// license:BSD-3-Clause
// copyright-holders:Aaron Giles
/*************************************************************************
Exidy 6502 hardware
*************************************************************************/
#include "emu.h"
#include "includes/exidy.h"
/*************************************
*
* Video configuration
*
*************************************/
void exidy_state::exidy_video_config(uint8_t _collision_mask, uint8_t _collision_invert, int _is_2bpp)
{
m_collision_mask = _collision_mask;
m_collision_invert = _collision_invert;
m_is_2bpp = _is_2bpp;
}
/*************************************
*
* Video startup
*
*************************************/
void exidy_state::video_start()
{
m_screen->register_screen_bitmap(m_background_bitmap);
m_motion_object_1_vid.allocate(16, 16);
m_motion_object_2_vid.allocate(16, 16);
m_motion_object_2_clip.allocate(16, 16);
save_item(NAME(m_collision_mask));
save_item(NAME(m_collision_invert));
save_item(NAME(m_is_2bpp));
save_item(NAME(m_int_condition));
save_item(NAME(m_background_bitmap));
save_item(NAME(m_motion_object_1_vid));
save_item(NAME(m_motion_object_2_vid));
save_item(NAME(m_motion_object_2_clip));
}
/*************************************
*
* Interrupt generation
*
*************************************/
inline void exidy_state::latch_condition(int collision)
{
collision ^= m_collision_invert;
m_int_condition = (ioport("INTSOURCE")->read() & ~0x1c) | (collision & m_collision_mask);
}
INTERRUPT_GEN_MEMBER(exidy_state::exidy_vblank_interrupt)
{
/* latch the current condition */
latch_condition(0);
m_int_condition &= ~0x80;
/* set the IRQ line */
device.execute().set_input_line(0, ASSERT_LINE);
}
READ8_MEMBER(exidy_state::exidy_interrupt_r)
{
/* clear any interrupts */
m_maincpu->set_input_line(0, CLEAR_LINE);
/* return the latched condition */
return m_int_condition;
}
/*************************************
*
* Palette handling
*
*************************************/
inline void exidy_state::set_1_color(int index, int which)
{
m_palette->set_pen_color(index,
pal1bit(m_color_latch[2] >> which),
pal1bit(m_color_latch[1] >> which),
pal1bit(m_color_latch[0] >> which));
}
void exidy_state::set_colors()
{
/* motion object 1 */
set_1_color(0, 0);
set_1_color(1, 7);
/* motion object 2 */
set_1_color(2, 0);
set_1_color(3, 6);
/* characters */
set_1_color(4, 4);
set_1_color(5, 3);
set_1_color(6, 2);
set_1_color(7, 1);
}
/*************************************
*
* Background update
*
*************************************/
void exidy_state::draw_background()
{
offs_t offs;
pen_t off_pen = 0;
for (offs = 0; offs < 0x400; offs++)
{
uint8_t cy;
pen_t on_pen_1, on_pen_2;
uint8_t y = offs >> 5 << 3;
uint8_t code = m_videoram[offs];
if (m_is_2bpp)
{
on_pen_1 = 4 + ((code >> 6) & 0x02);
on_pen_2 = 5 + ((code >> 6) & 0x02);
}
else
{
on_pen_1 = 4 + ((code >> 6) & 0x03);
on_pen_2 = off_pen; /* unused */
}
for (cy = 0; cy < 8; cy++)
{
int i;
uint8_t x = offs << 3;
if (m_is_2bpp)
{
uint8_t data1 = m_characterram[0x000 | (code << 3) | cy];
uint8_t data2 = m_characterram[0x800 | (code << 3) | cy];
for (i = 0; i < 8; i++)
{
if (data1 & 0x80)
m_background_bitmap.pix16(y, x) = (data2 & 0x80) ? on_pen_2 : on_pen_1;
else
m_background_bitmap.pix16(y, x) = off_pen;
x = x + 1;
data1 = data1 << 1;
data2 = data2 << 1;
}
}
/* 1bpp */
else
{
uint8_t data = m_characterram[(code << 3) | cy];
for (i = 0; i < 8; i++)
{
m_background_bitmap.pix16(y, x) = (data & 0x80) ? on_pen_1 : off_pen;
x = x + 1;
data = data << 1;
}
}
y = y + 1;
}
}
}
/*************************************
*
* Sprite hardware
*
*************************************/
inline int exidy_state::sprite_1_enabled()
{
/* if the collision_mask is 0x00, then we are on old hardware that always has */
/* sprite 1 enabled regardless */
return (!(*m_sprite_enable & 0x80) || (*m_sprite_enable & 0x10) || (m_collision_mask == 0x00));
}
void exidy_state::draw_sprites(bitmap_ind16 &bitmap, const rectangle &cliprect)
{
/* draw sprite 2 first */
int sprite_set_2 = ((*m_sprite_enable & 0x40) != 0);
int sx = 236 - *m_sprite2_xpos - 4;
int sy = 244 - *m_sprite2_ypos - 4;
m_gfxdecode->gfx(0)->transpen(bitmap,cliprect,
((*m_spriteno >> 4) & 0x0f) + 32 + 16 * sprite_set_2, 1,
0, 0, sx, sy, 0);
/* draw sprite 1 next */
if (sprite_1_enabled())
{
int sprite_set_1 = ((*m_sprite_enable & 0x20) != 0);
sx = 236 - *m_sprite1_xpos - 4;
sy = 244 - *m_sprite1_ypos - 4;
if (sy < 0) sy = 0;
m_gfxdecode->gfx(0)->transpen(bitmap,cliprect,
(*m_spriteno & 0x0f) + 16 * sprite_set_1, 0,
0, 0, sx, sy, 0);
}
}
/*************************************
*
* Collision detection
*
*************************************/
/***************************************************************************
Exidy hardware checks for two types of collisions based on the video
signals. If the Motion Object 1 and Motion Object 2 signals are on at
the same time, an M1M2 collision bit gets set. If the Motion Object 1
and Background Character signals are on at the same time, an M1CHAR
collision bit gets set. So effectively, there's a pixel-by-pixel
collision check comparing Motion Object 1 (the player) to the
background and to the other Motion Object (typically a bad guy).
***************************************************************************/
void exidy_state::device_timer(emu_timer &timer, device_timer_id id, int param, void *ptr)
{
switch (id)
{
case TIMER_COLLISION_IRQ:
/* latch the collision bits */
latch_condition(param);
/* set the IRQ line */
m_maincpu->set_input_line(0, ASSERT_LINE);
break;
default:
assert_always(false, "Unknown id in exidy_state::device_timer");
}
}
void exidy_state::check_collision()
{
uint8_t sprite_set_1 = ((*m_sprite_enable & 0x20) != 0);
uint8_t sprite_set_2 = ((*m_sprite_enable & 0x40) != 0);
const rectangle clip(0, 15, 0, 15);
int org_1_x = 0, org_1_y = 0;
int org_2_x = 0, org_2_y = 0;
int sx, sy;
int count = 0;
/* if there is nothing to detect, bail */
if (m_collision_mask == 0)
return;
/* draw sprite 1 */
m_motion_object_1_vid.fill(0xff, clip);
if (sprite_1_enabled())
{
org_1_x = 236 - *m_sprite1_xpos - 4;
org_1_y = 244 - *m_sprite1_ypos - 4;
m_gfxdecode->gfx(0)->transpen(m_motion_object_1_vid,clip,
(*m_spriteno & 0x0f) + 16 * sprite_set_1, 0,
0, 0, 0, 0, 0);
}
/* draw sprite 2 */
m_motion_object_2_vid.fill(0xff, clip);
org_2_x = 236 - *m_sprite2_xpos - 4;
org_2_y = 244 - *m_sprite2_ypos - 4;
m_gfxdecode->gfx(0)->transpen(m_motion_object_2_vid,clip,
((*m_spriteno >> 4) & 0x0f) + 32 + 16 * sprite_set_2, 0,
0, 0, 0, 0, 0);
/* draw sprite 2 clipped to sprite 1's location */
m_motion_object_2_clip.fill(0xff, clip);
if (sprite_1_enabled())
{
sx = org_2_x - org_1_x;
sy = org_2_y - org_1_y;
m_gfxdecode->gfx(0)->transpen(m_motion_object_2_clip,clip,
((*m_spriteno >> 4) & 0x0f) + 32 + 16 * sprite_set_2, 0,
0, 0, sx, sy, 0);
}
/* scan for collisions */
for (sy = 0; sy < 16; sy++)
for (sx = 0; sx < 16; sx++)
{
if (m_motion_object_1_vid.pix16(sy, sx) != 0xff)
{
uint8_t current_collision_mask = 0;
/* check for background collision (M1CHAR) */
if (m_background_bitmap.pix16(org_1_y + sy, org_1_x + sx) != 0)
current_collision_mask |= 0x04;
/* check for motion object collision (M1M2) */
if (m_motion_object_2_clip.pix16(sy, sx) != 0xff)
current_collision_mask |= 0x10;
/* if we got one, trigger an interrupt */
if ((current_collision_mask & m_collision_mask) && (count++ < 128))
timer_set(m_screen->time_until_pos(org_1_x + sx, org_1_y + sy), TIMER_COLLISION_IRQ, current_collision_mask);
}
if (m_motion_object_2_vid.pix16(sy, sx) != 0xff)
{
/* check for background collision (M2CHAR) */
if (m_background_bitmap.pix16(org_2_y + sy, org_2_x + sx) != 0)
if ((m_collision_mask & 0x08) && (count++ < 128))
timer_set(m_screen->time_until_pos(org_2_x + sx, org_2_y + sy), TIMER_COLLISION_IRQ, 0x08);
}
}
}
/*************************************
*
* Standard screen refresh callback
*
*************************************/
uint32_t exidy_state::screen_update_exidy(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
/* refresh the colors from the palette (static or dynamic) */
set_colors();
/* update the background and draw it */
draw_background();
copybitmap(bitmap, m_background_bitmap, 0, 0, 0, 0, cliprect);
/* draw the sprites */
draw_sprites(bitmap, cliprect);
/* check for collision, this will set the appropriate bits in collision_mask */
check_collision();
return 0;
}