AddressMapping.cpp

/*********************************************************************************
*  Copyright (c) 2010-2011, Elliott Cooper-Balis
*                             Paul Rosenfeld
*                             Bruce Jacob
*                             University of Maryland 
*                             dramninjas [at] gmail [dot] com
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#include "SystemConfiguration.h"
#include "AddressMapping.h"

namespace DRAMSim
{

void addressMapping(uint64_t physicalAddress, unsigned &newTransactionChan, unsigned &newTransactionRank, unsigned &newTransactionBank, unsigned &newTransactionRow, unsigned &newTransactionColumn)
{
	uint64_t tempA, tempB;
	unsigned transactionSize = (JEDEC_DATA_BUS_BITS/8)*BL; 
	uint64_t transactionMask =  transactionSize - 1; //ex: (64 bit bus width) x (8 Burst Length) - 1 = 64 bytes - 1 = 63 = 0x3f mask
	unsigned channelBitWidth = dramsim_log2(NUM_CHANS);
	unsigned	rankBitWidth = dramsim_log2(NUM_RANKS);
	unsigned	bankBitWidth = dramsim_log2(NUM_BANKS);
	unsigned	rowBitWidth = dramsim_log2(NUM_ROWS);
	unsigned	colBitWidth = dramsim_log2(NUM_COLS);
	// this forces the alignment to the width of a single burst (64 bits = 8 bytes = 3 address bits for DDR parts)
	unsigned	byteOffsetWidth = dramsim_log2((JEDEC_DATA_BUS_BITS/8));
	// Since we're assuming that a request is for BL*BUS_WIDTH, the bottom bits
	// of this address *should* be all zeros if it's not, issue a warning

	if ((physicalAddress & transactionMask) != 0)
	{
		DEBUG("WARNING: address 0x"<<std::hex<<physicalAddress<<std::dec<<" is not aligned to the request size of "<<transactionSize); 
	}

	// each burst will contain JEDEC_DATA_BUS_BITS/8 bytes of data, so the bottom bits (3 bits for a single channel DDR system) are
	// 	thrown away before mapping the other bits
	physicalAddress >>= byteOffsetWidth;

	// The next thing we have to consider is that when a request is made for a
	// we've taken into account the granulaity of a single burst by shifting 
	// off the bottom 3 bits, but a transaction has to take into account the
	// burst length (i.e. the requests will be aligned to cache line sizes which
	// should be equal to transactionSize above). 
	//
	// Since the column address increments internally on bursts, the bottom n 
	// bits of the column (colLow) have to be zero in order to account for the 
	// total size of the transaction. These n bits should be shifted off the 
	// address and also subtracted from the total column width. 
	//
	// I am having a hard time explaining the reasoning here, but it comes down
	// this: for a 64 byte transaction, the bottom 6 bits of the address must be 
	// zero. These zero bits must be made up of the byte offset (3 bits) and also
	// from the bottom bits of the column 
	// 
	// For example: cowLowBits = log2(64bytes) - 3 bits = 3 bits 
	unsigned colLowBitWidth = dramsim_log2(transactionSize) - byteOffsetWidth;

	physicalAddress >>= colLowBitWidth;
	unsigned colHighBitWidth = colBitWidth - colLowBitWidth; 
	if (DEBUG_ADDR_MAP)
	{
		DEBUG("Bit widths: ch:"<<channelBitWidth<<" r:"<<rankBitWidth<<" b:"<<bankBitWidth
				<<" row:"<<rowBitWidth<<" colLow:"<<colLowBitWidth
				<< " colHigh:"<<colHighBitWidth<<" off:"<<byteOffsetWidth 
				<< " Total:"<< (channelBitWidth + rankBitWidth + bankBitWidth + rowBitWidth + colLowBitWidth + colHighBitWidth + byteOffsetWidth));
	}

	//perform various address mapping schemes
	if (addressMappingScheme == Scheme1)
	{
		//chan:rank:row:col:bank
		tempA = physicalAddress;
		physicalAddress = physicalAddress >> bankBitWidth;
		tempB = physicalAddress << bankBitWidth;
		newTransactionBank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> colHighBitWidth;
		tempB = physicalAddress << colHighBitWidth;
		newTransactionColumn = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rowBitWidth;
		tempB = physicalAddress << rowBitWidth;
		newTransactionRow = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rankBitWidth;
		tempB = physicalAddress << rankBitWidth;
		newTransactionRank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> channelBitWidth;
		tempB = physicalAddress << channelBitWidth;
		newTransactionChan = tempA ^ tempB;

	}
	else if (addressMappingScheme == Scheme2)
	{
		//chan:row:col:bank:rank
		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rankBitWidth;
		tempB = physicalAddress << rankBitWidth;
		newTransactionRank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> bankBitWidth;
		tempB = physicalAddress << bankBitWidth;
		newTransactionBank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> colHighBitWidth;
		tempB = physicalAddress << colHighBitWidth;
		newTransactionColumn = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rowBitWidth;
		tempB = physicalAddress << rowBitWidth;
		newTransactionRow = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> channelBitWidth;
		tempB = physicalAddress << channelBitWidth;
		newTransactionChan = tempA ^ tempB;

	}
	else if (addressMappingScheme == Scheme3)
	{
		//chan:rank:bank:col:row
		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rowBitWidth;
		tempB = physicalAddress << rowBitWidth;
		newTransactionRow = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> colHighBitWidth;
		tempB = physicalAddress << colHighBitWidth;
		newTransactionColumn = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> bankBitWidth;
		tempB = physicalAddress << bankBitWidth;
		newTransactionBank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rankBitWidth;
		tempB = physicalAddress << rankBitWidth;
		newTransactionRank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> channelBitWidth;
		tempB = physicalAddress << channelBitWidth;
		newTransactionChan = tempA ^ tempB;

	}
	else if (addressMappingScheme == Scheme4)
	{
		//chan:rank:bank:row:col
		tempA = physicalAddress;
		physicalAddress = physicalAddress >> colHighBitWidth;
		tempB = physicalAddress << colHighBitWidth;
		newTransactionColumn = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rowBitWidth;
		tempB = physicalAddress << rowBitWidth;
		newTransactionRow = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> bankBitWidth;
		tempB = physicalAddress << bankBitWidth;
		newTransactionBank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rankBitWidth;
		tempB = physicalAddress << rankBitWidth;
		newTransactionRank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> channelBitWidth;
		tempB = physicalAddress << channelBitWidth;
		newTransactionChan = tempA ^ tempB;

	}
	else if (addressMappingScheme == Scheme5)
	{
		//chan:row:col:rank:bank

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> bankBitWidth;
		tempB = physicalAddress << bankBitWidth;
		newTransactionBank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rankBitWidth;
		tempB = physicalAddress << rankBitWidth;
		newTransactionRank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> colHighBitWidth;
		tempB = physicalAddress << colHighBitWidth;
		newTransactionColumn = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rowBitWidth;
		tempB = physicalAddress << rowBitWidth;
		newTransactionRow = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> channelBitWidth;
		tempB = physicalAddress << channelBitWidth;
		newTransactionChan = tempA ^ tempB;


	}
	else if (addressMappingScheme == Scheme6)
	{
		//chan:row:bank:rank:col

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> colHighBitWidth;
		tempB = physicalAddress << colHighBitWidth;
		newTransactionColumn = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rankBitWidth;
		tempB = physicalAddress << rankBitWidth;
		newTransactionRank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> bankBitWidth;
		tempB = physicalAddress << bankBitWidth;
		newTransactionBank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rowBitWidth;
		tempB = physicalAddress << rowBitWidth;
		newTransactionRow = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> channelBitWidth;
		tempB = physicalAddress << channelBitWidth;
		newTransactionChan = tempA ^ tempB;


	}
	// clone of scheme 5, but channel moved to lower bits
	else if (addressMappingScheme == Scheme7)
	{
		//row:col:rank:bank:chan
		tempA = physicalAddress;
		physicalAddress = physicalAddress >> channelBitWidth;
		tempB = physicalAddress << channelBitWidth;
		newTransactionChan = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> bankBitWidth;
		tempB = physicalAddress << bankBitWidth;
		newTransactionBank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rankBitWidth;
		tempB = physicalAddress << rankBitWidth;
		newTransactionRank = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> colHighBitWidth;
		tempB = physicalAddress << colHighBitWidth;
		newTransactionColumn = tempA ^ tempB;

		tempA = physicalAddress;
		physicalAddress = physicalAddress >> rowBitWidth;
		tempB = physicalAddress << rowBitWidth;
		newTransactionRow = tempA ^ tempB;

	}

	else
	{
		ERROR("== Error - Unknown Address Mapping Scheme");
		exit(-1);
	}
	if (DEBUG_ADDR_MAP)
	{
		DEBUG("Mapped Ch="<<newTransactionChan<<" Rank="<<newTransactionRank
				<<" Bank="<<newTransactionBank<<" Row="<<newTransactionRow
				<<" Col="<<newTransactionColumn<<"\n"); 
	}

}
};