Mercurial > repos > blastem
view sega_mapper.c @ 1637:95880d947257
Fix for VRAM byte write order broke VDP FIFO testing ROM results. This change cleans up VRAM writes and fixes the regression while preserving the correct VRAM byte write order
author | Michael Pavone <pavone@retrodev.com> |
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date | Sun, 11 Nov 2018 22:39:29 -0800 |
parents | 14a2834d010c |
children | 75172d440900 d60f2d7c02a5 |
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#include "genesis.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->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; } 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) { //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 { void *new_ptr = gen->cart + 0x40000*value; 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; } } return context; } m68k_context * write_bank_reg_b(uint32_t address, m68k_context * context, uint8_t value) { 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, sizeof(gen->bank_regs)); } void sega_mapper_deserialize(deserialize_buffer *buf, genesis_context *gen) { for (int i = 0; i < sizeof(gen->bank_regs); i++) { write_bank_reg_w(i * 2, gen->m68k, load_int8(buf)); } }