Mercurial > repos > blastem
diff realtec.c @ 1259:23c94f5266d1
Support for the Realtec mapper. Needs testing with games besides The Earth Defend
author | Michael Pavone <pavone@retrodev.com> |
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date | Thu, 02 Mar 2017 21:08:33 -0800 |
parents | |
children | f13f51e9f9f2 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/realtec.c Thu Mar 02 21:08:33 2017 -0800 @@ -0,0 +1,128 @@ +#include <stdint.h> +#include <stdlib.h> +#include <string.h> +#include "romdb.h" +#include "genesis.h" +#include "util.h" + +typedef struct { + uint8_t rom_space[512*1024]; + uint8_t regs[3]; +} realtec; + + +uint8_t realtec_detect(uint8_t *rom, uint32_t rom_size) +{ + //All Realtec mapper games are 512KB total + if (rom_size != 512*1024) { + return 0; + } + return memcmp(rom + 0x7E100, "SEGA", 4) == 0; +} + +static void *realtec_write_b(uint32_t address, void *context, uint8_t value) +{ + if (address & 1) { + return context; + } + m68k_context *m68k = context; + genesis_context *gen = m68k->system; + if (!gen->extra) { + gen->extra = m68k->mem_pointers[0]; + } + realtec *r = gen->extra; + uint32_t offset = address >> 13; + uint8_t dirty = 0; + if (offset < 3 && r->regs[offset] != value) { + r->regs[offset] = value; + //other regs are only 3 bits, so assume 3 for this one too + uint32_t size = (r->regs[1] & 0x7) << 17; + uint32_t start = (r->regs[2] & 7) << 17 | (r->regs[0] & 6) << 19; + if (size > 512*1024) { + size = 512*1024; + } + for(uint32_t cur = 0; cur < 512*1024; cur += size) + { + if (start + size > 512*1024) { + memcpy(r->rom_space + cur, gen->cart + start/2, 512*1024-start); + //assume it wraps + memcpy(r->rom_space + cur + 512*1024-start, gen->cart, size - (512*1024-start)); + } else { + memcpy(r->rom_space + cur, gen->cart + start/2, size); + } + } + m68k_invalidate_code_range(gen->m68k, 0, 0x400000); + } + return context; +} + +static void *realtec_write_w(uint32_t address, void *context, uint16_t value) +{ + return realtec_write_b(address, context, value >> 8); +} + +rom_info realtec_configure_rom(uint8_t *rom, uint32_t rom_size, memmap_chunk const *base_map, uint32_t base_chunks) +{ + rom_info info; + realtec *r = calloc(sizeof(realtec), 1); + for (uint32_t i = 0; i < 512*1024; i += 8*1024) + { + memcpy(r->rom_space + i, rom + 0x7E000, 8*1024); + } + byteswap_rom(512*1024, (uint16_t *)r->rom_space); + + uint8_t *name_start = NULL, *name_end = NULL; + for (int i = 0x90; i < 0xE0; i++) + { + if (name_start) { + if (rom[i] < ' ' || rom[i] > 0x80 || !memcmp(rom+i, "ARE", 3)) { + name_end = rom+i; + break; + } + } else if (rom[i] > ' ' && rom[i] < 0x80) { + name_start = rom + i; + } + } + if (name_start && !name_end) { + name_end = rom + 0xE0; + } + if (name_end) { + while (name_end > name_start && name_end[-1] == ' ') + { + name_end--; + } + info.name = malloc(name_end-name_start+1); + memcpy(info.name, name_start, name_end-name_start); + info.name[name_end-name_start] = 0; + } else { + info.name = strdup("Realtec Game"); + } + info.save_type = SAVE_NONE; + info.save_size = 0; + info.save_buffer = NULL; + info.num_eeprom = 0; + info.eeprom_map = NULL; + info.port1_override = info.port2_override = info.ext_override = info.mouse_mode = NULL; + info.map_chunks = base_chunks + 2; + info.map = calloc(sizeof(memmap_chunk), info.map_chunks); + info.map[0].mask = sizeof(r->rom_space)-1; + info.map[0].flags = MMAP_READ|MMAP_CODE|MMAP_PTR_IDX; + info.map[0].start = 0; + info.map[0].end = 0x400000; + info.map[0].buffer = r->rom_space; + info.map[0].write_16 = NULL; + info.map[0].read_16 = NULL; + info.map[0].write_8 = NULL; + info.map[0].read_8 = NULL; + info.map[1].mask = 0x7FFF; + info.map[1].flags = 0; + info.map[1].start = 0x400000; + info.map[1].end = 0x800000; + info.map[1].write_16 = realtec_write_w; + info.map[1].write_8 = realtec_write_b; + info.map[1].read_16 = NULL; + info.map[1].read_8 = NULL; + memcpy(info.map + 2, base_map, base_chunks * sizeof(memmap_chunk)); + + return info; +}