Peddle cleanup

Emulator/Components/CPU/Peddle/Peddle.cpp

@@ -92,7 +92,7 @@ template u16 Peddle::addrMask<MOS_6510>() const;
 template u16 Peddle::addrMask<MOS_8502>() const;
 
 void
-Peddle::pullDownNmiLine(IntSource bit)
+Peddle::pullDownNmiLine(u8 mask)
 {
     assert(bit != 0);
 
@@ -101,48 +101,48 @@ Peddle::pullDownNmiLine(IntSource bit)
         edgeDetector.write(1);
     }
 
-    nmiLine |= bit;
+    nmiLine |= mask;
 }
 
 void
-Peddle::releaseNmiLine(IntSource source)
+Peddle::releaseNmiLine(u8 mask)
 {
-    nmiLine &= ~source;
+    nmiLine &= ~mask;
 }
 
 void
-Peddle::pullDownIrqLine(IntSource source)
+Peddle::pullDownIrqLine(u8 mask)
 {
-    assert(source != 0);
+    assert(mask != 0);
 
-    irqLine |= source;
+    irqLine |= mask;
     levelDetector.write(irqLine);
 }
 
 void
-Peddle::releaseIrqLine(IntSource source)
+Peddle::releaseIrqLine(u8 mask)
 {
-    irqLine &= ~source;
+    irqLine &= ~mask;
     levelDetector.write(irqLine);
 }
 
 void
-Peddle::pullDownRdyLine(IntSource source)
+Peddle::pullDownRdyLine(u8 mask)
 {
-    assert(source != 0);
+    assert(mask != 0);
 
     auto old = rdyLine;
-    rdyLine |= source;
+    rdyLine |= mask;
     if (!old && rdyLine) rdyLineDown = clock;
 }
 
 void
-Peddle::releaseRdyLine(IntSource source)
+Peddle::releaseRdyLine(u8 mask)
 {
     assert(source != 0);
 
     auto old = rdyLine;
-    rdyLine &= ~source;
+    rdyLine &= ~mask;
     if (old && !rdyLine) rdyLineUp = clock;
 }
 

Emulator/Components/CPU/Peddle/Peddle.h

@@ -98,31 +98,34 @@ class Peddle : public SubComponent {
 
 protected:
 
-    /* Ready line (RDY).
+    /* Ready line (RDY)
      * 
-     * The variable is usually 0 which means that the RDY line is high. If
-     * pulled low, that is, the variable has a value different to 0, the CPU
-     * freezes on the next read access.
+     * The variable is usually 0, indicating the RDY line is high. If the
+     * variable differs from 0, the RDY line is considered low. In this case,
+     * the CPU freezes on the next read (writes are unaffected). The variable
+     * is a bit mask since multiple sources can drive the RDY line low. The
+     * line is considered low precisely if one or more bits are set.
      */
-    IntSource rdyLine;
+    u8 rdyLine;
 
     // Cycle of the most recent rising edge of the RDY line
     i64 rdyLineUp;
 
     // Cycle of the most recent falling edge of the RDY line
     i64 rdyLineDown;
 
-    /* Interrupt lines
+    /* Interrupt lines (NMI and IRQ)
      *
-     * Usally both variables equal 0 which means that the two interrupt lines
-     * are high. When an external component requests an interrupt, the NMI or
-     * the IRQ line is pulled low. In that case, the corresponding variable is
-     * set to a positive value which indicates the interrupt source. The
-     * variables are used in form of bit fields since both interrupt lines are
-     * driven by multiple sources.
+     * Usually, both variables equal 0, indicating the two interrupt lines are
+     * high. When an external component requests an interrupt, the NMI or the
+     * IRQ line is pulled low. In that case, the corresponding variable is set
+     * to a positive value, indicating the interrupt source. The variables are
+     * used as bit masks since both interrupt lines are driven by multiple
+     * sources. The corresponding line is considered low precisely if one or
+     * more bits are set.
      */
-    IntSource nmiLine;
-    IntSource irqLine;
+    u8 nmiLine;
+    u8 irqLine;
 
     /* Edge detector (NMI line)
      * https://wiki.nesdev.com/w/index.php/CPU_interrupts
@@ -282,19 +285,19 @@ class Peddle : public SubComponent {
 public:
 
     // Pulls down a line
-    void pullDownNmiLine(IntSource source);
-    void pullDownIrqLine(IntSource source);
-    void pullDownRdyLine(IntSource source);
+    void pullDownNmiLine(u8 mask);
+    void pullDownIrqLine(u8 mask);
+    void pullDownRdyLine(u8 mask);
 
     // Releases a line
-    void releaseNmiLine(IntSource source);
-    void releaseIrqLine(IntSource source);
-    void releaseRdyLine(IntSource source);
+    void releaseNmiLine(u8 mask);
+    void releaseIrqLine(u8 mask);
+    void releaseRdyLine(u8 mask);
 
     // Checks the status of a line
-    IntSource getNmiLine() const { return nmiLine; }
-    IntSource getIrqLine() const { return irqLine; }
-    IntSource getRdyLine() const { return rdyLine; }
+    u8 getNmiLine() const { return nmiLine; }
+    u8 getIrqLine() const { return irqLine; }
+    u8 getRdyLine() const { return rdyLine; }
 
 
     //

Emulator/Components/CPU/Peddle/PeddleExec_cpp.h

@@ -305,26 +305,29 @@ Peddle::execute()
 
         case fetch:
 
-            // Check interrupt lines
-            if (unlikely(doNmi)) {
-
-                nmiWillTrigger();
-                IDLE_FETCH
-                edgeDetector.clear();
-                next = nmi_2;
-                doNmi = false;
-                doIrq = false; // NMI wins
-                return;
-
-            } else if (unlikely(doIrq)) {
-
-                irqWillTrigger();
-                IDLE_FETCH
-                next = irq_2;
-                doIrq = false;
-                return;
+            if constexpr (C != MOS_6507) {
+
+                // Check interrupt lines
+                if (unlikely(doNmi)) {
+
+                    nmiWillTrigger();
+                    IDLE_FETCH
+                    edgeDetector.clear();
+                    next = nmi_2;
+                    doNmi = false;
+                    doIrq = false; // NMI wins
+                    return;
+
+                } else if (unlikely(doIrq)) {
+
+                    irqWillTrigger();
+                    IDLE_FETCH
+                    next = irq_2;
+                    doIrq = false;
+                    return;
+                }
             }
-            
+
             // Execute the Fetch phase
             FETCH_OPCODE
             next = actionFunc[instr];

Emulator/Components/CPU/Peddle/PeddleTypes.h

@@ -27,13 +27,6 @@ static constexpr isize V_FLAG = 0x40;
 static constexpr isize N_FLAG = 0x80;
 
 
-//
-// Bit fields
-//
-
-// Interrupt source
-typedef u8 IntSource;
-
 /* State flags
  *
  * CPU_LOG_INSTRUCTION:

Emulator/Media/Cartridges/CustomCartridges/Expert.cpp

@@ -159,8 +159,8 @@ Expert::pressButton(isize nr)
             u8 oldLine = cpu.getNmiLine();
             u8 newLine = oldLine | INTSRC_EXP;
 
-            cpu.releaseNmiLine((IntSource)0xFF);
-            cpu.pullDownNmiLine((IntSource)newLine);
+            cpu.releaseNmiLine(0xFF);
+            cpu.pullDownNmiLine(newLine);
             cpu.releaseNmiLine(INTSRC_EXP);
             break;
     }