Add IRQ to MMC3 mapper

- Gun Nac still crashing after first title screen
 - SMB3 halts after game start

src/map/mmc3.c

@@ -55,21 +55,15 @@ static inline void mmc3_update_rom_mode(mmc3_mapper* map) {
 static inline void mmc3_update_prg(mmc3_mapper* map, uint8_t bank) {
     int reg = (map->bank_select & mmc3_Bank_Select_Reg);
 
-    if (!(map->bank_select & mmc3_Bank_Select_PRG)) {
-        if (reg == 7) {
-            mmc3_map_prg(map, 1, bank);
-        } else {
-            mmc3_map_prg(map, 0, bank);
-        }
-
+    if (reg == 7) {
+        mmc3_map_prg(map, 1, bank);
     } else {
-        if (reg == 7) {
-            mmc3_map_prg(map, 1, bank);
+        if (!(map->bank_select & mmc3_Bank_Select_PRG)) {
+            mmc3_map_prg(map, 0, bank);
         } else {
             mmc3_map_prg(map, 2, bank);
         }
     }
-
 }
 
 static inline uint8_t* mmc3_chr_bank(mmc3_mapper* map, int bank) {
@@ -169,7 +163,7 @@ static uint8_t mmc3_read(nes_mapper* nes_map, uint16_t addr) {
     } else if ( addr >= nes_mem_wram_start &&
                 (map->flags & mmc3_Flag_WRAM_Enabled)) {
         ptr = mmc3_wram_addr(map, addr);
-        MAP_LOG("WRAM: $%04x > %02x", addr, *ptr);
+//        MAP_LOG("WRAM: $%04x > %02x", addr, *ptr);
     }
 
     uint8_t val = (NULL == ptr ? 0 : *ptr);
@@ -226,16 +220,36 @@ static void mmc3_write(nes_mapper* nes_map,
 
     } else if (addr < 0xE000U) {
         if (addr & 1) {
-            // TODO: IRQ reload
+            MAP_LOG("IRQ Reload");
+            map->irq_count = 0;
         } else {
-            // TODO: IRQ latch
+            MAP_LOG("IRQ Latch: %d", val);
+            map->irq_latch = val;
         }
 
     } else {
+        MAP_LOG("IRQ %s", (addr & 1) ? "Enable" : "Disable");
         if (addr & 1) {
-            // TODO: IRQ enable
+            map->flags |= mmc3_Flag_IRQ_Enabled;
         } else {
-            // TODO: IRQ disable
+            map->flags &= ~mmc3_Flag_IRQ_Enabled;
+            nes_map_trigger_irq(nes_map, 0);
+        }
+    }
+}
+
+static void mmc3_scanline(nes_mapper* nes_map) {
+    mmc3_mapper* map = (mmc3_mapper*)nes_map->data;
+
+    if (map->irq_count == 0) {
+        map->irq_count = map->irq_latch;
+
+    } else {
+        map->irq_count--;
+        if (    map->irq_count <= 0 &&
+                (map->flags & mmc3_Flag_IRQ_Enabled)) {
+            MAP_LOG("IRQ Trigger");
+            nes_map_trigger_irq(nes_map, 1);
         }
     }
 }
@@ -267,4 +281,5 @@ nes_mapper mapper_mmc3 = {
     .chr_addr = mmc3_chr_addr,
     .vram_addr = mmc3_vram_addr,
     .chr_write = mmc3_chr_write,
+    .scanline = mmc3_scanline,
 };

src/mapper.h

@@ -10,15 +10,23 @@
 struct nes_cart_t;
 
 typedef struct nes_mapper_t {
+    void* data;
+
     int (*init)(struct nes_mapper_t*, struct nes_cart_t* cart);
     void (*reset)(struct nes_mapper_t*);
     void (*done)(struct nes_mapper_t*);
+
     uint8_t (*read)(struct nes_mapper_t*, uint16_t addr);
     void (*write)(struct nes_mapper_t*, uint16_t addr, uint8_t val);
+
     uint8_t* (*chr_addr)(struct nes_mapper_t*, uint16_t addr);
     uint8_t* (*vram_addr)(struct nes_mapper_t*, uint16_t addr);
     void (*chr_write)(struct nes_mapper_t*, uint16_t addr, uint8_t val);
-    void* data;
+
+    void (*scanline)(struct nes_mapper_t*);
+    void (*irq_callback)(void*, int);
+    void* irq_arg;
+
 } nes_mapper;
 
 static inline int nes_map_init(nes_mapper* map,
@@ -34,6 +42,18 @@ static inline void nes_map_done(nes_mapper* map) {
     map->done(map);
 }
 
+static inline void nes_map_set_irq(nes_mapper* map,
+                                   void(*callback)(void*, int),
+                                   void* arg) {
+    map->irq_callback = callback;
+    map->irq_arg = arg;
+}
+
+static inline void nes_map_trigger_irq(nes_mapper* map,
+                                       int active) {
+    map->irq_callback(map->irq_arg, active);
+}
+
 static inline uint8_t nes_map_read(nes_mapper* map,
                                        uint16_t addr) {
     return map->read(map, addr);
@@ -75,6 +95,7 @@ static inline void nes_vram_write(nes_mapper* map,
     *(nes_map_vram_addr(map, addr)) = val;
 }
 
+
 extern nes_mapper* nes_mappers[];
 
 

src/nes.c

@@ -58,9 +58,14 @@ void nes_mem_write(nes* sys, uint16_t addr, uint8_t val) {
     }
 }
 
+static void nes_irq(void* sys, int active) {
+    e6502_set_irq(&((nes*)sys)->cpu, active);
+}
+
 int nes_init(nes* sys) {
     e6502_init(&sys->cpu, (e6502_Read*)nes_mem_read,
                (e6502_Write*)nes_mem_write, sys);
+    nes_map_set_irq(sys->cart.mapper, nes_irq, sys);
     return nes_ppu_init(&sys->ppu, &sys->cart);
 }
 

src/ppu.c

@@ -195,7 +195,15 @@ int nes_ppu_init(nes_ppu* ppu, const nes_cart* cart) {
 int nes_ppu_run(nes_ppu* ppu, int cycles) {
     nes_ppu_Result result = ppu_Result_Running;
 
-    ppu->cycle += cycles;
+    int next_cycle = ppu->cycle + cycles;
+
+    if (    NULL != ppu->mapper->scanline &&
+            ppu->scanline < nes_ppu_render &&
+            ppu->cycle < 260 && next_cycle >= 260) {
+        ppu->mapper->scanline(ppu->mapper);
+    }
+
+    ppu->cycle = next_cycle;
 
     while (ppu->cycle >= nes_ppu_dots) {
         ppu->cycle -= nes_ppu_dots;

src/ppu.h

@@ -38,9 +38,9 @@ struct nes_cart_t;
 #define nes_ppu_postrender  (1U)
 #define nes_ppu_vblank      (20U)
 
-#define nes_ppu_active  (nes_ppu_prerender + \
-                         nes_ppu_height +    \
-                         nes_ppu_postrender)
+#define nes_ppu_render  (nes_ppu_prerender + nes_ppu_height)
+
+#define nes_ppu_active  (nes_ppu_render + nes_ppu_postrender)
 
 #define nes_ppu_frame   (nes_ppu_active + nes_ppu_vblank)