1 files changed, 37 insertions, 11 deletions

diff --git a/mappers/mapper.c b/mappers/mapper.c
index 5636705..0b5612b 100644
--- a/mappers/mapper.c
+++ b/mappers/mapper.c
@@ -18,9 +18,32 @@ static void mapper_default_ciram_write(struct nes_state *state, uint32_t addr, u
 	state->ciram[addr] = value;
 }
 
-static void mapper_default_prg_write(struct nes_state *state, uint32_t addr, uint8_t value) { }
-static void mapper_default_chr_write(struct nes_state *state, uint32_t addr, uint8_t value) { }
-static void mapper_default_tick(struct nes_state *state) { }
+// static void mapper_default_prg_rom_write(struct nes_state *state, uint32_t addr, uint8_t value) { }
+// static uint8_t	mapper_default_prg_ram_read(struct nes_state *state, uint32_t addr) { return 0; }
+// static void	mapper_default_prg_ram_write(struct nes_state *state, uint32_t addr, uint8_t value) { }
+// static void mapper_default_chr_write(struct nes_state *state, uint32_t addr, uint8_t value) { }
+// static void mapper_default_tick(struct nes_state *state) { }
+
+__attribute__((naked)) void mapper_default_prg_rom_write(struct nes_state *state, uint32_t addr, uint8_t value) {
+	__asm__ __volatile__("ret");
+}
+
+__attribute__((naked)) uint8_t mapper_default_prg_ram_read(struct nes_state *state, uint32_t addr) {
+	__asm__ __volatile__("xor %%al, %%al\n\t" "ret" : : : "al");
+}
+
+__attribute__((naked)) void mapper_default_prg_ram_write(struct nes_state *state, uint32_t addr, uint8_t value) {
+	__asm__ __volatile__("ret");
+}
+
+__attribute__((naked)) void mapper_default_chr_write(struct nes_state *state, uint32_t addr, uint8_t value) {
+	__asm__ __volatile__("ret");
+}
+
+__attribute__((naked)) void mapper_default_tick(struct nes_state *state) {
+	__asm__ __volatile__("ret");
+}
+
 
 #include "mapper_000_0.c"
 #include "mapper_001_0.c"
@@ -46,14 +69,17 @@ static void (*mapper_table[4096])(struct nes_state *state) = {
 	[MAPPER_ID(66, 0)] = mapper_066_0_init,
 };
 
+// NOTE(peter): The entries with 0x0 will always have to be supplied/set by the mapper!
 static void mapper_reset(struct nes_state *state) {
-	state->mapper.prg_read = 0;
-	state->mapper.prg_write = mapper_default_prg_write;
-	state->mapper.chr_read = 0;
-	state->mapper.chr_write = mapper_default_chr_write;
-	state->mapper.ciram_read = mapper_default_ciram_read;
-	state->mapper.ciram_write = mapper_default_ciram_write;
-	state->mapper.tick = mapper_default_tick;
+	state->mapper_function.prg_rom_read = 0x0;
+	state->mapper_function.prg_rom_write = mapper_default_prg_rom_write;
+	state->mapper_function.prg_ram_read = mapper_default_prg_ram_read;
+	state->mapper_function.prg_ram_write = mapper_default_prg_ram_write;
+	state->mapper_function.chr_read = 0x0;
+	state->mapper_function.chr_write = mapper_default_chr_write;
+	state->mapper_function.ciram_read = mapper_default_ciram_read;
+	state->mapper_function.ciram_write = mapper_default_ciram_write;
+	state->mapper_function.tick = 0;
 }
 
 static void mapper_setup(struct nes_state *state) {
@@ -64,7 +90,7 @@ static void mapper_setup(struct nes_state *state) {
 	if(mapper_table[mapper]) {
 		mapper_table[mapper](state);
 	} else {
-		printf("Unsupported mapper %d_%x, falling back to NROM\n", state->ines.mapper, state->ines.submapper);
+		printf("Unsupported mapper %d_%x, falling back to NROM (mapper 0)\n", state->ines.mapper, state->ines.submapper);
 		mapper_table[0](state);
 	}
 }