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Code Issues Releases Wiki Activity

Tweaked algorithm

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This commit is contained in:
David Weber 2012-11-14 23:54:24 -05:00
parent c062724071
commit 616ef7b785
3 changed files with 224 additions and 20 deletions
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123
BestFitAlgorithm.java
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@ -1,15 +1,120 @@
/* /*
* To change this template, choose Tools | Templates * Best Fit Algorithm by David Weber
* and open the template in the editor. * ITCS 3146
* 11/9/2012
*/ */
/** import java.util.ArrayList;
*
* @author djw612 public class BestFitAlgorithm implements baseAlgorithm{
*/
public class BestFitAlgorithm { int memoryBlock[];
public BestFitAlgorithm()
public BestFitAlgorithm(int memorySize)
{ {
//Constructor goes here //Initialize memory block to whatever the size is
memoryBlock = new int[memorySize];
} }
public int getBestSizeIndex(int jobSize)
{
int bestSize = 0;
int bestSizeIndex = 0;
ArrayList<Integer> candidates = new ArrayList<Integer>(); //Dynamically resizable array list for allocation candidates (interleaved with index and memory size)
int counter = 0; //Counter for measuring unallocated memory
//Scan through memory block and get free blocks
for(int i = 0; i < memoryBlock.length; i++)
{
//If position in memory block here is 0, iterate from that index and count up sequential 0's
if(memoryBlock[i] == 0)
{
for(int j = i; j < memoryBlock.length - i; j++)
{
if(memoryBlock[j] == 0)
{
counter++;
}
}
if(counter >= jobSize)
{
candidates.add(i); //Store index
candidates.add(counter); //Store size of free memory chunk
}
counter = 0;
}
}
//Iterate through candidate sizes
bestSizeIndex = 0; //Initialize best index to first spot in array list
bestSize = candidates.get(1).intValue(); //Initialize bestSize to first space size in candidate
//Iterate through sizes and find the best fit
for(int i = 1; i < candidates.size(); i=i+2)
{
//Best possible case: job size = free block size (you're done)
if(candidates.get(i).intValue() == jobSize)
{
bestSizeIndex = i - 1;
return bestSizeIndex; //You're done. Return the value.
}
//If the current size is less than the previous best size, make this the new best size
else if(candidates.get(i).intValue() < bestSize)
{
bestSize = candidates.get(i+1).intValue();
bestSizeIndex = i - 1;
}
}
//If the best size is less than the job size, run this again
if(candidates.isEmpty())
{
return -1;
}
return bestSizeIndex;
}
@Override
public void allocate(int jobID, int jobSize, int jobTime)
{
int bestSizeIndex = getBestSizeIndex(jobSize);
if(bestSizeIndex == -1) //No candidates found
{
//Try compacting, then attempt to get an index again
compact();
bestSizeIndex = getBestSizeIndex(jobSize);
//Compacting still didn't produce an appropriate block
if(bestSizeIndex == -1)
{
//TODO .....
}
}
//Allocate the memory
for(int i = bestSizeIndex; i < jobSize; i++)
{
memoryBlock[i] = jobID;
}
}
public void compact()
{
//TODO: Compact memory if no suitable allocation candidates are found on the first pass
}
@Override
public void deallocate(int jobSize, int beginningLocation)
{
for(int i = beginningLocation; i < jobSize; i++)
{
memoryBlock[i] = 0;
}
}
} }

117
WorstFitAlgorithm.java
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@ -1,15 +1,114 @@
/* /*
* To change this template, choose Tools | Templates * Worst Fit Algorithm by David Weber
* and open the template in the editor. * ITCS 3146
* 11/9/2012
*/ */
/** import java.util.ArrayList;
*
* @author djw612 public class WorstFitAlgorithm implements baseAlgorithm{
*/
public class WorstFitAlgorithm { int memoryBlock[];
public WorstFitAlgorithm()
public WorstFitAlgorithm(int memorySize)
{ {
//Constructor goes here //Initialize memory block to whatever the size is
memoryBlock = new int[memorySize];
} }
public int getWorstSizeIndex(int jobSize)
{
int worstSize = 0;
int worstSizeIndex = 0;
ArrayList<Integer> candidates = new ArrayList<Integer>(); //Dynamically resizable array list for allocation candidates (interleaved with index and memory size)
int counter = 0; //Counter for measuring unallocated memory
//Scan through memory block and get free blocks
for(int i = 0; i < memoryBlock.length; i++)
{
//If position in memory block here is 0, iterate from that index and count up sequential 0's
if(memoryBlock[i] == 0)
{
for(int j = i; j < memoryBlock.length - i; j++)
{
if(memoryBlock[j] == 0)
{
counter++;
}
}
if(counter >= jobSize)
{
candidates.add(i); //Store index
candidates.add(counter); //Store size of free memory chunk
}
counter = 0;
}
}
//Iterate through candidate sizes
worstSizeIndex = 0; //Initialize best index to first spot in array list
worstSize = candidates.get(1).intValue(); //Initialize bestSize to first space size in candidate
//Iterate through sizes and find the best fit
for(int i = 1; i < candidates.size(); i=i+2)
{
//If the current size is greater than the previous best size, make this the new best size
if(candidates.get(i).intValue() > worstSize)
{
worstSize = candidates.get(i+1).intValue();
worstSizeIndex = i - 1;
}
}
//If the best size is less than the job size, run this again
if(candidates.isEmpty())
{
return -1;
}
return worstSizeIndex;
}
@Override
public void allocate(int jobID, int jobSize, int jobTime)
{
int worstSizeIndex = getWorstSizeIndex(jobSize);
if(worstSizeIndex == -1) //No candidates found
{
//Try compacting, then attempt to get an index again
compact();
worstSizeIndex = getWorstSizeIndex(jobSize);
//Compacting still didn't produce an appropriate block
if(worstSizeIndex == -1)
{
//TODO .....
}
}
//Allocate the memory
for(int i = worstSizeIndex; i < jobSize; i++)
{
memoryBlock[i] = jobID;
}
}
public void compact()
{
//TODO: Compact memory if no suitable allocation candidates are found on the first pass
}
@Override
public void deallocate(int jobSize, int beginningLocation)
{
for(int i = beginningLocation; i < jobSize; i++)
{
memoryBlock[i] = 0;
}
}
} }

4
baseAlgorithm.java
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@ -1,5 +1,5 @@
interface baseAlgorithm{ interface baseAlgorithm{
void allocate(int jobID, int jobSize, int jobTime); public void allocate(int jobID, int jobSize, int jobTime);
void deallocate(int jobSize, int beginningLocation); public void deallocate(int jobSize, int beginningLocation);
} }