Mercurial > repos > blastem
view sega_mapper.c @ 2069:8e51c0c3f2e3 segacd
Initial attempt at implementing the Sega CD graphics hardware
author | Michael Pavone <pavone@retrodev.com> |
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date | Sun, 30 Jan 2022 19:55:33 -0800 |
parents | 3748a2a8a4b7 |
children | b6fdedd3b070 |
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#include "genesis.h" #include "util.h" uint16_t read_sram_w(uint32_t address, m68k_context * context) { genesis_context * gen = context->system; address &= gen->save_ram_mask; switch(gen->save_type) { case RAM_FLAG_BOTH: return gen->save_storage[address] << 8 | gen->save_storage[address+1]; case RAM_FLAG_EVEN: return gen->save_storage[address >> 1] << 8 | 0xFF; case RAM_FLAG_ODD: return gen->save_storage[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_type) { case RAM_FLAG_BOTH: return gen->save_storage[address]; case RAM_FLAG_EVEN: if (address & 1) { return 0xFF; } else { return gen->save_storage[address >> 1]; } case RAM_FLAG_ODD: if (address & 1) { return gen->save_storage[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->mapper_type == MAPPER_SEGA_MED_V2) { if (gen->bank_regs[8] & 0x20) { uint32_t bank = address >> 19; address &= 0x7FFFF; context->mem_pointers[gen->mapper_start_index + bank][address >> 1] = value; } return context; } if ((gen->bank_regs[0] & 0x3) == 1) { address &= gen->save_ram_mask; switch(gen->save_type) { case RAM_FLAG_BOTH: gen->save_storage[address] = value >> 8; gen->save_storage[address+1] = value; break; case RAM_FLAG_EVEN: gen->save_storage[address >> 1] = value >> 8; break; case RAM_FLAG_ODD: gen->save_storage[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_type) { case RAM_FLAG_BOTH: gen->save_storage[address] = value; break; case RAM_FLAG_EVEN: if (!(address & 1)) { gen->save_storage[address >> 1] = value; } break; case RAM_FLAG_ODD: if (address & 1) { gen->save_storage[address >> 1] = value; } break; } } return context; } static void* write_med_ram_w(uint32_t address, void *vcontext, uint16_t value, uint16_t bank) { m68k_context *context = vcontext; genesis_context * gen = context->system; if (gen->bank_regs[8] & 0x20) { context->mem_pointers[gen->mapper_start_index + bank][address >> 1] = value; address += bank * 0x80000; m68k_invalidate_code_range(gen->m68k, address, address + 2); } return vcontext; } void* write_med_ram0_w(uint32_t address, void *vcontext, uint16_t value) { return write_med_ram_w(address, vcontext, value, 0); } void* write_med_ram1_w(uint32_t address, void *vcontext, uint16_t value) { return write_med_ram_w(address, vcontext, value, 1); } void* write_med_ram2_w(uint32_t address, void *vcontext, uint16_t value) { return write_med_ram_w(address, vcontext, value, 2); } void* write_med_ram3_w(uint32_t address, void *vcontext, uint16_t value) { return write_med_ram_w(address, vcontext, value, 3); } void* write_med_ram4_w(uint32_t address, void *vcontext, uint16_t value) { return write_med_ram_w(address, vcontext, value, 4); } void* write_med_ram5_w(uint32_t address, void *vcontext, uint16_t value) { return write_med_ram_w(address, vcontext, value, 5); } void* write_med_ram6_w(uint32_t address, void *vcontext, uint16_t value) { return write_med_ram_w(address, vcontext, value, 6); } void* write_med_ram7_w(uint32_t address, void *vcontext, uint16_t value) { return write_med_ram_w(address, vcontext, value, 7); } static void* write_med_ram_b(uint32_t address, void *vcontext, uint8_t value, uint16_t bank) { m68k_context *context = vcontext; genesis_context * gen = context->system; if (gen->bank_regs[8] & 0x20) { ((uint8_t*)context->mem_pointers[gen->mapper_start_index + bank])[address ^ 1] = value; address += bank * 0x80000; m68k_invalidate_code_range(gen->m68k, address, address + 1); } return vcontext; } void* write_med_ram0_b(uint32_t address, void *vcontext, uint8_t value) { return write_med_ram_b(address, vcontext, value, 0); } void* write_med_ram1_b(uint32_t address, void *vcontext, uint8_t value) { return write_med_ram_b(address, vcontext, value, 1); } void* write_med_ram2_b(uint32_t address, void *vcontext, uint8_t value) { return write_med_ram_b(address, vcontext, value, 2); } void* write_med_ram3_b(uint32_t address, void *vcontext, uint8_t value) { return write_med_ram_b(address, vcontext, value, 3); } void* write_med_ram4_b(uint32_t address, void *vcontext, uint8_t value) { return write_med_ram_b(address, vcontext, value, 4); } void* write_med_ram5_b(uint32_t address, void *vcontext, uint8_t value) { return write_med_ram_b(address, vcontext, value, 5); } void* write_med_ram6_b(uint32_t address, void *vcontext, uint8_t value) { return write_med_ram_b(address, vcontext, value, 6); } void* write_med_ram7_b(uint32_t address, void *vcontext, uint8_t value) { return write_med_ram_b(address, vcontext, value, 7); } m68k_context * write_bank_reg_w(uint32_t address, m68k_context * context, uint16_t value) { genesis_context * gen = context->system; address &= 0xE; address >>= 1; if (!address) { if (gen->mapper_type == MAPPER_SEGA_MED_V2) { if (!value & 0x8000) { //writes without protection bit set are ignored return context; } gen->bank_regs[8] = value >> 8; void *new_ptr = gen->cart + 0x40000*(value & 0x1F); if (context->mem_pointers[gen->mapper_start_index] != new_ptr) { m68k_invalidate_code_range(gen->m68k, 0, 0x80000); context->mem_pointers[gen->mapper_start_index] = new_ptr; } } else if (value & 1) { //Used for games that only use the mapper for SRAM if (context->mem_pointers[gen->mapper_start_index]) { gen->mapper_temp = context->mem_pointers[gen->mapper_start_index]; } context->mem_pointers[gen->mapper_start_index] = NULL; //For games that need more than 4MB for (int i = 4; i < 8; i++) { context->mem_pointers[gen->mapper_start_index + i] = NULL; } } else { //Used for games that only use the mapper for SRAM if (!context->mem_pointers[gen->mapper_start_index]) { context->mem_pointers[gen->mapper_start_index] = gen->mapper_temp; } //For games that need more than 4MB for (int i = 4; i < 8; i++) { context->mem_pointers[gen->mapper_start_index + i] = gen->cart + 0x40000*gen->bank_regs[i]; } } } else if (gen->mapper_type != MAPPER_SEGA_SRAM) { uint32_t mask = ((gen->mapper_type == MAPPER_SEGA_MED_V2 ? (16 *1024 * 1024) : nearest_pow2(gen->header.info.rom_size)) >> 1) - 1; void *new_ptr = gen->cart + ((0x40000*value) & mask); if (context->mem_pointers[gen->mapper_start_index + address] != new_ptr) { m68k_invalidate_code_range(gen->m68k, address * 0x80000, (address + 1) * 0x80000); context->mem_pointers[gen->mapper_start_index + address] = new_ptr; } } gen->bank_regs[address] = value; return context; } m68k_context * write_bank_reg_b(uint32_t address, m68k_context * context, uint8_t value) { genesis_context * gen = context->system; if (gen->mapper_type == MAPPER_SEGA_MED_V2) { address &= 0xF; if (!address) { //not sure if this is correct, possible byte sized writes are always rejected to $A130F0 write_bank_reg_w(address, context, value << 8 | value); } else if (address > 2 && (address & 1)) { write_bank_reg_w(address, context, value); } } else if (address & 1) { write_bank_reg_w(address, context, value); } return context; } void sega_mapper_serialize(genesis_context *gen, serialize_buffer *buf) { save_buffer8(buf, gen->bank_regs, gen->mapper_type == MAPPER_SEGA_MED_V2 ? sizeof(gen->bank_regs) : sizeof(gen->bank_regs) - 1); } void sega_mapper_deserialize(deserialize_buffer *buf, genesis_context *gen) { if (gen->mapper_type == MAPPER_SEGA_MED_V2) { uint16_t reg0 = load_int8(buf); for (int i = 1; i < sizeof(gen->bank_regs) - 1; i++) { write_bank_reg_w(i * 2, gen->m68k, load_int8(buf)); } reg0 |= load_int8(buf) << 8; write_bank_reg_w(0, gen->m68k, reg0); } else { for (int i = 0; i < sizeof(gen->bank_regs) - 1; i++) { write_bank_reg_w(i * 2, gen->m68k, load_int8(buf)); } } }