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

    Amiga AGA hardware

    Driver by: Ernesto Corvi, Mariusz Wojcieszek, Aaron Giles

Done:
    - palette
    - bitplane data fetching
    - support for up to 8 standard bitplanes
    - HAM8 mode
    - preliminary sprites

To do:
    - incorrect hstart/hstop values in CD32 logo, lsrquiz & lsrquiz2
    - sprite collisions

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

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



/*************************************
 *
 *  Statics
 *
 *************************************/

/*************************************
 *
 *  Palette
 *
 *************************************/

void amiga_aga_palette_write(running_machine &machine, int color_reg, UINT16 data)
{
	amiga_state *state = machine.driver_data<amiga_state>();
	pen_t *aga_palette = state->m_aga_palette;
	int r,g,b;
	int cr,cg,cb;
	int color;

	color = ((CUSTOM_REG(REG_BPLCON3) >> 13) & 0x07)*32 + color_reg;
	r = (data & 0xf00) >> 8;
	g = (data & 0x0f0) >> 4;
	b = (data & 0x00f) >> 0;
	cr = RGB_RED(aga_palette[color]);
	cg = RGB_GREEN(aga_palette[color]);
	cb = RGB_BLUE(aga_palette[color]);
	if (BIT(CUSTOM_REG(REG_BPLCON3),9))
	{
		// load low nibbles
		cr = (cr & 0xf0) | r;
		cg = (cg & 0xf0) | g;
		cb = (cb & 0xf0) | b;
	}
	else
	{
		cr = (r << 4) | r;
		cg = (g << 4) | g;
		cb = (b << 4) | b;
	}
	aga_palette[color] = MAKE_RGB(cr,cg,cb);
}

/*************************************
 *
 *  Video startup
 *
 *************************************/

VIDEO_START( amiga_aga )
{
	amiga_state *state = machine.driver_data<amiga_state>();

	VIDEO_START_CALL( amiga );

	state->m_aga_diwhigh_written = 0;
}



/*************************************
 *
 *  Per-scanline sprite fetcher
 *
 *************************************/

INLINE void fetch_sprite_data(amiga_state *state, int scanline, int sprite)
{
	switch((CUSTOM_REG(REG_FMODE) >> 2) & 0x03)
	{
		case 0:
			state->m_aga_sprdata[sprite][0] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 0);
			state->m_aga_sprdatb[sprite][0] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 2);
			CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) += 4;
			state->m_aga_sprite_fetched_words = 1;
			if (LOG_SPRITE_DMA) logerror("%3d:sprite %d fetch: data=%04X-%04X\n", scanline, sprite, state->m_aga_sprdata[sprite][0], state->m_aga_sprdatb[sprite][0]);
			break;
		case 1:
		case 2:
			state->m_aga_sprdata[sprite][0] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 0);
			state->m_aga_sprdata[sprite][1] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 2);
			CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) += 4;
			state->m_aga_sprdatb[sprite][0] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 0);
			state->m_aga_sprdatb[sprite][1] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 2);
			CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) += 4;
			state->m_aga_sprite_fetched_words = 2;
			if (LOG_SPRITE_DMA) logerror("%3d:sprite %d fetch: data=%04X-%04X %04X-%04X\n", scanline, sprite, state->m_aga_sprdata[sprite][0], state->m_aga_sprdatb[sprite][0], state->m_aga_sprdata[sprite][1], state->m_aga_sprdatb[sprite][1] );
			break;
		case 3:
			state->m_aga_sprdata[sprite][0] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 0);
			state->m_aga_sprdata[sprite][1] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 2);
			CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) += 4;
			state->m_aga_sprdata[sprite][2] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 0);
			state->m_aga_sprdata[sprite][3] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 2);
			CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) += 4;
			state->m_aga_sprdatb[sprite][0] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 0);
			state->m_aga_sprdatb[sprite][1] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 2);
			CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) += 4;
			state->m_aga_sprdatb[sprite][2] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 0);
			state->m_aga_sprdatb[sprite][3] = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) + 2);
			CUSTOM_REG_LONG(REG_SPR0PTH + 2 * sprite) += 4;
			state->m_aga_sprite_fetched_words = 4;
			if (LOG_SPRITE_DMA) logerror("%3d:sprite %d fetch: data=%04X-%04X %04X-%04X %04X-%04X %04X-%04X\n",
										scanline, sprite,
										state->m_aga_sprdata[sprite][0], state->m_aga_sprdatb[sprite][0],
										state->m_aga_sprdata[sprite][1], state->m_aga_sprdatb[sprite][1],
										state->m_aga_sprdata[sprite][2], state->m_aga_sprdatb[sprite][2],
										state->m_aga_sprdata[sprite][3], state->m_aga_sprdatb[sprite][3]);
			break;
	}
	state->m_aga_sprite_dma_used_words[sprite] = 0;
}

static void update_sprite_dma(amiga_state *state, int scanline)
{
	int dmaenable = (CUSTOM_REG(REG_DMACON) & (DMACON_SPREN | DMACON_DMAEN)) == (DMACON_SPREN | DMACON_DMAEN);
	int num, maxdma;

	/* channels are limited by DDFSTART */
	maxdma = (CUSTOM_REG(REG_DDFSTRT) - 0x14) / 4;
	if (maxdma > 8)
		maxdma = 8;

	/* loop over sprite channels */
	for (num = 0; num < maxdma; num++)
	{
		int bitmask = 1 << num;
		int vstart, vstop;

		/* if we are == VSTOP, fetch new control words */
		if (dmaenable && (state->m_sprite_dma_live_mask & bitmask) && (state->m_sprite_dma_reload_mask & bitmask) && !(state->m_sprite_ctl_written & bitmask))
		{
			/* disable the sprite */
			state->m_sprite_comparitor_enable_mask &= ~bitmask;
			state->m_sprite_dma_reload_mask &= ~bitmask;

			/* fetch data into the control words */
			CUSTOM_REG(REG_SPR0POS + 4 * num) = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * num) + 0);
			CUSTOM_REG(REG_SPR0CTL + 4 * num) = (*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_SPR0PTH + 2 * num) + 2);
			CUSTOM_REG_LONG(REG_SPR0PTH + 2 * num) += 4;
			/* fetch additional words */
			switch((CUSTOM_REG(REG_FMODE) >> 2) & 0x03)
			{
				case 0:
					break;
				case 1:
				case 2:
					CUSTOM_REG_LONG(REG_SPR0PTH + 2 * num) += 4;
					break;
				case 3:
					CUSTOM_REG_LONG(REG_SPR0PTH + 2 * num) += 3*4;
					break;
			}
			if (LOG_SPRITE_DMA) logerror("%3d:sprite %d fetch: pos=%04X ctl=%04X\n", scanline, num, CUSTOM_REG(REG_SPR0POS + 4 * num), CUSTOM_REG(REG_SPR0CTL + 4 * num));
		}

		/* compute vstart/vstop */
		vstart = (CUSTOM_REG(REG_SPR0POS + 4 * num) >> 8) | ((CUSTOM_REG(REG_SPR0CTL + 4 * num) << 6) & 0x100);
		vstop = (CUSTOM_REG(REG_SPR0CTL + 4 * num) >> 8) | ((CUSTOM_REG(REG_SPR0CTL + 4 * num) << 7) & 0x100);

		/* if we hit vstart, enable the comparitor */
		if (scanline == vstart)
		{
			state->m_sprite_comparitor_enable_mask |= 1 << num;
			if (LOG_SPRITE_DMA) logerror("%3d:sprite %d comparitor enable\n", scanline, num);
		}

		/* if we hit vstop, disable the comparitor and trigger a reload for the next scanline */
		if (scanline == vstop)
		{
			state->m_sprite_ctl_written &= ~bitmask;
			state->m_sprite_comparitor_enable_mask &= ~bitmask;
			state->m_sprite_dma_reload_mask |= 1 << num;
			CUSTOM_REG(REG_SPR0DATA + 4 * num) = 0;		/* just a guess */
			CUSTOM_REG(REG_SPR0DATB + 4 * num) = 0;
			if (LOG_SPRITE_DMA) logerror("%3d:sprite %d comparitor disable, prepare for reload\n", scanline, num);
		}

		/* fetch data if this sprite is enabled */
		if (dmaenable && (state->m_sprite_dma_live_mask & bitmask) && (state->m_sprite_comparitor_enable_mask & bitmask))
		{
			fetch_sprite_data(state, scanline, num);
		}
	}
}



/*************************************
 *
 *  Per-pixel sprite computations
 *
 *************************************/

INLINE UINT32 interleave_sprite_data(UINT16 lobits, UINT16 hibits)
{
	return (amiga_expand_byte[lobits & 0xff] << 0) | (amiga_expand_byte[lobits >> 8] << 16) |
		   (amiga_expand_byte[hibits & 0xff] << 1) | (amiga_expand_byte[hibits >> 8] << 17);
}


static int get_sprite_pixel(amiga_state *state, int x)
{
	int pixels = 0;
	int num, pair;

	/* loop over sprite channels */
	for (num = 0; num < 8; num++)
		if (state->m_sprite_comparitor_enable_mask & (1 << num))
		{
			/* if we're not currently clocking, check against hstart */
			if (state->m_sprite_remain[num] == 0)
			{
				int hstart = ((CUSTOM_REG(REG_SPR0POS + 4 * num) & 0xff) << 1) | (CUSTOM_REG(REG_SPR0CTL + 4 * num) & 1);
				if (hstart == x)
				{
					state->m_sprite_remain[num] = 16;
					state->m_sprite_shiftreg[num] = interleave_sprite_data(state->m_aga_sprdata[num][0], state->m_aga_sprdatb[num][0]);
					state->m_aga_sprite_dma_used_words[num] = 1;
				}
			}

			/* clock the next pixel if we're doing it */
			if (state->m_sprite_remain[num] != 0)
			{
				state->m_sprite_remain[num]--;
				pixels |= (state->m_sprite_shiftreg[num] & 0xc0000000) >> (16 + 2 * (7 - num));
				state->m_sprite_shiftreg[num] <<= 2;

				if (state->m_sprite_remain[num] == 0)
				{
					if (state->m_aga_sprite_dma_used_words[num] < state->m_aga_sprite_fetched_words)
					{
						int w = state->m_aga_sprite_dma_used_words[num];
						state->m_sprite_remain[num] = 16;
						state->m_sprite_shiftreg[num] = interleave_sprite_data(state->m_aga_sprdata[num][w], state->m_aga_sprdatb[num][w]);
						state->m_aga_sprite_dma_used_words[num]++;
					}
				}
			}
		}

	/* if we have pixels, determine the actual color and get out */
	if (pixels)
	{
		static const UINT16 ormask[16] =
		{
			0x0000, 0x000c, 0x00c0, 0x00cc, 0x0c00, 0x0c0c, 0x0cc0, 0x0ccc,
			0xc000, 0xc00c, 0xc0c0, 0xc0cc, 0xcc00, 0xcc0c, 0xccc0, 0xcccc
		};
		static const UINT16 spritecollide[16] =
		{
			0x0000, 0x0000, 0x0000, 0x0200, 0x0000, 0x0400, 0x1000, 0x1600,
			0x0000, 0x0800, 0x2000, 0x2a00, 0x4000, 0x4c00, 0x7000, 0x7e00
		};
		int collide;
		int esprm, osprm;

		esprm = CUSTOM_REG(REG_BPLCON4) & 0x00f0;
		osprm = (CUSTOM_REG(REG_BPLCON4) & 0x000f) << 4;

		/* OR the two sprite bits together so we only have 1 bit per sprite */
		collide = pixels | (pixels >> 1);

		/* based on the CLXCON, merge even/odd sprite results */
		collide |= (collide & ormask[CUSTOM_REG(REG_CLXCON) >> 12]) >> 2;

		/* collapse down to a 4-bit final "sprite present" mask */
		collide = (collide & 1) | ((collide >> 3) & 2) | ((collide >> 6) & 4) | ((collide >> 9) & 8);

		/* compute sprite-sprite collisions */
		CUSTOM_REG(REG_CLXDAT) |= spritecollide[collide];

		/* now determine the actual color */
		for (pair = 0; pixels; pair++, pixels >>= 4)
			if (pixels & 0x0f)
			{
				/* final result is:
                    topmost sprite color in bits 0-7
                    sprite present bitmask in bits 8-9
                    topmost sprite pair index in bits 12-13
                */
				UINT32 result = (collide << 8) | (pair << 12);

				/* attached case */
				if (CUSTOM_REG(REG_SPR1CTL + 8 * pair) & 0x0080)
					return (pixels & 0xf) | osprm | result;

				/* lower-numbered sprite of pair */
				else if (pixels & 3)
					return (pixels & 3) | esprm | (pair << 2) | result;

				/* higher-numbered sprite of pair */
				else
					return ((pixels >> 2) & 3) | osprm | (pair << 2) | result;
			}
	}

	return 0;
}



/*************************************
 *
 *  Bitplane assembly
 *
 *************************************/

INLINE UINT8 assemble_odd_bitplanes(amiga_state *state, int planes, int obitoffs)
{
	UINT64 *aga_bpldat = state->m_aga_bpldat;
	UINT8 pix = (aga_bpldat[0] >> obitoffs) & 1;
	if (planes >= 3)
	{
		pix |= ((aga_bpldat[2] >> obitoffs) & 1) << 2;
		if (planes >= 5)
		{
			pix |= ((aga_bpldat[4] >> obitoffs) & 1) << 4;
			if (planes >= 7)
				pix |= ((aga_bpldat[6] >> obitoffs) & 1) << 6;
		}
	}
	return pix;
}


INLINE UINT8 assemble_even_bitplanes(amiga_state *state, int planes, int ebitoffs)
{
	UINT8 pix = 0;
	if (planes >= 2)
	{
		UINT64 *aga_bpldat = state->m_aga_bpldat;
		pix |= ((aga_bpldat[1] >> ebitoffs) & 1) << 1;
		if (planes >= 4)
		{
			pix |= ((aga_bpldat[3] >> ebitoffs) & 1) << 3;
			if (planes >= 6)
			{
				pix |= ((aga_bpldat[5] >> ebitoffs) & 1) << 5;
				if (planes >= 8)
					pix |= ((aga_bpldat[7] >> ebitoffs) & 1) << 7;
			}
		}
	}
	return pix;
}

INLINE void fetch_bitplane_data(amiga_state *state, int plane)
{
	UINT64 *aga_bpldat = state->m_aga_bpldat;

	switch (CUSTOM_REG(REG_FMODE) & 0x03)
	{
		case 0:
			aga_bpldat[plane] = (UINT64)(*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2));
			CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2) += 2;
			break;
		case 1:
		case 2:
			aga_bpldat[plane] = (UINT64)(*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2)) << 16;
			CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2) += 2;
			aga_bpldat[plane] |= ((UINT64)(*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2)));
			CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2) += 2;
			break;
		case 3:
			aga_bpldat[plane] = (UINT64)(*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2)) << 48;
			CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2) += 2;
			aga_bpldat[plane] |= ((UINT64)(*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2))) << 32;
			CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2) += 2;
			aga_bpldat[plane] |= ((UINT64)(*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2))) << 16;
			CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2) += 2;
			aga_bpldat[plane] |= (UINT64)(*state->m_chip_ram_r)(state, CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2));
			CUSTOM_REG_LONG(REG_BPL1PTH + plane * 2) += 2;
			break;
	}
}

void amiga_aga_diwhigh_written(running_machine &machine, int written)
{
	amiga_state *state = machine.driver_data<amiga_state>();

	state->m_aga_diwhigh_written = written;
}

/*************************************
 *
 *  Hold and modify pixel computations
 *
 *************************************/

INLINE int update_ham(amiga_state *state, int newpix)
{
	switch (newpix & 0x03)
	{
		case 0:
			state->m_ham_color = state->m_aga_palette[(newpix >> 2) & 0x3f];
			break;

		case 1:
			state->m_ham_color = MAKE_RGB(RGB_RED(state->m_ham_color), RGB_GREEN(state->m_ham_color), (newpix & 0xfc) | (RGB_BLUE(state->m_ham_color) & 0x03));
			break;

		case 2:
			state->m_ham_color = MAKE_RGB((newpix & 0xfc) | (RGB_RED(state->m_ham_color) & 0x03), RGB_GREEN(state->m_ham_color), RGB_BLUE(state->m_ham_color));
			break;

		case 3:
			state->m_ham_color = MAKE_RGB(RGB_RED(state->m_ham_color), (newpix & 0xfc) | (RGB_GREEN(state->m_ham_color) & 0x03), RGB_BLUE(state->m_ham_color));
			break;
	}
	return state->m_ham_color;
}



/*************************************
 *
 *  Single scanline rasterizer
 *
 *************************************/

void amiga_aga_render_scanline(running_machine &machine, bitmap_t *bitmap, int scanline)
{
	amiga_state *state = machine.driver_data<amiga_state>();
	UINT16 save_color0 = CUSTOM_REG(REG_COLOR00);
	int ddf_start_pixel = 0, ddf_stop_pixel = 0;
	int hires = 0, dualpf = 0, ham = 0;
	int hstart = 0, hstop = 0;
	int vstart = 0, vstop = 0;
	int pf1pri = 0, pf2pri = 0;
	int planes = 0;

	int x;
	UINT32 *dst = NULL;
	int ebitoffs = 0, obitoffs = 0;
	int ecolmask = 0, ocolmask = 0;
	int edelay = 0, odelay = 0;
	int next_copper_x;
	int pl;
	int defbitoffs = 0;
	pen_t *aga_palette = state->m_aga_palette;

	state->m_last_scanline = scanline;

	/* on the first scanline, reset the COPPER and HAM color */
	if (scanline == 0)
	{
		amiga_copper_setpc(machine, CUSTOM_REG_LONG(REG_COP1LCH));
		state->m_ham_color = CUSTOM_REG(REG_COLOR00);
	}

	/* update sprite data fetching */
	update_sprite_dma(state, scanline);

	/* start of a new line, signal we're not done with it and fill up vars */
	if (bitmap != NULL)
		dst = BITMAP_ADDR32(bitmap, scanline, 0);

	/* all sprites off at the start of the line */
	memset(state->m_sprite_remain, 0, sizeof(state->m_sprite_remain));

	/* temporary set color 0 to the genlock color */
	if (state->m_genlock_color != 0xffff)
		CUSTOM_REG(REG_COLOR00) = state->m_genlock_color;

	/* loop over the line */
	next_copper_x = 2;	/* copper runs on odd timeslots */
	for (x = 0; x < 0xe8*2; x++)
	{
		int sprpix;

		/* time to execute the copper? */
		if (x == next_copper_x)
		{
			/* execute the next batch, restoring and re-saving color 0 around it */
			CUSTOM_REG(REG_COLOR00) = save_color0;
			next_copper_x = amiga_copper_execute_next(machine, x);
			save_color0 = CUSTOM_REG(REG_COLOR00);
			if (state->m_genlock_color != 0xffff)
				CUSTOM_REG(REG_COLOR00) = state->m_genlock_color;

			/* compute update-related register values */
			planes = (CUSTOM_REG(REG_BPLCON0) & (BPLCON0_BPU0 | BPLCON0_BPU1 | BPLCON0_BPU2)) >> 12;
			if ( CUSTOM_REG(REG_BPLCON0) & BPLCON0_BPU3 )
				planes |= 8;

			hires = CUSTOM_REG(REG_BPLCON0) & BPLCON0_HIRES;
			ham = CUSTOM_REG(REG_BPLCON0) & BPLCON0_HOMOD;
			dualpf = CUSTOM_REG(REG_BPLCON0) & BPLCON0_DBLPF;
//          lace = CUSTOM_REG(REG_BPLCON0) & BPLCON0_LACE;

			/* get default bitoffset */
			switch(CUSTOM_REG(REG_FMODE) & 0x3)
			{
				case 0: defbitoffs = 15; break;
				case 1:
				case 2: defbitoffs = 31; break;
				case 3: defbitoffs = 63; break;
			}

			/* compute the pixel fetch parameters */
			ddf_start_pixel = ( CUSTOM_REG(REG_DDFSTRT) & 0xfc ) * 2 + (hires ? 9 : 17);
			ddf_stop_pixel = ( CUSTOM_REG(REG_DDFSTOP) & 0xfc ) * 2 + (hires ? (9 + defbitoffs - ((defbitoffs >= 31) ? 16 : 0)) : (17 + defbitoffs));

			if ( ( CUSTOM_REG(REG_DDFSTRT) ^ CUSTOM_REG(REG_DDFSTOP) ) & 0x04 )
				ddf_stop_pixel += 8;

			/* compute the horizontal start/stop */
			hstart = CUSTOM_REG(REG_DIWSTRT) & 0xff;
			hstop = (CUSTOM_REG(REG_DIWSTOP) & 0xff);

			if (state->m_aga_diwhigh_written)
			{
				hstart |= ((CUSTOM_REG(REG_DIWHIGH) >> 5) & 1) << 8;
				hstop |= ((CUSTOM_REG(REG_DIWHIGH) >> 13) & 1) << 8;
			}
			else
			{
				hstop |= 0x100;
			}
			if ( hstop < hstart )
			{
				hstart = 0x00;
				hstop = 0x1ff;
			}

			/* compute the vertical start/stop */
			vstart = CUSTOM_REG(REG_DIWSTRT) >> 8;
			vstop = (CUSTOM_REG(REG_DIWSTOP) >> 8);
			if (state->m_aga_diwhigh_written)
			{
				vstart |= (CUSTOM_REG(REG_DIWHIGH) & 7) << 8;
				vstop |= ((CUSTOM_REG(REG_DIWHIGH) >> 8) & 7) << 8;
			}
			else
			{
				vstop |= ((~CUSTOM_REG(REG_DIWSTOP) >> 7) & 0x100);
			}

			/* extract playfield priorities */
			pf1pri = CUSTOM_REG(REG_BPLCON2) & 7;
			pf2pri = (CUSTOM_REG(REG_BPLCON2) >> 3) & 7;

			/* extract collision masks */
			ocolmask = (CUSTOM_REG(REG_CLXCON) >> 6) & 0x15;
			ecolmask = (CUSTOM_REG(REG_CLXCON) >> 6) & 0x2a;
		}

		/* clear the target pixels to the background color as a starting point */
		if (dst != NULL)
			dst[x*2+0] =
			dst[x*2+1] = aga_palette[0];

		/* if we hit the first fetch pixel, reset the counters and latch the delays */
		if (x == ddf_start_pixel)
		{
			odelay = CUSTOM_REG(REG_BPLCON1) & 0xf;
			edelay = ( CUSTOM_REG(REG_BPLCON1) >> 4 ) & 0x0f;

			if ( hires )
			{
				obitoffs = defbitoffs + ( odelay << 1 );
				ebitoffs = defbitoffs + ( edelay << 1 );
			}
			else
			{
				if ( CUSTOM_REG(REG_DDFSTRT) & 0x04 )
				{
					odelay = ( odelay + 8 ) & 0x0f;
					edelay = ( edelay + 8 ) & 0x0f;
				}

				obitoffs = defbitoffs + odelay;
				ebitoffs = defbitoffs + edelay;
			}

			for (pl = 0; pl < 8; pl++)
				state->m_aga_bpldat[pl] = 0;
		}

		/* need to run the sprite engine every pixel to ensure display */
		sprpix = get_sprite_pixel(state, x);

		/* to render, we must have bitplane DMA enabled, at least 1 plane, and be within the */
		/* vertical display window */
		if ((CUSTOM_REG(REG_DMACON) & (DMACON_BPLEN | DMACON_DMAEN)) == (DMACON_BPLEN | DMACON_DMAEN) &&
			planes > 0 && scanline >= vstart && scanline < vstop)
		{
			int pfpix0 = 0, pfpix1 = 0, collide;

			/* fetch the odd bits if we are within the fetching region */
			if (x >= ddf_start_pixel && x <= ddf_stop_pixel + odelay)
			{
				/* if we need to fetch more data, do it now */
				if (obitoffs == defbitoffs)
				{
					for (pl = 0; pl < planes; pl += 2)
					{
						fetch_bitplane_data(state, pl);
					}
				}

				/* now assemble the bits */
				pfpix0 |= assemble_odd_bitplanes(state, planes, obitoffs);
				obitoffs--;

				/* for high res, assemble a second set of bits */
				if (hires)
				{
					/* reset bit offsets and fetch more data if needed */
					if (obitoffs < 0)
					{
						obitoffs = defbitoffs;

						for (pl = 0; pl < planes; pl += 2)
						{
							fetch_bitplane_data(state, pl);
						}
					}

					pfpix1 |= assemble_odd_bitplanes(state, planes, obitoffs);
					obitoffs--;
				}
				else
					pfpix1 |= pfpix0 & 0x55; // 0x15

				/* reset bit offsets if needed */
				if (obitoffs < 0)
					obitoffs = defbitoffs;
			}

			/* fetch the even bits if we are within the fetching region */
			if (x >= ddf_start_pixel && x <= ddf_stop_pixel + edelay)
			{
				/* if we need to fetch more data, do it now */
				if (ebitoffs == defbitoffs)
				{
					for (pl = 1; pl < planes; pl += 2)
					{
						fetch_bitplane_data(state, pl);
					}
				}

				/* now assemble the bits */
				pfpix0 |= assemble_even_bitplanes(state, planes, ebitoffs);
				ebitoffs--;

				/* for high res, assemble a second set of bits */
				if (hires)
				{
					/* reset bit offsets and fetch more data if needed */
					if (ebitoffs < 0)
					{
						ebitoffs = defbitoffs;

						for (pl = 1; pl < planes; pl += 2)
						{
							fetch_bitplane_data(state, pl);
						}
					}

					pfpix1 |= assemble_even_bitplanes(state, planes, ebitoffs);
					ebitoffs--;
				}
				else
					pfpix1 |= pfpix0 & 0xaa;

				/* reset bit offsets if needed */
				if (ebitoffs < 0)
					ebitoffs = defbitoffs;
			}

			/* compute playfield/sprite collisions for first pixel */
			collide = pfpix0 ^ CUSTOM_REG(REG_CLXCON);
			if ((collide & ocolmask) == 0)
				CUSTOM_REG(REG_CLXDAT) |= (sprpix >> 5) & 0x01e;
			if ((collide & ecolmask) == 0)
				CUSTOM_REG(REG_CLXDAT) |= (sprpix >> 1) & 0x1e0;
			if ((collide & (ecolmask | ocolmask)) == 0)
				CUSTOM_REG(REG_CLXDAT) |= 0x001;

			/* compute playfield/sprite collisions for second pixel */
			collide = pfpix1 ^ CUSTOM_REG(REG_CLXCON);
			if ((collide & ocolmask) == 0)
				CUSTOM_REG(REG_CLXDAT) |= (sprpix >> 5) & 0x01e;
			if ((collide & ecolmask) == 0)
				CUSTOM_REG(REG_CLXDAT) |= (sprpix >> 1) & 0x1e0;
			if ((collide & (ecolmask | ocolmask)) == 0)
				CUSTOM_REG(REG_CLXDAT) |= 0x001;

			/* if we are within the display region, render */
			if (dst != NULL && x >= hstart && x < hstop)
			{
				int pix, pri;

				/* hold-and-modify mode -- assume low-res (hi-res not supported by the hardware) */
				if (ham)
				{
					/* update the HAM color */
					pfpix0 = update_ham(state, pfpix0);

					pix = sprpix & 0xff;
					pri = (sprpix >> 10);

					/* sprite has priority */
					if (sprpix && pf1pri > pri)
					{
						dst[x*2+0] =
						dst[x*2+1] = aga_palette[pix];
					}

					/* playfield has priority */
					else
					{
						dst[x*2+0] =
						dst[x*2+1] = pfpix0;
					}
				}

				/* dual playfield mode */
				else if (dualpf)
				{
					/* mask out the sprite if it doesn't have priority */
					pix = sprpix & 0x1f;
					pri = (sprpix >> 12);
					if (pix)
					{
						if ((pfpix0 & 0x15) && pf1pri <= pri)
							pix = 0;
						if ((pfpix0 & 0x2a) && pf2pri <= pri)
							pix = 0;
					}

					/* write out the left pixel */
					if (pix)
						dst[x*2+0] = aga_palette[pix];
					else
						dst[x*2+0] = aga_palette[state->m_separate_bitplanes[(CUSTOM_REG(REG_BPLCON2) >> 6) & 1][pfpix0]];

					/* mask out the sprite if it doesn't have priority */
					pix = sprpix & 0xff;
					if (pix)
					{
						if ((pfpix1 & 0x15) && pf1pri <= pri)
							pix = 0;
						if ((pfpix1 & 0x2a) && pf2pri <= pri)
							pix = 0;
					}

					/* write out the right pixel */
					if (pix)
						dst[x*2+1] = aga_palette[pix];
					else
						dst[x*2+1] = aga_palette[state->m_separate_bitplanes[(CUSTOM_REG(REG_BPLCON2) >> 6) & 1][pfpix1]];
				}

				/* single playfield mode */
				else
				{
					pix = sprpix & 0xff;
					pri = (sprpix >> 12);

					/* sprite has priority */
					if (sprpix && pf1pri > pri)
					{
						dst[x*2+0] =
						dst[x*2+1] = aga_palette[pix];
					}

					/* playfield has priority */
					else
					{
						dst[x*2+0] = aga_palette[pfpix0];
						dst[x*2+1] = aga_palette[pfpix1];
					}
				}
			}
		}
	}

#if 0
	if ( machine.primary_screen->frame_number() % 16 == 0 && scanline == 250 )
	{
		const char *m_lores = "LORES";
		const char *m_hires = "HIRES";
		const char *m_ham = "HAM";
		const char *m_dualpf = "DUALPF";
		const char *m_lace = "LACE";
		const char *m_hilace = "HI-LACE";
		const char *p = m_lores;

		if ( hires ) p = m_hires;
		if ( ham ) p = m_ham;
		if ( dualpf ) p = m_dualpf;
		if ( lace ) p = m_lace;

		if ( hires && lace ) p = m_hilace;

		popmessage("%s(%d pl od=%02x ed=%02x start=%d stop=%d hstart=%04x hstop=%04x diwhigh=%04x fetchbits=%d )", p, planes, odelay, edelay, ddf_start_pixel, ddf_stop_pixel, CUSTOM_REG(REG_DIWSTRT), CUSTOM_REG(REG_DIWSTOP), CUSTOM_REG(REG_DIWHIGH), defbitoffs );
		//popmessage("%s(%d pl bplpt1=%06X, bpl1mod=%04x, offset=%x)", p, planes, CUSTOM_REG_LONG(REG_BPL1PTH), CUSTOM_REG(REG_BPL1MOD), hires_modulo_offset );
	}
#endif

	/* end of the line: time to add the modulos */
	if (scanline >= vstart && scanline < vstop)
	{
		/* update odd planes */
		for (pl = 0; pl < planes; pl += 2)
			CUSTOM_REG_LONG(REG_BPL1PTH + pl * 2) += CUSTOM_REG_SIGNED(REG_BPL1MOD);

		/* update even planes */
		for (pl = 1; pl < planes; pl += 2)
			CUSTOM_REG_LONG(REG_BPL1PTH + pl * 2) += CUSTOM_REG_SIGNED(REG_BPL2MOD);
	}

	/* restore color00 */
	CUSTOM_REG(REG_COLOR00) = save_color0;

#if GUESS_COPPER_OFFSET
	if (machine.primary_screen->frame_number() % 64 == 0 && scanline == 0)
	{
		if (machine.input().code_pressed(KEYCODE_Q))
			popmessage("%d", wait_offset -= 1);
		if (machine.input().code_pressed(KEYCODE_W))
			popmessage("%d", wait_offset += 1);
	}
#endif
}



/*************************************
 *
 *  Update
 *
 *************************************/

SCREEN_UPDATE( amiga_aga )
{
	int y;

	/* render each scanline in the visible region */
	for (y = cliprect->min_y; y <= cliprect->max_y; y++)
		amiga_aga_render_scanline(screen->machine(), bitmap, y);

	return 0;
}
