Add CHR RAM support to NROM (homebrew and testing only)

src/map/nrom.c

@@ -22,7 +22,11 @@ static int nrom_init(nes_mapper* nes_map, nes_cart* cart) {
     if (NULL != map) {
         map->prg_rom       = cart->prg_rom;
         map->prg_rom_banks = cart->prg_rom_banks;
-        map->chr_rom       = cart->chr_rom;
+        if (cart->chr_rom_banks <= 0) {
+            map->chr_rom = calloc(8, 1024);
+        } else {
+            map->chr_rom = cart->chr_rom;
+        }
         map->chr_rom_banks = cart->chr_rom_banks;
         map->mirror = (cart->flags & Cart_Flag_Horizontal) ? 0 : 1;
     }
@@ -30,7 +34,13 @@ static int nrom_init(nes_mapper* nes_map, nes_cart* cart) {
 }
 
 static void nrom_done(nes_mapper* nes_map) {
-    free(nes_map->data);
+    nrom_mapper* map = (nrom_mapper*)nes_map->data;
+    if (NULL != map) {
+        if (map->chr_rom_banks <= 0) {
+            free(map->chr_rom);
+        }
+        free(nes_map->data);
+    }
 }
 
 static inline uint8_t* nrom_prg_addr(nrom_mapper* map,
@@ -78,10 +88,13 @@ static uint8_t* nrom_vram_addr(nes_mapper* nes_map,
     return &map->vram[addr];
 }
 
-static void nrom_chr_write(nes_mapper* map,
+static void nrom_chr_write(nes_mapper* nes_map,
                            uint16_t addr, uint8_t val) {
-    // ROM only.
-    printf("CHR ROM Write: $%04x < %02x\n", addr, val);
+    nrom_mapper* map = (nrom_mapper*)nes_map->data;
+    if (map->chr_rom_banks <= 0) {
+        *(nrom_chr_addr(nes_map, addr)) = val;
+    }
+//    printf("CHR ROM Write: $%04x < %02x\n", addr, val);
 }
 
 nes_mapper mapper_nrom = {