1#include <stdint.h>
  2#include <stdlib.h>
  3#include <string.h>
  4#include "romdb.h"
  5#include "genesis.h"
  6#include "util.h"
  7
  8typedef struct {
  9	uint8_t rom_space[512*1024];
 10	uint8_t regs[3];
 11} realtec;
 12
 13
 14uint8_t realtec_detect(uint8_t *rom, uint32_t rom_size)
 15{
 16	//All Realtec mapper games are 512KB total
 17	if (rom_size != 512*1024) {
 18		return 0;
 19	}
 20	return memcmp(rom + 0x7E100, "SEGA", 4) == 0;
 21}
 22
 23static realtec *get_realtec(genesis_context *gen)
 24{
 25	if (!gen->extra) {
 26		gen->extra = gen->m68k->mem_pointers[0];
 27	}
 28	return gen->extra;
 29}
 30
 31static void *realtec_write_b(uint32_t address, void *context, uint8_t value)
 32{
 33	if (address & 1) {
 34		return context;
 35	}
 36	m68k_context *m68k = context;
 37	genesis_context *gen = m68k->system;
 38	realtec *r = get_realtec(gen);
 39	uint32_t offset = address >> 13;
 40	if (offset < 3 && r->regs[offset] != value) {
 41		r->regs[offset] = value;
 42		//other regs are only 3 bits, so assume 3 for this one too
 43		uint32_t size = (r->regs[1] & 0x7) << 17;
 44		uint32_t start = (r->regs[2] & 7) << 17 | (r->regs[0] & 6) << 19;
 45		if (!size || size > 512*1024) {
 46			size = 512*1024;
 47		}
 48		for(uint32_t cur = 0; cur < 512*1024; cur += size)
 49		{
 50			if (start + size > 512*1024) {
 51				memcpy(r->rom_space + cur, gen->cart + start/2, 512*1024-start);
 52				//assume it wraps
 53				memcpy(r->rom_space + cur + 512*1024-start, gen->cart, size - (512*1024-start));
 54			} else {
 55				memcpy(r->rom_space + cur, gen->cart + start/2, size);
 56			}
 57		}
 58		m68k_invalidate_code_range(gen->m68k, 0, 0x400000);
 59	}
 60	return context;
 61}
 62
 63static void *realtec_write_w(uint32_t address, void *context, uint16_t value)
 64{
 65	return realtec_write_b(address, context, value >> 8);
 66}
 67
 68void realtec_serialize(genesis_context *gen, serialize_buffer *buf)
 69{
 70	realtec *r = get_realtec(gen);
 71	save_buffer8(buf, r->regs, sizeof(r->regs));
 72}
 73
 74void realtec_deserialize(deserialize_buffer *buf, genesis_context *gen)
 75{
 76	realtec *r = get_realtec(gen);
 77	for (int i = 0; i < sizeof(r->regs); i++)
 78	{
 79		realtec_write_b(i << 13, gen->m68k, load_int8(buf));
 80	}
 81}
 82
 83rom_info realtec_configure_rom(uint8_t *rom, uint32_t rom_size, memmap_chunk const *base_map, uint32_t base_chunks)
 84{
 85	rom_info info;
 86	realtec *r = calloc(sizeof(realtec), 1);
 87	for (uint32_t i = 0; i < 512*1024; i += 8*1024)
 88	{
 89		memcpy(r->rom_space + i, rom + 0x7E000, 8*1024);
 90	}
 91	byteswap_rom(512*1024, (uint16_t *)r->rom_space);
 92	
 93	uint8_t *name_start = NULL, *name_end = NULL;
 94	for (int i = 0x94; i < 0xE0; i++)
 95	{
 96		if (name_start) {
 97			if (rom[i] < ' ' || rom[i] > 0x80 || !memcmp(rom+i, "ARE", 3) || !memcmp(rom+i, "are", 3)) {
 98				name_end = rom+i;
 99				break;
100			}
101		} else if (rom[i] > ' ' && rom[i] < 0x80 && rom[i] != ':') {
102			name_start = rom + i;
103		}
104	}
105	if (name_start && !name_end) {
106		name_end = rom + 0xE0;
107	}
108	if (name_end) {
109		while (name_end > name_start && name_end[-1] == ' ')
110		{
111			name_end--;
112		}
113		info.name = malloc(name_end-name_start+1);
114		memcpy(info.name, name_start, name_end-name_start);
115		info.name[name_end-name_start] = 0;
116	} else {
117		info.name = strdup("Realtec Game");
118	}
119	info.save_type = SAVE_NONE;
120	info.save_size = 0;
121	info.save_buffer = NULL;
122	info.num_eeprom = 0;
123	info.eeprom_map = NULL;
124	info.rom = rom;
125	info.rom_size = rom_size;
126	info.mapper_type = MAPPER_REALTEC;
127	info.is_save_lock_on = 0;
128	info.port1_override = info.port2_override = info.ext_override = info.mouse_mode = NULL;
129	info.map_chunks = base_chunks + 2;
130	info.map = calloc(sizeof(memmap_chunk), info.map_chunks);
131	info.map[0].mask = sizeof(r->rom_space)-1;
132	info.map[0].flags = MMAP_READ|MMAP_CODE|MMAP_PTR_IDX;
133	info.map[0].start = 0;
134	info.map[0].end = 0x400000;
135	info.map[0].buffer = r->rom_space;
136	info.map[0].write_16 = NULL;
137	info.map[0].read_16 = NULL;
138	info.map[0].write_8 = NULL;
139	info.map[0].read_8 = NULL;
140	info.map[1].mask = 0x7FFF;
141	info.map[1].flags = 0;
142	info.map[1].start = 0x400000;
143	info.map[1].end = 0x800000;
144	info.map[1].write_16 = realtec_write_w;
145	info.map[1].write_8 = realtec_write_b;
146	info.map[1].read_16 = NULL;
147	info.map[1].read_8 = NULL;
148	memcpy(info.map + 2, base_map, base_chunks * sizeof(memmap_chunk));
149	
150	return info;
151}