// license:BSD-3-Clause
// copyright-holders:Aaron Giles
/***************************************************************************
Jaleco Exerion
***************************************************************************/
#include "emu.h"
#include "video/resnet.h"
#include "includes/exerion.h"
#define BACKGROUND_X_START 32
#define VISIBLE_X_MIN (12*8)
#define VISIBLE_X_MAX (52*8)
#define VISIBLE_Y_MIN (2*8)
#define VISIBLE_Y_MAX (30*8)
/***************************************************************************
Convert the color PROMs into a more useable format.
The palette PROM is connected to the RGB output this way:
bit 7 -- 220 ohm resistor -- BLUE
-- 470 ohm resistor -- BLUE
-- 220 ohm resistor -- GREEN
-- 470 ohm resistor -- GREEN
-- 1 kohm resistor -- GREEN
-- 220 ohm resistor -- RED
-- 470 ohm resistor -- RED
bit 0 -- 1 kohm resistor -- RED
***************************************************************************/
void exerion_state::exerion_palette(palette_device &palette) const
{
const uint8_t *color_prom = memregion("proms")->base();
static constexpr int resistances_rg[3] = { 1000, 470, 220 };
static constexpr int resistances_b [2] = { 470, 220 };
// compute the color output resistor weights
double rweights[3], gweights[3], bweights[2];
compute_resistor_weights(0, 255, -1.0,
3, &resistances_rg[0], rweights, 0, 0,
3, &resistances_rg[0], gweights, 0, 0,
2, &resistances_b[0], bweights, 0, 0);
// create a lookup table for the palette
for (int i = 0; i < 0x20; i++)
{
int bit0, bit1, bit2;
// red component
bit0 = BIT(color_prom[i], 0);
bit1 = BIT(color_prom[i], 1);
bit2 = BIT(color_prom[i], 2);
int const r = combine_weights(rweights, bit0, bit1, bit2);
// green component
bit0 = BIT(color_prom[i], 3);
bit1 = BIT(color_prom[i], 4);
bit2 = BIT(color_prom[i], 5);
int const g = combine_weights(gweights, bit0, bit1, bit2);
// blue component
bit0 = BIT(color_prom[i], 6);
bit1 = BIT(color_prom[i], 7);
int const b = combine_weights(bweights, bit0, bit1);
palette.set_indirect_color(i, rgb_t(r, g, b));
}
// color_prom now points to the beginning of the lookup table
color_prom += 0x20;
// fg chars and sprites
for (int i = 0; i < 0x200; i++)
{
uint8_t const ctabentry = 0x10 | (color_prom[(i & 0x1c0) | ((i & 3) << 4) | ((i >> 2) & 0x0f)] & 0x0f);
palette.set_pen_indirect(i, ctabentry);
}
// bg chars (this is not the full story... there are four layers mixed using another PROM
for (int i = 0x200; i < 0x300; i++)
{
uint8_t const ctabentry = color_prom[i] & 0x0f;
palette.set_pen_indirect(i, ctabentry);
}
}
/*************************************
*
* Video system startup
*
*************************************/
void exerion_state::video_start()
{
int i;
uint8_t *gfx;
/* get pointers to the mixing and lookup PROMs */
m_background_mixer = memregion("proms")->base() + 0x320;
/* allocate memory for the decoded background graphics */
m_background_gfx[0] = std::make_unique<uint16_t[]>(256 * 256);
m_background_gfx[1] = std::make_unique<uint16_t[]>(256 * 256);
m_background_gfx[2] = std::make_unique<uint16_t[]>(256 * 256);
m_background_gfx[3] = std::make_unique<uint16_t[]>(256 * 256);
save_pointer(NAME(m_background_gfx[0]), 256 * 256);
save_pointer(NAME(m_background_gfx[1]), 256 * 256);
save_pointer(NAME(m_background_gfx[2]), 256 * 256);
save_pointer(NAME(m_background_gfx[3]), 256 * 256);
/*---------------------------------
* Decode the background graphics
*
* We decode the 4 background layers separately, but shuffle the bits so that
* we can OR all four layers together. Each layer has 2 bits per pixel. Each
* layer is decoded into the following bit patterns:
*
* 000a 0000 00AA
* 00b0 0000 BB00
* 0c00 00CC 0000
* d000 DD00 0000
*
* Where AA,BB,CC,DD are the 2bpp data for the pixel,and a,b,c,d are the OR
* of these two bits together.
*/
gfx = memregion("gfx3")->base();
for (i = 0; i < 4; i++)
{
int y;
uint8_t *src = gfx + i * 0x2000;
uint16_t *dst = m_background_gfx[i].get();
for (y = 0; y < 0x100; y++)
{
int x;
for (x = 0; x < 0x80; x += 4)
{
uint8_t data = *src++;
uint16_t val;
val = ((data >> 3) & 2) | ((data >> 0) & 1);
if (val) val |= 0x100 >> i;
*dst++ = val << (2 * i);
val = ((data >> 4) & 2) | ((data >> 1) & 1);
if (val) val |= 0x100 >> i;
*dst++ = val << (2 * i);
val = ((data >> 5) & 2) | ((data >> 2) & 1);
if (val) val |= 0x100 >> i;
*dst++ = val << (2 * i);
val = ((data >> 6) & 2) | ((data >> 3) & 1);
if (val) val |= 0x100 >> i;
*dst++ = val << (2 * i);
}
for (; x < 0x100; x++)
*dst++ = 0;
}
}
}
/*************************************
*
* Video register I/O
*
*************************************/
WRITE8_MEMBER(exerion_state::exerion_videoreg_w)
{
/* bit 0 = flip screen and joystick input multiplexer */
m_cocktail_flip = data & 1;
/* bits 1-2 char lookup table bank */
m_char_palette = (data & 0x06) >> 1;
/* bits 3 char bank */
m_char_bank = (data & 0x08) >> 3;
/* bits 4-5 unused */
/* bits 6-7 sprite lookup table bank */
m_sprite_palette = (data & 0xc0) >> 6;
}
WRITE8_MEMBER(exerion_state::exerion_video_latch_w)
{
int scanline = m_screen->vpos();
if (scanline > 0)
m_screen->update_partial(scanline - 1);
m_background_latches[offset] = data;
}
READ8_MEMBER(exerion_state::exerion_video_timing_r)
{
/* bit 0 is the SNMI signal, which is the negated value of H6, if H7=1 & H8=1 & VBLANK=0, otherwise 1 */
/* bit 1 is VBLANK */
uint16_t hcounter = m_screen->hpos() + EXERION_HCOUNT_START;
uint8_t snmi = 1;
if (((hcounter & 0x180) == 0x180) && !m_screen->vblank())
snmi = !((hcounter >> 6) & 0x01);
return (m_screen->vblank() << 1) | snmi;
}
/*************************************
*
* Background rendering
*
*************************************/
void exerion_state::draw_background( bitmap_ind16 &bitmap, const rectangle &cliprect)
{
int x, y;
/* loop over all visible scanlines */
for (y = cliprect.min_y; y <= cliprect.max_y; y++)
{
uint16_t *src0 = &m_background_gfx[0][m_background_latches[1] * 256];
uint16_t *src1 = &m_background_gfx[1][m_background_latches[3] * 256];
uint16_t *src2 = &m_background_gfx[2][m_background_latches[5] * 256];
uint16_t *src3 = &m_background_gfx[3][m_background_latches[7] * 256];
int xoffs0 = m_background_latches[0];
int xoffs1 = m_background_latches[2];
int xoffs2 = m_background_latches[4];
int xoffs3 = m_background_latches[6];
int start0 = m_background_latches[8] & 0x0f;
int start1 = m_background_latches[9] & 0x0f;
int start2 = m_background_latches[10] & 0x0f;
int start3 = m_background_latches[11] & 0x0f;
int stop0 = m_background_latches[8] >> 4;
int stop1 = m_background_latches[9] >> 4;
int stop2 = m_background_latches[10] >> 4;
int stop3 = m_background_latches[11] >> 4;
uint8_t *mixer = &m_background_mixer[(m_background_latches[12] << 4) & 0xf0];
uint16_t scanline[VISIBLE_X_MAX];
pen_t pen_base = 0x200 + ((m_background_latches[12] >> 4) << 4);
/* the cocktail flip flag controls whether we count up or down in X */
if (!m_cocktail_flip)
{
/* skip processing anything that's not visible */
for (x = BACKGROUND_X_START; x < cliprect.min_x; x++)
{
if (!(++xoffs0 & 0x1f)) start0++, stop0++;
if (!(++xoffs1 & 0x1f)) start1++, stop1++;
if (!(++xoffs2 & 0x1f)) start2++, stop2++;
if (!(++xoffs3 & 0x1f)) start3++, stop3++;
}
/* draw the rest of the scanline fully */
for (x = cliprect.min_x; x <= cliprect.max_x; x++)
{
uint16_t combined = 0;
uint8_t lookupval;
/* the output enable is controlled by the carries on the start/stop counters */
/* they are only active when the start has carried but the stop hasn't */
if ((start0 ^ stop0) & 0x10) combined |= src0[xoffs0 & 0xff];
if ((start1 ^ stop1) & 0x10) combined |= src1[xoffs1 & 0xff];
if ((start2 ^ stop2) & 0x10) combined |= src2[xoffs2 & 0xff];
if ((start3 ^ stop3) & 0x10) combined |= src3[xoffs3 & 0xff];
/* bits 8-11 of the combined value contains the lookup for the mixer PROM */
lookupval = mixer[combined >> 8] & 3;
/* the color index comes from the looked up value combined with the pixel data */
scanline[x] = pen_base | (lookupval << 2) | ((combined >> (2 * lookupval)) & 3);
/* the start/stop counters are clocked when the low 5 bits of the X counter overflow */
if (!(++xoffs0 & 0x1f)) start0++, stop0++;
if (!(++xoffs1 & 0x1f)) start1++, stop1++;
if (!(++xoffs2 & 0x1f)) start2++, stop2++;
if (!(++xoffs3 & 0x1f)) start3++, stop3++;
}
}
else
{
/* skip processing anything that's not visible */
for (x = BACKGROUND_X_START; x < cliprect.min_x; x++)
{
if (!(xoffs0-- & 0x1f)) start0++, stop0++;
if (!(xoffs1-- & 0x1f)) start1++, stop1++;
if (!(xoffs2-- & 0x1f)) start2++, stop2++;
if (!(xoffs3-- & 0x1f)) start3++, stop3++;
}
/* draw the rest of the scanline fully */
for (x = cliprect.min_x; x <= cliprect.max_x; x++)
{
uint16_t combined = 0;
uint8_t lookupval;
/* the output enable is controlled by the carries on the start/stop counters */
/* they are only active when the start has carried but the stop hasn't */
if ((start0 ^ stop0) & 0x10) combined |= src0[xoffs0 & 0xff];
if ((start1 ^ stop1) & 0x10) combined |= src1[xoffs1 & 0xff];
if ((start2 ^ stop2) & 0x10) combined |= src2[xoffs2 & 0xff];
if ((start3 ^ stop3) & 0x10) combined |= src3[xoffs3 & 0xff];
/* bits 8-11 of the combined value contains the lookup for the mixer PROM */
lookupval = mixer[combined >> 8] & 3;
/* the color index comes from the looked up value combined with the pixel data */
scanline[x] = pen_base | (lookupval << 2) | ((combined >> (2 * lookupval)) & 3);
/* the start/stop counters are clocked when the low 5 bits of the X counter overflow */
if (!(xoffs0-- & 0x1f)) start0++, stop0++;
if (!(xoffs1-- & 0x1f)) start1++, stop1++;
if (!(xoffs2-- & 0x1f)) start2++, stop2++;
if (!(xoffs3-- & 0x1f)) start3++, stop3++;
}
}
/* draw the scanline */
draw_scanline16(bitmap, cliprect.min_x, y, cliprect.width(), &scanline[cliprect.min_x], nullptr);
}
}
/*************************************
*
* Core refresh routine
*
*************************************/
uint32_t exerion_state::screen_update_exerion(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
int sx, sy, offs, i;
/* draw background */
draw_background(bitmap, cliprect);
/* draw sprites */
for (i = 0; i < m_spriteram.bytes(); i += 4)
{
int flags = m_spriteram[i + 0];
int y = m_spriteram[i + 1] ^ 255;
int code = m_spriteram[i + 2];
int x = m_spriteram[i + 3] * 2 + 72;
int xflip = flags & 0x80;
int yflip = flags & 0x40;
int doubled = flags & 0x10;
int wide = flags & 0x08;
int code2 = code;
int color = ((flags >> 1) & 0x03) | ((code >> 5) & 0x04) | (code & 0x08) | (m_sprite_palette * 16);
gfx_element *gfx = doubled ? m_gfxdecode->gfx(2) : m_gfxdecode->gfx(1);
if (m_cocktail_flip)
{
x = 64*8 - gfx->width() - x;
y = 32*8 - gfx->height() - y;
if (wide) y -= gfx->height();
xflip = !xflip;
yflip = !yflip;
}
if (wide)
{
if (yflip)
code |= 0x10, code2 &= ~0x10;
else
code &= ~0x10, code2 |= 0x10;
gfx->transmask(bitmap,cliprect, code2, color, xflip, yflip, x, y + gfx->height(),
m_palette->transpen_mask(*gfx, color, 0x10));
}
gfx->transmask(bitmap,cliprect, code, color, xflip, yflip, x, y,
m_palette->transpen_mask(*gfx, color, 0x10));
if (doubled) i += 4;
}
/* draw the visible text layer */
for (sy = cliprect.min_y/8; sy <= cliprect.max_y/8; sy++)
for (sx = VISIBLE_X_MIN/8; sx < VISIBLE_X_MAX/8; sx++)
{
int x = m_cocktail_flip ? (63*8 - 8*sx) : 8*sx;
int y = m_cocktail_flip ? (31*8 - 8*sy) : 8*sy;
offs = sx + sy * 64;
m_gfxdecode->gfx(0)->transpen(bitmap,cliprect,
m_videoram[offs] + 256 * m_char_bank,
((m_videoram[offs] & 0xf0) >> 4) + m_char_palette * 16,
m_cocktail_flip, m_cocktail_flip, x, y, 0);
}
return 0;
}