Correct memory view updates for uncached and write-through case.

Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>

6 files changed, 45 insertions, 24 deletions

diff --git a/qtmips_machine/cache.cpp b/qtmips_machine/cache.cpp
index acc48b1..9f4bfb0 100644
--- a/qtmips_machine/cache.cpp
+++ b/qtmips_machine/cache.cpp
@@ -40,17 +40,18 @@ Cache::Cache(Memory *m, const MachineConfigCache *cc, unsigned memory_access_pen
     }
 }
 
-void Cache::wword(std::uint32_t address, std::uint32_t value) {
+bool Cache::wword(std::uint32_t address, std::uint32_t value) {
+    bool changed;
     if (!cnf.enabled()) {
-        mem->write_word(address, value);
-        return;
+        return mem->write_word(address, value);
     }
 
     std::uint32_t data;
-    access(address, &data, true, value);
+    changed = access(address, &data, true, value);
 
     if (cnf.write_policy() == MachineConfigCache::WP_TROUGH)
-        mem->wword(address, value);
+        return mem->wword(address, value);
+    return changed;
 }
 
 std::uint32_t Cache::rword(std::uint32_t address) const {
@@ -131,7 +132,8 @@ const MachineConfigCache &Cache::config() const {
     return cnf;
 }
 
-void Cache::access(std::uint32_t address, std::uint32_t *data, bool write, std::uint32_t value) const {
+bool Cache::access(std::uint32_t address, std::uint32_t *data, bool write, std::uint32_t value) const {
+    bool changed = false;
     address = address >> 2;
     unsigned ssize = cnf.blocks() * cnf.sets();
     std::uint32_t tag = address / ssize;
@@ -218,10 +220,13 @@ void Cache::access(std::uint32_t address, std::uint32_t *data, bool write, std::
     cd.tag = tag;
     *data = cd.data[col];
 
-    if (write)
+    if (write) {
+        changed = cd.data[col] != value;
         cd.data[col] = value;
+    }
 
     emit cache_update(indx, row, cd.valid, cd.dirty, cd.tag, cd.data);
+    return changed;
 }
 
 void Cache::kick(unsigned associat_indx, unsigned row) const {
diff --git a/qtmips_machine/cache.h b/qtmips_machine/cache.h
index 6cf3a2c..1c356c7 100644
--- a/qtmips_machine/cache.h
+++ b/qtmips_machine/cache.h
@@ -13,7 +13,7 @@ class Cache : public MemoryAccess {
 public:
     Cache(Memory *m, const MachineConfigCache *c, unsigned memory_access_penalty_r = 1, unsigned memory_access_penalty_w = 1);
 
-    void wword(std::uint32_t address, std::uint32_t value);
+    bool wword(std::uint32_t address, std::uint32_t value);
     std::uint32_t rword(std::uint32_t address) const;
 
     void flush(); // flush cache
@@ -54,7 +54,7 @@ private:
 
     mutable unsigned hit_read, miss_read, hit_write, miss_write; // Hit and miss counters
 
-    void access(std::uint32_t address, std::uint32_t *data, bool write, std::uint32_t value = 0) const;
+    bool access(std::uint32_t address, std::uint32_t *data, bool write, std::uint32_t value = 0) const;
     void kick(unsigned associat_indx, unsigned row) const;
     std::uint32_t base_address(std::uint32_t tag, unsigned row) const;
     void update_statistics() const;
diff --git a/qtmips_machine/memory.cpp b/qtmips_machine/memory.cpp
index 3b47ca7..77f2909 100644
--- a/qtmips_machine/memory.cpp
+++ b/qtmips_machine/memory.cpp
@@ -10,20 +10,20 @@ using namespace machine;
 #define SH_NTH_16(OFFSET) (((OFFSET) & 0b10) * 16)
 #endif
 
-void MemoryAccess::write_byte(std::uint32_t offset, std::uint8_t value) {
+bool MemoryAccess::write_byte(std::uint32_t offset, std::uint8_t value) {
     int nth = SH_NTH_8(offset);
     std::uint32_t mask = 0xff << nth; // Mask for n-th byte
-    wword(offset, (rword(offset) & ~mask) | (((std::uint32_t)value << nth) & mask));
+    return wword(offset, (rword(offset) & ~mask) | (((std::uint32_t)value << nth) & mask));
 }
 
-void MemoryAccess::write_hword(std::uint32_t offset, std::uint16_t value) {
+bool MemoryAccess::write_hword(std::uint32_t offset, std::uint16_t value) {
     int nth = SH_NTH_16(offset);
     std::uint32_t mask = 0xffff << nth; // Mask for n-th half-word
-    wword(offset, (rword(offset) & ~mask) | (((std::uint32_t)value << nth) & mask));
+    return wword(offset, (rword(offset) & ~mask) | (((std::uint32_t)value << nth) & mask));
 }
 
-void MemoryAccess::write_word(std::uint32_t offset, std::uint32_t value) {
-    wword(offset, value);
+bool MemoryAccess::write_word(std::uint32_t offset, std::uint32_t value) {
+    return wword(offset, value);
 }
 
 std::uint8_t MemoryAccess::read_byte(std::uint32_t offset) const {
@@ -101,11 +101,14 @@ MemorySection::~MemorySection() {
     delete this->dt;
 }
 
-void MemorySection::wword(std::uint32_t offset, std::uint32_t value) {
+bool MemorySection::wword(std::uint32_t offset, std::uint32_t value) {
+    bool changed;
     offset = offset >> 2;
     if (offset >= this->len)
         throw QTMIPS_EXCEPTION(OutOfMemoryAccess, "Trying to write outside of the memory section", QString("Accessing using offset: ") + QString(offset));
+    changed = this->dt[offset] != value;
     this->dt[offset] = value;
+    return changed;
 }
 
 std::uint32_t MemorySection::rword(std::uint32_t offset) const {
@@ -206,9 +209,14 @@ MemorySection *Memory::get_section(std::uint32_t address, bool create) const {
 
 #define SECTION_OFFSET_MASK(ADDR) (ADDR & GENMASK(MEMORY_SECTION_BITS, 2))
 
-void Memory::wword(std::uint32_t address, std::uint32_t value) {
+bool Memory::wword(std::uint32_t address, std::uint32_t value) {
+    bool changed;
     MemorySection *section = this->get_section(address, true);
-    section->write_word(SECTION_OFFSET_MASK(address), value);
+    changed = section->write_word(SECTION_OFFSET_MASK(address), value);
+    write_counter++;
+    if (changed)
+        change_counter++;
+    return changed;
 }
 
 std::uint32_t Memory::rword(std::uint32_t address) const {
diff --git a/qtmips_machine/memory.h b/qtmips_machine/memory.h
index e4777b3..4b40243 100644
--- a/qtmips_machine/memory.h
+++ b/qtmips_machine/memory.h
@@ -12,9 +12,9 @@ class MemoryAccess : public QObject {
     Q_OBJECT
 public:
     // Note: hword and word methods are throwing away lowest bits so unaligned access is ignored without error.
-    void write_byte(std::uint32_t offset, std::uint8_t value);
-    void write_hword(std::uint32_t offset, std::uint16_t value);
-    void write_word(std::uint32_t offset, std::uint32_t value);
+    bool write_byte(std::uint32_t offset, std::uint8_t value);
+    bool write_hword(std::uint32_t offset, std::uint16_t value);
+    bool write_word(std::uint32_t offset, std::uint32_t value);
 
     std::uint8_t read_byte(std::uint32_t offset) const;
     std::uint16_t read_hword(std::uint32_t offset) const;
@@ -34,7 +34,7 @@ public:
     virtual void sync();
 
 protected:
-    virtual void wword(std::uint32_t offset, std::uint32_t value) = 0;
+    virtual bool wword(std::uint32_t offset, std::uint32_t value) = 0;
     virtual std::uint32_t rword(std::uint32_t offset) const = 0;
 
 private:
@@ -47,7 +47,7 @@ public:
     MemorySection(const MemorySection&);
     ~MemorySection();
 
-    void wword(std::uint32_t offset, std::uint32_t value);
+    bool wword(std::uint32_t offset, std::uint32_t value);
     std::uint32_t rword(std::uint32_t offset) const;
     void merge(MemorySection&);
 
@@ -77,7 +77,7 @@ public:
     void reset(const Memory&);
 
     MemorySection *get_section(std::uint32_t address, bool create) const; // returns section containing given address
-    void wword(std::uint32_t address, std::uint32_t value);
+    bool wword(std::uint32_t address, std::uint32_t value);
     std::uint32_t rword(std::uint32_t address) const;
 
     bool operator==(const Memory&) const;
@@ -85,8 +85,14 @@ public:
 
     const union MemoryTree *get_memorytree_root() const;
 
+    inline std::uint32_t get_change_counter() const {
+        return change_counter;
+    }
+
 private:
     union MemoryTree *mt_root;
+    std::uint32_t change_counter;
+    std::uint32_t write_counter;
     static union MemoryTree *allocate_section_tree();
     static void free_section_tree(union MemoryTree*, size_t depth);
     static bool compare_section_tree(const union MemoryTree*, const union MemoryTree*, size_t depth);
diff --git a/qtmips_machine/qtmipsmachine.cpp b/qtmips_machine/qtmipsmachine.cpp
index 75d8b8e..9f769c7 100644
--- a/qtmips_machine/qtmipsmachine.cpp
+++ b/qtmips_machine/qtmipsmachine.cpp
@@ -108,6 +108,7 @@ void QtMipsMachine::step() {
         if (stat == ST_BUSY)
             set_status(stat_prev);
     }
+    emit post_tick();
 }
 
 void QtMipsMachine::restart() {
diff --git a/qtmips_machine/qtmipsmachine.h b/qtmips_machine/qtmipsmachine.h
index 46405e5..b7f229d 100644
--- a/qtmips_machine/qtmipsmachine.h
+++ b/qtmips_machine/qtmipsmachine.h
@@ -50,6 +50,7 @@ signals:
     void program_trap(machine::QtMipsException &e);
     void status_change(enum machine::QtMipsMachine::Status st);
     void tick(); // Time tick
+    void post_tick(); // Emitted after tick to allow updates
 
 private:
     MachineConfig mcnf;