--- a/romdb.c	Thu Jul 02 20:43:01 2015 -0700
+++ b/romdb.c	Sun Jul 05 14:21:34 2015 -0700
@@ -3,13 +3,140 @@
 #include "config.h"
 #include "romdb.h"
 #include "util.h"
+#include "blastem.h"
 
 #define TITLE_START 0x150
 #define TITLE_END (TITLE_START+48)
 #define GAME_ID_OFF 0x183
 #define GAME_ID_LEN 8
+#define ROM_END   0x1A4
+#define RAM_ID    0x1B0
+#define RAM_FLAGS 0x1B2
+#define RAM_START 0x1B4
+#define RAM_END   0x1B8
 #define REGION_START 0x1F0
 
+uint16_t read_sram_w(uint32_t address, m68k_context * context)
+{
+	genesis_context * gen = context->system;
+	address &= gen->save_ram_mask;
+	switch(gen->save_flags)
+	{
+	case RAM_FLAG_BOTH:
+		return gen->save_ram[address] << 8 | gen->save_ram[address+1];
+	case RAM_FLAG_EVEN:
+		return gen->save_ram[address >> 1] << 8 | 0xFF;
+	case RAM_FLAG_ODD:
+		return gen->save_ram[address >> 1] | 0xFF00;
+	}
+	return 0xFFFF;//We should never get here
+}
+
+uint8_t read_sram_b(uint32_t address, m68k_context * context)
+{
+	genesis_context * gen = context->system;
+	address &= gen->save_ram_mask;
+	switch(gen->save_flags)
+	{
+	case RAM_FLAG_BOTH:
+		return gen->save_ram[address];
+	case RAM_FLAG_EVEN:
+		if (address & 1) {
+			return 0xFF;
+		} else {
+			return gen->save_ram[address >> 1];
+		}
+	case RAM_FLAG_ODD:
+		if (address & 1) {
+			return gen->save_ram[address >> 1];
+		} else {
+			return 0xFF;
+		}
+	}
+	return 0xFF;//We should never get here
+}
+
+m68k_context * write_sram_area_w(uint32_t address, m68k_context * context, uint16_t value)
+{
+	genesis_context * gen = context->system;
+	if ((gen->bank_regs[0] & 0x3) == 1) {
+		address &= gen->save_ram_mask;
+		switch(gen->save_flags)
+		{
+		case RAM_FLAG_BOTH:
+			gen->save_ram[address] = value >> 8;
+			gen->save_ram[address+1] = value;
+			break;
+		case RAM_FLAG_EVEN:
+			gen->save_ram[address >> 1] = value >> 8;
+			break;
+		case RAM_FLAG_ODD:
+			gen->save_ram[address >> 1] = value;
+			break;
+		}
+	}
+	return context;
+}
+
+m68k_context * write_sram_area_b(uint32_t address, m68k_context * context, uint8_t value)
+{
+	genesis_context * gen = context->system;
+	if ((gen->bank_regs[0] & 0x3) == 1) {
+		address &= gen->save_ram_mask;
+		switch(gen->save_flags)
+		{
+		case RAM_FLAG_BOTH:
+			gen->save_ram[address] = value;
+			break;
+		case RAM_FLAG_EVEN:
+			if (!(address & 1)) {
+				gen->save_ram[address >> 1] = value;
+			}
+			break;
+		case RAM_FLAG_ODD:
+			if (address & 1) {
+				gen->save_ram[address >> 1] = value;
+			}
+			break;
+		}
+	}
+	return context;
+}
+
+m68k_context * write_bank_reg_w(uint32_t address, m68k_context * context, uint16_t value)
+{
+	genesis_context * gen = context->system;
+	address &= 0xE;
+	address >>= 1;
+	gen->bank_regs[address] = value;
+	if (!address) {
+		if (value & 1) {
+			context->mem_pointers[2] = NULL;
+		} else {
+			context->mem_pointers[2] = cart + 0x200000/2;
+		}
+	}
+	return context;
+}
+
+m68k_context * write_bank_reg_b(uint32_t address, m68k_context * context, uint8_t value)
+{
+	if (address & 1) {
+		genesis_context * gen = context->system;
+		address &= 0xE;
+		address >>= 1;
+		gen->bank_regs[address] = value;
+		if (!address) {
+			if (value & 1) {
+				context->mem_pointers[2] = NULL;
+			} else {
+				context->mem_pointers[2] = cart + 0x200000/2;
+			}
+		}
+	}
+	return context;
+}
+
 tern_node *load_rom_db()
 {
 	char *exe_dir = get_exe_dir();
@@ -77,16 +204,96 @@
 	return regions;
 }
 
+uint32_t get_u32be(uint8_t *data)
+{
+	return *data << 24 | data[1] << 16 | data[2] << 8 | data[3];
+}
 
-rom_info configure_rom_heuristics(uint8_t *rom)
+void add_memmap_header(rom_info *info, uint8_t *rom, uint32_t size, memmap_chunk const *base_map, int base_chunks)
+{
+	if (rom[RAM_ID] == 'R' && rom[RAM_ID+1] == 'A') {
+		uint32_t rom_end = get_u32be(rom + ROM_END) + 1;
+		uint32_t ram_start = get_u32be(rom + RAM_START);
+		uint32_t ram_end = get_u32be(rom + RAM_END);
+		uint32_t ram_flags = info->save_type = rom[RAM_FLAGS] & RAM_FLAG_MASK;
+		ram_start &= 0xFFFFFE;
+		ram_end |= 1;
+		
+		info->map_chunks = base_chunks + (ram_start >= rom_end ? 2 : 3);
+		info->map = malloc(sizeof(memmap_chunk) * info->map_chunks);
+		memset(info->map, 0, sizeof(memmap_chunk)*2);
+		memcpy(info->map+2, base_map, sizeof(memmap_chunk) * base_chunks);
+		
+		if (ram_start >= rom_end) {
+			info->map[0].end = rom_end;
+			//TODO: ROM mirroring
+			info->map[0].mask = 0xFFFFFF;
+			info->map[0].flags = MMAP_READ;
+			info->map[0].buffer = rom;
+			
+			info->map[1].start = ram_start;
+			info->map[1].mask = ram_end - ram_start;
+			info->map[1].end = ram_end + 1;
+			info->map[1].flags = MMAP_READ | MMAP_WRITE;
+			uint32_t size = info->map[1].mask + 1;
+			if (ram_flags == RAM_FLAG_ODD) {
+				info->map[1].flags |= MMAP_ONLY_ODD;
+				size /= 2;
+			} else if (ram_flags == RAM_FLAG_EVEN) {
+				info->map[1].flags |= MMAP_ONLY_EVEN;
+				size /= 2;
+			}
+			info->map[1].buffer = malloc(size);
+		} else {
+			//Assume the standard Sega mapper
+			info->map[0].end = 0x200000;
+			info->map[0].mask = 0xFFFFFF;
+			info->map[0].flags = MMAP_READ;
+			info->map[0].buffer = rom;
+			
+			info->map[1].start = 0x200000;
+			info->map[1].end = 0x400000;
+			info->map[1].mask = 0x1FFFFF;
+			info->map[1].flags = MMAP_READ | MMAP_PTR_IDX | MMAP_FUNC_NULL;
+			info->map[1].ptr_index = 2;
+			info->map[1].read_16 = (read_16_fun)read_sram_w;//these will only be called when mem_pointers[2] == NULL
+			info->map[1].read_8 = (read_8_fun)read_sram_b;
+			info->map[1].write_16 = (write_16_fun)write_sram_area_w;//these will be called all writes to the area
+			info->map[1].write_8 = (write_8_fun)write_sram_area_b;
+			info->map[1].buffer = cart + 0x200000;
+			
+			memmap_chunk *last = info->map + info->map_chunks - 1;
+			memset(last, 0, sizeof(memmap_chunk));
+			last->start = 0xA13000;
+			last->end = 0xA13100;
+			last->mask = 0xFF;
+			last->write_16 = (write_16_fun)write_bank_reg_w;
+			last->write_8 = (write_8_fun)write_bank_reg_b;
+		}
+	} else {
+		info->map_chunks = base_chunks + 1;
+		info->map = malloc(sizeof(memmap_chunk) * info->map_chunks);
+		memset(info->map, 0, sizeof(memmap_chunk));
+		memcpy(info->map+1, base_map, sizeof(memmap_chunk) * base_chunks);
+		
+		info->map[0].end = 0x400000;
+		info->map[0].mask = 0xFFFFFF;
+		info->map[0].flags = MMAP_READ;
+		info->map[0].buffer = rom;
+		info->save_type = SAVE_NONE;
+	}
+}
+
+rom_info configure_rom_heuristics(uint8_t *rom, uint32_t rom_size, memmap_chunk const *base_map, uint32_t base_chunks)
 {
 	rom_info info;
 	info.name = get_header_name(rom);
 	info.regions = get_header_regions(rom);
+	add_memmap_header(&info, rom, rom_size, base_map, base_chunks);
 	return info;
 }
 
-rom_info configure_rom(tern_node *rom_db, void *vrom)
+rom_info configure_rom(tern_node *rom_db, void *vrom, uint32_t rom_size, memmap_chunk const *base_map, uint32_t base_chunks)
 {
 	uint8_t product_id[GAME_ID_LEN+1];
 	uint8_t *rom = vrom;
@@ -102,7 +309,7 @@
 	}
 	tern_node * entry = tern_find_prefix(rom_db, product_id);
 	if (!entry) {
-		return configure_rom_heuristics(rom);
+		return configure_rom_heuristics(rom, rom_size, base_map, base_chunks);
 	}
 	rom_info info;
 	info.name = tern_find_ptr(entry, "name");
@@ -123,5 +330,18 @@
 	if (!info.regions) {
 		info.regions = get_header_regions(rom);
 	}
+	
+	tern_node *map = tern_find_prefix(entry, "map");
+	if (map) {
+		uint32_t map_count = tern_count(map);
+		if (map_count) {
+			
+		} else {
+			add_memmap_header(&info, rom, rom_size, base_map, base_chunks);
+		}
+	} else {
+		add_memmap_header(&info, rom, rom_size, base_map, base_chunks);
+	}
+	
 	return info;
 }