dsp2emu.c

/*******************************************************************************
  Snes9x - Portable Super Nintendo Entertainment System (TM) emulator.
 
  (c) Copyright 1996 - 2003 Gary Henderson (gary.henderson@ntlworld.com) and
                            Jerremy Koot (jkoot@snes9x.com)

  (c) Copyright 2002 - 2003 Matthew Kendora and
                            Brad Jorsch (anomie@users.sourceforge.net)
 

                      
  C4 x86 assembler and some C emulation code
  (c) Copyright 2000 - 2003 zsKnight (zsknight@zsnes.com),
                            _Demo_ (_demo_@zsnes.com), and
                            Nach (n-a-c-h@users.sourceforge.net)
                                          
  C4 C++ code
  (c) Copyright 2003 Brad Jorsch

  DSP-1 emulator code
  (c) Copyright 1998 - 2003 Ivar (ivar@snes9x.com), _Demo_, Gary Henderson,
                            John Weidman (jweidman@slip.net),
                            neviksti (neviksti@hotmail.com), and
                            Kris Bleakley (stinkfish@bigpond.com)
 
  DSP-2 emulator code
  (c) Copyright 2003 Kris Bleakley, John Weidman, neviksti, Matthew Kendora, and
                     Lord Nightmare (lord_nightmare@users.sourceforge.net

  OBC1 emulator code
  (c) Copyright 2001 - 2003 zsKnight, pagefault (pagefault@zsnes.com)
  Ported from x86 assembler to C by sanmaiwashi

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

  S-RTC C emulator code
  (c) Copyright 2001 John Weidman
  
  Super FX x86 assembler emulator code 
  (c) Copyright 1998 - 2003 zsKnight, _Demo_, and pagefault 

  Super FX C emulator code 
  (c) Copyright 1997 - 1999 Ivar and Gary Henderson.



 
  Specific ports contains the works of other authors. See headers in
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*******************************************************************************/

uint16 DSP2Op09Word1=0;
uint16 DSP2Op09Word2=0;
bool DSP2Op05HasLen=false;
int DSP2Op05Len=0;
bool DSP2Op06HasLen=false;
int DSP2Op06Len=0;
uint8 DSP2Op05Transparent=0;

void DSP2_Op05 ()
{
	uint8 color;
	// Overlay bitmap with transparency.
	// Input:
	//
	//   Bitmap 1:  i[0] <=> i[size-1]
	//   Bitmap 2:  i[size] <=> i[2*size-1]
	//
	// Output:
	//
	//   Bitmap 3:  o[0] <=> o[size-1]
	//
	// Processing:
	//
	//   Process all 4-bit pixels (nibbles) in the bitmap
	//
	//   if ( BM2_pixel == transparent_color )
	//      pixelout = BM1_pixel
	//   else
	//      pixelout = BM2_pixel

	// The max size bitmap is limited to 255 because the size parameter is a byte
	// I think size=0 is an error.  The behavior of the chip on size=0 is to
	// return the last value written to DR if you read DR on Op05 with
	// size = 0.  I don't think it's worth implementing this quirk unless it's
	// proven necessary.

	int n;
	unsigned char c1;
	unsigned char c2;
	unsigned char *p1 = DSP1.parameters;
	unsigned char *p2 = &DSP1.parameters[DSP2Op05Len];
	unsigned char *p3 = DSP1.output;

	color = DSP2Op05Transparent&0x0f;

	for( n = 0; n < DSP2Op05Len; n++ )
	{
		c1 = *p1++;
		c2 = *p2++;
		*p3++ = ( ((c2 >> 4) == color ) ? c1 & 0xf0: c2 & 0xf0 ) |
		        ( ((c2 & 0x0f)==color) ? c1 & 0x0f: c2 & 0x0f );
	}
}

void DSP2_Op01 ()
{
	// Op01 size is always 32 bytes input and output.
	// The hardware does strange things if you vary the size.
	
	int j;
	unsigned char c0, c1, c2, c3;
	unsigned char *p1 = DSP1.parameters;
	unsigned char *p2a = DSP1.output;
	unsigned char *p2b = &DSP1.output[16];	// halfway

	// Process 8 blocks of 4 bytes each

	for ( j = 0; j < 8; j++ )
	{
		c0 = *p1++;
		c1 = *p1++;
		c2 = *p1++;
		c3 = *p1++;

		*p2a++ = (c0 & 0x10) << 3 |
			     (c0 & 0x01) << 6 |
			     (c1 & 0x10) << 1 |
			     (c1 & 0x01) << 4 |
			     (c2 & 0x10) >> 1 |
			     (c2 & 0x01) << 2 |
			     (c3 & 0x10) >> 3 |
			     (c3 & 0x01);

		*p2a++ = (c0 & 0x20) << 2 |
			     (c0 & 0x02) << 5 |
			     (c1 & 0x20)      |
			     (c1 & 0x02) << 3 |
			     (c2 & 0x20) >> 2 |
			     (c2 & 0x02) << 1 |
			     (c3 & 0x20) >> 4 |
			     (c3 & 0x02) >> 1;

		*p2b++ = (c0 & 0x40) << 1 |
			     (c0 & 0x04) << 4 |
			     (c1 & 0x40) >> 1 |
			     (c1 & 0x04) << 2 |
			     (c2 & 0x40) >> 3 |
			     (c2 & 0x04)      |
			     (c3 & 0x40) >> 5 |
			     (c3 & 0x04) >> 2;


		*p2b++ = (c0 & 0x80)      |
			     (c0 & 0x08) << 3 |
			     (c1 & 0x80) >> 2 |
			     (c1 & 0x08) << 1 |
			     (c2 & 0x80) >> 4 |
			     (c2 & 0x08) >> 1 |
			     (c3 & 0x80) >> 6 |
			     (c3 & 0x08) >> 3;
	}
	return;
}

void DSP2_Op06 ()
{
	// Input:
	//    size
	//    bitmap

	int	i, j;

	for ( i = 0, j = DSP2Op06Len - 1; i < DSP2Op06Len; i++, j-- )
	{
		DSP1.output[j] = (DSP1.parameters[i] << 4) | (DSP1.parameters[i] >> 4);
	}
}

bool DSP2Op0DHasLen=false;
int DSP2Op0DOutLen=0;
int DSP2Op0DInLen=0;

#ifndef DSP2_BIT_ACCURRATE_CODE

// Scale bitmap based on input length out output length

void DSP2_Op0D()
{
	// Overload's algorithm - use this unless doing hardware testing

	// One note:  the HW can do odd byte scaling but since we divide
	// by two to get the count of bytes this won't work well for
	// odd byte scaling (in any of the current algorithm implementations).
	// So far I haven't seen Dungeon Master use it.
	// If it does we can adjust the parameters and code to work with it

	int i;
	int pixel_offset;
	uint8 pixelarray[512];

	for(i=0; i<DSP2Op0DOutLen*2; i++)
	{
		pixel_offset = (i * DSP2Op0DInLen) / DSP2Op0DOutLen;
		if ( (pixel_offset&1) == 0 )
			pixelarray[i] = DSP1.parameters[pixel_offset>>1] >> 4;
		else
			pixelarray[i] = DSP1.parameters[pixel_offset>>1] & 0x0f; 
	}

	for ( i=0; i < DSP2Op0DOutLen; i++ )
		DSP1.output[i] = ( pixelarray[i<<1] << 4 ) | pixelarray[(i<<1)+1];
}

#else

void DSP2_Op0D()
{
	// Bit accurate hardware algorithm - uses fixed point math
	// This should match the DSP2 Op0D output exactly
	// I wouldn't recommend using this unless you're doing hardware debug.
	// In some situations it has small visual artifacts that
	// are not readily apparent on a TV screen but show up clearly
	// on a monitor.  Use Overload's scaling instead.
	// This is for hardware verification testing.
	//
	// One note:  the HW can do odd byte scaling but since we divide
	// by two to get the count of bytes this won't work well for
	// odd byte scaling (in any of the current algorithm implementations).
	// So far I haven't seen Dungeon Master use it.
	// If it does we can adjust the parameters and code to work with it


	uint32 multiplier;	// Any size int >= 32-bits
	uint32 pixloc;		// match size of multiplier
	int	i, j;
	uint8 pixelarray[512];

	if (DSP2Op0DInLen <= DSP2Op0DOutLen)
		multiplier = 0x10000;	// In our self defined fixed point 0x10000 == 1
	else
		multiplier = (DSP2Op0DInLen << 17) / ((DSP2Op0DOutLen<<1) + 1);

	pixloc = 0;
	for ( i=0; i < DSP2Op0DOutLen * 2; i++ )
	{
		j = pixloc >> 16;

		if ( j & 1 )
			pixelarray[i] = DSP1.parameters[j>>1] & 0x0f;
		else
			pixelarray[i] = (DSP1.parameters[j>>1] & 0xf0) >> 4;

		pixloc += multiplier;
	}

	for ( i=0; i < DSP2Op0DOutLen; i++ )
		DSP1.output[i] = ( pixelarray[i<<1] << 4 ) | pixelarray[(i<<1)+1];
}

#endif

#if 0	// Probably no reason to use this code - it's not quite bit accurate and it doesn't look as good as Overload's algorithm

void DSP2_Op0D()
{
	// Float implementation of Neviksti's algorithm
	// This is the right algorithm to match the DSP2 bits but the precision
	// of the PC float does not match the precision of the fixed point math
	// on the DSP2 causing occasional one off data mismatches (which should
	// be no problem because its just a one pixel difference in a scaled image
	// to be displayed).

	float multiplier;
	float pixloc;
	int	i, j;
	uint8 pixelarray[512];

	if (DSP2Op0DInLen <= DSP2Op0DOutLen)
		multiplier = (float) 1.0;
	else
		multiplier = (float) ((DSP2Op0DInLen * 2.0) / (DSP2Op0DOutLen * 2.0 + 1.0));

	pixloc = 0.0;
	for ( i=0; i < DSP2Op0DOutLen * 2; i++ )
	{
		// j = (int)(i * multiplier);
		j = (int) pixloc;

		if ( j & 1 )
			pixelarray[i] = DSP1.parameters[j>>1] & 0x0f;
		else
			pixelarray[i] = (DSP1.parameters[j>>1] & 0xf0) >> 4;

		pixloc += multiplier;	// use an add in the loop instead of multiply to increase loop speed
	}

	for ( i=0; i < DSP2Op0DOutLen; i++ )
		DSP1.output[i] = ( pixelarray[i<<1] << 4 ) | pixelarray[(i<<1)+1];
}

#endif