diff --git a/src/main/java/com/loomcom/symon/Simulator.java b/src/main/java/com/loomcom/symon/Simulator.java
index 7ec8455..94dbd9e 100644
--- a/src/main/java/com/loomcom/symon/Simulator.java
+++ b/src/main/java/com/loomcom/symon/Simulator.java
@@ -24,6 +24,7 @@
package com.loomcom.symon;
import com.loomcom.symon.devices.Acia;
+import com.loomcom.symon.devices.Acia6551;
import com.loomcom.symon.devices.Crtc;
import com.loomcom.symon.devices.Memory;
import com.loomcom.symon.devices.Via;
@@ -157,7 +158,7 @@ public class Simulator {
this.cpu = new Cpu();
this.ram = new Memory(MEMORY_BASE, MEMORY_BASE + MEMORY_SIZE - 1, false);
this.via = new Via(VIA_BASE);
- this.acia = new Acia(ACIA_BASE);
+ this.acia = new Acia6551(ACIA_BASE);
this.crtc = new Crtc(CRTC_BASE, ram);
bus.addCpu(cpu);
diff --git a/src/main/java/com/loomcom/symon/devices/Acia.java b/src/main/java/com/loomcom/symon/devices/Acia.java
index 8606c0c..e8664ef 100644
--- a/src/main/java/com/loomcom/symon/devices/Acia.java
+++ b/src/main/java/com/loomcom/symon/devices/Acia.java
@@ -23,179 +23,47 @@
package com.loomcom.symon.devices;
-import com.loomcom.symon.exceptions.MemoryAccessException;
import com.loomcom.symon.exceptions.MemoryRangeException;
/**
- * This is a simulation of the MOS 6551 ACIA, with limited
- * functionality. Interrupts are not supported.
- *
- * Unlike a 16550 UART, the 6551 ACIA has only one-byte transmit and
- * receive buffers. It is the programmer's responsibility to check the
- * status (full or empty) for transmit and receive buffers before
- * writing / reading.
+ * Abstract base class for ACIAS such as the 6551 and 6580
*/
-public class Acia extends Device {
- public static final int ACIA_SIZE = 4;
-
- static final int DATA_REG = 0;
- static final int STAT_REG = 1;
- static final int CMND_REG = 2;
- static final int CTRL_REG = 3;
+public abstract class Acia extends Device {
+ private String name;
+
/**
* Register addresses
*/
- private int baseAddress;
+ int baseAddress;
- /**
- * Registers. These are ignored in the current implementation.
- */
- private int commandRegister;
- private int controlRegister;
-
- private boolean receiveIrqEnabled = false;
- private boolean transmitIrqEnabled = false;
- private boolean overrun = false;
-
- private long lastTxWrite = 0;
- private long lastRxRead = 0;
- private int baudRate = 0;
- private long baudRateDelay = 0;
-
- /**
+ boolean receiveIrqEnabled = false;
+ boolean transmitIrqEnabled = false;
+ boolean overrun = false;
+
+ long lastTxWrite = 0;
+ long lastRxRead = 0;
+ int baudRate = 0;
+ long baudRateDelay = 0;
+
+ /**
* Read/Write buffers
*/
- private int rxChar = 0;
- private int txChar = 0;
+ int rxChar = 0;
+ int txChar = 0;
- private boolean rxFull = false;
- private boolean txEmpty = true;
-
- public Acia(int address) throws MemoryRangeException {
- super(address, address + ACIA_SIZE - 1, "ACIA");
+ boolean rxFull = false;
+ boolean txEmpty = true;
+
+
+ public Acia(int address, int size, String name) throws MemoryRangeException {
+ super(address, address + size - 1, name);
+ this.name = name;
this.baseAddress = address;
}
- @Override
- public int read(int address) throws MemoryAccessException {
- switch (address) {
- case DATA_REG:
- return rxRead();
- case STAT_REG:
- return statusReg();
- case CMND_REG:
- return commandRegister;
- case CTRL_REG:
- return controlRegister;
- default:
- throw new MemoryAccessException("No register.");
- }
- }
-
- @Override
- public void write(int address, int data) throws MemoryAccessException {
- switch (address) {
- case 0:
- txWrite(data);
- break;
- case 1:
- reset();
- break;
- case 2:
- setCommandRegister(data);
- break;
- case 3:
- setControlRegister(data);
- break;
- default:
- throw new MemoryAccessException("No register.");
- }
- }
-
-
- private void setCommandRegister(int data) {
- commandRegister = data;
-
- // Bit 1 controls receiver IRQ behavior
- receiveIrqEnabled = (commandRegister & 0x02) == 0;
- // Bits 2 & 3 controls transmit IRQ behavior
- transmitIrqEnabled = (commandRegister & 0x08) == 0 && (commandRegister & 0x04) != 0;
- }
-
- /**
- * Set the control register and associated state.
- *
- * @param data
- */
- private void setControlRegister(int data) {
- controlRegister = data;
-
- // If the value of the data is 0, this is a request to reset,
- // otherwise it's a control update.
-
- if (data == 0) {
- reset();
- } else {
- // Mask the lower three bits to get the baud rate.
- int baudSelector = data & 0x0f;
- switch (baudSelector) {
- case 0:
- baudRate = 0;
- break;
- case 1:
- baudRate = 50;
- break;
- case 2:
- baudRate = 75;
- break;
- case 3:
- baudRate = 110; // Real rate is actually 109.92
- break;
- case 4:
- baudRate = 135; // Real rate is actually 134.58
- break;
- case 5:
- baudRate = 150;
- break;
- case 6:
- baudRate = 300;
- break;
- case 7:
- baudRate = 600;
- break;
- case 8:
- baudRate = 1200;
- break;
- case 9:
- baudRate = 1800;
- break;
- case 10:
- baudRate = 2400;
- break;
- case 11:
- baudRate = 3600;
- break;
- case 12:
- baudRate = 4800;
- break;
- case 13:
- baudRate = 7200;
- break;
- case 14:
- baudRate = 9600;
- break;
- case 15:
- baudRate = 19200;
- break;
- }
-
- // Recalculate the baud rate delay.
- baudRateDelay = calculateBaudRateDelay();
- }
- }
/*
* Calculate the delay in nanoseconds between successive read/write operations, based on the
@@ -225,26 +93,17 @@ public class Acia extends Device {
*/
public void setBaudRate(int rate) {
this.baudRate = rate;
+ this.baudRateDelay = calculateBaudRateDelay();
}
/**
* @return The contents of the status register.
*/
- public int statusReg() {
- // TODO: Overrun, Parity Error, Framing Error, DTR, DSR, and Interrupt flags.
- int stat = 0;
- if (rxFull && System.nanoTime() >= (lastRxRead + baudRateDelay)) {
- stat |= 0x08;
- }
- if (txEmpty && System.nanoTime() >= (lastTxWrite + baudRateDelay)) {
- stat |= 0x10;
- }
- return stat;
- }
+ public abstract int statusReg();
@Override
public String toString() {
- return "ACIA@" + String.format("%04X", baseAddress);
+ return name + "@" + String.format("%04X", baseAddress);
}
public synchronized int rxRead() {
@@ -293,13 +152,4 @@ public class Acia extends Device {
return rxFull;
}
- private synchronized void reset() {
- txChar = 0;
- txEmpty = true;
- rxChar = 0;
- rxFull = false;
- receiveIrqEnabled = false;
- transmitIrqEnabled = false;
- }
-
}
diff --git a/src/main/java/com/loomcom/symon/devices/Acia6551.java b/src/main/java/com/loomcom/symon/devices/Acia6551.java
new file mode 100644
index 0000000..e56e79c
--- /dev/null
+++ b/src/main/java/com/loomcom/symon/devices/Acia6551.java
@@ -0,0 +1,205 @@
+/*
+ * Copyright (c) 2008-2013 Seth J. Morabito
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+package com.loomcom.symon.devices;
+
+import com.loomcom.symon.exceptions.MemoryAccessException;
+import com.loomcom.symon.exceptions.MemoryRangeException;
+
+
+/**
+ * This is a simulation of the MOS 6551 ACIA, with limited
+ * functionality. Interrupts are not supported.
+ *
+ * Unlike a 16550 UART, the 6551 ACIA has only one-byte transmit and
+ * receive buffers. It is the programmer's responsibility to check the
+ * status (full or empty) for transmit and receive buffers before
+ * writing / reading.
+ */
+public class Acia6551 extends Acia {
+
+ public static final int ACIA_SIZE = 4;
+
+ static final int DATA_REG = 0;
+ static final int STAT_REG = 1;
+ static final int CMND_REG = 2;
+ static final int CTRL_REG = 3;
+
+
+ /**
+ * Registers. These are ignored in the current implementation.
+ */
+ private int commandRegister;
+ private int controlRegister;
+
+
+ public Acia6551(int address) throws MemoryRangeException {
+ super(address, ACIA_SIZE, "ACIA");
+ }
+
+ @Override
+ public int read(int address) throws MemoryAccessException {
+ switch (address) {
+ case DATA_REG:
+ return rxRead();
+ case STAT_REG:
+ return statusReg();
+ case CMND_REG:
+ return commandRegister;
+ case CTRL_REG:
+ return controlRegister;
+ default:
+ throw new MemoryAccessException("No register.");
+ }
+ }
+
+ @Override
+ public void write(int address, int data) throws MemoryAccessException {
+ switch (address) {
+ case 0:
+ txWrite(data);
+ break;
+ case 1:
+ reset();
+ break;
+ case 2:
+ setCommandRegister(data);
+ break;
+ case 3:
+ setControlRegister(data);
+ break;
+ default:
+ throw new MemoryAccessException("No register.");
+ }
+ }
+
+
+ private void setCommandRegister(int data) {
+ commandRegister = data;
+
+ // Bit 1 controls receiver IRQ behavior
+ receiveIrqEnabled = (commandRegister & 0x02) == 0;
+ // Bits 2 & 3 controls transmit IRQ behavior
+ transmitIrqEnabled = (commandRegister & 0x08) == 0 && (commandRegister & 0x04) != 0;
+ }
+
+ /**
+ * Set the control register and associated state.
+ *
+ * @param data
+ */
+ private void setControlRegister(int data) {
+ controlRegister = data;
+ int rate = 0;
+
+ // If the value of the data is 0, this is a request to reset,
+ // otherwise it's a control update.
+
+ if (data == 0) {
+ reset();
+ } else {
+ // Mask the lower three bits to get the baud rate.
+ int baudSelector = data & 0x0f;
+ switch (baudSelector) {
+ case 0:
+ rate = 0;
+ break;
+ case 1:
+ rate = 50;
+ break;
+ case 2:
+ rate = 75;
+ break;
+ case 3:
+ rate = 110; // Real rate is actually 109.92
+ break;
+ case 4:
+ rate = 135; // Real rate is actually 134.58
+ break;
+ case 5:
+ rate = 150;
+ break;
+ case 6:
+ rate = 300;
+ break;
+ case 7:
+ rate = 600;
+ break;
+ case 8:
+ rate = 1200;
+ break;
+ case 9:
+ rate = 1800;
+ break;
+ case 10:
+ rate = 2400;
+ break;
+ case 11:
+ rate = 3600;
+ break;
+ case 12:
+ rate = 4800;
+ break;
+ case 13:
+ rate = 7200;
+ break;
+ case 14:
+ rate = 9600;
+ break;
+ case 15:
+ rate = 19200;
+ break;
+ }
+
+ setBaudRate(rate);
+ }
+ }
+
+
+ /**
+ * @return The contents of the status register.
+ */
+ @Override
+ public int statusReg() {
+ // TODO: Overrun, Parity Error, Framing Error, DTR, DSR, and Interrupt flags.
+ int stat = 0;
+ if (rxFull && System.nanoTime() >= (lastRxRead + baudRateDelay)) {
+ stat |= 0x08;
+ }
+ if (txEmpty && System.nanoTime() >= (lastTxWrite + baudRateDelay)) {
+ stat |= 0x10;
+ }
+ return stat;
+ }
+
+
+ private synchronized void reset() {
+ txChar = 0;
+ txEmpty = true;
+ rxChar = 0;
+ rxFull = false;
+ receiveIrqEnabled = false;
+ transmitIrqEnabled = false;
+ }
+
+}
diff --git a/src/main/java/com/loomcom/symon/devices/Acia6850.java b/src/main/java/com/loomcom/symon/devices/Acia6850.java
index cc8bf27..0eb7917 100644
--- a/src/main/java/com/loomcom/symon/devices/Acia6850.java
+++ b/src/main/java/com/loomcom/symon/devices/Acia6850.java
@@ -37,7 +37,7 @@ import com.loomcom.symon.exceptions.MemoryRangeException;
* status (full or empty) for transmit and receive buffers before
* writing / reading.
*/
-public class Acia6850 extends Device {
+public class Acia6850 extends Acia {
public static final int ACIA_SIZE = 2;
@@ -48,38 +48,15 @@ public class Acia6850 extends Device {
static final int RX_REG = 1; // read-only
static final int TX_REG = 1; // write-only
-
- /**
- * Register addresses
- */
- private int baseAddress;
-
+
/**
* Registers. These are ignored in the current implementation.
*/
private int commandRegister;
- private boolean receiveIrqEnabled = false;
- private boolean transmitIrqEnabled = false;
- private boolean overrun = false;
-
- private long lastTxWrite = 0;
- private long lastRxRead = 0;
- private int baudRate = 0;
- private long baudRateDelay = 0;
-
- /**
- * Read/Write buffers
- */
- private int rxChar = 0;
- private int txChar = 0;
-
- private boolean rxFull = false;
- private boolean txEmpty = true;
public Acia6850(int address) throws MemoryRangeException {
- super(address, address + ACIA_SIZE - 1, "ACIA");
- this.baseAddress = address;
+ super(address, ACIA_SIZE, "ACIA6850");
setBaudRate(2400);
}
@@ -126,40 +103,11 @@ public class Acia6850 extends Device {
}
- /*
- * Calculate the delay in nanoseconds between successive read/write operations, based on the
- * configured baud rate.
- */
- private long calculateBaudRateDelay() {
- if (baudRate > 0) {
- // TODO: This is a pretty rough approximation based on 8 bits per character,
- // and 1/baudRate per bit. It could certainly be improved
- return (long)((1.0 / baudRate) * 1000000000 * 8);
- } else {
- return 0;
- }
- }
-
- /**
- * @return The simulated baud rate in bps.
- */
- public int getBaudRate() {
- return baudRate;
- }
-
- /**
- * Set the baud rate of the simulated ACIA.
- *
- * @param rate The baud rate in bps. 0 means no simulated baud rate delay.
- */
- public void setBaudRate(int rate) {
- this.baudRate = rate;
- this.baudRateDelay = calculateBaudRateDelay();
- }
/**
* @return The contents of the status register.
*/
+ @Override
public int statusReg() {
// TODO: Parity Error, Framing Error, DTR, DSR, and Interrupt flags.
int stat = 0;
@@ -176,62 +124,6 @@ public class Acia6850 extends Device {
return stat;
}
- @Override
- public String toString() {
- return "ACIA6850@" + String.format("%04X", baseAddress);
- }
-
- public synchronized int rxRead() {
- lastRxRead = System.nanoTime();
- rxFull = false;
- overrun = false;
- return rxChar;
- }
-
- public synchronized void rxWrite(int data) {
- // when receiving while full: overrun
- if(rxFull) {
- overrun = true;
- }
-
- rxFull = true;
-
- if (receiveIrqEnabled) {
- getBus().assertIrq();
- }
-
- rxChar = data;
- }
-
- public synchronized int txRead() {
- txEmpty = true;
-
- if (transmitIrqEnabled) {
- getBus().assertIrq();
- }
-
- return txChar;
- }
-
- public synchronized void txWrite(int data) {
- lastTxWrite = System.nanoTime();
- txChar = data;
- txEmpty = false;
- }
-
- /**
- * @return true if there is character data in the TX register.
- */
- public boolean hasTxChar() {
- return !txEmpty;
- }
-
- /**
- * @return true if there is character data in the RX register.
- */
- public boolean hasRxChar() {
- return rxFull;
- }
private synchronized void reset() {
overrun = false;
diff --git a/src/test/java/com/loomcom/symon/AciaTest.java b/src/test/java/com/loomcom/symon/AciaTest.java
index bcb4784..6fa3638 100644
--- a/src/test/java/com/loomcom/symon/AciaTest.java
+++ b/src/test/java/com/loomcom/symon/AciaTest.java
@@ -1,6 +1,7 @@
package com.loomcom.symon;
import com.loomcom.symon.devices.Acia;
+import com.loomcom.symon.devices.Acia6551;
import org.junit.Test;
import static org.junit.Assert.assertEquals;
@@ -12,7 +13,7 @@ public class AciaTest {
public void shouldTriggerInterruptOnRxFullIfRxIrqEnabled() throws Exception {
Bus mockBus = mock(Bus.class);
- Acia acia = new Acia(0x000);
+ Acia acia = new Acia6551(0x000);
acia.setBus(mockBus);
// Disable TX IRQ, Enable RX IRQ
@@ -27,7 +28,7 @@ public class AciaTest {
public void shouldNotTriggerInterruptOnRxFullIfRxIrqNotEnabled() throws Exception {
Bus mockBus = mock(Bus.class);
- Acia acia = new Acia(0x000);
+ Acia acia = new Acia6551(0x000);
acia.setBus(mockBus);
// Disable TX IRQ, Disable RX IRQ
@@ -42,7 +43,7 @@ public class AciaTest {
public void shouldTriggerInterruptOnTxEmptyIfTxIrqEnabled() throws Exception {
Bus mockBus = mock(Bus.class);
- Acia acia = new Acia(0x000);
+ Acia acia = new Acia6551(0x000);
acia.setBus(mockBus);
// Enable TX IRQ, Disable RX IRQ
@@ -63,7 +64,7 @@ public class AciaTest {
public void shouldNotTriggerInterruptOnTxEmptyIfTxIrqNotEnabled() throws Exception {
Bus mockBus = mock(Bus.class);
- Acia acia = new Acia(0x000);
+ Acia acia = new Acia6551(0x000);
acia.setBus(mockBus);
// Disable TX IRQ, Disable RX IRQ
@@ -80,14 +81,14 @@ public class AciaTest {
@Test
public void newAciaShouldHaveTxEmptyStatus() throws Exception {
- Acia acia = new Acia(0x000);
+ Acia acia = new Acia6551(0x000);
assertEquals(0x10, acia.read(0x0001));
}
@Test
public void aciaShouldHaveTxEmptyStatusOffIfTxHasData() throws Exception {
- Acia acia = new Acia(0x000);
+ Acia acia = new Acia6551(0x000);
acia.txWrite('a');
assertEquals(0x00, acia.read(0x0001));
@@ -95,7 +96,7 @@ public class AciaTest {
@Test
public void aciaShouldHaveRxFullStatusOffIfRxHasData() throws Exception {
- Acia acia = new Acia(0x000);
+ Acia acia = new Acia6551(0x000);
acia.rxWrite('a');
assertEquals(0x18, acia.read(0x0001));
@@ -104,7 +105,7 @@ public class AciaTest {
@Test
public void aciaShouldHaveTxEmptyAndRxFullStatusOffIfRxAndTxHaveData()
throws Exception {
- Acia acia = new Acia(0x000);
+ Acia acia = new Acia6551(0x000);
acia.rxWrite('a');
acia.txWrite('b');
@@ -115,7 +116,7 @@ public class AciaTest {
@Test
public void readingBuffersShouldResetStatus()
throws Exception {
- Acia acia = new Acia(0x0000);
+ Acia acia = new Acia6551(0x0000);
acia.rxWrite('a');
acia.txWrite('b');