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//
//  BinaryDataScanner.m
//
//  Copyright 2009 Dave Peck <davepeck [at] davepeck [dot] org>. All rights reserved.
//  http://davepeck.org/
//
//  This class makes it quite a bit easier to read sequential binary files in Objective-C.
//
//  This code is released under the BSD license. If you use it in your product, please
//  let me know and, if possible, please put me in your credits.
//


#import "BinaryDataScanner.h"

// NS byte order stuff is not useful here -- CF byte order ensures we're always dealing
// with the right size on either 32 or 64 bit platforms.
#import <CoreFoundation/CFByteOrder.h>


@interface BinaryDataScanner (Private)

-(id)initWithData:(NSData*)data littleEndian:(BOOL)littleEndian defaultEncoding:(NSStringEncoding)defaultEncoding;
-(void)dealloc;
-(NSException *)buildScanException;
-(void)moveBy:(NSUInteger)count;

@end


@implementation BinaryDataScanner (Private)

-(id)initWithData:(NSData*)initData littleEndian:(BOOL)isLittleEndian defaultEncoding:(NSStringEncoding)theDefaultEncoding
{
	self = [super init];
	if (self != nil)
	{
		data = [initData retain];		
		littleEndian = isLittleEndian;
		encoding = theDefaultEncoding;
		current = (const uint8_t *) [data bytes];
		scanRemain = [data length];
	}
	return self;
}

-(void)dealloc
{
	[data release];
	data = nil;
	[super dealloc];
}

-(void)moveBy:(NSUInteger)count
{
	if (scanRemain < count)
	{
		@throw [self buildScanException];
	}
		
	scanRemain -= count;
	current += count;
}

-(NSException *)buildScanException
{
	return [NSException exceptionWithName:@"OrangeDataScanException" reason:@"Failure scanning desired information from the bytes." userInfo:nil];	
}

@end


@implementation BinaryDataScanner

+(id)binaryDataScannerWithData:(NSData*)data littleEndian:(BOOL)littleEndian defaultEncoding:(NSStringEncoding)defaultEncoding
{
	return [[[BinaryDataScanner alloc] initWithData:data littleEndian:littleEndian defaultEncoding:defaultEncoding] autorelease];
}

-(NSUInteger) remainingBytes
{
	return scanRemain;
}

-(const uint8_t *) currentPointer
{
	return current;
}

-(void) skipBytes:(NSUInteger)count
{
	[self moveBy:count];
}

-(uint8_t) readByte
{
	const uint8_t *old = current;
	[self moveBy:1];
	return old[0];
}

-(uint16_t) readWord
{
	const uint16_t *word = (const uint16_t *) current;
	[self moveBy:sizeof(uint16_t)];
	if (littleEndian)
	{
		return CFSwapInt16LittleToHost(*word);
	}
	else
	{
		return CFSwapInt16BigToHost(*word);
	}
}

-(uint32_t) readDoubleWord
{
	const uint32_t *dword = (const uint32_t *) current;
	[self moveBy:sizeof(uint32_t)];
	if (littleEndian)
	{
		return CFSwapInt32LittleToHost(*dword);
	}
	else
	{
		return CFSwapInt32BigToHost(*dword);
	}
}

-(NSString*) readNullTerminatedString
{
	return [self readNullTerminatedStringWithEncoding:encoding];
}

-(NSString*) readNullTerminatedStringWithEncoding:(NSStringEncoding)overrideEncoding
{
	return [self readStringUntilDelimiter:0 encoding:overrideEncoding];
}

-(NSString*) readStringUntilDelimiter:(uint8_t)delim
{
	return [self readStringUntilDelimiter:delim encoding:encoding];
}

-(NSString*) readStringUntilDelimiter:(uint8_t)delim encoding:(NSStringEncoding)overrideEncoding
{
	const uint8_t *start = current;
	NSUInteger stringLength = 0;
	
	while (scanRemain > 0 && *current != delim)
	{		
		scanRemain -= 1;
		current += 1;
		stringLength += 1;
	}
	
	if (scanRemain < 1 || *current != delim)
	{
		@throw [self buildScanException];
	}
	
	// move over the delimiter
	[self moveBy:1];
	
	NSString *result = [[NSString alloc] initWithBytes:(const void*)start length:stringLength encoding:overrideEncoding];	
	return [result autorelease];
}

-(NSString*) readStringOfLength:(NSUInteger)count handleNullTerminatorAfter:(BOOL)handleNull
{
	return [self readStringOfLength:count handleNullTerminatorAfter:handleNull encoding:encoding];
}

-(NSString*) readStringOfLength:(NSUInteger)count handleNullTerminatorAfter:(BOOL)handleNull encoding:(NSStringEncoding)overrideEncoding
{
	const uint8_t *start = current;
	[self moveBy:count];

	if (handleNull)
	{
		const uint8_t *nullTerminator = current;
		[self moveBy:1];
		if (*nullTerminator != 0) 
		{
			@throw [self buildScanException];
		}
	}
	
	NSString *result = [[NSString alloc] initWithBytes:(const void*)start length:count encoding:overrideEncoding];
	return [result autorelease];
}

-(NSArray*) readArrayOfNullTerminatedStrings:(NSUInteger)count
{
	return [self readArrayOfNullTerminatedStrings:count encoding:encoding];
}

-(NSArray*) readArrayOfNullTerminatedStrings:(NSUInteger)count encoding:(NSStringEncoding)overrideEncoding
{
	NSMutableArray *array = [NSMutableArray arrayWithCapacity:count];
	
	for (NSUInteger i = 0; i < count; i++)
	{
		[array addObject:[self readNullTerminatedStringWithEncoding:overrideEncoding]];
	}
	
	return [array autorelease];
}

@end

//
//  BinaryDataScanner.m
//
//  Copyright 2009 Dave Peck <davepeck [at] davepeck [dot] org>. All rights reserved.
//  http://davepeck.org/
//
//  This class makes it quite a bit easier to read sequential binary files in Objective-C.
//
//  This code is released under the BSD license. If you use it in your product, please
//  let me know and, if possible, please put me in your credits.
//

#import <UIKit/UIKit.h>

@interface BinaryDataScanner : NSObject {
	BOOL littleEndian;
	NSStringEncoding encoding;
	NSData *data;
	const uint8_t *current;
	NSUInteger scanRemain;
}

+(id)binaryDataScannerWithData:(NSData*)data littleEndian:(BOOL)littleEndian defaultEncoding:(NSStringEncoding)defaultEncoding;

-(NSUInteger) remainingBytes;
-(const uint8_t *) currentPointer;

-(void) skipBytes:(NSUInteger)count;
-(uint8_t) readByte;
-(uint16_t) readWord;
-(uint32_t) readDoubleWord;
-(NSString*) readNullTerminatedString;
-(NSString*) readNullTerminatedStringWithEncoding:(NSStringEncoding)overrideEncoding;
-(NSString*) readStringUntilDelimiter:(uint8_t)delim;
-(NSString*) readStringUntilDelimiter:(uint8_t)delim encoding:(NSStringEncoding)overrideEncoding;
-(NSString*) readStringOfLength:(NSUInteger)count handleNullTerminatorAfter:(BOOL)handleNull;
-(NSString*) readStringOfLength:(NSUInteger)count handleNullTerminatorAfter:(BOOL)handleNull encoding:(NSStringEncoding)overrideEncoding;
-(NSArray*) readArrayOfNullTerminatedStrings:(NSUInteger)count;
-(NSArray*) readArrayOfNullTerminatedStrings:(NSUInteger)count encoding:(NSStringEncoding)overrideEncoding;

@end