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implement overrun status flag for the 6551 ACIA

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This commit is contained in:
Maik Merten 2014-07-19 17:30:23 +02:00
parent 4a37dd7463
commit 252ebe0569
2 changed files with 23 additions and 1 deletions
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5
src/main/java/com/loomcom/symon/devices/Acia6551.java
View File

@ -181,7 +181,7 @@ public class Acia6551 extends Acia {
*/
@Override
public int statusReg() {
// TODO: Overrun, Parity Error, Framing Error, DTR, DSR, and Interrupt flags.
// TODO: Parity Error, Framing Error, DTR, DSR, and Interrupt flags.
int stat = 0;
if (rxFull && System.nanoTime() >= (lastRxRead + baudRateDelay)) {
stat |= 0x08;
@ -189,6 +189,9 @@ public class Acia6551 extends Acia {
if (txEmpty && System.nanoTime() >= (lastTxWrite + baudRateDelay)) {
stat |= 0x10;
}
if (overrun) {
stat |= 0x04;
}
return stat;
}

19
src/test/java/com/loomcom/symon/AciaTest.java
View File

@ -112,6 +112,25 @@ public class AciaTest {
assertEquals(0x08, acia.read(0x0001));
}
@Test
public void aciaShouldOverrunAndReadShouldReset()
throws Exception {
Acia acia = new Acia6551(0x0000);
// overrun ACIA
acia.rxWrite('a');
acia.rxWrite('b');
assertEquals(0x04, acia.read(0x0001) & 0x04);
// read should reset
acia.rxRead();
assertEquals(0x00, acia.read(0x0001) & 0x04);
}
@Test
public void readingBuffersShouldResetStatus()