Implement r/w status register

src/apu.c

@@ -8,6 +8,14 @@ void create_apu(apu_t *apu, interrupt_t *interrupt) {
 
 void destroy_apu(apu_t *apu) { destroy_buffer(&apu->buffer); }
 
+unsigned char read_status_apu(apu_t *apu) { return apu->status; }
+
+void write_status_apu(apu_t *apu, unsigned char value) {
+    // Clear DMC interrupt flag
+    apu->status = value;
+    apu->channel_registers.dmc[0] &= ~APU_DMC_INTERRUPT;
+}
+
 void update_apu(apu_t *apu) {
     // TODO: Implement this
     apu->cycles++;

src/apu.h

@@ -5,35 +5,30 @@
 #include "./interrupt.h"
 
 #define AUDIO_BUFFER_SIZE 0x400
+#define APU_DMC_INTERRUPT 0x80
 
 /**
  * @brief APU registers.
  *
  */
 typedef struct {
     /**
-     * @brief Pulse 1 channel registers.
+     * @brief Pulse (1 and 2) channel registers.
      *
      */
-    unsigned char pulse1[4];
-
-    /**
-     * @brief Pulse 2 channel registers.
-     *
-     */
-    unsigned char pulse2[4];
+    unsigned char pulse[8];
 
     /**
      * @brief Triangle channel registers.
      *
      */
-    unsigned char triangle[4];
+    unsigned char triangle[3];
 
     /**
      * @brief Noise channel registers.
      *
      */
-    unsigned char noise[4];
+    unsigned char noise[3];
 
     /**
      * @brief DMC channel registers.
@@ -99,6 +94,22 @@ void create_apu(apu_t *apu, interrupt_t *interrupt);
  */
 void destroy_apu(apu_t *apu);
 
+/**
+ * @brief Read the status register of the APU.
+ *
+ * @param apu
+ * @return unsigned char
+ */
+unsigned char read_status_apu(apu_t *apu);
+
+/**
+ * @brief Write to the status register of the APU.
+ *
+ * @param apu
+ * @param value
+ */
+void write_status_apu(apu_t *apu, unsigned char value);
+
 /**
  * @brief Update the APU.
  *

src/cpu_bus.c

@@ -57,7 +57,8 @@ unsigned char read_cpu_bus(cpu_bus_t *bus, address_t address) {
             return read_joy1_controller(bus->controller);
         case CTRL_REG_JOYPAD2:
             return read_joy2_controller(bus->controller);
-        // TODO: Handle APU registers
+        case APU_REG_STATUS:
+            return read_status_apu(bus->apu);
         default:
             return bus->memory[address];
         }
@@ -100,6 +101,9 @@ void write_cpu_bus(cpu_bus_t *bus, address_t address, unsigned char value) {
             write_strobe_controller(bus->controller, value);
             break;
         // TODO: Handle APU registers
+        case APU_REG_STATUS:
+            write_status_apu(bus->apu, value);
+            break;
         default:
             bus->memory[address] = value;
             break;