PPU

.idea/misc.xml

@@ -1,4 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <project version="4">
+  <component name="CMakePythonSetting">
+    <option name="pythonIntegrationState" value="YES" />
+  </component>
   <component name="CMakeWorkspace" PROJECT_DIR="$PROJECT_DIR$" />
 </project>

cpu/decoding.c

@@ -422,17 +422,18 @@ char *get_op_code_name(byte op) {
         case 0xaa:
             return "TAX";
         case 0xc6:
-        case 0xca:
         case 0xce:
         case 0xd6:
         case 0xde:
             return "DEC";
+        case 0xca:
+            return "DEX";
+
         case 0xe6:
         case 0xee:
         case 0xf6:
         case 0xfe:
             return "INC";
-
         case 0x02:
         case 0x12:
         case 0x22:

cpu/memory.c

@@ -22,7 +22,7 @@ byte mem_get_byte(address addr) {
 
     if (addr >= RAM_MAX_ADDR && addr < PPU_MAX_ADDR) {
         byte reg = (addr - RAM_MAX_ADDR) % PPU_BANK_SIZE;
-        ppu_read_register(reg);
+        ppu_sig_read_register(reg);
     }
 
     return ram[addr];
@@ -64,7 +64,7 @@ void mem_set_byte(address addr, byte byte) {
             ram[ram_addr] = byte;
         }
 
-        ppu_write_register(reg_addr);
+        ppu_sig_write_register(reg_addr);
     } else {
         ram[addr] = byte;
 

include/ppu.h

@@ -57,7 +57,7 @@ typedef struct ppu {
     byte x;
     bool w;
 
-    void (*trigger_nmi)();
+
 } PPU;
 
 PPU *ppu_get_state();
@@ -93,8 +93,8 @@ bool ppu_read_flag(size_t reg, byte mask);
  * @param reg The register index
  * @param mask The value mask
  */
-void ppu_read_register(byte reg);
+void ppu_sig_read_register(byte reg);
 
-void ppu_write_register(byte reg);
+void ppu_sig_write_register(byte reg);
 
 #endif //NESEMULATOR_PPU_H

ppu/ppu.c

@@ -15,6 +15,7 @@
 //
 
 #include "../include/ppu.h"
+#include "../cpu/cpu.h"
 
 PPU ppu_state;
 
@@ -44,6 +45,15 @@ void ppu_status_set(byte mask, bool enabled) {
     }
 }
 
+void ppu_trigger_vbl_nmi() {
+    if (!ppu_read_flag(PPU_REGISTER_CTRL, PPU_CTRL_GEN_VBLANK_NMI)) {
+        // VBlank NMI generation is disabled
+        return;
+    }
+
+    cpu_trigger_nmi();
+}
+
 long frame = 0;
 int x, y = 0;
 
@@ -52,6 +62,7 @@ void ppu_cycle() {
         if (y == 241) {
             // VBlank start
             ppu_status_set(PPU_STATUS_VBLANK, true);
+            ppu_trigger_vbl_nmi();
         }
 
         if (y == 261) {
@@ -87,17 +98,26 @@ bool ppu_read_flag(size_t reg, byte mask) {
     return ppu_state.registers[reg] & mask;
 }
 
-//byte ppu_read_register(size_t reg, byte mask) {
+//byte ppu_sig_read_register(size_t reg, byte mask) {
 //    return ppu_state.registers[reg] & mask;
 //}
 
-void ppu_read_register(byte reg) {
+void ppu_sig_read_register(byte reg) {
     if (reg == PPU_REGISTER_STATUS) {
         ppu_state.w = false;
     }
 }
 
-void ppu_write_register(byte reg) {
+void ppu_sig_write_register(byte reg) {
+    if (reg == PPU_REGISTER_ADDR) {
+        byte addr_write = ppu_state.registers[PPU_REGISTER_ADDR];
+        if (!ppu_state.w) {
+            ppu_state.v &= (addr_write << 8) | 0x0f;
+        } else {
+            ppu_state.v &= 0xff & addr_write;
+        }
+    }
+
     if (reg == PPU_REGISTER_SCROLL || reg == PPU_REGISTER_ADDR) {
         ppu_state.w = !ppu_state.w;
     }

utils/linked_list.c

@@ -51,7 +51,7 @@ void linked_list_add(LinkedList *list, void *data) {
     list->size++;
 }
 
-LinkedListNode *linked_list_next(LinkedList* list) {
+LinkedListNode *linked_list_next(LinkedList *list) {
     assert(list != NULL);
 
     if (list->head == NULL) {
@@ -92,18 +92,20 @@ LinkedListNode *linked_list_get_near(LinkedList *list, int(*compute_distance)(vo
 
     LinkedListNode *near_node = list->head;
 
-    int current_distance = compute_distance(near_node->data, userdata);
-    if (current_distance == 0) {
-        return near_node;
-    }
+//    int current_distance = compute_distance(near_node->data, userdata);
+//    if (current_distance == 0) {
+//        return near_node;
+//    }
 
-    // TODO
-    int last_distance = 0x7fffffff;
-    LinkedListNode *node = near_node->next;
-    while (current_distance < last_distance && near_node->next != NULL) {
-        node = near_node->next;
-        last_distance = current_distance;
-        current_distance = compute_distance(node->data, userdata);
+    int current_distance = 0x7fffffff;
+    while (near_node->next != NULL && current_distance != 0) {
+        int next_distance = compute_distance(near_node->next->data, userdata);
+        if (next_distance > current_distance) {
+            break;
+        }
+
+        near_node = near_node->next;
+        current_distance = next_distance;
     }
 
     // After the loop, we have found the nearest node in the list, assuming there is only one point of convergence