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-rw-r--r--qtmips_machine/cache.cpp70
-rw-r--r--qtmips_machine/cache.h4
2 files changed, 41 insertions, 33 deletions
diff --git a/qtmips_machine/cache.cpp b/qtmips_machine/cache.cpp
index 30771b0..231aa81 100644
--- a/qtmips_machine/cache.cpp
+++ b/qtmips_machine/cache.cpp
@@ -51,7 +51,7 @@ Cache::Cache(MemoryAccess *m, const MachineConfigCache *cc, unsigned memory_acc
dt = nullptr;
replc.lfu = nullptr;
replc.lru = nullptr;
- p_change_counter = new std::uint32_t(0);
+ change_counter = 0;
// Skip any other initialization if cache is disabled
if (!cc->enabled())
@@ -82,7 +82,7 @@ Cache::Cache(MemoryAccess *m, const MachineConfigCache *cc, unsigned memory_acc
for (unsigned int row = 0; row < cnf.sets(); row++) {
replc.lru[row] = new unsigned int[cnf.associativity()];
for (unsigned int i = 0; i < cnf.associativity(); i++)
- replc.lru[row][i] = 0;
+ replc.lru[row][i] = i;
}
break;
case MachineConfigCache::RP_RAND:
@@ -92,7 +92,6 @@ Cache::Cache(MemoryAccess *m, const MachineConfigCache *cc, unsigned memory_acc
}
Cache::~Cache(){
- delete p_change_counter;
if (dt != nullptr) {
for (unsigned i = 0; i < cnf.associativity(); i++) {
if (dt[i]) {
@@ -160,7 +159,7 @@ void Cache::flush() {
if (!cnf.enabled())
return;
- for (unsigned as = 0; as < cnf.associativity(); as++)
+ for (unsigned as = cnf.associativity(); as-- > 0 ; )
for (unsigned st = 0; st < cnf.sets(); st++)
if (dt[as][st].valid)
kick(as, st);
@@ -268,6 +267,11 @@ bool Cache::access(std::uint32_t address, std::uint32_t *data, bool write, std::
case MachineConfigCache::RP_RAND:
indx = rand() % cnf.associativity();
break;
+ case MachineConfigCache::RP_LRU:
+ {
+ indx = replc.lru[row][0];
+ break;
+ }
case MachineConfigCache::RP_LFU:
{
unsigned lowest = replc.lfu[row][0];
@@ -284,23 +288,6 @@ bool Cache::access(std::uint32_t address, std::uint32_t *data, bool write, std::
}
break;
}
- case MachineConfigCache::RP_LRU:
- {
- unsigned int least = 0xffff;
- indx = 0;
- for (unsigned i = 0; i < cnf.associativity(); i++) {
- if (!dt[i][row].valid) {
- // found free one, use it directly
- indx = i;
- break;
- }
- if (least < replc.lru[row][i]) {
- least = replc.lru[row][i];
- indx = i;
- }
- }
- break;
- }
}
}
SANITY_ASSERT(indx < cnf.associativity(), "Probably unimplemented replacement policy");
@@ -310,7 +297,7 @@ bool Cache::access(std::uint32_t address, std::uint32_t *data, bool write, std::
// Verify if we are not replacing
if (cd.valid && cd.tag != tag) {
kick(indx, row);
- (*p_change_counter)++;
+ change_counter++;
}
// Update statistics and otherwise read from memory
@@ -330,20 +317,27 @@ bool Cache::access(std::uint32_t address, std::uint32_t *data, bool write, std::
update_statistics();
for (unsigned i = 0; i < cnf.blocks(); i++) {
cd.data[i] = mem->read_word(base_address(tag, row) + (4*i));
- (*p_change_counter)++;
+ change_counter++;
}
}
// Update replcement data
switch (cnf.replacement_policy()) {
- case MachineConfigCache::RP_LFU:
- if (cd.valid && replc.lru[row][indx] == 0)
- break;
- for (unsigned i = 1; i < cnf.associativity(); i++)
- replc.lru[row][i]++;
- replc.lru[row][indx] = 0;
- break;
case MachineConfigCache::RP_LRU:
+ {
+ unsigned next_asi = indx;
+ int i = cnf.associativity() - 1;
+ unsigned tmp_asi = replc.lru[row][i];
+ while (tmp_asi != indx) {
+ SANITY_ASSERT(i >= 0, "LRU lost the way from priority queue - access");
+ tmp_asi = replc.lru[row][i];
+ replc.lru[row][i] = next_asi;
+ next_asi = tmp_asi;
+ i--;
+ }
+ break;
+ }
+ case MachineConfigCache::RP_LFU:
replc.lfu[row][indx]++;
break;
default:
@@ -362,7 +356,7 @@ bool Cache::access(std::uint32_t address, std::uint32_t *data, bool write, std::
emit cache_update(indx, row, cd.valid, cd.dirty, cd.tag, cd.data);
if (changed)
- (*p_change_counter)++;
+ change_counter++;
return changed;
}
@@ -375,6 +369,20 @@ void Cache::kick(unsigned associat_indx, unsigned row) const {
cd.dirty = false;
switch (cnf.replacement_policy()) {
+ case MachineConfigCache::RP_LRU:
+ {
+ unsigned next_asi = associat_indx;
+ unsigned tmp_asi = replc.lru[row][0];
+ int i = 1;
+ while (tmp_asi != associat_indx) {
+ SANITY_ASSERT(i < (int)cnf.associativity(), "LRU lost the way from priority queue - kick");
+ tmp_asi = replc.lru[row][i];
+ replc.lru[row][i] = next_asi;
+ next_asi = tmp_asi;
+ i++;
+ }
+ break;
+ }
case MachineConfigCache::RP_LFU:
break;
default:
diff --git a/qtmips_machine/cache.h b/qtmips_machine/cache.h
index 200f3ce..827631b 100644
--- a/qtmips_machine/cache.h
+++ b/qtmips_machine/cache.h
@@ -67,7 +67,7 @@ public:
enum LocationStatus location_status(std::uint32_t address) const;
inline std::uint32_t get_change_counter() const {
- return *p_change_counter;
+ return change_counter;
}
signals:
void hit_update(unsigned) const;
@@ -76,7 +76,6 @@ signals:
void cache_update(unsigned associat, unsigned set, bool valid, bool dirty, std::uint32_t tag, const std::uint32_t *data) const;
private:
- std::uint32_t* p_change_counter;
MachineConfigCache cnf;
MemoryAccess *mem;
unsigned access_pen_r, access_pen_w;
@@ -96,6 +95,7 @@ private:
} replc; // Data used for replacement policy
mutable unsigned hit_read, miss_read, hit_write, miss_write; // Hit and miss counters
+ mutable std::uint32_t change_counter;
std::uint32_t debug_rword(std::uint32_t address) const;
bool access(std::uint32_t address, std::uint32_t *data, bool write, std::uint32_t value = 0) const;