dolphin/Source/Plugins/Plugin_DSP_LLE/Src/gdsp_condition_codes.cpp

// Copyright (C) 2003-2009 Dolphin Project.

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, version 2.0.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License 2.0 for more details.

// A copy of the GPL 2.0 should have been included with the program.
// If not, see http://www.gnu.org/licenses/

// Official SVN repository and contact information can be found at
// http://code.google.com/p/dolphin-emu/

// Additional copyrights go to Duddie and Tratax (c) 2004


// HELPER FUNCTIONS

#include "gdsp_condition_codes.h"
#include "gdsp_interpreter.h"
#include "DSPInterpreter.h"

namespace DSPInterpreter {

void Update_SR_Register64(s64 _Value)
{
	g_dsp.r[DSP_REG_SR] &= ~SR_CMP_MASK;

	if (_Value < 0)
	{
		g_dsp.r[DSP_REG_SR] |= 0x8;
	}

	if (_Value == 0)
	{
		g_dsp.r[DSP_REG_SR] |= 0x4;
	}

	// weird
	if ((_Value >> 62) == 0)
	{
		g_dsp.r[DSP_REG_SR] |= 0x20;
	}
}

void Update_SR_Register16(s16 _Value)
{
	g_dsp.r[DSP_REG_SR] &= ~SR_CMP_MASK;

	if (_Value < 0)
	{
		g_dsp.r[DSP_REG_SR] |= 0x8;
	}

	if (_Value == 0)
	{
		g_dsp.r[DSP_REG_SR] |= 0x4;
	}

	// weird
	if ((_Value >> 14) == 0)
	{
		g_dsp.r[DSP_REG_SR] |= 0x20;
	}
}

// If this always returns 1, Hermes' demo sounds better.
// However, most AX games are negatively affected.
int GetMultiplyModifier()
{
	if (g_dsp.r[DSP_REG_SR] & (1 << 13))
		return 1;
	else	
		return 2;
}


// 0x02 - overflow????
// 0x04 - Zero bit
// 0x08 - Sign bit
// 0x40 - Logical Zero bit 
bool CheckCondition(u8 _Condition)
{
	bool taken = false;
	switch (_Condition & 0xf)
	{
	case 0x0: //NS - NOT SIGN
		if ((!(g_dsp.r[DSP_REG_SR] & 0x02)) && (!(g_dsp.r[DSP_REG_SR] & 0x08)))
			taken = true;
		break;
		
	case 0x1: // S - SIGN
		if ((!(g_dsp.r[DSP_REG_SR] & 0x02)) && (g_dsp.r[DSP_REG_SR] & 0x08))
			taken = true;
		break;
 
	case 0x2: // G - GREATER

		if ((!(g_dsp.r[DSP_REG_SR] & 0x02)) && (!(g_dsp.r[DSP_REG_SR] & 0x08)) && !((g_dsp.r[DSP_REG_SR] & 0x04))) // gets zelda stuck
			taken = true;
		break;

	case 0x3: // LE - LESS EQUAL
		if ((!(g_dsp.r[DSP_REG_SR] & 0x02)) && ((g_dsp.r[DSP_REG_SR] & 0x08) || (g_dsp.r[DSP_REG_SR] & 0x04)))
			taken = true;
		break;

	case 0x4: // NZ - NOT ZERO

		if (!(g_dsp.r[DSP_REG_SR] & 0x04))
			taken = true;
		break;

	case 0x5: // Z - ZERO 

		if (g_dsp.r[DSP_REG_SR] & 0x04)
			taken = true;
		break;

	case 0x6: // L - LESS
		if (!(g_dsp.r[DSP_REG_SR] & 0x02) && (g_dsp.r[DSP_REG_SR] & 0x08))
			taken = true;
		break;

	case 0x7: // GE - GREATER EQUAL
		if ((!(g_dsp.r[DSP_REG_SR] & 0x02)) && (!(g_dsp.r[DSP_REG_SR] & 0x08) || (g_dsp.r[DSP_REG_SR] & 0x04)))
			taken = true;
		break;

	case 0xc: // LNZ  - LOGIC NOT ZERO

		if (!(g_dsp.r[DSP_REG_SR] & 0x40))
			taken = true;
		break;

	case 0xd: // LZ - LOGIC ZERO

		if (g_dsp.r[DSP_REG_SR] & 0x40)
			taken = true;
		break;

	case 0xf: // Empty
		taken = true;
		break;

	default:
		ERROR_LOG(DSPLLE, "Unknown condition check: 0x%04x\n", _Condition & 0xf);
		break;
	}

	return taken;
}

}  // namespace