/*
 *
 * @APPLE_LICENSE_HEADER_START@
 *
 * Copyright (c) 1999-2001 Apple Computer, Inc.  All Rights Reserved. The
 * contents of this file constitute Original Code as defined in and are
 * subject to the Apple Public Source License Version 1.2 (the 'License').
 * You may not use this file except in compliance with the License.  Please
 * obtain a copy of the License at http://www.apple.com/publicsource and
 * read it before using this file.
 *
 * This Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.  Please
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 * @APPLE_LICENSE_HEADER_END@
 *
 */
/*
	File:		OS.h

	Contains:  	OS utility functions. Memory allocation, time, etc.



*/

#ifndef _OS_H_
#define _OS_H_

#include "OSHeaders.h"
#include <string.h>

class OS
{
	public:
	
		//call this before calling anything else
		static void	Initialize();

		static SInt32 Min(SInt32 a, SInt32 b) 	{ if (a < b) return a; return b; }
		
		//
		// Milliseconds always returns milliseconds since Jan 1, 1970 GMT.
		// This basically makes it the same as a POSIX time_t value, except
		// in msec, not seconds. To convert to a time_t, divide by 1000.
		static SInt64 	Milliseconds();

		static SInt64	Microseconds();
		
		// Some processors (MIPS, Sparc) cannot handle non word aligned memory
		// accesses. So, we need to provide functions to safely get at non-word
		// aligned memory.
		static inline UInt32	GetUInt32FromMemory(UInt32* inP);

		//because the OS doesn't seem to have these functions
		static SInt64	HostToNetworkSInt64(SInt64 hostOrdered);
		static SInt64	NetworkToHostSInt64(SInt64 networkOrdered);
							
		static SInt64	TimeMilli_To_Fixed64Secs(SInt64 inMilliseconds)
                        { return (SInt64) ( (Float64) inMilliseconds / 1000) * ((SInt64) 1 << 32 ) ; }
		
		static SInt64	TimeMilli_To_1900Fixed64Secs(SInt64 inMilliseconds)
							{ return TimeMilli_To_Fixed64Secs(sMsecSince1900) + TimeMilli_To_Fixed64Secs(inMilliseconds); }

		static SInt64	TimeMilli_To_UnixTimeMilli(SInt64 inMilliseconds)
							{ return inMilliseconds; }

		static time_t	TimeMilli_To_UnixTimeSecs(SInt64 inMilliseconds)
							{ return (time_t)  ( (SInt64) TimeMilli_To_UnixTimeMilli(inMilliseconds) / (SInt64) 1000); }
		
		static time_t 	UnixTime_Secs(void) // Seconds since 1970
							{ return TimeMilli_To_UnixTimeSecs(Milliseconds()); }

        static time_t   Time1900Fixed64Secs_To_UnixTimeSecs(SInt64 in1900Fixed64Secs)
                        { return (time_t)( (SInt64)  ((SInt64)  ( in1900Fixed64Secs - TimeMilli_To_Fixed64Secs(sMsecSince1900) ) /  ((SInt64) 1 << 32)  ) ); }
                            
        static SInt64   Time1900Fixed64Secs_To_TimeMilli(SInt64 in1900Fixed64Secs)
                        { return   ( (SInt64) ( (Float64) ((SInt64) in1900Fixed64Secs - (SInt64) TimeMilli_To_Fixed64Secs(sMsecSince1900) ) / (Float64)  ((SInt64) 1 << 32) ) * 1000) ; }
							
		// Returns the offset in hours between local time and GMT (or UTC) time.
		static SInt32	GetGMTOffset();
							
		//Both these functions return QTSS_NoErr, QTSS_FileExists, or POSIX errorcode
		//Makes whatever directories in this path that don't exist yet 
		static OS_Error RecursiveMakeDir(char *inPath);
		//Makes the directory at the end of this path
		static OS_Error MakeDir(char *inPath);
		
		// Discovery of how many processors are on this machine
		static UInt32	GetNumProcessors();
		
		// CPU Load
		static Float32	GetCurrentCPULoadPercent();
		
	private:
	
		static double sDivisor;
		static double sMicroDivisor;
		static SInt64 sMsecSince1900;
		static SInt64 sMsecSince1970;
		static SInt64 sInitialMsec;
		static SInt32 sMemoryErr;
		static void SetDivisor();
		static SInt64 sWrapTime;
		static SInt64 sCompareWrap;
		static SInt64 sLastTimeMilli;
};

inline UInt32	OS::GetUInt32FromMemory(UInt32* inP)
{
#if ALLOW_NON_WORD_ALIGN_ACCESS
	return *inP;
#else
	char* tempPtr = (char*)inP;
	UInt32 temp = 0;
	::memcpy(&temp, tempPtr, sizeof(UInt32));
	return temp;
#endif
}


#endif