteram[m_palettebank_io * 512 + offset] = data;
/* if we're modifying the active palette, change the color immediately */
if (m_palettebank_io == m_palettebank_vis)
{
int word;
/* combine two bytes into a word */
offset = m_palettebank_vis * 512 + (offset & 0x1fe);
word = (m_local_paletteram[offset] << 8) + m_local_paletteram[offset + 1];
/* extract the 5-5-5 RGB colors */
m_palette->set_pen_color(offset / 2, pal5bit(word >> 10), pal5bit(word >> 5), pal5bit(word >> 0));
}
}
/*************************************
*
* Horizontal/vertical positions
*
*************************************/
READ8_MEMBER(exidy440_state::exidy440_horizontal_pos_r)
{
/* clear the FIRQ on a read here */
m_firq_beam = 0;
exidy440_update_firq();
/* according to the schems, this value is only latched on an FIRQ
* caused by collision or beam */
return m_latched_x;
}
READ8_MEMBER(exidy440_state::exidy440_vertical_pos_r)
{
int result;
/* according to the schems, this value is latched on any FIRQ
* caused by collision or beam, ORed together with CHRCLK,
* which probably goes off once per scanline; for now, we just
* always return the current scanline */
result = m_screen->vpos();
return (result < 255) ? result : 255;
}
/*************************************
*
* Sprite RAM handler
*
*************************************/
WRITE8_MEMBER(exidy440_state::exidy440_spriteram_w)
{
m_screen->update_partial(m_screen->vpos());
m_spriteram[offset] = data;
}
/*************************************
*
* Interrupt and I/O control regs
*
*************************************/
WRITE8_MEMBER(exidy440_state::exidy440_control_w)
{
int oldvis = m_palettebank_vis;
/* extract the various bits */
exidy440_bank_select(data >> 4);
m_firq_enable = (data >> 3) & 1;
m_firq_select = (data >> 2) & 1;
m_palettebank_io = (data >> 1) & 1;
m_palettebank_vis = data & 1;
/* update the FIRQ in case we enabled something */
exidy440_update_firq();
/* if we're swapping palettes, change all the colors */
if (oldvis != m_palettebank_vis)
{
int i;
/* pick colors from the visible bank */
offset = m_palettebank_vis * 512;
for (i = 0; i < 256; i++, offset += 2)
{
/* extract a word and the 5-5-5 RGB components */
int word = (m_local_paletteram[offset] << 8) + m_local_paletteram[offset + 1];
m_palette->set_pen_color(i, pal5bit(word >> 10), pal5bit(word >> 5), pal5bit(word >> 0));
}
}
}
WRITE8_MEMBER(exidy440_state::exidy440_interrupt_clear_w)
{
/* clear the VBLANK FIRQ on a write here */
m_firq_vblank = 0;
exidy440_update_firq();
}
/*************************************
*
* Interrupt generators
*
*************************************/
void exidy440_state::exidy440_update_firq()
{
if (m_firq_vblank || (m_firq_enable && m_firq_beam))
m_maincpu->set_input_line(1, ASSERT_LINE);
else
m_maincpu->set_input_line(1, CLEAR_LINE);
}
WRITE_LINE_MEMBER(exidy440_state::vblank_interrupt_w)
{
/* set the FIRQ line on a VBLANK */
if (state)
{
m_firq_vblank = 1;
exidy440_update_firq();
}
}
/*************************************
*
* IRQ callback handlers
*
*************************************/
TIMER_CALLBACK_MEMBER(exidy440_state::beam_firq_callback)
{
/* generate the interrupt, if we're selected */
if (m_firq_select && m_firq_enable)
{
m_firq_beam = 1;
exidy440_update_firq();
}
/* round the x value to the nearest byte */
param = (param + 1) / 2;
/* latch the x value; this convolution comes from the read routine */
m_latched_x = (param + 3) ^ 2;
}
TIMER_CALLBACK_MEMBER(exidy440_state::collide_firq_callback)
{
/* generate the interrupt, if we're selected */
if (!m_firq_select && m_firq_enable)
{
m_firq_beam = 1;
exidy440_update_firq();
}
/* round the x value to the nearest byte */
param = (param + 1) / 2;
/* latch the x value; this convolution comes from the read routine */
m_latched_x = (param + 3) ^ 2;
}
/*************************************
*
* Sprite drawing
*
*************************************/
void exidy440_state::draw_sprites(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect, int scroll_offset, int check_collision)
{
/* get a pointer to the palette to look for collision flags */
uint8_t *palette = &m_local_paletteram[m_palettebank_vis * 512];
int count = 0;
/* draw the sprite images, checking for collisions along the way */
uint8_t *sprite = m_spriteram + (SPRITE_COUNT - 1) * 4;
for (int i = 0; i < SPRITE_COUNT; i++, sprite -= 4)
{
int image = (~sprite[3] & 0x3f);
int xoffs = (~((sprite[1] << 8) | sprite[2]) & 0x1ff);
int yoffs = (~sprite[0] & 0xff) + 1;
int x, y, sy;
uint8_t *src;
/* skip if out of range */
if (yoffs < cliprect.min_y || yoffs >= cliprect.max_y + 16)
continue;
/* get a pointer to the source image */
src = &m_imageram[image * 128];
/* account for large positive offsets meaning small negative values */
if (xoffs >= 0x1ff - 16)
xoffs -= 0x1ff;
/* loop over y */
sy = yoffs + scroll_offset;
for (y = 0; y < 16; y++, yoffs--, sy--)
{
/* wrap at the top and bottom of the screen */
if (sy >= VBSTART)
sy -= (VBSTART - VBEND);
else if (sy < VBEND)
sy += (VBSTART - VBEND);
/* stop if we get before the current scanline */
if (yoffs < cliprect.min_y)
break;
/* only draw scanlines that are in this cliprect */
if (yoffs <= cliprect.max_y)
{
uint8_t *old = &m_local_videoram[sy * 512 + xoffs];
int currx = xoffs;
/* loop over x */
for (x = 0; x < 8; x++, old += 2)
{
int ipixel = *src++;
int left = ipixel & 0xf0;
int right = (ipixel << 4) & 0xf0;
int pen;
/* left pixel */
if (left && currx >= HBEND && currx < HBSTART)
{
/* combine with the background */
pen = left | old[0];
bitmap.pix16(yoffs, currx) = pen;
/* check the collisions bit */
if (check_collision && (palette[2 * pen] & 0x80) && (count++ < 128))
m_collide_firq_timer->adjust(screen.time_until_pos(yoffs, currx), currx);
}
currx++;
/* right pixel */
if (right && currx >= HBEND && currx < HBSTART)
{
/* combine with the background */
pen = right | old[1];
bitmap.pix16(yoffs, currx) = pen;
/* check the collisions bit */
if (check_collision && (palette[2 * pen] & 0x80) && (count++ < 128))
m_collide_firq_timer->adjust(screen.time_until_pos(yoffs, currx), currx);
}
currx++;
}
}
else
src += 8;
}
}
}
/*************************************
*
* Core refresh routine
*
*************************************/
void exidy440_state::update_screen(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect, int scroll_offset, int check_collision)
{
/* draw any dirty scanlines from the VRAM directly */
int sy = scroll_offset + cliprect.min_y;
for (int y = cliprect.min_y; y <= cliprect.max_y; y++, sy++)
{
/* wrap at the bottom of the screen */
if (sy >= VBSTART)
sy -= (VBSTART - VBEND);
/* draw line */
draw_scanline8(bitmap, 0, y, (HBSTART - HBEND), &m_local_videoram[sy * 512], nullptr);
}
/* draw the sprites */
draw_sprites(screen, bitmap, cliprect, scroll_offset, check_collision);
}
/*************************************
*
* Standard screen refresh callback
*
*************************************/
uint32_t exidy440_state::screen_update_exidy440(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
/* redraw the screen */
update_screen(screen, bitmap, cliprect, 0, true);
/* generate an interrupt once/frame for the beam */
if (cliprect.max_y == screen.visible_area().max_y)
{
int i;
int beamx = ((ioport("AN0")->read() & 0xff) * (HBSTART - HBEND)) >> 8;
int beamy = ((ioport("AN1")->read() & 0xff) * (VBSTART - VBEND)) >> 8;
/* The timing of this FIRQ is very important. The games look for an FIRQ
and then wait about 650 cycles, clear the old FIRQ, and wait a
very short period of time (~130 cycles) for another one to come in.
From this, it appears that they are expecting to get beams over
a 12 scanline period, and trying to pick roughly the middle one.
This is how it is implemented. */
attotime increment = screen.scan_period();
attotime time = screen.time_until_pos(beamy, beamx) - increment * 6;
for (i = 0; i <= 12; i++)
{
machine().scheduler().timer_set(time, timer_expired_delegate(FUNC(exidy440_state::beam_firq_callback),this), beamx);
time += increment;
}
}
return 0;
}
uint32_t topsecex_state::screen_update_topsecex(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
/* redraw the screen */
update_screen(screen, bitmap, cliprect, m_topsecex_yscroll, false);
return 0;
}
/*************************************
*
* Machine drivers
*
*************************************/
MACHINE_CONFIG_START(exidy440_state::exidy440_video)
MCFG_PALETTE_ADD("palette", 256)
MCFG_SCREEN_ADD("screen", RASTER)
MCFG_SCREEN_VIDEO_ATTRIBUTES(VIDEO_ALWAYS_UPDATE)
MCFG_SCREEN_RAW_PARAMS(PIXEL_CLOCK, HTOTAL, HBEND, HBSTART, VTOTAL, VBEND, VBSTART)
MCFG_SCREEN_UPDATE_DRIVER(exidy440_state, screen_update_exidy440)
MCFG_SCREEN_PALETTE("palette")
MCFG_SCREEN_VBLANK_CALLBACK(WRITELINE(*this, exidy440_state, vblank_interrupt_w))
MCFG_DEVCB_CHAIN_OUTPUT(WRITELINE("440audio", exidy440_sound_device, sound_interrupt_w))
MACHINE_CONFIG_END
MACHINE_CONFIG_START(topsecex_state::topsecex_video)
MCFG_SCREEN_MODIFY("screen")
MCFG_SCREEN_VIDEO_ATTRIBUTES(0)
MCFG_SCREEN_RAW_PARAMS(PIXEL_CLOCK, HTOTAL, HBEND, HBSTART, VTOTAL, VBEND, TOPSECEX_VBSTART)
MCFG_SCREEN_UPDATE_DRIVER(topsecex_state, screen_update_topsecex)
MACHINE_CONFIG_END