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Adds fairly standard memory map indirection.

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This commit is contained in:
Thomas Harte 2018-09-23 17:36:30 -04:00
parent 00b2db4fb9
commit e155dc8d6e
1 changed files with 34 additions and 20 deletions
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54
Machines/MasterSystem/MasterSystem.cpp
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@ -42,13 +42,29 @@ class ConcreteMachine:
speaker_.set_input_rate(3579545.0f / static_cast<float>(sn76489_divider));
set_clock_rate(3579545);
const auto roms = rom_fetcher("MasterSystem", {"bios.sms"});
if(!roms[0]) {
throw ROMMachine::Error::MissingROMs;
for(auto &pointer: read_pointers_) {
pointer = nullptr;
}
for(auto &pointer: write_pointers_) {
pointer = nullptr;
}
roms[0]->resize(8*1024);
memcpy(&bios_, roms[0]->data(), roms[0]->size());
if(target.model == Analyser::Static::Sega::Target::Model::MasterSystem) {
const auto roms = rom_fetcher("MasterSystem", {"bios.sms"});
if(!roms[0]) {
throw ROMMachine::Error::MissingROMs;
}
roms[0]->resize(8*1024);
memcpy(&bios_, roms[0]->data(), roms[0]->size());
map(read_pointers_, bios_, 8*1024, 0);
map(read_pointers_, ram_, 8*1024, 0xc000, 0x10000);
map(write_pointers_, ram_, 8*1024, 0xc000, 0x10000);
} else {
map(read_pointers_, ram_, 1024, 0xc000, 0x10000);
map(write_pointers_, ram_, 1024, 0xc000, 0x10000);
}
}
~ConcreteMachine() {
@ -84,25 +100,12 @@ class ConcreteMachine:
uint16_t address = cycle.address ? *cycle.address : 0x0000;
switch(cycle.operation) {
case CPU::Z80::PartialMachineCycle::ReadOpcode:
// printf("%04x\n", address);
case CPU::Z80::PartialMachineCycle::Read:
if(address < 0x2000) {
*cycle.value = bios_[address];
} else if(address >= 0xc000) {
*cycle.value = ram_[address & 8191];
} else {
// printf("lr %04x\n", address);
*cycle.value = 0xff;
}
*cycle.value = read_pointers_[address >> 10] ? read_pointers_[address >> 10][address & 1023] : 0xff;
break;
case CPU::Z80::PartialMachineCycle::Write:
if(address >= 0xc000) {
ram_[address & 8191] = *cycle.value;
// printf("w %04x\n", address);
} else {
// printf("mw %04x\n", address);
}
if(write_pointers_[address >> 10]) write_pointers_[address >> 10][address & 1023] = *cycle.value;
break;
case CPU::Z80::PartialMachineCycle::Input:
@ -216,6 +219,17 @@ class ConcreteMachine:
uint8_t ram_[8*1024];
uint8_t bios_[8*1024];
std::vector<uint8_t> cartridge_;
// The memory map has a 1kb granularity; this is determined by the SG1000's 1kb of RAM.
const uint8_t *read_pointers_[64];
uint8_t *write_pointers_[64];
template <typename T> void map(T **target, uint8_t *source, int size, int start_address, int end_address = -1) {
if(end_address == -1) end_address = start_address + size;
for(int address = start_address; address < end_address; address += 1024) {
target[address >> 10] = &source[(address - start_address) & (size - 1)];
}
}
};
}