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// license:BSD-3-Clause
// copyright-holders:Bryan McPhail
/*************************************************************************

    deco_ace.cpp

    Data East 99 "ACE" Chip Emulation

    Original source (from deco32.cpp) by Bryan McPhail, Splited by cam900.

**************************************************************************/
/*Some notes pieced together from Tattoo Assassins info(from deco32.cpp):

    Bytes 0 to 0x1f : Alpha Control
    Tattoo Assassins :
    Bytes 0x00 to 0x16(0x58) - object alpha control?
    Bytes 0x17(0x5c) to 0x1f(0x7c) - tilemap alpha control

    Boogie Wings:
    Bytes 0x00 to 0x0f(0x1f) - object alpha control (if ((pix & 0x100) == 0))
    Bytes 0x10(0x20) to 0x13(0x26) - another object alpha control?
    Bytes 0x14(0x28) to 0x19(0x32) - fixed value 0x1c 0x18 0x14 0x10 0x0c 0x08. it controls explosion object's alpha?
    Bytes 0x1a(0x34) to 0x1f(0x3f) - tilemap alpha control?

    0 = opaque, 0x10 = 50% transparent, 0x20 = fully transparent

    Byte 0x00: ACEO000P0
                        P8
                        1P0
                        1P8
                        O010C1
                        o010C8
                        ??

    Hardware fade registers:

    Byte 0x20(0x80): fadeptred
    Byte 0x21(0x84): fadeptgreen
    Byte 0x22(0x88): fadeptblue
    Byte 0x23(0x8c): fadestred
    Byte 0x24(0x90): fadestgreen
    Byte 0x25(0x94): fadestblue
    Byte 0x26(0x98): fadetype
    Byte 0x27(0x9c): unused/unknown

    The 'ST' value lerps between the 'PT' value and the palette entries.  So, if PT==0,
    then ST ranging from 0 to 255 will cause a fade to black (when ST==255 the palette
    becomes zero).

    'fadetype' - 1100 for multiplicative fade, 1000 for additive

    TODO:
        additive fade is correct? verify additive fading from real pcb.
*/


#include "emu.h"
#include "video/deco_ace.h"
#include <algorithm>


DEFINE_DEVICE_TYPE(DECO_ACE, deco_ace_device, "deco_ace", "Data East 99 'ACE' Chip")

deco_ace_device::deco_ace_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
	: device_t(mconfig, DECO_ACE, tag, owner, clock),
	device_video_interface(mconfig, *this),
	device_palette_interface(mconfig, *this),
	m_palette_effect_min(0x100),
	m_palette_effect_max(0xfff),
	m_paletteram(nullptr),
	m_paletteram_buffered(nullptr),
	m_ace_ram(nullptr)
{
}

//-------------------------------------------------
//  device_start - device-specific startup
//-------------------------------------------------

void deco_ace_device::device_start()
{
	m_paletteram = make_unique_clear<uint32_t[]>(2048);
	m_paletteram_buffered = make_unique_clear<uint32_t[]>(2048);
	m_ace_ram = make_unique_clear<uint16_t[]>(0x28);

	save_pointer(NAME(m_paletteram), 2048);
	save_pointer(NAME(m_paletteram_buffered), 2048);
	save_pointer(NAME(m_ace_ram), 0x28);
}

//-------------------------------------------------
//  device_reset - device-specific reset
//-------------------------------------------------

void deco_ace_device::device_reset()
{
	m_palette_effect_min = 0x100; /* Screenshots seem to suggest ACE fades do not affect playfield 1 palette (0-255) */
	m_palette_effect_max = 0xfff;
	memset(m_ace_ram.get(),0,0x28);
}

//-------------------------------------------------
//  device_post_load - device-specific post-load
//-------------------------------------------------

void deco_ace_device::device_post_load()
{
	palette_update();
}

/*****************************************************************************
    DEVICE HANDLERS
*****************************************************************************/

/* Games have double buffered paletteram - the real palette ram is
only updated on a DMA call */

// nslasher
READ32_MEMBER( deco_ace_device::buffered_palette_r )
{
	return m_paletteram[offset];
}

WRITE32_MEMBER( deco_ace_device::buffered_palette_w )
{
	COMBINE_DATA(&m_paletteram[offset]);
}

// boogwing has 16 bit cpu data bus(M68000 Based)
READ16_MEMBER( deco_ace_device::buffered_palette16_r )
{
	if ((offset & 1) == 0)
		return (m_paletteram[offset >> 1] >> 16) & 0xffff;
	else
		return m_paletteram[offset >> 1] & 0xffff;
}

WRITE16_MEMBER( deco_ace_device::buffered_palette16_w )
{
	if ((offset & 1) == 0)
		m_paletteram[offset >> 1] = (m_paletteram[offset >> 1] & ~(mem_mask<<16)) | ((data & mem_mask)<<16);
	else
		m_paletteram[offset >> 1] = (m_paletteram[offset >> 1] & ~mem_mask) | (data & mem_mask);
}

READ16_MEMBER( deco_ace_device::ace_r )
{
	return m_ace_ram[offset];
}

WRITE16_MEMBER( deco_ace_device::ace_w )
{
	COMBINE_DATA(&m_ace_ram[offset]);
	if ((offset >= 0x20) && (offset <= 0x26))
		palette_update();
}

void deco_ace_device::palette_update()
{
	uint8_t fadeptr=m_ace_ram[0x20] & 0xff;
	uint8_t fadeptg=m_ace_ram[0x21] & 0xff;
	uint8_t fadeptb=m_ace_ram[0x22] & 0xff;
	uint8_t fadepsr=m_ace_ram[0x23] & 0xff;
	uint8_t fadepsg=m_ace_ram[0x24] & 0xff;
	uint8_t fadepsb=m_ace_ram[0x25] & 0xff;
	uint16_t mode=m_ace_ram[0x26] & 0xffff;

	for (int i = 0; i < 2048; i++)
	{
		/* Lerp palette entry to 'fadept' according to 'fadeps' */
		uint8_t b = (m_paletteram_buffered[i] >>16) & 0xff;
		uint8_t g = (m_paletteram_buffered[i] >> 8) & 0xff;
		uint8_t r = (m_paletteram_buffered[i] >> 0) & 0xff;

		if ((i>=m_palette_effect_min) && (i<=m_palette_effect_max))
		{
			switch (mode)
			{
				default:
				case 0x1100: // multiplicative fade
					/* Yeah, this should really be fixed point, I know */
					b = (uint8_t)((float)b + (((float)fadeptb - (float)b) * (float)fadepsb/255.0f));
					g = (uint8_t)((float)g + (((float)fadeptg - (float)g) * (float)fadepsg/255.0f));
					r = (uint8_t)((float)r + (((float)fadeptr - (float)r) * (float)fadepsr/255.0f));
					break;
				case 0x1000: // additive fade, correct?
					b = std::min(b + fadepsb, 0xff);
					g = std::min(g + fadepsg, 0xff);
					r = std::min(r + fadepsr, 0xff);
					break;
			}
		}
		set_pen_color(i, rgb_t(r, g, b));
	}
}

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

    set_palette_effect_max : Change Palette effect max bound (uses boogwing)

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

void deco_ace_device::set_palette_effect_max(uint32_t val)
{
	if (m_palette_effect_max != val)
	{
		m_palette_effect_max = val;
		palette_update();
	}
}

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

    get_alpha : Get alpha value (ACE RAM Area 0x00 - 0x1f)

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

uint8_t deco_ace_device::get_alpha(uint8_t val)
{
	val &= 0x1f;
	int alpha = m_ace_ram[val] & 0xff;
	if (alpha > 0x20)
	{
		return 0x80; // TODO : Special blending command? 0x21, 0x22 confirmed
	}
	else
	{
		alpha = 255 - (alpha << 3);
		if (alpha < 0)
			alpha = 0;

		return (uint8_t)alpha;
	}
}

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

    get_aceram : Get ACE RAM value

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

uint16_t deco_ace_device::get_aceram(uint8_t val)
{
	if (val >= 0x28)
		return 0;

	return m_ace_ram[val];
}

WRITE16_MEMBER( deco_ace_device::palette_dma_w )
{
	std::copy(&m_paletteram[0], &m_paletteram[2048], &m_paletteram_buffered[0]);
	palette_update();
}

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