Issue #16: Memory window should not reset device registers

src/main/java/com/loomcom/symon/devices/Acia.java

@@ -107,10 +107,12 @@ public abstract class Acia extends Device {
         return name + "@" + String.format("%04X", baseAddress);
     }
 
-    public synchronized int rxRead() {
-        lastRxRead = System.nanoTime();
-        overrun = false;
-        rxFull = false;
+    public synchronized int rxRead(boolean cpuAccess) {
+        if (cpuAccess) {
+            lastRxRead = System.nanoTime();
+            overrun = false;
+            rxFull = false;
+        }
         return rxChar;
     }
 
@@ -128,13 +130,14 @@ public abstract class Acia extends Device {
         rxChar = data;
     }
 
-    public synchronized int txRead() {
-        txEmpty = true;
+    public synchronized int txRead(boolean cpuAccess) {
+        if (cpuAccess) {
+          txEmpty = true;
 
-        if (transmitIrqEnabled) {
+          if (transmitIrqEnabled) {
             getBus().assertIrq();
+           }
         }
-
         return txChar;
     }
 

src/main/java/com/loomcom/symon/devices/Acia6551.java

@@ -56,10 +56,10 @@ public class Acia6551 extends Acia {
     }
 
     @Override
-    public int read(int address) throws MemoryAccessException {
+    public int read(int address, boolean cpuAccess) throws MemoryAccessException {
         switch (address) {
             case DATA_REG:
-                return rxRead();
+                return rxRead(cpuAccess);
             case STAT_REG:
                 return statusReg();
             case CMND_REG:

src/main/java/com/loomcom/symon/devices/Acia6850.java

@@ -53,10 +53,10 @@ public class Acia6850 extends Acia {
     }
 
     @Override
-    public int read(int address) throws MemoryAccessException {
+    public int read(int address, boolean cpuAccess) throws MemoryAccessException {
         switch (address) {
             case RX_REG:
-                return rxRead();
+                return rxRead(cpuAccess);
             case STAT_REG:
                 return statusReg();
 

src/main/java/com/loomcom/symon/devices/Crtc.java

@@ -119,7 +119,7 @@ public class Crtc extends Device {
     }
 
     @Override
-    public int read(int address) throws MemoryAccessException {
+    public int read(int address, boolean cpuAccess) throws MemoryAccessException {
         switch (address) {
             case REGISTER_RW:
                 switch (currentRegister) {
@@ -142,7 +142,7 @@ public class Crtc extends Device {
 
     public int getCharAtAddress(int address) throws MemoryAccessException {
         // TODO: Row/Column addressing
-        return memory.read(address);
+        return memory.read(address, false);
     }
 
     public int getHorizontalDisplayed() {

src/main/java/com/loomcom/symon/devices/Device.java

@@ -72,7 +72,7 @@ public abstract class Device implements Comparable<Device> {
     /* Methods required to be implemented by inheriting classes. */
     public abstract void write(int address, int data) throws MemoryAccessException;
 
-    public abstract int read(int address) throws MemoryAccessException;
+    public abstract int read(int address, boolean cpuAccess) throws MemoryAccessException;
 
     public abstract String toString();
 

src/main/java/com/loomcom/symon/devices/Memory.java

@@ -94,7 +94,7 @@ public class Memory extends Device {
 
     }
 
-    public int read(int address) throws MemoryAccessException {
+    public int read(int address, boolean cpuAccess) throws MemoryAccessException {
         return this.mem[address];
     }
 

src/main/java/com/loomcom/symon/devices/SdController.java

@@ -94,7 +94,7 @@ public class SdController extends Device {
     }
 
     @Override
-    public int read(int address) throws MemoryAccessException {
+    public int read(int address, boolean cpuAccess) throws MemoryAccessException {
         switch (address) {
             case 0:
                 return readData();

src/main/java/com/loomcom/symon/devices/Via6522.java

@@ -75,7 +75,7 @@ public class Via6522 extends Pia {
     }
 
     @Override
-    public int read(int address) throws MemoryAccessException {
+    public int read(int address, boolean cpuAccess) throws MemoryAccessException {
         Register[] registers = Register.values();
 
         if (address >= registers.length) {