[#314] z80-cpu: fix mode 1 interrupt

emustudio · Apr 30, 2023 · 0eae970 · 0eae970
1 parent d220ffd
commit 0eae970
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Showing 8 changed files with 83 additions and 32 deletions.
diff --git a/plugins/cpu/8080-cpu/src/main/java/net/emustudio/plugins/cpu/intel8080/EmulatorEngine.java b/plugins/cpu/8080-cpu/src/main/java/net/emustudio/plugins/cpu/intel8080/EmulatorEngine.java
@@ -85,7 +85,7 @@ public void setDispatchListener(DispatchListener dispatchListener) {
     }
 
     @Override
-    public long getAndResetExecutedCycles() {
+    public long getAndResetGlobalExecutedCycles() {
         long tmpExecutedCycles = executedCycles;
         executedCycles = 0;
         return tmpExecutedCycles;

diff --git a/plugins/cpu/8080-cpu/src/main/java/net/emustudio/plugins/cpu/intel8080/api/CpuEngine.java b/plugins/cpu/8080-cpu/src/main/java/net/emustudio/plugins/cpu/intel8080/api/CpuEngine.java
@@ -20,7 +20,7 @@
 
 public interface CpuEngine {
 
-    long getAndResetExecutedCycles();
+    long getAndResetGlobalExecutedCycles();
 
     void fireFrequencyChanged(float newFrequency);
 

diff --git a/.../cpu/8080-cpu/src/main/java/net/emustudio/plugins/cpu/intel8080/api/FrequencyUpdater.java b/.../cpu/8080-cpu/src/main/java/net/emustudio/plugins/cpu/intel8080/api/FrequencyUpdater.java
@@ -40,7 +40,7 @@ public void run() {
         synchronized (this) {
             long endTime = System.nanoTime();
             long time = endTime - startTimeSaved;
-            long executedCycles = cpu.getAndResetExecutedCycles();
+            long executedCycles = cpu.getAndResetGlobalExecutedCycles();
 
             if (executedCycles > 0) {
                 frequency = (float) (executedCycles / (time / 1000000.0));

diff --git a/.../8080-cpu/src/test/java/net/emustudio/plugins/cpu/intel8080/api/FrequencyUpdaterTest.java b/.../8080-cpu/src/test/java/net/emustudio/plugins/cpu/intel8080/api/FrequencyUpdaterTest.java
@@ -28,7 +28,7 @@ public class FrequencyUpdaterTest {
     @Test
     public void testFrequencyNotChanged() throws Exception {
         CpuEngine cpuEngine = createMock(CpuEngine.class);
-        expect(cpuEngine.getAndResetExecutedCycles()).andReturn(0L);
+        expect(cpuEngine.getAndResetGlobalExecutedCycles()).andReturn(0L);
         replay(cpuEngine);
 
         new FrequencyUpdater(cpuEngine).run();
@@ -39,7 +39,7 @@ public void testFrequencyNotChanged() throws Exception {
     @Test
     public void testFrequencyChanged() throws Exception {
         CpuEngine cpuEngine = createMock(CpuEngine.class);
-        expect(cpuEngine.getAndResetExecutedCycles()).andReturn(2000L);
+        expect(cpuEngine.getAndResetGlobalExecutedCycles()).andReturn(2000L);
         cpuEngine.fireFrequencyChanged(anyFloat());
         expectLastCall().once();
         replay(cpuEngine);

diff --git a/plugins/cpu/z80-cpu/src/main/java/net/emustudio/plugins/cpu/zilogZ80/ContextZ80Impl.java b/plugins/cpu/z80-cpu/src/main/java/net/emustudio/plugins/cpu/zilogZ80/ContextZ80Impl.java
@@ -114,6 +114,11 @@ public void signalNonMaskableInterrupt() {
         engine.requestNonMaskableInterrupt();
     }
 
+    @Override
+    public void addCycles(int tStates) {
+        engine.addExecutedCyclesPerTimeSlice(tStates);
+    }
+
     @Override
     public Optional<TimedEventsProcessor> getTimedEventsProcessor() {
         return Optional.of(tep);

diff --git a/plugins/cpu/z80-cpu/src/main/java/net/emustudio/plugins/cpu/zilogZ80/EmulatorEngine.java b/plugins/cpu/z80-cpu/src/main/java/net/emustudio/plugins/cpu/zilogZ80/EmulatorEngine.java
@@ -36,7 +36,9 @@
 import java.util.Queue;
 import java.util.concurrent.ConcurrentLinkedQueue;
 import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicLong;
 
 import static net.emustudio.plugins.cpu.zilogZ80.DispatchTables.*;
@@ -67,7 +69,8 @@ public class EmulatorEngine implements CpuEngine {
     private final TimedEventsProcessor tep;
     private final MemoryContext<Byte> memory;
     private final List<FrequencyChangedListener> frequencyChangedListeners = new CopyOnWriteArrayList<>();
-    private final AtomicLong executedCycles = new AtomicLong(0);
+    private final AtomicLong cyclesExecutedGlobal = new AtomicLong(0);
+    private final AtomicInteger cyclesExecutedPerTimeSlice = new AtomicInteger(0);
 
     public final int[] regs = new int[8];
     public final int[] regs2 = new int[8];
@@ -138,8 +141,12 @@ public void setDispatchListener(DispatchListener dispatchListener) {
     }
 
     @Override
-    public long getAndResetExecutedCycles() {
-        return executedCycles.getAndSet(0);
+    public long getAndResetGlobalExecutedCycles() {
+        return cyclesExecutedGlobal.getAndSet(0);
+    }
+
+    public void addExecutedCyclesPerTimeSlice(int tstates) {
+        cyclesExecutedPerTimeSlice.addAndGet(tstates);
     }
 
     public void addFrequencyChangedListener(FrequencyChangedListener listener) {
@@ -193,26 +200,22 @@ CPU.RunState step() throws Exception {
     }
 
     public CPU.RunState run(CPU cpu) {
-        long startTime, endTime;
-        int cycles_executed;
         // In Z80, 1 t-state = 250 ns = 0.25 microseconds = 0.00025 milliseconds
-        // in 10 milliseconds = 10 / 0.00025 = 40000 t-states are executed uncontrollably
-        // in 1 millisecond = 1 / 0.00025 = 4000 t-states :(
+        // in 1 millisecond time slice = 1 / 0.00025 = 4000 t-states are executed uncontrollably
 
-        int checkTimeSlice = (int) Math.ceil(SleepUtils.SLEEP_PRECISION / 1000000.0); // milliseconds
-        int cycles_to_execute = checkTimeSlice * context.getCPUFrequency();
-        int cycles;
-        long slice = checkTimeSlice * 1000000L; // nanoseconds
+        long timeSliceNanos = SleepUtils.SLEEP_PRECISION;
+        int timeSliceMillis = (int) Math.ceil(timeSliceNanos / 1000000.0);
+        int cyclesPerTimeSlice = timeSliceMillis * context.getCPUFrequency();
 
         currentRunState = CPU.RunState.STATE_RUNNING;
         while (!Thread.currentThread().isInterrupted() && (currentRunState == CPU.RunState.STATE_RUNNING)) {
-            startTime = System.nanoTime();
-            cycles_executed = 0;
-            while ((cycles_executed < cycles_to_execute) && !Thread.currentThread().isInterrupted() && (currentRunState == CPU.RunState.STATE_RUNNING)) {
+            long startTime = System.nanoTime();
+            cyclesExecutedPerTimeSlice.set(0);
+            while ((cyclesExecutedPerTimeSlice.get() < cyclesPerTimeSlice) && !Thread.currentThread().isInterrupted() && (currentRunState == CPU.RunState.STATE_RUNNING)) {
                 try {
-                    cycles = dispatch();
-                    cycles_executed += cycles;
-                    executedCycles.addAndGet(cycles);
+                    int cycles = dispatch();
+                    cyclesExecutedPerTimeSlice.addAndGet(cycles);
+                    cyclesExecutedGlobal.addAndGet(cycles);
                     tep.advanceClock(cycles);
                     if (cpu.isBreakpointSet(PC)) {
                         throw new Breakpoint();
@@ -227,10 +230,10 @@ public CPU.RunState run(CPU cpu) {
                     return CPU.RunState.STATE_STOPPED_BAD_INSTR;
                 }
             }
-            endTime = System.nanoTime() - startTime;
-            if (endTime < slice) {
+            long endTime = System.nanoTime() - startTime;
+            if (endTime < timeSliceNanos) {
                 // time correction
-                SleepUtils.preciseSleepNanos(slice - endTime);
+                SleepUtils.preciseSleepNanos(timeSliceNanos - endTime);
             }
         }
         return currentRunState;
@@ -344,7 +347,12 @@ private int doInterrupt() throws Throwable {
                 break;
             case 1:
                 cycles += 12;
-                writeWord((SP - 2) & 0xFFFF, PC);
+                if (memory.read(PC) == 0x76) {
+                    // jump over HALT
+                    writeWord((SP - 2) & 0xFFFF, (PC + 1) & 0xFFFF);
+                } else {
+                    writeWord((SP - 2) & 0xFFFF, PC);
+                }
                 SP = (SP - 2) & 0xffff;
                 PC = 0x38;
                 memptr = PC;
@@ -1866,24 +1874,31 @@ int I_IN_R_REF_C(int reg) {
     int I_OUT_REF_C_B() {
         return I_OUT_REF_C_R(regs[REG_B]);
     }
+
     int I_OUT_REF_C_C() {
         return I_OUT_REF_C_R(regs[REG_C]);
     }
+
     int I_OUT_REF_C_D() {
         return I_OUT_REF_C_R(regs[REG_D]);
     }
+
     int I_OUT_REF_C_E() {
         return I_OUT_REF_C_R(regs[REG_E]);
     }
+
     int I_OUT_REF_C_H() {
         return I_OUT_REF_C_R(regs[REG_H]);
     }
+
     int I_OUT_REF_C_L() {
         return I_OUT_REF_C_R(regs[REG_L]);
     }
+
     int I_OUT_REF_C_A() {
         return I_OUT_REF_C_R(regs[REG_A]);
     }
+
     int I_OUT_REF_C_R(int reg) {
         memptr = (regs[REG_B] << 8) | regs[REG_C];
         context.writeIO(memptr, (byte) reg);

diff --git a/plugins/cpu/z80-cpu/src/main/java/net/emustudio/plugins/cpu/zilogZ80/api/ContextZ80.java b/plugins/cpu/z80-cpu/src/main/java/net/emustudio/plugins/cpu/zilogZ80/api/ContextZ80.java
@@ -32,4 +32,13 @@ public interface ContextZ80 extends Context8080 {
      * at address 0066h. Routines should exit with RETN instruction.
      */
     void signalNonMaskableInterrupt();
+
+    /**
+     * Explicitly adds machine cycles (slows down CPU).
+     * <p>
+     * Used primarily in contention implementation.
+     *
+     * @param tStates number of t-states (machine cycles) to add
+     */
+    void addCycles(int tStates);
 }
diff --git a/...trum-bus/src/main/java/net/emustudio/plugins/device/zxspectrum/bus/ZxSpectrumBusImpl.java b/...trum-bus/src/main/java/net/emustudio/plugins/device/zxspectrum/bus/ZxSpectrumBusImpl.java
@@ -18,7 +18,6 @@
  */
 package net.emustudio.plugins.device.zxspectrum.bus;
 
-import net.emustudio.emulib.plugins.annotations.PluginContext;
 import net.emustudio.emulib.plugins.cpu.TimedEventsProcessor;
 import net.emustudio.emulib.plugins.memory.AbstractMemoryContext;
 import net.emustudio.emulib.plugins.memory.MemoryContext;
@@ -28,26 +27,49 @@
 import net.emustudio.plugins.device.zxspectrum.bus.api.ZxSpectrumBus;
 import net.jcip.annotations.NotThreadSafe;
 
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Objects;
-import java.util.Optional;
+import java.util.*;
 
 /**
- * Also a memory proxy
+ * ZX Spectrum bus.
+ * Adds memory & I/O port contention.
+ * <p>
+ * At cycle 14335 (just one cycle before the top left corner is reached) the delay is 6 cycles.
+ * At cycle 14336 the delay is 5 cycles, and so on according to the following table:
+ *
+ * Cycle #    Delay
+ * -------    -----
+ * 14335       6 (until 14341)
+ * 14336       5 (  "     "  )
+ * 14337       4 (  "     "  )
+ * 14338       3 (  "     "  )
+ * 14339       2 (  "     "  )
+ * 14340       1 (  "     "  )
+ * 14341   No delay
+ * 14342   No delay
+ * 14343       6 (until 14349)
+ * 14344       5 (  "     "  )
+ * 14345       4 (  "     "  )
+ * 14346       3 (  "     "  )
+ * 14347       2 (  "     "  )
+ * 14348       1 (  "     "  )
+ * 14349   No delay
+ * 14350   No delay
  */
 @NotThreadSafe
 public class ZxSpectrumBusImpl extends AbstractMemoryContext<Byte> implements ZxSpectrumBus {
     private ContextZ80 cpu;
     private MemoryContext<Byte> memory;
     private volatile byte busData; // data on the bus
+    private TimedEventsProcessor ted;
 
     private final Map<Integer, Context8080.CpuPortDevice> deferredAttachments = new HashMap<>();
 
 
     public void initialize(ContextZ80 cpu, MemoryContext<Byte> memory) {
         this.cpu = Objects.requireNonNull(cpu);
         this.memory = Objects.requireNonNull(memory);
+        this.ted = cpu.getTimedEventsProcessor().orElseThrow(() -> new RuntimeException("CPU must provide TimedEventProcessor"));
+
 
         for (Map.Entry<Integer, Context8080.CpuPortDevice> attachment : deferredAttachments.entrySet()) {
             // TODO: contended device proxy if needed