NESPPUEmulator.h

/* NESPPUEmulator.h
 * 
 * Copyright (c) 2010 Auston Stewart
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#import <Foundation/Foundation.h>

#define CYCLES_OF_VBLANK 6820
#define CYCLES_BEFORE_RENDERING_SHORT 7160
#define CYCLES_BEFORE_RENDERING_NORMAL 7161
#define CYCLES_IN_SCANLINE_SHORT 340
#define CYCLES_IN_SCANLINE_NORMAL 341
#define CYCLES_IN_FRAME_SHORT 89341
#define CYCLES_IN_FRAME_NORMAL 89342

typedef uint8_t (*RegisterReadMethod)(id, SEL, uint_fast32_t);
typedef void (*RegisterWriteMethod)(id, SEL, uint8_t, uint_fast32_t);
typedef uint16_t (*NametableMirroringMethod)(uint16_t);

typedef enum {

	NESHorizontalMirroring = 0,
	NESVerticalMirroring = 1,
	NESSingleScreenLowerMirroring = 2,
	NESSingleScreenUpperMirroring = 3
} NESMirroringType;

typedef struct {
	
	uint8_t controlRegister1;
	uint8_t controlRegister2;
	uint8_t statusRegister;
	uint_fast32_t cycle;
	
} PPUState;

@interface NESPPUEmulator : NSObject {

	uint8_t _ppuControlRegister1;
	uint8_t _ppuControlRegister2;
	uint8_t _ppuStatusRegister;
	uint8_t _bufferedVRAMRead;
	uint8_t *_backgroundTable;
	uint8_t *_spriteTable;
	uint8_t *_selectedNameTable;
	uint8_t *_sprRAM;
	uint8_t *_spritePalette;
	uint8_t *_backgroundPalette;
	uint8_t *_playfieldBuffer;
	uint_fast8_t _spritesOnCurrentScanline[8];
	uint_fast8_t _numberOfSpritesOnScanline;
	uint8_t _sprRAMAddress;
	uint8_t *_nameAndAttributeTables;
	uint8_t *_palettes;
		
	uint_fast32_t _spriteTileCacheIndex;
	uint_fast32_t _backgroundTileCacheIndex;
	uint_fast32_t *_chrromBankIndices;
	BOOL *_chrramWriteHistory;
	uint8_t *_chrrom;
	uint8_t ****_tileCache;
	
	uint_fast32_t _sprite0HitCycle;
	uint_fast32_t _lastCPUCycle;
	uint_fast32_t _cyclesSinceVINT;
	uint_fast32_t _videoBufferIndex;
	uint_fast32_t _lastCycleOverage;
	
	uint16_t _VRAMAddress;
	uint16_t _temporaryVRAMAddress;
	
	uint8_t _fineHorizontalScroll;
	uint8_t _addressIncrement;
	uint8_t _colorIntensity;
	
	uint16_t _nameAndAttributeTablesMask;
	uint16_t *_nameAndAttributeTablesMasks;
	NametableMirroringMethod _nameTableMirroring;
	RegisterWriteMethod *_registerWriteMethods;
	RegisterReadMethod *_registerReadMethods;
	
	uint_fast32_t *_videoBuffer;
	
	BOOL _ppuDebugging;
	BOOL _sprite0Hit;
	BOOL _triggeredNMI;
	BOOL _NMIOnVBlank;
	BOOL _8x16Sprites;
	BOOL _monochrome;
	BOOL _clipBackground;
	BOOL _clipSprites;
	BOOL _backgroundEnabled;
	BOOL _spritesEnabled;
	BOOL _firstWriteOccurred;
	BOOL _oddFrame;
	BOOL _usingCHRRAM;
	BOOL _frameEnded;
	BOOL _shortenPrimingScanline;
	
	NSInvocation *_stateObservingInvocation;
	PPUState *_observerState;
}

- (id)initWithBuffer:(uint_fast32_t *)buffer;
- (void)cacheCHRROM:(uint8_t *)chrrom length:(uint_fast32_t)size bankIndices:(uint_fast32_t *)indices isWritable:(BOOL)isWritable;
- (void)toggleDebugging:(BOOL)flag;
- (void)runPPU:(uint_fast32_t)cycles;
- (BOOL)runPPUUntilCPUCycle:(uint_fast32_t)cycle;
- (BOOL)triggeredNMI;
- (uint_fast32_t)cyclesSinceVINT;
- (void)resetCPUCycleCounter;
- (void)resetPPUstatus;
- (uint8_t)readByteFromCPUAddress:(uint16_t)address onCycle:(uint_fast32_t)cycle;
- (void)writeByte:(uint8_t)byte toPPUFromCPUAddress:(uint16_t)address onCycle:(uint_fast32_t)cycle;
- (void)writeToPPUControlRegister1:(uint8_t)byte onCycle:(uint_fast32_t)cycle;
- (void)writeToPPUControlRegister2:(uint8_t)byte onCycle:(uint_fast32_t)cycle;
- (void)writeToSPRRAMAddressRegister:(uint8_t)byte onCycle:(uint_fast32_t)cycle;
- (void)writeToSPRRAMIOControlRegister:(uint8_t)byte onCycle:(uint_fast32_t)cycle;
- (void)writeToVRAMAddressRegister1:(uint8_t)byte onCycle:(uint_fast32_t)cycle;
- (void)writeToVRAMAddressRegister2:(uint8_t)byte onCycle:(uint_fast32_t)cycle;
- (void)writeToVRAMIORegister:(uint8_t)byte onCycle:(uint_fast32_t)cycle;
- (uint8_t)readFromPPUStatusRegisterOnCycle:(uint_fast32_t)cycle;
- (void)DMAtransferToSPRRAM:(uint8_t *)bytes onCycle:(uint_fast32_t)cycle;
- (uint8_t)readFromVRAMIORegisterOnCycle:(uint_fast32_t)cycle;
- (uint8_t)readFromSPRRAMIORegisterOnCycle:(uint_fast32_t)cycle;
- (void)writeByte:(uint8_t)byte toPPUAddress:(uint16_t)address onCycle:(uint_fast32_t)cycle;
- (void)setMirroringType:(NESMirroringType)type;
- (void)changeMirroringTypeTo:(NESMirroringType)type onCycle:(uint_fast32_t)cycle;
- (uint_fast32_t)cpuCyclesUntilVblank;
- (uint_fast32_t)cpuCyclesUntilPrimingScanline;
- (BOOL)shortenPrimingScanline;
- (void)observeStateForTarget:(id)target andSelector:(SEL)selector;

@end