dsp4.cpp

/***********************************************************************************
  Snes9x - Portable Super Nintendo Entertainment System (TM) emulator.

  (c) Copyright 1996 - 2002  Gary Henderson (gary.henderson@ntlworld.com),
                             Jerremy Koot (jkoot@snes9x.com)

  (c) Copyright 2002 - 2004  Matthew Kendora

  (c) Copyright 2002 - 2005  Peter Bortas (peter@bortas.org)

  (c) Copyright 2004 - 2005  Joel Yliluoma (http://iki.fi/bisqwit/)

  (c) Copyright 2001 - 2006  John Weidman (jweidman@slip.net)

  (c) Copyright 2002 - 2006  funkyass (funkyass@spam.shaw.ca),
                             Kris Bleakley (codeviolation@hotmail.com)

  (c) Copyright 2002 - 2010  Brad Jorsch (anomie@users.sourceforge.net),
                             Nach (n-a-c-h@users.sourceforge.net),

  (c) Copyright 2002 - 2011  zones (kasumitokoduck@yahoo.com)

  (c) Copyright 2006 - 2007  nitsuja

  (c) Copyright 2009 - 2011  BearOso,
                             OV2


  BS-X C emulator code
  (c) Copyright 2005 - 2006  Dreamer Nom,
                             zones

  C4 x86 assembler and some C emulation code
  (c) Copyright 2000 - 2003  _Demo_ (_demo_@zsnes.com),
                             Nach,
                             zsKnight (zsknight@zsnes.com)

  C4 C++ code
  (c) Copyright 2003 - 2006  Brad Jorsch,
                             Nach

  DSP-1 emulator code
  (c) Copyright 1998 - 2006  _Demo_,
                             Andreas Naive (andreasnaive@gmail.com),
                             Gary Henderson,
                             Ivar (ivar@snes9x.com),
                             John Weidman,
                             Kris Bleakley,
                             Matthew Kendora,
                             Nach,
                             neviksti (neviksti@hotmail.com)

  DSP-2 emulator code
  (c) Copyright 2003         John Weidman,
                             Kris Bleakley,
                             Lord Nightmare (lord_nightmare@users.sourceforge.net),
                             Matthew Kendora,
                             neviksti

  DSP-3 emulator code
  (c) Copyright 2003 - 2006  John Weidman,
                             Kris Bleakley,
                             Lancer,
                             z80 gaiden

  DSP-4 emulator code
  (c) Copyright 2004 - 2006  Dreamer Nom,
                             John Weidman,
                             Kris Bleakley,
                             Nach,
                             z80 gaiden

  OBC1 emulator code
  (c) Copyright 2001 - 2004  zsKnight,
                             pagefault (pagefault@zsnes.com),
                             Kris Bleakley
                             Ported from x86 assembler to C by sanmaiwashi

  SPC7110 and RTC C++ emulator code used in 1.39-1.51
  (c) Copyright 2002         Matthew Kendora with research by
                             zsKnight,
                             John Weidman,
                             Dark Force

  SPC7110 and RTC C++ emulator code used in 1.52+
  (c) Copyright 2009         byuu,
                             neviksti

  S-DD1 C emulator code
  (c) Copyright 2003         Brad Jorsch with research by
                             Andreas Naive,
                             John Weidman

  S-RTC C emulator code
  (c) Copyright 2001 - 2006  byuu,
                             John Weidman

  ST010 C++ emulator code
  (c) Copyright 2003         Feather,
                             John Weidman,
                             Kris Bleakley,
                             Matthew Kendora

  Super FX x86 assembler emulator code
  (c) Copyright 1998 - 2003  _Demo_,
                             pagefault,
                             zsKnight

  Super FX C emulator code
  (c) Copyright 1997 - 1999  Ivar,
                             Gary Henderson,
                             John Weidman

  Sound emulator code used in 1.5-1.51
  (c) Copyright 1998 - 2003  Brad Martin
  (c) Copyright 1998 - 2006  Charles Bilyue'

  Sound emulator code used in 1.52+
  (c) Copyright 2004 - 2007  Shay Green (gblargg@gmail.com)

  SH assembler code partly based on x86 assembler code
  (c) Copyright 2002 - 2004  Marcus Comstedt (marcus@mc.pp.se)

  2xSaI filter
  (c) Copyright 1999 - 2001  Derek Liauw Kie Fa

  HQ2x, HQ3x, HQ4x filters
  (c) Copyright 2003         Maxim Stepin (maxim@hiend3d.com)

  NTSC filter
  (c) Copyright 2006 - 2007  Shay Green

  GTK+ GUI code
  (c) Copyright 2004 - 2011  BearOso

  Win32 GUI code
  (c) Copyright 2003 - 2006  blip,
                             funkyass,
                             Matthew Kendora,
                             Nach,
                             nitsuja
  (c) Copyright 2009 - 2011  OV2

  Mac OS GUI code
  (c) Copyright 1998 - 2001  John Stiles
  (c) Copyright 2001 - 2011  zones


  Specific ports contains the works of other authors. See headers in
  individual files.


  Snes9x homepage: http://www.snes9x.com/

  Permission to use, copy, modify and/or distribute Snes9x in both binary
  and source form, for non-commercial purposes, is hereby granted without
  fee, providing that this license information and copyright notice appear
  with all copies and any derived work.

  This software is provided 'as-is', without any express or implied
  warranty. In no event shall the authors be held liable for any damages
  arising from the use of this software or it's derivatives.

  Snes9x is freeware for PERSONAL USE only. Commercial users should
  seek permission of the copyright holders first. Commercial use includes,
  but is not limited to, charging money for Snes9x or software derived from
  Snes9x, including Snes9x or derivatives in commercial game bundles, and/or
  using Snes9x as a promotion for your commercial product.

  The copyright holders request that bug fixes and improvements to the code
  should be forwarded to them so everyone can benefit from the modifications
  in future versions.

  Super NES and Super Nintendo Entertainment System are trademarks of
  Nintendo Co., Limited and its subsidiary companies.
 ***********************************************************************************/

/*
  Due recognition and credit are given on Overload's DSP website.
  Thank those contributors for their hard work on this chip.

  Fixed-point math reminder:
  [sign, integer, fraction]
  1.15.00 * 1.15.00 = 2.30.00 -> 1.30.00 (DSP) -> 1.31.00 (LSB is '0')
  1.15.00 * 1.00.15 = 2.15.15 -> 1.15.15 (DSP) -> 1.15.16 (LSB is '0')
*/


#include "snes9x.h"
#include "memmap.h"

#define DSP4_CLEAR_OUT() \
	{ DSP4.out_count = 0; DSP4.out_index = 0; }

#define DSP4_WRITE_BYTE(d) \
	{ WRITE_WORD(DSP4.output + DSP4.out_count, (d)); DSP4.out_count++; }

#define DSP4_WRITE_WORD(d) \
	{ WRITE_WORD(DSP4.output + DSP4.out_count, (d)); DSP4.out_count += 2; }

#ifndef MSB_FIRST
#define DSP4_WRITE_16_WORD(d) \
	{ memcpy(DSP4.output + DSP4.out_count, (d), 32); DSP4.out_count += 32; }
#else
#define DSP4_WRITE_16_WORD(d) \
	{ for (int p = 0; p < 16; p++) DSP4_WRITE_WORD((d)[p]); }
#endif

// used to wait for dsp i/o
#define DSP4_WAIT(x) \
	DSP4.in_index = 0; DSP4.Logic = (x); return

// 1.7.8 -> 1.15.16
#define SEX78(a)	(((int32) ((int16) (a))) << 8)

// 1.15.0 -> 1.15.16
#define SEX16(a)	(((int32) ((int16) (a))) << 16)

static int16 DSP4_READ_WORD (void);
static int32 DSP4_READ_DWORD (void);
static int16 DSP4_Inverse (int16);
static void DSP4_Multiply (int16, int16, int32 *);
static void DSP4_OP01 (void);
static void DSP4_OP03 (void);
static void DSP4_OP05 (void);
static void DSP4_OP06 (void);
static void DSP4_OP07 (void);
static void DSP4_OP08 (void);
static void DSP4_OP09 (void);
static void DSP4_OP0A (int16, int16 *, int16 *, int16 *, int16 *);
static void DSP4_OP0B (bool8 *, int16, int16, int16, bool8, bool8);
static void DSP4_OP0D (void);
static void DSP4_OP0E (void);
static void DSP4_OP0F (void);
static void DSP4_OP10 (void);
static void DSP4_OP11 (int16, int16, int16, int16, int16 *);
static void DSP4_SetByte (void);
static void DSP4_GetByte (void);


static int16 DSP4_READ_WORD (void)
{
	int16	out;

	out = READ_WORD(DSP4.parameters + DSP4.in_index);
	DSP4.in_index += 2;

	return (out);
}

static int32 DSP4_READ_DWORD (void)
{
	int32	out;

	out = READ_DWORD(DSP4.parameters + DSP4.in_index);
	DSP4.in_index += 4;

	return (out);
}

static int16 DSP4_Inverse (int16 value)
{
	// Attention: This lookup table is not verified
	const uint16	div_lut[64] =
	{
		0x0000, 0x8000, 0x4000, 0x2aaa, 0x2000, 0x1999, 0x1555, 0x1249,
		0x1000, 0x0e38, 0x0ccc, 0x0ba2, 0x0aaa, 0x09d8, 0x0924, 0x0888,
		0x0800, 0x0787, 0x071c, 0x06bc, 0x0666, 0x0618, 0x05d1, 0x0590,
		0x0555, 0x051e, 0x04ec, 0x04bd, 0x0492, 0x0469, 0x0444, 0x0421,
		0x0400, 0x03e0, 0x03c3, 0x03a8, 0x038e, 0x0375, 0x035e, 0x0348,
		0x0333, 0x031f, 0x030c, 0x02fa, 0x02e8, 0x02d8, 0x02c8, 0x02b9,
		0x02aa, 0x029c, 0x028f, 0x0282, 0x0276, 0x026a, 0x025e, 0x0253,
		0x0249, 0x023e, 0x0234, 0x022b, 0x0222, 0x0219, 0x0210, 0x0208
	};

	// saturate bounds
	if (value < 0)
		value = 0;
	if (value > 63)
		value = 63;

	return (div_lut[value]);
}

static void DSP4_Multiply (int16 Multiplicand, int16 Multiplier, int32 *Product)
{
	*Product = (Multiplicand * Multiplier << 1) >> 1;
}

static void DSP4_OP01 (void)
{
	DSP4.waiting4command = FALSE;

	// op flow control
	switch (DSP4.Logic)
	{
		case 1: goto resume1; break;
		case 2: goto resume2; break;
		case 3: goto resume3; break;
	}

	////////////////////////////////////////////////////
	// process initial inputs

	// sort inputs
	DSP4.world_y           = DSP4_READ_DWORD();
	DSP4.poly_bottom[0][0] = DSP4_READ_WORD();
	DSP4.poly_top[0][0]    = DSP4_READ_WORD();
	DSP4.poly_cx[1][0]     = DSP4_READ_WORD();
	DSP4.viewport_bottom   = DSP4_READ_WORD();
	DSP4.world_x           = DSP4_READ_DWORD();
	DSP4.poly_cx[0][0]     = DSP4_READ_WORD();
	DSP4.poly_ptr[0][0]    = DSP4_READ_WORD();
	DSP4.world_yofs        = DSP4_READ_WORD();
	DSP4.world_dy          = DSP4_READ_DWORD();
	DSP4.world_dx          = DSP4_READ_DWORD();
	DSP4.distance          = DSP4_READ_WORD();
	DSP4_READ_WORD(); // 0x0000
	DSP4.world_xenv        = DSP4_READ_DWORD();
	DSP4.world_ddy         = DSP4_READ_WORD();
	DSP4.world_ddx         = DSP4_READ_WORD();
	DSP4.view_yofsenv      = DSP4_READ_WORD();

	// initial (x, y, offset) at starting raster line
	DSP4.view_x1         = (DSP4.world_x + DSP4.world_xenv) >> 16;
	DSP4.view_y1         = DSP4.world_y >> 16;
	DSP4.view_xofs1      = DSP4.world_x >> 16;
	DSP4.view_yofs1      = DSP4.world_yofs;
	DSP4.view_turnoff_x  = 0;
	DSP4.view_turnoff_dx = 0;

	// first raster line
	DSP4.poly_raster[0][0] = DSP4.poly_bottom[0][0];

	do
	{
		////////////////////////////////////////////////////
		// process one iteration of projection

		// perspective projection of world (x, y, scroll) points
		// based on the current projection lines
		DSP4.view_x2    = (((DSP4.world_x + DSP4.world_xenv) >> 16) * DSP4.distance >> 15) + (DSP4.view_turnoff_x * DSP4.distance >> 15);
		DSP4.view_y2    = (DSP4.world_y >> 16) * DSP4.distance >> 15;
		DSP4.view_xofs2 = DSP4.view_x2;
		DSP4.view_yofs2 = (DSP4.world_yofs * DSP4.distance >> 15) + DSP4.poly_bottom[0][0] - DSP4.view_y2;

		// 1. World x-location before transformation
		// 2. Viewer x-position at the next
		// 3. World y-location before perspective projection
		// 4. Viewer y-position below the horizon
		// 5. Number of raster lines drawn in this iteration
		DSP4_CLEAR_OUT();
		DSP4_WRITE_WORD((DSP4.world_x + DSP4.world_xenv) >> 16);
		DSP4_WRITE_WORD(DSP4.view_x2);
		DSP4_WRITE_WORD(DSP4.world_y >> 16);
		DSP4_WRITE_WORD(DSP4.view_y2);

		//////////////////////////////////////////////////////

		// SR = 0x00

		// determine # of raster lines used
		DSP4.segments = DSP4.poly_raster[0][0] - DSP4.view_y2;

		// prevent overdraw
		if (DSP4.view_y2 >= DSP4.poly_raster[0][0])
			DSP4.segments = 0;
		else
			DSP4.poly_raster[0][0] = DSP4.view_y2;

		// don't draw outside the window
		if (DSP4.view_y2 < DSP4.poly_top[0][0])
		{
			DSP4.segments = 0;

			// flush remaining raster lines
			if (DSP4.view_y1 >= DSP4.poly_top[0][0])
				DSP4.segments = DSP4.view_y1 - DSP4.poly_top[0][0];
		}

		// SR = 0x80

		DSP4_WRITE_WORD(DSP4.segments);

		//////////////////////////////////////////////////////

		// scan next command if no SR check needed
		if (DSP4.segments)
		{
			int32	px_dx, py_dy;
			int32	x_scroll, y_scroll;

			// SR = 0x00

			// linear interpolation (lerp) between projected points
			px_dx = (DSP4.view_xofs2 - DSP4.view_xofs1) * DSP4_Inverse(DSP4.segments) << 1;
			py_dy = (DSP4.view_yofs2 - DSP4.view_yofs1) * DSP4_Inverse(DSP4.segments) << 1;

			// starting step values
			x_scroll = SEX16(DSP4.poly_cx[0][0] + DSP4.view_xofs1);
			y_scroll = SEX16(-DSP4.viewport_bottom + DSP4.view_yofs1 + DSP4.view_yofsenv + DSP4.poly_cx[1][0] - DSP4.world_yofs);

			// SR = 0x80

			// rasterize line
			for (DSP4.lcv = 0; DSP4.lcv < DSP4.segments; DSP4.lcv++)
			{
				// 1. HDMA memory pointer (bg1)
				// 2. vertical scroll offset ($210E)
				// 3. horizontal scroll offset ($210D)
				DSP4_WRITE_WORD(DSP4.poly_ptr[0][0]);
				DSP4_WRITE_WORD((y_scroll + 0x8000) >> 16);
				DSP4_WRITE_WORD((x_scroll + 0x8000) >> 16);

				// update memory address
				DSP4.poly_ptr[0][0] -= 4;

				// update screen values
				x_scroll += px_dx;
				y_scroll += py_dy;
			}
		}

		////////////////////////////////////////////////////
		// Post-update

		// update new viewer (x, y, scroll) to last raster line drawn
		DSP4.view_x1    = DSP4.view_x2;
		DSP4.view_y1    = DSP4.view_y2;
		DSP4.view_xofs1 = DSP4.view_xofs2;
		DSP4.view_yofs1 = DSP4.view_yofs2;

		// add deltas for projection lines
		DSP4.world_dx += SEX78(DSP4.world_ddx);
		DSP4.world_dy += SEX78(DSP4.world_ddy);

		// update projection lines
		DSP4.world_x += (DSP4.world_dx + DSP4.world_xenv);
		DSP4.world_y += DSP4.world_dy;

		// update road turnoff position
		DSP4.view_turnoff_x += DSP4.view_turnoff_dx;

		////////////////////////////////////////////////////
		// command check

		// scan next command
		DSP4.in_count = 2;
		DSP4_WAIT(1);
		
		resume1:

		// check for termination
		DSP4.distance = DSP4_READ_WORD();
		if (DSP4.distance == -0x8000)
			break;

		// road turnoff
		if ((uint16) DSP4.distance == 0x8001)
		{
			DSP4.in_count = 6;
			DSP4_WAIT(2);

			resume2:

			DSP4.distance        = DSP4_READ_WORD();
			DSP4.view_turnoff_x  = DSP4_READ_WORD();
			DSP4.view_turnoff_dx = DSP4_READ_WORD();

			// factor in new changes
			DSP4.view_x1    += (DSP4.view_turnoff_x * DSP4.distance >> 15);
			DSP4.view_xofs1 += (DSP4.view_turnoff_x * DSP4.distance >> 15);

			// update stepping values
			DSP4.view_turnoff_x += DSP4.view_turnoff_dx;

			DSP4.in_count = 2;
			DSP4_WAIT(1);
		}

		// already have 2 bytes read
		DSP4.in_count = 6;
		DSP4_WAIT(3);

		resume3:

		// inspect inputs
		DSP4.world_ddy    = DSP4_READ_WORD();
		DSP4.world_ddx    = DSP4_READ_WORD();
		DSP4.view_yofsenv = DSP4_READ_WORD();

		// no envelope here
		DSP4.world_xenv = 0;
	}
	while (1);

	// terminate op
	DSP4.waiting4command = TRUE;
}

static void DSP4_OP03 (void)
{
	DSP4.OAM_RowMax = 33;
	memset(DSP4.OAM_Row, 0, 64);
}

static void DSP4_OP05 (void)
{
	DSP4.OAM_index = 0;
	DSP4.OAM_bits = 0;
	memset(DSP4.OAM_attr, 0, 32);
	DSP4.sprite_count = 0;
}

static void DSP4_OP06 (void)
{
	DSP4_CLEAR_OUT();
	DSP4_WRITE_16_WORD(DSP4.OAM_attr);
}

static void DSP4_OP07 (void)
{
	DSP4.waiting4command = FALSE;

	// op flow control
	switch (DSP4.Logic)
	{
		case 1: goto resume1; break;
		case 2: goto resume2; break;
	}

	////////////////////////////////////////////////////
	// sort inputs

	DSP4.world_y           = DSP4_READ_DWORD();
	DSP4.poly_bottom[0][0] = DSP4_READ_WORD();
	DSP4.poly_top[0][0]    = DSP4_READ_WORD();
	DSP4.poly_cx[1][0]     = DSP4_READ_WORD();
	DSP4.viewport_bottom   = DSP4_READ_WORD();
	DSP4.world_x           = DSP4_READ_DWORD();
	DSP4.poly_cx[0][0]     = DSP4_READ_WORD();
	DSP4.poly_ptr[0][0]    = DSP4_READ_WORD();
	DSP4.world_yofs        = DSP4_READ_WORD();
	DSP4.distance          = DSP4_READ_WORD();
	DSP4.view_y2           = DSP4_READ_WORD();
	DSP4.view_dy           = DSP4_READ_WORD() * DSP4.distance >> 15;
	DSP4.view_x2           = DSP4_READ_WORD();
	DSP4.view_dx           = DSP4_READ_WORD() * DSP4.distance >> 15;
	DSP4.view_yofsenv      = DSP4_READ_WORD();

	// initial (x, y, offset) at starting raster line
	DSP4.view_x1    = DSP4.world_x >> 16;
	DSP4.view_y1    = DSP4.world_y >> 16;
	DSP4.view_xofs1 = DSP4.view_x1;
	DSP4.view_yofs1 = DSP4.world_yofs;

	// first raster line
	DSP4.poly_raster[0][0] = DSP4.poly_bottom[0][0];

	do
	{
		////////////////////////////////////////////////////
		// process one iteration of projection

		// add shaping
		DSP4.view_x2 += DSP4.view_dx;
		DSP4.view_y2 += DSP4.view_dy;

		// vertical scroll calculation
		DSP4.view_xofs2 = DSP4.view_x2;
		DSP4.view_yofs2 = (DSP4.world_yofs * DSP4.distance >> 15) + DSP4.poly_bottom[0][0] - DSP4.view_y2;

		// 1. Viewer x-position at the next
		// 2. Viewer y-position below the horizon
		// 3. Number of raster lines drawn in this iteration
		DSP4_CLEAR_OUT();
		DSP4_WRITE_WORD(DSP4.view_x2);
		DSP4_WRITE_WORD(DSP4.view_y2);

		//////////////////////////////////////////////////////

		// SR = 0x00

		// determine # of raster lines used
		DSP4.segments = DSP4.view_y1 - DSP4.view_y2;

		// prevent overdraw
		if (DSP4.view_y2 >= DSP4.poly_raster[0][0])
			DSP4.segments = 0;
		else
			DSP4.poly_raster[0][0] = DSP4.view_y2;

		// don't draw outside the window
		if (DSP4.view_y2 < DSP4.poly_top[0][0])
		{
			DSP4.segments = 0;

			// flush remaining raster lines
			if (DSP4.view_y1 >= DSP4.poly_top[0][0])
				DSP4.segments = DSP4.view_y1 - DSP4.poly_top[0][0];
		}

		// SR = 0x80

		DSP4_WRITE_WORD(DSP4.segments);

		//////////////////////////////////////////////////////

		// scan next command if no SR check needed
		if (DSP4.segments)
		{
			int32	px_dx, py_dy;
			int32	x_scroll, y_scroll;

			// SR = 0x00

			// linear interpolation (lerp) between projected points
			px_dx = (DSP4.view_xofs2 - DSP4.view_xofs1) * DSP4_Inverse(DSP4.segments) << 1;
			py_dy = (DSP4.view_yofs2 - DSP4.view_yofs1) * DSP4_Inverse(DSP4.segments) << 1;

			// starting step values
			x_scroll = SEX16(DSP4.poly_cx[0][0] + DSP4.view_xofs1);
			y_scroll = SEX16(-DSP4.viewport_bottom + DSP4.view_yofs1 + DSP4.view_yofsenv + DSP4.poly_cx[1][0] - DSP4.world_yofs);

			// SR = 0x80

			// rasterize line
			for (DSP4.lcv = 0; DSP4.lcv < DSP4.segments; DSP4.lcv++)
			{
				// 1. HDMA memory pointer (bg2)
				// 2. vertical scroll offset ($2110)
				// 3. horizontal scroll offset ($210F)
				DSP4_WRITE_WORD(DSP4.poly_ptr[0][0]);
				DSP4_WRITE_WORD((y_scroll + 0x8000) >> 16);
				DSP4_WRITE_WORD((x_scroll + 0x8000) >> 16);

				// update memory address
				DSP4.poly_ptr[0][0] -= 4;

				// update screen values
				x_scroll += px_dx;
				y_scroll += py_dy;
			}
		}

		/////////////////////////////////////////////////////
		// Post-update

		// update new viewer (x, y, scroll) to last raster line drawn
		DSP4.view_x1    = DSP4.view_x2;
		DSP4.view_y1    = DSP4.view_y2;
		DSP4.view_xofs1 = DSP4.view_xofs2;
		DSP4.view_yofs1 = DSP4.view_yofs2;

		////////////////////////////////////////////////////
		// command check

		// scan next command
		DSP4.in_count = 2;
		DSP4_WAIT(1);

		resume1:

		// check for opcode termination
		DSP4.distance = DSP4_READ_WORD();
		if (DSP4.distance == -0x8000)
			break;

		// already have 2 bytes in queue
		DSP4.in_count = 10;
		DSP4_WAIT(2);

		resume2:

		// inspect inputs
		DSP4.view_y2      = DSP4_READ_WORD();
		DSP4.view_dy      = DSP4_READ_WORD() * DSP4.distance >> 15;
		DSP4.view_x2      = DSP4_READ_WORD();
		DSP4.view_dx      = DSP4_READ_WORD() * DSP4.distance >> 15;
		DSP4.view_yofsenv = DSP4_READ_WORD();
	}
	while (1);

	DSP4.waiting4command = TRUE;
}

static void DSP4_OP08 (void)
{
	int16	win_left, win_right;
	int16	view_x[2], view_y[2];
	int16	envelope[2][2];

	DSP4.waiting4command = FALSE;

	// op flow control
	switch (DSP4.Logic)
	{
		case 1: goto resume1; break;
		case 2: goto resume2; break;
	}

	////////////////////////////////////////////////////
	// process initial inputs for two polygons

	// clip values
	DSP4.poly_clipRt[0][0] = DSP4_READ_WORD();
	DSP4.poly_clipRt[0][1] = DSP4_READ_WORD();
	DSP4.poly_clipRt[1][0] = DSP4_READ_WORD();
	DSP4.poly_clipRt[1][1] = DSP4_READ_WORD();

	DSP4.poly_clipLf[0][0] = DSP4_READ_WORD();
	DSP4.poly_clipLf[0][1] = DSP4_READ_WORD();
	DSP4.poly_clipLf[1][0] = DSP4_READ_WORD();
	DSP4.poly_clipLf[1][1] = DSP4_READ_WORD();

	// unknown (constant) (ex. 1P/2P = $00A6, $00A6, $00A6, $00A6)
	DSP4_READ_WORD();
	DSP4_READ_WORD();
	DSP4_READ_WORD();
	DSP4_READ_WORD();

	// unknown (constant) (ex. 1P/2P = $00A5, $00A5, $00A7, $00A7)
	DSP4_READ_WORD();
	DSP4_READ_WORD();
	DSP4_READ_WORD();
	DSP4_READ_WORD();

	// polygon centering (left, right)
	DSP4.poly_cx[0][0] = DSP4_READ_WORD();
	DSP4.poly_cx[0][1] = DSP4_READ_WORD();
	DSP4.poly_cx[1][0] = DSP4_READ_WORD();
	DSP4.poly_cx[1][1] = DSP4_READ_WORD();

	// HDMA pointer locations
	DSP4.poly_ptr[0][0] = DSP4_READ_WORD();
	DSP4.poly_ptr[0][1] = DSP4_READ_WORD();
	DSP4.poly_ptr[1][0] = DSP4_READ_WORD();
	DSP4.poly_ptr[1][1] = DSP4_READ_WORD();

	// starting raster line below the horizon
	DSP4.poly_bottom[0][0] = DSP4_READ_WORD();
	DSP4.poly_bottom[0][1] = DSP4_READ_WORD();
	DSP4.poly_bottom[1][0] = DSP4_READ_WORD();
	DSP4.poly_bottom[1][1] = DSP4_READ_WORD();

	// top boundary line to clip
	DSP4.poly_top[0][0] = DSP4_READ_WORD();
	DSP4.poly_top[0][1] = DSP4_READ_WORD();
	DSP4.poly_top[1][0] = DSP4_READ_WORD();
	DSP4.poly_top[1][1] = DSP4_READ_WORD();

	// unknown
	// (ex. 1P = $2FC8, $0034, $FF5C, $0035)
	//
	// (ex. 2P = $3178, $0034, $FFCC, $0035)
	// (ex. 2P = $2FC8, $0034, $FFCC, $0035)
	DSP4_READ_WORD();
	DSP4_READ_WORD();
	DSP4_READ_WORD();
	DSP4_READ_WORD();

	// look at guidelines for both polygon shapes
	DSP4.distance = DSP4_READ_WORD();
	view_x[0] = DSP4_READ_WORD();
	view_y[0] = DSP4_READ_WORD();
	view_x[1] = DSP4_READ_WORD();
	view_y[1] = DSP4_READ_WORD();

	// envelope shaping guidelines (one frame only)
	envelope[0][0] = DSP4_READ_WORD();
	envelope[0][1] = DSP4_READ_WORD();
	envelope[1][0] = DSP4_READ_WORD();
	envelope[1][1] = DSP4_READ_WORD();

	// starting base values to project from
	DSP4.poly_start[0] = view_x[0];
	DSP4.poly_start[1] = view_x[1];

	// starting raster lines to begin drawing
	DSP4.poly_raster[0][0] = view_y[0];
	DSP4.poly_raster[0][1] = view_y[0];
	DSP4.poly_raster[1][0] = view_y[1];
	DSP4.poly_raster[1][1] = view_y[1];

	// starting distances
	DSP4.poly_plane[0] = DSP4.distance;
	DSP4.poly_plane[1] = DSP4.distance;

	// SR = 0x00

	// re-center coordinates
	win_left  = DSP4.poly_cx[0][0] - view_x[0] + envelope[0][0];
	win_right = DSP4.poly_cx[0][1] - view_x[0] + envelope[0][1];

	// saturate offscreen data for polygon #1
	if (win_left  < DSP4.poly_clipLf[0][0])
		win_left  = DSP4.poly_clipLf[0][0];
	if (win_left  > DSP4.poly_clipRt[0][0])
		win_left  = DSP4.poly_clipRt[0][0];
	if (win_right < DSP4.poly_clipLf[0][1])
		win_right = DSP4.poly_clipLf[0][1];
	if (win_right > DSP4.poly_clipRt[0][1])
		win_right = DSP4.poly_clipRt[0][1];

	// SR = 0x80

	// initial output for polygon #1
	DSP4_CLEAR_OUT();
	DSP4_WRITE_BYTE(win_left  & 0xff);
	DSP4_WRITE_BYTE(win_right & 0xff);

	do
	{
		int16	polygon;

		////////////////////////////////////////////////////
		// command check

		// scan next command
		DSP4.in_count = 2;
		DSP4_WAIT(1);

		resume1:

		// terminate op
		DSP4.distance = DSP4_READ_WORD();
		if (DSP4.distance == -0x8000)
			break;

		// already have 2 bytes in queue
		DSP4.in_count = 16;
		DSP4_WAIT(2);

		resume2:

		// look at guidelines for both polygon shapes
		view_x[0] = DSP4_READ_WORD();
		view_y[0] = DSP4_READ_WORD();
		view_x[1] = DSP4_READ_WORD();
		view_y[1] = DSP4_READ_WORD();

		// envelope shaping guidelines (one frame only)
		envelope[0][0] = DSP4_READ_WORD();
		envelope[0][1] = DSP4_READ_WORD();
		envelope[1][0] = DSP4_READ_WORD();
		envelope[1][1] = DSP4_READ_WORD();

		////////////////////////////////////////////////////
		// projection begins

		// init
		DSP4_CLEAR_OUT();

		//////////////////////////////////////////////
		// solid polygon renderer - 2 shapes

		for (polygon = 0; polygon < 2; polygon++)
		{
			int32	left_inc, right_inc;
			int16	x1_final, x2_final;
			int16	env[2][2];
			int16	poly;

			// SR = 0x00

			// # raster lines to draw
			DSP4.segments = DSP4.poly_raster[polygon][0] - view_y[polygon];

			// prevent overdraw
			if (DSP4.segments > 0)
			{
				// bump drawing cursor
				DSP4.poly_raster[polygon][0] = view_y[polygon];
				DSP4.poly_raster[polygon][1] = view_y[polygon];
			}
			else
				DSP4.segments = 0;

			// don't draw outside the window
			if (view_y[polygon] < DSP4.poly_top[polygon][0])
			{
				DSP4.segments = 0;

				// flush remaining raster lines
				if (view_y[polygon] >= DSP4.poly_top[polygon][0])
					DSP4.segments = view_y[polygon] - DSP4.poly_top[polygon][0];
			}

			// SR = 0x80

			// tell user how many raster structures to read in
			DSP4_WRITE_WORD(DSP4.segments);

			// normal parameters
			poly = polygon;

			/////////////////////////////////////////////////////

			// scan next command if no SR check needed
			if (DSP4.segments)
			{
				int32	w_left, w_right;

				// road turnoff selection
				if ((uint16) envelope[polygon][0] == (uint16) 0xc001)
					poly = 1;
				else
				if (envelope[polygon][1] == 0x3fff)
					poly = 1;

				///////////////////////////////////////////////
				// left side of polygon

				// perspective correction on additional shaping parameters
				env[0][0] = envelope[polygon][0] * DSP4.poly_plane[poly] >> 15;
				env[0][1] = envelope[polygon][0] * DSP4.distance >> 15;

				// project new shapes (left side)
				x1_final = view_x[poly] + env[0][0];
				x2_final = DSP4.poly_start[poly] + env[0][1];

				// interpolate between projected points with shaping
				left_inc = (x2_final - x1_final) * DSP4_Inverse(DSP4.segments) << 1;
				if (DSP4.segments == 1)
					left_inc = -left_inc;

				///////////////////////////////////////////////
				// right side of polygon

				// perspective correction on additional shaping parameters
				env[1][0] = envelope[polygon][1] * DSP4.poly_plane[poly] >> 15;
				env[1][1] = envelope[polygon][1] * DSP4.distance >> 15;

				// project new shapes (right side)
				x1_final = view_x[poly] + env[1][0];
				x2_final = DSP4.poly_start[poly] + env[1][1];

				// interpolate between projected points with shaping
				right_inc = (x2_final - x1_final) * DSP4_Inverse(DSP4.segments) << 1;
				if (DSP4.segments == 1)
					right_inc = -right_inc;

				///////////////////////////////////////////////
				// update each point on the line

				w_left  = SEX16(DSP4.poly_cx[polygon][0] - DSP4.poly_start[poly] + env[0][0]);
				w_right = SEX16(DSP4.poly_cx[polygon][1] - DSP4.poly_start[poly] + env[1][0]);

				// update distance drawn into world
				DSP4.poly_plane[polygon] = DSP4.distance;

				// rasterize line
				for (DSP4.lcv = 0; DSP4.lcv < DSP4.segments; DSP4.lcv++)
				{
					int16	x_left, x_right;

					// project new coordinates
					w_left  += left_inc;
					w_right += right_inc;

					// grab integer portion, drop fraction (no rounding)
					x_left  = w_left  >> 16;
					x_right = w_right >> 16;

					// saturate offscreen data
					if (x_left  < DSP4.poly_clipLf[polygon][0])
						x_left  = DSP4.poly_clipLf[polygon][0];
					if (x_left  > DSP4.poly_clipRt[polygon][0])
						x_left  = DSP4.poly_clipRt[polygon][0];
					if (x_right < DSP4.poly_clipLf[polygon][1])
						x_right = DSP4.poly_clipLf[polygon][1];
					if (x_right > DSP4.poly_clipRt[polygon][1])
						x_right = DSP4.poly_clipRt[polygon][1];

					// 1. HDMA memory pointer
					// 2. Left window position ($2126/$2128)
					// 3. Right window position ($2127/$2129)
					DSP4_WRITE_WORD(DSP4.poly_ptr[polygon][0]);
					DSP4_WRITE_BYTE(x_left  & 0xff);
					DSP4_WRITE_BYTE(x_right & 0xff);

					// update memory pointers
					DSP4.poly_ptr[polygon][0] -= 4;
					DSP4.poly_ptr[polygon][1] -= 4;
				} // end rasterize line
			}

			////////////////////////////////////////////////
			// Post-update

			// new projection spot to continue rasterizing from
			DSP4.poly_start[polygon] = view_x[poly];
		} // end polygon rasterizer
	}
	while (1);

	// unknown output
	DSP4_CLEAR_OUT();
	DSP4_WRITE_WORD(0);

	DSP4.waiting4command = TRUE;
}

static void DSP4_OP09 (void)
{
	DSP4.waiting4command = FALSE;

	// op flow control
	switch (DSP4.Logic)
	{
		case 1: goto resume1; break;
		case 2: goto resume2; break;
		case 3: goto resume3; break;
		case 4: goto resume4; break;
		case 5: goto resume5; break;
		case 6: goto resume6; break;
	}

	////////////////////////////////////////////////////
	// process initial inputs

	// grab screen information
	DSP4.viewport_cx     = DSP4_READ_WORD();
	DSP4.viewport_cy     = DSP4_READ_WORD();
	DSP4_READ_WORD(); // 0x0000
	DSP4.viewport_left   = DSP4_READ_WORD();
	DSP4.viewport_right  = DSP4_READ_WORD();
	DSP4.viewport_top    = DSP4_READ_WORD();
	DSP4.viewport_bottom = DSP4_READ_WORD();

	// starting raster line below the horizon
	DSP4.poly_bottom[0][0] = DSP4.viewport_bottom - DSP4.viewport_cy;
	DSP4.poly_raster[0][0] = 0x100;

	do
	{
		////////////////////////////////////////////////////
		// check for new sprites

		DSP4.in_count = 4;
		DSP4_WAIT(1);

		resume1:

		////////////////////////////////////////////////
		// raster overdraw check

		DSP4.raster = DSP4_READ_WORD();

		// continue updating the raster line where overdraw begins
		if (DSP4.raster < DSP4.poly_raster[0][0])
		{
			DSP4.sprite_clipy = DSP4.viewport_bottom - (DSP4.poly_bottom[0][0] - DSP4.raster);
			DSP4.poly_raster[0][0] = DSP4.raster;
		}

		/////////////////////////////////////////////////
		// identify sprite

		// op termination
		DSP4.distance = DSP4_READ_WORD();
		if (DSP4.distance == -0x8000)
			goto terminate;

		// no sprite
		if (DSP4.distance == 0x0000)
			continue;

		////////////////////////////////////////////////////
		// process projection information

		// vehicle sprite
		if ((uint16) DSP4.distance == 0x9000)
		{
			int16	car_left, car_right, car_back;
			int16	impact_left, impact_back;
			int16	world_spx, world_spy;
			int16	view_spx, view_spy;
			uint16	energy;

			// we already have 4 bytes we want
			DSP4.in_count = 14;
			DSP4_WAIT(2);

			resume2:

			// filter inputs
			energy        = DSP4_READ_WORD();
			impact_back   = DSP4_READ_WORD();
			car_back      = DSP4_READ_WORD();
			impact_left   = DSP4_READ_WORD();
			car_left      = DSP4_READ_WORD();
			DSP4.distance = DSP4_READ_WORD();
			car_right     = DSP4_READ_WORD();

			// calculate car's world (x, y) values
			world_spx = car_right - car_left;
			world_spy = car_back;

			// add in collision vector [needs bit-twiddling]
			world_spx -= energy * (impact_left - car_left) >> 16;
			world_spy -= energy * (car_back - impact_back) >> 16;

			// perspective correction for world (x, y)
			view_spx = world_spx * DSP4.distance >> 15;
			view_spy = world_spy * DSP4.distance >> 15;

			// convert to screen values
			DSP4.sprite_x = DSP4.viewport_cx + view_spx;
			DSP4.sprite_y = DSP4.viewport_bottom - (DSP4.poly_bottom[0][0] - view_spy);

			// make the car's (x)-coordinate available
			DSP4_CLEAR_OUT();
			DSP4_WRITE_WORD(world_spx);

			// grab a few remaining vehicle values
			DSP4.in_count = 4;
			DSP4_WAIT(3);

			resume3:

			// add vertical lift factor
			DSP4.sprite_y += DSP4_READ_WORD();
		}
		// terrain sprite
		else
		{
			int16	world_spx, world_spy;
			int16	view_spx, view_spy;

			// we already have 4 bytes we want
			DSP4.in_count = 10;
			DSP4_WAIT(4);

			resume4:

			// sort loop inputs
			DSP4.poly_cx[0][0]     = DSP4_READ_WORD();
			DSP4.poly_raster[0][1] = DSP4_READ_WORD();
			world_spx              = DSP4_READ_WORD();
			world_spy              = DSP4_READ_WORD();

			// compute base raster line from the bottom
			DSP4.segments = DSP4.poly_bottom[0][0] - DSP4.raster;

			// perspective correction for world (x, y)
			view_spx = world_spx * DSP4.distance >> 15;
			view_spy = world_spy * DSP4.distance >> 15;

			// convert to screen values
			DSP4.sprite_x = DSP4.viewport_cx + view_spx - DSP4.poly_cx[0][0];
			DSP4.sprite_y = DSP4.viewport_bottom - DSP4.segments + view_spy;
		}

		// default sprite size: 16x16
		DSP4.sprite_size = 1;
		DSP4.sprite_attr = DSP4_READ_WORD();

		////////////////////////////////////////////////////
		// convert tile data to SNES OAM format

		do
		{
			int16	sp_x, sp_y, sp_attr, sp_dattr;
			int16	sp_dx, sp_dy;
			int16	pixels;
			uint16	header;
			bool8	draw;

			DSP4.in_count = 2;
			DSP4_WAIT(5);

			resume5:

			draw = TRUE;

			// opcode termination
			DSP4.raster = DSP4_READ_WORD();
			if (DSP4.raster == -0x8000)
				goto terminate;

			// stop code
			if (DSP4.raster == 0x0000 && !DSP4.sprite_size)
				break;

			// toggle sprite size
			if (DSP4.raster == 0x0000)
			{
				DSP4.sprite_size = !DSP4.sprite_size;
				continue;
			}

			// check for valid sprite header
			header = DSP4.raster;
			header >>= 8;
			if (header != 0x20 &&
				header != 0x2e && // This is for attractor sprite
				header != 0x40 &&
				header != 0x60 &&
				header != 0xa0 &&
				header != 0xc0 &&
				header != 0xe0)
				break;

			// read in rest of sprite data
			DSP4.in_count = 4;
			DSP4_WAIT(6);

			resume6:

			draw = TRUE;

			/////////////////////////////////////
			// process tile data

			// sprite deltas
			sp_dattr = DSP4.raster;
			sp_dy = DSP4_READ_WORD();
			sp_dx = DSP4_READ_WORD();

			// update coordinates to screen space
			sp_x = DSP4.sprite_x + sp_dx;
			sp_y = DSP4.sprite_y + sp_dy;

			// update sprite nametable/attribute information
			sp_attr = DSP4.sprite_attr + sp_dattr;

			// allow partially visibile tiles
			pixels = DSP4.sprite_size ? 15 : 7;

			DSP4_CLEAR_OUT();

			// transparent tile to clip off parts of a sprite (overdraw)
			if (DSP4.sprite_clipy - pixels <= sp_y && sp_y <= DSP4.sprite_clipy && sp_x >= DSP4.viewport_left - pixels && sp_x <= DSP4.viewport_right && DSP4.sprite_clipy >= DSP4.viewport_top - pixels && DSP4.sprite_clipy <= DSP4.viewport_bottom)
				DSP4_OP0B(&draw, sp_x, DSP4.sprite_clipy, 0x00EE, DSP4.sprite_size, 0);

			// normal sprite tile
			if (sp_x >= DSP4.viewport_left - pixels && sp_x <= DSP4.viewport_right && sp_y >= DSP4.viewport_top - pixels && sp_y <= DSP4.viewport_bottom && sp_y <= DSP4.sprite_clipy)
				DSP4_OP0B(&draw, sp_x, sp_y, sp_attr, DSP4.sprite_size, 0);

			// no following OAM data
			DSP4_OP0B(&draw, 0, 0x0100, 0, 0, 1);
		}
		while (1);
	}
	while (1);

	terminate:
	DSP4.waiting4command = TRUE;
}

static void DSP4_OP0A (int16 n2, int16 *o1, int16 *o2, int16 *o3, int16 *o4)
{
	const uint16	OP0A_Values[16] =
	{
		0x0000, 0x0030, 0x0060, 0x0090, 0x00c0, 0x00f0, 0x0120, 0x0150,
		0xfe80, 0xfeb0, 0xfee0, 0xff10, 0xff40, 0xff70, 0xffa0, 0xffd0
	};

	*o4 = OP0A_Values[(n2 & 0x000f)];
	*o3 = OP0A_Values[(n2 & 0x00f0) >> 4];
	*o2 = OP0A_Values[(n2 & 0x0f00) >> 8];
	*o1 = OP0A_Values[(n2 & 0xf000) >> 12];
}

static void DSP4_OP0B (bool8 *draw, int16 sp_x, int16 sp_y, int16 sp_attr, bool8 size, bool8 stop)
{
	int16	Row1, Row2;

	// SR = 0x00

	// align to nearest 8-pixel row
	Row1 = (sp_y >> 3) & 0x1f;
	Row2 = (Row1 + 1)  & 0x1f;

	// check boundaries
	if (!((sp_y < 0) || ((sp_y & 0x01ff) < 0x00eb)))
		*draw = 0;

	if (size)
	{
		if (DSP4.OAM_Row[Row1] + 1 >= DSP4.OAM_RowMax)
			*draw = 0;
		if (DSP4.OAM_Row[Row2] + 1 >= DSP4.OAM_RowMax)
			*draw = 0;
	}
	else
	{
		if (DSP4.OAM_Row[Row1] >= DSP4.OAM_RowMax)
			*draw = 0;
	}

	// emulator fail-safe (unknown if this really exists)
	if (DSP4.sprite_count >= 128)
		*draw = 0;

	// SR = 0x80

	if (*draw)
	{
		// Row tiles
		if (size)
		{
			DSP4.OAM_Row[Row1] += 2;
			DSP4.OAM_Row[Row2] += 2;
		}
		else
			DSP4.OAM_Row[Row1]++;

		// yield OAM output
		DSP4_WRITE_WORD(1);

		// pack OAM data: x, y, name, attr
		DSP4_WRITE_BYTE(sp_x & 0xff);
		DSP4_WRITE_BYTE(sp_y & 0xff);
		DSP4_WRITE_WORD(sp_attr);

		DSP4.sprite_count++;

		// OAM: size, msb data
		// save post-oam table data for future retrieval
		DSP4.OAM_attr[DSP4.OAM_index] |= ((sp_x < 0 || sp_x > 255) << DSP4.OAM_bits);
		DSP4.OAM_bits++;

		DSP4.OAM_attr[DSP4.OAM_index] |= (size << DSP4.OAM_bits);
		DSP4.OAM_bits++;

		// move to next byte in buffer
		if (DSP4.OAM_bits == 16)
		{
			DSP4.OAM_bits = 0;
			DSP4.OAM_index++;
		}
	}
	else
	if (stop)
		// yield no OAM output
		DSP4_WRITE_WORD(0);
}

static void DSP4_OP0D (void)
{
	DSP4.waiting4command = FALSE;

	// op flow control
	switch (DSP4.Logic)
	{
		case 1: goto resume1; break;
		case 2: goto resume2; break;
	}

	////////////////////////////////////////////////////
	// process initial inputs

	// sort inputs
	DSP4.world_y           = DSP4_READ_DWORD();
	DSP4.poly_bottom[0][0] = DSP4_READ_WORD();
	DSP4.poly_top[0][0]    = DSP4_READ_WORD();
	DSP4.poly_cx[1][0]     = DSP4_READ_WORD();
	DSP4.viewport_bottom   = DSP4_READ_WORD();
	DSP4.world_x           = DSP4_READ_DWORD();
	DSP4.poly_cx[0][0]     = DSP4_READ_WORD();
	DSP4.poly_ptr[0][0]    = DSP4_READ_WORD();
	DSP4.world_yofs        = DSP4_READ_WORD();
	DSP4.world_dy          = DSP4_READ_DWORD();
	DSP4.world_dx          = DSP4_READ_DWORD();
	DSP4.distance          = DSP4_READ_WORD();
	DSP4_READ_WORD(); // 0x0000
	DSP4.world_xenv        = SEX78(DSP4_READ_WORD());
	DSP4.world_ddy         = DSP4_READ_WORD();
	DSP4.world_ddx         = DSP4_READ_WORD();
	DSP4.view_yofsenv      = DSP4_READ_WORD();

	// initial (x, y, offset) at starting raster line
	DSP4.view_x1    = (DSP4.world_x + DSP4.world_xenv) >> 16;
	DSP4.view_y1    = DSP4.world_y >> 16;
	DSP4.view_xofs1 = DSP4.world_x >> 16;
	DSP4.view_yofs1 = DSP4.world_yofs;

	// first raster line
	DSP4.poly_raster[0][0] = DSP4.poly_bottom[0][0];

	do
	{
		////////////////////////////////////////////////////
		// process one iteration of projection

		// perspective projection of world (x, y, scroll) points
		// based on the current projection lines
		DSP4.view_x2    = (((DSP4.world_x + DSP4.world_xenv) >> 16) * DSP4.distance >> 15) + (DSP4.view_turnoff_x * DSP4.distance >> 15);
		DSP4.view_y2    = (DSP4.world_y >> 16) * DSP4.distance >> 15;
		DSP4.view_xofs2 = DSP4.view_x2;
		DSP4.view_yofs2 = (DSP4.world_yofs * DSP4.distance >> 15) + DSP4.poly_bottom[0][0] - DSP4.view_y2;

		// 1. World x-location before transformation
		// 2. Viewer x-position at the current
		// 3. World y-location before perspective projection
		// 4. Viewer y-position below the horizon
		// 5. Number of raster lines drawn in this iteration
		DSP4_CLEAR_OUT();
		DSP4_WRITE_WORD((DSP4.world_x + DSP4.world_xenv) >> 16);
		DSP4_WRITE_WORD(DSP4.view_x2);
		DSP4_WRITE_WORD(DSP4.world_y >> 16);
		DSP4_WRITE_WORD(DSP4.view_y2);

		//////////////////////////////////////////////////////////

		// SR = 0x00

		// determine # of raster lines used
		DSP4.segments = DSP4.view_y1 - DSP4.view_y2;

		// prevent overdraw
		if (DSP4.view_y2 >= DSP4.poly_raster[0][0])
			DSP4.segments = 0;
		else
			DSP4.poly_raster[0][0] = DSP4.view_y2;

		// don't draw outside the window
		if (DSP4.view_y2 < DSP4.poly_top[0][0])
		{
			DSP4.segments = 0;

			// flush remaining raster lines
			if (DSP4.view_y1 >= DSP4.poly_top[0][0])
				DSP4.segments = DSP4.view_y1 - DSP4.poly_top[0][0];
		}

		// SR = 0x80

		DSP4_WRITE_WORD(DSP4.segments);

		//////////////////////////////////////////////////////////

		// scan next command if no SR check needed
		if (DSP4.segments)
		{
			int32	px_dx, py_dy;
			int32	x_scroll, y_scroll;

			// SR = 0x00

			// linear interpolation (lerp) between projected points
			px_dx = (DSP4.view_xofs2 - DSP4.view_xofs1) * DSP4_Inverse(DSP4.segments) << 1;
			py_dy = (DSP4.view_yofs2 - DSP4.view_yofs1) * DSP4_Inverse(DSP4.segments) << 1;

			// starting step values
			x_scroll = SEX16(DSP4.poly_cx[0][0] + DSP4.view_xofs1);
			y_scroll = SEX16(-DSP4.viewport_bottom + DSP4.view_yofs1 + DSP4.view_yofsenv + DSP4.poly_cx[1][0] - DSP4.world_yofs);

			// SR = 0x80

			// rasterize line
			for (DSP4.lcv = 0; DSP4.lcv < DSP4.segments; DSP4.lcv++)
			{
				// 1. HDMA memory pointer (bg1)
				// 2. vertical scroll offset ($210E)
				// 3. horizontal scroll offset ($210D)
				DSP4_WRITE_WORD(DSP4.poly_ptr[0][0]);
				DSP4_WRITE_WORD((y_scroll + 0x8000) >> 16);
				DSP4_WRITE_WORD((x_scroll + 0x8000) >> 16);

				// update memory address
				DSP4.poly_ptr[0][0] -= 4;

				// update screen values
				x_scroll += px_dx;
				y_scroll += py_dy;
			}
		}

		/////////////////////////////////////////////////////
		// Post-update

		// update new viewer (x, y, scroll) to last raster line drawn
		DSP4.view_x1    = DSP4.view_x2;
		DSP4.view_y1    = DSP4.view_y2;
		DSP4.view_xofs1 = DSP4.view_xofs2;
		DSP4.view_yofs1 = DSP4.view_yofs2;

		// add deltas for projection lines
		DSP4.world_dx += SEX78(DSP4.world_ddx);
		DSP4.world_dy += SEX78(DSP4.world_ddy);

		// update projection lines
		DSP4.world_x += (DSP4.world_dx + DSP4.world_xenv);
		DSP4.world_y += DSP4.world_dy;

		////////////////////////////////////////////////////
		// command check

		// scan next command
		DSP4.in_count = 2;
		DSP4_WAIT(1);

		resume1:

		// inspect input
		DSP4.distance = DSP4_READ_WORD();

		// terminate op
		if (DSP4.distance == -0x8000)
			break;

		// already have 2 bytes in queue
		DSP4.in_count = 6;
		DSP4_WAIT(2);

		resume2:

		// inspect inputs
		DSP4.world_ddy    = DSP4_READ_WORD();
		DSP4.world_ddx    = DSP4_READ_WORD();
		DSP4.view_yofsenv = DSP4_READ_WORD();

		// no envelope here
		DSP4.world_xenv = 0;
	}
	while (1);

	DSP4.waiting4command = TRUE;
}

static void DSP4_OP0E (void)
{
	DSP4.OAM_RowMax = 16;
	memset(DSP4.OAM_Row, 0, 64);
}

static void DSP4_OP0F (void)
{
	DSP4.waiting4command = FALSE;

	// op flow control
	switch (DSP4.Logic)
	{
		case 1: goto resume1; break;
		case 2: goto resume2; break;
		case 3: goto resume3; break;
		case 4: goto resume4; break;
	}

	////////////////////////////////////////////////////
	// process initial inputs

	// sort inputs
	DSP4_READ_WORD(); // 0x0000
	DSP4.world_y           = DSP4_READ_DWORD();
	DSP4.poly_bottom[0][0] = DSP4_READ_WORD();
	DSP4.poly_top[0][0]    = DSP4_READ_WORD();
	DSP4.poly_cx[1][0]     = DSP4_READ_WORD();
	DSP4.viewport_bottom   = DSP4_READ_WORD();
	DSP4.world_x           = DSP4_READ_DWORD();
	DSP4.poly_cx[0][0]     = DSP4_READ_WORD();
	DSP4.poly_ptr[0][0]    = DSP4_READ_WORD();
	DSP4.world_yofs        = DSP4_READ_WORD();
	DSP4.world_dy          = DSP4_READ_DWORD();
	DSP4.world_dx          = DSP4_READ_DWORD();
	DSP4.distance          = DSP4_READ_WORD();
	DSP4_READ_WORD(); // 0x0000
	DSP4.world_xenv        = DSP4_READ_DWORD();
	DSP4.world_ddy         = DSP4_READ_WORD();
	DSP4.world_ddx         = DSP4_READ_WORD();
	DSP4.view_yofsenv      = DSP4_READ_WORD();

	// initial (x, y, offset) at starting raster line
	DSP4.view_x1         = (DSP4.world_x + DSP4.world_xenv) >> 16;
	DSP4.view_y1         = DSP4.world_y >> 16;
	DSP4.view_xofs1      = DSP4.world_x >> 16;
	DSP4.view_yofs1      = DSP4.world_yofs;
	DSP4.view_turnoff_x  = 0;
	DSP4.view_turnoff_dx = 0;

	// first raster line
	DSP4.poly_raster[0][0] = DSP4.poly_bottom[0][0];

	do
	{
		////////////////////////////////////////////////////
		// process one iteration of projection

		// perspective projection of world (x, y, scroll) points
		// based on the current projection lines
		DSP4.view_x2    = ((DSP4.world_x + DSP4.world_xenv) >> 16) * DSP4.distance >> 15;
		DSP4.view_y2    = (DSP4.world_y >> 16) * DSP4.distance >> 15;
		DSP4.view_xofs2 = DSP4.view_x2;
		DSP4.view_yofs2 = (DSP4.world_yofs * DSP4.distance >> 15) + DSP4.poly_bottom[0][0] - DSP4.view_y2;

		// 1. World x-location before transformation
		// 2. Viewer x-position at the next
		// 3. World y-location before perspective projection
		// 4. Viewer y-position below the horizon
		// 5. Number of raster lines drawn in this iteration
		DSP4_CLEAR_OUT();
		DSP4_WRITE_WORD((DSP4.world_x + DSP4.world_xenv) >> 16);
		DSP4_WRITE_WORD(DSP4.view_x2);
		DSP4_WRITE_WORD(DSP4.world_y >> 16);
		DSP4_WRITE_WORD(DSP4.view_y2);

		//////////////////////////////////////////////////////

		// SR = 0x00

		// determine # of raster lines used
		DSP4.segments = DSP4.poly_raster[0][0] - DSP4.view_y2;

		// prevent overdraw
		if (DSP4.view_y2 >= DSP4.poly_raster[0][0])
			DSP4.segments = 0;
		else
			DSP4.poly_raster[0][0] = DSP4.view_y2;

		// don't draw outside the window
		if (DSP4.view_y2 < DSP4.poly_top[0][0])
		{
			DSP4.segments = 0;

			// flush remaining raster lines
			if (DSP4.view_y1 >= DSP4.poly_top[0][0])
				DSP4.segments = DSP4.view_y1 - DSP4.poly_top[0][0];
		}

		// SR = 0x80

		DSP4_WRITE_WORD(DSP4.segments);

		//////////////////////////////////////////////////////

		// scan next command if no SR check needed
		if (DSP4.segments)
		{
			int32	px_dx, py_dy;
			int32	x_scroll, y_scroll;

			for (DSP4.lcv = 0; DSP4.lcv < 4; DSP4.lcv++)
			{
				// grab inputs
				DSP4.in_count = 4;
				DSP4_WAIT(1);

				resume1:

				for (;;)
				{
					int16	dist;
					int16	color, red, green, blue;

					dist  = DSP4_READ_WORD();
					color = DSP4_READ_WORD();

					// U1+B5+G5+R5
					red   =  color        & 0x1f;
					green = (color >>  5) & 0x1f;
					blue  = (color >> 10) & 0x1f;

					// dynamic lighting
					red   = (red   * dist >> 15) & 0x1f;
					green = (green * dist >> 15) & 0x1f;
					blue  = (blue  * dist >> 15) & 0x1f;
					color = red | (green << 5) | (blue << 10);

					DSP4_CLEAR_OUT();
					DSP4_WRITE_WORD(color);

					break;
				}
			}

			//////////////////////////////////////////////////////

			// SR = 0x00

			// linear interpolation (lerp) between projected points
			px_dx = (DSP4.view_xofs2 - DSP4.view_xofs1) * DSP4_Inverse(DSP4.segments) << 1;
			py_dy = (DSP4.view_yofs2 - DSP4.view_yofs1) * DSP4_Inverse(DSP4.segments) << 1;

			// starting step values
			x_scroll = SEX16(DSP4.poly_cx[0][0] + DSP4.view_xofs1);
			y_scroll = SEX16(-DSP4.viewport_bottom + DSP4.view_yofs1 + DSP4.view_yofsenv + DSP4.poly_cx[1][0] - DSP4.world_yofs);

			// SR = 0x80

			// rasterize line
			for (DSP4.lcv = 0; DSP4.lcv < DSP4.segments; DSP4.lcv++)
			{
				// 1. HDMA memory pointer
				// 2. vertical scroll offset ($210E)
				// 3. horizontal scroll offset ($210D)
				DSP4_WRITE_WORD(DSP4.poly_ptr[0][0]);
				DSP4_WRITE_WORD((y_scroll + 0x8000) >> 16);
				DSP4_WRITE_WORD((x_scroll + 0x8000) >> 16);

				// update memory address
				DSP4.poly_ptr[0][0] -= 4;

				// update screen values
				x_scroll += px_dx;
				y_scroll += py_dy;
			}
		}

		////////////////////////////////////////////////////
		// Post-update

		// update new viewer (x, y, scroll) to last raster line drawn
		DSP4.view_x1    = DSP4.view_x2;
		DSP4.view_y1    = DSP4.view_y2;
		DSP4.view_xofs1 = DSP4.view_xofs2;
		DSP4.view_yofs1 = DSP4.view_yofs2;

		// add deltas for projection lines
		DSP4.world_dx += SEX78(DSP4.world_ddx);
		DSP4.world_dy += SEX78(DSP4.world_ddy);

		// update projection lines
		DSP4.world_x += (DSP4.world_dx + DSP4.world_xenv);
		DSP4.world_y += DSP4.world_dy;

		// update road turnoff position
		DSP4.view_turnoff_x += DSP4.view_turnoff_dx;

		////////////////////////////////////////////////////
		// command check

		// scan next command
		DSP4.in_count = 2;
		DSP4_WAIT(2);

		resume2:

		// check for termination
		DSP4.distance = DSP4_READ_WORD();
		if (DSP4.distance == -0x8000)
			break;

		// road splice
		if ((uint16) DSP4.distance == 0x8001)
		{
			DSP4.in_count = 6;
			DSP4_WAIT(3);

			resume3:

			DSP4.distance        = DSP4_READ_WORD();
			DSP4.view_turnoff_x  = DSP4_READ_WORD();
			DSP4.view_turnoff_dx = DSP4_READ_WORD();

			// factor in new changes
			DSP4.view_x1    += (DSP4.view_turnoff_x * DSP4.distance >> 15);
			DSP4.view_xofs1 += (DSP4.view_turnoff_x * DSP4.distance >> 15);

			// update stepping values
			DSP4.view_turnoff_x += DSP4.view_turnoff_dx;

			DSP4.in_count = 2;
			DSP4_WAIT(2);
		}

		// already have 2 bytes in queue
		DSP4.in_count = 6;
		DSP4_WAIT(4);

		resume4:

		// inspect inputs
		DSP4.world_ddy    = DSP4_READ_WORD();
		DSP4.world_ddx    = DSP4_READ_WORD();
		DSP4.view_yofsenv = DSP4_READ_WORD();

		// no envelope here
		DSP4.world_xenv = 0;
	}
	while (1);

	// terminate op
	DSP4.waiting4command = TRUE;
}

static void DSP4_OP10 (void)
{
	DSP4.waiting4command = FALSE;

	// op flow control
	switch (DSP4.Logic)
	{
		case 1: goto resume1; break;
		case 2: goto resume2; break;
		case 3: goto resume3; break;
	}

	////////////////////////////////////////////////////
	// sort inputs

	DSP4_READ_WORD(); // 0x0000
	DSP4.world_y           = DSP4_READ_DWORD();
	DSP4.poly_bottom[0][0] = DSP4_READ_WORD();
	DSP4.poly_top[0][0]    = DSP4_READ_WORD();
	DSP4.poly_cx[1][0]     = DSP4_READ_WORD();
	DSP4.viewport_bottom   = DSP4_READ_WORD();
	DSP4.world_x           = DSP4_READ_DWORD();
	DSP4.poly_cx[0][0]     = DSP4_READ_WORD();
	DSP4.poly_ptr[0][0]    = DSP4_READ_WORD();
	DSP4.world_yofs        = DSP4_READ_WORD();
	DSP4.distance          = DSP4_READ_WORD();
	DSP4.view_y2           = DSP4_READ_WORD();
	DSP4.view_dy           = DSP4_READ_WORD() * DSP4.distance >> 15;
	DSP4.view_x2           = DSP4_READ_WORD();
	DSP4.view_dx           = DSP4_READ_WORD() * DSP4.distance >> 15;
	DSP4.view_yofsenv      = DSP4_READ_WORD();

	// initial (x, y, offset) at starting raster line
	DSP4.view_x1    = DSP4.world_x >> 16;
	DSP4.view_y1    = DSP4.world_y >> 16;
	DSP4.view_xofs1 = DSP4.view_x1;
	DSP4.view_yofs1 = DSP4.world_yofs;

	// first raster line
	DSP4.poly_raster[0][0] = DSP4.poly_bottom[0][0];

	do
	{
		////////////////////////////////////////////////////
		// process one iteration of projection

		// add shaping
		DSP4.view_x2 += DSP4.view_dx;
		DSP4.view_y2 += DSP4.view_dy;

		// vertical scroll calculation
		DSP4.view_xofs2 = DSP4.view_x2;
		DSP4.view_yofs2 = (DSP4.world_yofs * DSP4.distance >> 15) + DSP4.poly_bottom[0][0] - DSP4.view_y2;

		// 1. Viewer x-position at the next
		// 2. Viewer y-position below the horizon
		// 3. Number of raster lines drawn in this iteration
		DSP4_CLEAR_OUT();
		DSP4_WRITE_WORD(DSP4.view_x2);
		DSP4_WRITE_WORD(DSP4.view_y2);

		//////////////////////////////////////////////////////

		// SR = 0x00

		// determine # of raster lines used
		DSP4.segments = DSP4.view_y1 - DSP4.view_y2;

		// prevent overdraw
		if (DSP4.view_y2 >= DSP4.poly_raster[0][0])
			DSP4.segments = 0;
		else
			DSP4.poly_raster[0][0] = DSP4.view_y2;

		// don't draw outside the window
		if (DSP4.view_y2 < DSP4.poly_top[0][0])
		{
			DSP4.segments = 0;

			// flush remaining raster lines
			if (DSP4.view_y1 >= DSP4.poly_top[0][0])
				DSP4.segments = DSP4.view_y1 - DSP4.poly_top[0][0];
		}

		// SR = 0x80

		DSP4_WRITE_WORD(DSP4.segments);

		//////////////////////////////////////////////////////

		// scan next command if no SR check needed
		if (DSP4.segments)
		{
			for (DSP4.lcv = 0; DSP4.lcv < 4; DSP4.lcv++)
			{
				// grab inputs
				DSP4.in_count = 4;
				DSP4_WAIT(1);

				resume1:

				for (;;)
				{
					int16	dist;
					int16	color, red, green, blue;

					dist  = DSP4_READ_WORD();
					color = DSP4_READ_WORD();

					// U1+B5+G5+R5
					red   =  color        & 0x1f;
					green = (color >>  5) & 0x1f;
					blue  = (color >> 10) & 0x1f;

					// dynamic lighting
					red   = (red   * dist >> 15) & 0x1f;
					green = (green * dist >> 15) & 0x1f;
					blue  = (blue  * dist >> 15) & 0x1f;
					color = red | (green << 5) | (blue << 10);

					DSP4_CLEAR_OUT();
					DSP4_WRITE_WORD(color);

					break;
				}
			}
		}

		//////////////////////////////////////////////////////

		// scan next command if no SR check needed
		if (DSP4.segments)
		{
			int32	px_dx, py_dy;
			int32	x_scroll, y_scroll;

			// SR = 0x00

			// linear interpolation (lerp) between projected points
			px_dx = (DSP4.view_xofs2 - DSP4.view_xofs1) * DSP4_Inverse(DSP4.segments) << 1;
			py_dy = (DSP4.view_yofs2 - DSP4.view_yofs1) * DSP4_Inverse(DSP4.segments) << 1;

			// starting step values
			x_scroll = SEX16(DSP4.poly_cx[0][0] + DSP4.view_xofs1);
			y_scroll = SEX16(-DSP4.viewport_bottom + DSP4.view_yofs1 + DSP4.view_yofsenv + DSP4.poly_cx[1][0] - DSP4.world_yofs);

			// SR = 0x80

			// rasterize line
			for (DSP4.lcv = 0; DSP4.lcv < DSP4.segments; DSP4.lcv++)
			{
				// 1. HDMA memory pointer (bg2)
				// 2. vertical scroll offset ($2110)
				// 3. horizontal scroll offset ($210F)
				DSP4_WRITE_WORD(DSP4.poly_ptr[0][0]);
				DSP4_WRITE_WORD((y_scroll + 0x8000) >> 16);
				DSP4_WRITE_WORD((x_scroll + 0x8000) >> 16);

				// update memory address
				DSP4.poly_ptr[0][0] -= 4;

				// update screen values
				x_scroll += px_dx;
				y_scroll += py_dy;
			}
		}

		/////////////////////////////////////////////////////
		// Post-update

		// update new viewer (x, y, scroll) to last raster line drawn
		DSP4.view_x1    = DSP4.view_x2;
		DSP4.view_y1    = DSP4.view_y2;
		DSP4.view_xofs1 = DSP4.view_xofs2;
		DSP4.view_yofs1 = DSP4.view_yofs2;

		////////////////////////////////////////////////////
		// command check

		// scan next command
		DSP4.in_count = 2;
		DSP4_WAIT(2);

		resume2:

		// check for opcode termination
		DSP4.distance = DSP4_READ_WORD();
		if (DSP4.distance == -0x8000)
			break;

		// already have 2 bytes in queue
		DSP4.in_count = 10;
		DSP4_WAIT(3);

		resume3:

		// inspect inputs
		DSP4.view_y2 = DSP4_READ_WORD();
		DSP4.view_dy = DSP4_READ_WORD() * DSP4.distance >> 15;
		DSP4.view_x2 = DSP4_READ_WORD();
		DSP4.view_dx = DSP4_READ_WORD() * DSP4.distance >> 15;
	}
	while (1);

	DSP4.waiting4command = TRUE;
}

static void DSP4_OP11 (int16 A, int16 B, int16 C, int16 D, int16 *M)
{
	// 0x155 = 341 = Horizontal Width of the Screen
	*M = ((A * 0x0155 >> 2) & 0xf000) | ((B * 0x0155 >> 6) & 0x0f00) | ((C * 0x0155 >> 10) & 0x00f0) | ((D * 0x0155 >> 14) & 0x000f);
}

static void DSP4_SetByte (void)
{
	// clear pending read
	if (DSP4.out_index < DSP4.out_count)
	{
		DSP4.out_index++;
		return;
	}

	if (DSP4.waiting4command)
	{
		if (DSP4.half_command)
		{
			DSP4.command |= (DSP4.byte << 8);
			DSP4.in_index        = 0;
			DSP4.waiting4command = FALSE;
			DSP4.half_command    = FALSE;
			DSP4.out_count       = 0;
			DSP4.out_index       = 0;

			DSP4.Logic = 0;

			switch (DSP4.command)
			{
				case 0x0000: DSP4.in_count =  4; break;
				case 0x0001: DSP4.in_count = 44; break;
				case 0x0003: DSP4.in_count =  0; break;
				case 0x0005: DSP4.in_count =  0; break;
				case 0x0006: DSP4.in_count =  0; break;
				case 0x0007: DSP4.in_count = 34; break;
				case 0x0008: DSP4.in_count = 90; break;
				case 0x0009: DSP4.in_count = 14; break;
				case 0x000a: DSP4.in_count =  6; break;
				case 0x000b: DSP4.in_count =  6; break;
				case 0x000d: DSP4.in_count = 42; break;
				case 0x000e: DSP4.in_count =  0; break;
				case 0x000f: DSP4.in_count = 46; break;
				case 0x0010: DSP4.in_count = 36; break;
				case 0x0011: DSP4.in_count =  8; break;
				default:
					DSP4.waiting4command = TRUE;
					break;
			}
		}
		else
		{
			DSP4.command = DSP4.byte;
			DSP4.half_command = TRUE;
		}
	}
	else
	{
		DSP4.parameters[DSP4.in_index] = DSP4.byte;
		DSP4.in_index++;
	}

	if (!DSP4.waiting4command && DSP4.in_count == DSP4.in_index)
	{
		// Actually execute the command
		DSP4.waiting4command = TRUE;
		DSP4.out_index       = 0;
		DSP4.in_index        = 0;

		switch (DSP4.command)
		{
			// 16-bit multiplication
			case 0x0000:
			{
				int16	multiplier, multiplicand;
				int32	product;

				multiplier   = DSP4_READ_WORD();
				multiplicand = DSP4_READ_WORD();

				DSP4_Multiply(multiplicand, multiplier, &product);

				DSP4_CLEAR_OUT();
				DSP4_WRITE_WORD(product);
				DSP4_WRITE_WORD(product >> 16);

				break;
			}

			// single-player track projection
			case 0x0001:
				DSP4_OP01();
				break;

			// single-player selection
			case 0x0003:
				DSP4_OP03();
				break;

			// clear OAM
			case 0x0005:
				DSP4_OP05();
				break;

			// transfer OAM
			case 0x0006:
				DSP4_OP06();
				break;

			// single-player track turnoff projection
			case 0x0007:
				DSP4_OP07();
				break;

			// solid polygon projection
			case 0x0008:
				DSP4_OP08();
				break;

			// sprite projection
			case 0x0009:
				DSP4_OP09();
				break;

			// unknown
			case 0x000A:
			{
				DSP4_READ_WORD();
				int16	in2a = DSP4_READ_WORD();
				DSP4_READ_WORD();
				int16	out1a, out2a, out3a, out4a;

				DSP4_OP0A(in2a, &out2a, &out1a, &out4a, &out3a);

				DSP4_CLEAR_OUT();
				DSP4_WRITE_WORD(out1a);
				DSP4_WRITE_WORD(out2a);
				DSP4_WRITE_WORD(out3a);
				DSP4_WRITE_WORD(out4a);

				break;
			}

			// set OAM
			case 0x000B:
			{
				int16	sp_x    = DSP4_READ_WORD();
				int16	sp_y    = DSP4_READ_WORD();
				int16	sp_attr = DSP4_READ_WORD();
				bool8	draw = TRUE;

				DSP4_CLEAR_OUT();
				DSP4_OP0B(&draw, sp_x, sp_y, sp_attr, 0, 1);

				break;
			}

			// multi-player track projection
			case 0x000D:
				DSP4_OP0D();
				break;

			// multi-player selection
			case 0x000E:
				DSP4_OP0E();
				break;

			// single-player track projection with lighting
			case 0x000F:
				DSP4_OP0F();
				break;

			// single-player track turnoff projection with lighting
			case 0x0010:
				DSP4_OP10();
				break;

			// unknown: horizontal mapping command
			case 0x0011:
			{
				int16	a, b, c, d, m;

				d = DSP4_READ_WORD();
				c = DSP4_READ_WORD();
				b = DSP4_READ_WORD();
				a = DSP4_READ_WORD();

				DSP4_OP11(a, b, c, d, &m);

				DSP4_CLEAR_OUT();
				DSP4_WRITE_WORD(m);

				break;
			}

			default:
				break;
		}
	}
}

static void DSP4_GetByte (void)
{
	if (DSP4.out_count)
	{
		DSP4.byte = (uint8) DSP4.output[DSP4.out_index & 0x1FF];

		DSP4.out_index++;
		if (DSP4.out_count == DSP4.out_index)
			DSP4.out_count = 0;
	}
	else
		DSP4.byte = 0xff;
}

void DSP4SetByte (uint8 byte, uint16 address)
{
	if (address < DSP0.boundary)
	{
		DSP4.byte    = byte;
		DSP4.address = address;
		DSP4_SetByte();
	}
}

uint8 DSP4GetByte (uint16 address)
{
	if (address < DSP0.boundary)
	{
		DSP4.address = address;
		DSP4_GetByte();
		return (DSP4.byte);
	}

	return (0x80);
}