/*
This file is part of JOP, the Java Optimized Processor
see <http://www.jopdesign.com/>
Copyright (C) 2001-2008, Martin Schoeberl (martin@jopdesign.com)
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/**
*
* Simulation of simple cache (as in JOP)
*
*/
package com.jopdesign.tools;
public class LRUBlockCache extends Cache {
int[] ctag;
// int[] clen; // for different replace policy
int[] lrucnt;
// int[] addr = {0, 0};
int next = 0;
// int currentBlock = 0;
int numBlocks;
LRUBlockCache(int[] main, JopSim js, int cnt) {
mem = main;
sim = js;
numBlocks = cnt;
bc = new byte[MAX_BC*numBlocks];
ctag = new int[numBlocks];
lrucnt = new int[numBlocks];
for (int i=0; i<numBlocks; ++i) {
ctag[i] = -1;
lrucnt[i] = 0;
}
}
int corrPc(int pc) {
// save block relative pc on invoke
return pc & (MAX_BC_MASK);
}
int invoke(int start, int len) {
int off = testCache(start, len);
return off;
}
int ret(int start, int len, int pc) {
int off = testCache(start, len);
return off+pc;
}
int testCache(int start, int len) {
this.lastHit = true;
if(flush) {
flush = false;
for(int i = 0; i < numBlocks; i++) ctag[i] = 0;
} else {
for (int i=0; i<numBlocks; ++i) {
if (ctag[i]==start) { // HIT
lrucnt[i]++;
return i*MAX_BC;
}
}
}
// not found
this.lastHit = false;
//
// LRU system
//
int min = lrucnt[0]; // finde last recently used block
int max = lrucnt[0]; // and max lru count
int usenr = 0;
for (int i=1; i<numBlocks; ++i) {
if (lrucnt[i] < min) {
min = lrucnt[i];
usenr = i;
} else if (lrucnt[i] > max) {
max = lrucnt[i];
}
}
//for (int i=0; i<4; ++i) System.out.print(lrucnt[i]+" "); System.out.println("\t\tnew usenr="+usenr);
//
// discard smallest
//
/* not really good!!!
int small = clen[0];
usenr = 0;
for (int i=1; i<4; ++i) {
if (clen[i] < small) {
small = clen[i];
usenr = i;
}
}
for (int i=0; i<4; ++i) System.out.print(clen[i]+" "); System.out.println(" new usenr="+usenr);
*/
ctag[usenr] = start; // use block usenr
lrucnt[usenr] = max+1;
// clen[usenr] = len;
for (int i=0; i<numBlocks; ++i) { // bring lru counters back to low value
lrucnt[i] -= min;
}
int off = usenr*MAX_BC;
loadBc(off, start, len);
return off;
}
void loadBc(int off, int start, int len) {
// high byte of word is first bc!!!
for (int i=0; i<len; ++i) {
int val = sim.readInstrMem(start+i);
for (int j=0; j<4; ++j) {
bc[off+i*4+(3-j)] = (byte) val;
val >>>= 8;
}
}
memRead += len*4;
memTrans++;
}
byte bc(int addr) {
++cacheRead;
return bc[addr];
}
public String toString() {
return super.toString()+" ("+numBlocks+" blocks)";
}
}