Mercurial > repos > blastem
diff sega_mapper.c @ 1415:f7d653bb8899
Move Sega mapper implementation out of romdb.c
author | Michael Pavone <pavone@retrodev.com> |
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date | Fri, 23 Jun 2017 23:16:44 -0700 |
parents | |
children | 14a2834d010c |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/sega_mapper.c Fri Jun 23 23:16:44 2017 -0700 @@ -0,0 +1,135 @@ +#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; +}