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// license:BSD-3-Clause
// copyright-holders:Mirko Buffoni
/***************************************************************************

  video.c

  Functions to emulate the video hardware of the machine.

***************************************************************************/

#include "emu.h"
#include "includes/sonson.h"

/***************************************************************************

  Convert the color PROMs into a more useable format.

  Son Son has two 32x8 palette PROMs and two 256x4 lookup table PROMs (one
  for characters, one for sprites).
  The palette PROMs are connected to the RGB output this way:

  I don't know the exact values of the resistors between the PROMs and the
  RGB output. I assumed these values (the same as Commando)
  bit 7 -- 220 ohm resistor  -- GREEN
        -- 470 ohm resistor  -- GREEN
        -- 1  kohm resistor  -- GREEN
        -- 2.2kohm resistor  -- GREEN
        -- 220 ohm resistor  -- BLUE
        -- 470 ohm resistor  -- BLUE
        -- 1  kohm resistor  -- BLUE
  bit 0 -- 2.2kohm resistor  -- BLUE

  bit 7 -- unused
        -- unused
        -- unused
        -- unused
        -- 220 ohm resistor  -- RED
        -- 470 ohm resistor  -- RED
        -- 1  kohm resistor  -- RED
  bit 0 -- 2.2kohm resistor  -- RED

***************************************************************************/

void sonson_state::sonson_palette(palette_device &palette) const
{
	const uint8_t *color_prom = memregion("proms")->base();

	// create a lookup table for the palette
	for (int i = 0; i < 0x20; i++)
	{
		int bit0, bit1, bit2, bit3;

		// red component
		bit0 = (color_prom[i + 0x20] >> 0) & 0x01;
		bit1 = (color_prom[i + 0x20] >> 1) & 0x01;
		bit2 = (color_prom[i + 0x20] >> 2) & 0x01;
		bit3 = (color_prom[i + 0x20] >> 3) & 0x01;
		int const r = 0x0e * bit0 + 0x1f * bit1 + 0x43 * bit2 + 0x8f * bit3;

		// green component
		bit0 = (color_prom[i + 0x00] >> 4) & 0x01;
		bit1 = (color_prom[i + 0x00] >> 5) & 0x01;
		bit2 = (color_prom[i + 0x00] >> 6) & 0x01;
		bit3 = (color_prom[i + 0x00] >> 7) & 0x01;
		int const g = 0x0e * bit0 + 0x1f * bit1 + 0x43 * bit2 + 0x8f * bit3;

		// blue component
		bit0 = (color_prom[i + 0x00] >> 0) & 0x01;
		bit1 = (color_prom[i + 0x00] >> 1) & 0x01;
		bit2 = (color_prom[i + 0x00] >> 2) & 0x01;
		bit3 = (color_prom[i + 0x00] >> 3) & 0x01;
		int const b = 0x0e * bit0 + 0x1f * bit1 + 0x43 * bit2 + 0x8f * bit3;

		palette.set_indirect_color(i, rgb_t(r, g, b));
	}

	// color_prom now points to the beginning of the lookup table
	color_prom += 0x40;

	// characters use colors 0-0x0f
	for (int i = 0; i < 0x100; i++)
	{
		uint8_t const ctabentry = color_prom[i] & 0x0f;
		palette.set_pen_indirect(i, ctabentry);
	}

	// sprites use colors 0x10-0x1f
	for (int i = 0x100; i < 0x200; i++)
	{
		uint8_t const ctabentry = (color_prom[i] & 0x0f) | 0x10;
		palette.set_pen_indirect(i, ctabentry);
	}
}

WRITE8_MEMBER(sonson_state::sonson_videoram_w)
{
	m_videoram[offset] = data;
	m_bg_tilemap->mark_tile_dirty(offset);
}

WRITE8_MEMBER(sonson_state::sonson_colorram_w)
{
	m_colorram[offset] = data;
	m_bg_tilemap->mark_tile_dirty(offset);
}

WRITE8_MEMBER(sonson_state::sonson_scrollx_w)
{
	int row;

	for (row = 5; row < 32; row++)
		m_bg_tilemap->set_scrollx(row, data);
}

WRITE_LINE_MEMBER(sonson_state::flipscreen_w)
{
	flip_screen_set(!state);
}

TILE_GET_INFO_MEMBER(sonson_state::get_bg_tile_info)
{
	int attr = m_colorram[tile_index];
	int code = m_videoram[tile_index] + 256 * (attr & 0x03);
	int color = attr >> 2;

	SET_TILE_INFO_MEMBER(0, code, color, 0);
}

void sonson_state::video_start()
{
	m_bg_tilemap = &machine().tilemap().create(*m_gfxdecode, tilemap_get_info_delegate(*this, FUNC(sonson_state::get_bg_tile_info)), TILEMAP_SCAN_ROWS, 8, 8, 32, 32);
	m_bg_tilemap->set_scroll_rows(32);
}

void sonson_state::draw_sprites( bitmap_ind16 &bitmap, const rectangle &cliprect )
{
	uint8_t *spriteram = m_spriteram;
	int offs;

	for (offs = m_spriteram.bytes() - 4; offs >= 0; offs -= 4)
	{
		int code = spriteram[offs + 2] + ((spriteram[offs + 1] & 0x20) << 3);
		int color = spriteram[offs + 1] & 0x1f;
		int flipx = ~spriteram[offs + 1] & 0x40;
		int flipy = ~spriteram[offs + 1] & 0x80;
		int sx = spriteram[offs + 3];
		int sy = spriteram[offs + 0];

		if (flip_screen())
		{
			sx = 240 - sx;
			sy = 240 - sy;
			flipx = !flipx;
			flipy = !flipy;
		}


			m_gfxdecode->gfx(1)->transpen(bitmap,cliprect,
			code, color,
			flipx, flipy,
			sx, sy, 0);

		/* wrap-around */
		m_gfxdecode->gfx(1)->transpen(bitmap,cliprect, code, color, flipx, flipy, sx - 256, sy, 0);
		m_gfxdecode->gfx(1)->transpen(bitmap,cliprect, code, color, flipx, flipy, sx, sy - 256, 0);
	}
}

uint32_t sonson_state::screen_update_sonson(screen_device &screen, bitmap_ind16 &bitmap, const rectangle &cliprect)
{
	m_bg_tilemap->draw(screen, bitmap, cliprect, 0, 0);
	draw_sprites(bitmap, cliprect);
	return 0;
}