From 030724a9aea346e4a9843d5842fb28c6d6c4cf1a Mon Sep 17 00:00:00 2001
From: Peter Fors <peter.fors@mindkiller.com>
Date: Thu, 9 Oct 2025 22:07:52 +0200
Subject: Rearrangement and refactoring and optimizations and more accuracy

---
 mknes_mapper.c | 112 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 112 insertions(+)
 create mode 100644 mknes_mapper.c

(limited to 'mknes_mapper.c')

diff --git a/mknes_mapper.c b/mknes_mapper.c
new file mode 100644
index 0000000..32e8017
--- /dev/null
+++ b/mknes_mapper.c
@@ -0,0 +1,112 @@
+
+#define MIRROR_HORIZONTAL       0
+#define MIRROR_VERTICAL         1
+#define MIRROR_FOUR_SCREEN      2
+#define MIRROR_ONESCREEN_LOW    3
+#define MIRROR_ONESCREEN_HIGH   4
+
+
+static uint8_t mapper_default_ciram_read(struct nes_state *state, uint32_t addr) {
+	if(state->ines.mirroring == MIRROR_HORIZONTAL) { // Horizontal: NT0↔NT1, NT2↔NT3
+		addr = ((addr >> 1) & 0x400) | (addr & 0x3ff);
+	} else { // Vertical (default fallback): NT0↔NT2, NT1↔NT3
+		addr = addr & 0x7ff;
+	}
+
+	return state->ciram[addr];
+}
+
+static void mapper_default_ciram_write(struct nes_state *state, uint32_t addr, uint8_t value) {
+	if(state->ines.mirroring == MIRROR_HORIZONTAL) { // Horizontal: NT0↔NT1, NT2↔NT3
+		addr = ((addr >> 1) & 0x400) | (addr & 0x3ff);
+	} else { // Vertical (default fallback): NT0↔NT2, NT1↔NT3
+		addr = addr & 0x7ff;
+	}
+	state->ciram[addr] = value;
+}
+
+__attribute__((naked, no_instrument_function, no_profile_instrument_function)) static void mapper_default_prg_rom_write(struct nes_state *state, uint32_t addr, uint8_t value) {
+	__asm__ __volatile__("ret");
+}
+
+__attribute__((naked, no_instrument_function, no_profile_instrument_function)) static 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, no_instrument_function, no_profile_instrument_function)) static void mapper_default_prg_ram_write(struct nes_state *state, uint32_t addr, uint8_t value) {
+	__asm__ __volatile__("ret");
+}
+
+__attribute__((naked, no_instrument_function, no_profile_instrument_function)) static void mapper_default_chr_write(struct nes_state *state, uint32_t addr, uint8_t value) {
+	__asm__ __volatile__("ret");
+}
+
+// __attribute__((naked, no_instrument_function, no_profile_instrument_function)) static void mapper_default_tick(struct nes_state *state) {
+// 	__asm__ __volatile__("ret");
+// }
+
+
+#include "mappers/mapper_000_0.c"
+#include "mappers/mapper_001_0.c"
+#include "mappers/mapper_002_2.c"
+#include "mappers/mapper_003_0.c"
+#include "mappers/mapper_003_1.c"
+#include "mappers/mapper_003_2.c"
+#include "mappers/mapper_007_2.c"
+#include "mappers/mapper_011_0.c"
+#include "mappers/mapper_066_0.c"
+
+#define MAPPER_ID(mapper, submapper) (((mapper) << 4) | (submapper))
+
+struct supported_mapper {
+	uint32_t id;
+	void (*mapper_init)(struct nes_state *state);
+};
+
+static struct supported_mapper supported_mappers[] = {
+	{ MAPPER_ID( 0, 0), mapper_000_0_init },
+	{ MAPPER_ID( 1, 0), mapper_001_0_init },
+	{ MAPPER_ID( 2, 2), mapper_002_2_init },
+	{ MAPPER_ID( 3, 0), mapper_003_0_init },
+	{ MAPPER_ID( 3, 1), mapper_003_1_init },
+	{ MAPPER_ID( 3, 2), mapper_003_2_init },
+	{ MAPPER_ID( 7, 2), mapper_007_2_init },
+	{ MAPPER_ID(11, 0), mapper_011_0_init },
+	{ MAPPER_ID(66, 0), mapper_066_0_init },
+	{ 0, 0 }
+};
+
+// 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_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) {
+	uint32_t mapper_id = state->ines.mapper << 4 | state->ines.submapper;
+	printf("Mapper %d_%x requested.\n", state->ines.mapper, state->ines.submapper);
+
+	mapper_reset(state);
+
+	struct supported_mapper *m = supported_mappers;
+
+	while(m->mapper_init) {
+		if(m->id == mapper_id) {
+			m->mapper_init(state);
+			return;
+		}
+		m++;
+	}
+
+	printf("Unsupported mapper %d_%x, falling back to NROM (mapper 0)\n", state->ines.mapper, state->ines.submapper);
+	mapper_000_0_init(state);
+
+}
+
-- 
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