fix random bit generation if no disk or no track

src/drive.cpp

@@ -72,8 +72,13 @@ void Disk2Drive::rotateDiskOneBit() {
     this->disk.rotateOneBit(this->head.position());
 
     bitBufferRead <<= 1;
-    bitBufferRead |= this->disk.getBit(this->head.position());
-    if (bitBufferRead & 0x0Fu) {
+
+    const bool exists(this->disk.exists(this->head.position()));
+    if (exists) {
+        bitBufferRead |= this->disk.getBit(this->head.position());
+    }
+
+    if ((bitBufferRead & 0x0Fu) && exists) {
         this->pulse = (bitBufferRead & 0x02u) >> 1;
     } else {
         this->pulse = randomBit();

src/wozfile.cpp

@@ -533,19 +533,11 @@ void WozFile::rotateOneBit(std::uint8_t currentQuarterTrack) {
     }
 }
 
-
+bool WozFile::exists(std::uint8_t currentQuarterTrack) {
+    return isLoaded() && (this->tmap[currentQuarterTrack] != 0xFFu);
+}
 
 bool WozFile::getBit(std::uint8_t currentQuarterTrack) {
-    if (!isLoaded()) {
-//        printf("No disk to read from; will generate random data.\n");
-        return false; // there's no disk, so no pulse
-    }
-
-    if (this->tmap[currentQuarterTrack] == 0xFFu) {
-//        printf("Reading from uninitialized track; will generate random data.\n");
-        return false; // empty track
-    }
-
     return this->trk[this->tmap[currentQuarterTrack]][this->byt] & this->bit;
 }
 

src/wozfile.h

@@ -131,6 +131,7 @@ public:
     }
 
     void rotateOneBit(std::uint8_t currentQuarterTrack);
+    bool exists(std::uint8_t currentQuarterTrack);
     bool getBit(std::uint8_t currentQuarterTrack);
     void setBit(std::uint8_t currentQuarterTrack, bool on);
     void rawSet();