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Makes an attempt to perform MSX memory paging.

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This commit is contained in:
Thomas Harte 2017-11-28 21:56:15 -05:00
parent ecd7d4731b
commit 69ec8a362e
1 changed files with 51 additions and 8 deletions
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59
Machines/MSX/MSX.cpp
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@ -20,13 +20,6 @@
namespace MSX {
class i8255PortHandler: public Intel::i8255::PortHandler {
public:
void set_value(int port, uint8_t value) {
printf("8255 set %d to %02x\n", port, value);
}
};
class AYPortHandler: public GI::AY38910::PortHandler {
};
@ -38,9 +31,11 @@ class ConcreteMachine:
public:
ConcreteMachine():
z80_(*this),
i8255_(i8255_port_handler_) {
i8255_(i8255_port_handler_),
i8255_port_handler_(*this) {
ay_.set_port_handler(&ay_port_handler_);
set_clock_rate(3579545);
std::memset(unpopulated_, 0xff, sizeof(unpopulated_));
}
void setup_output(float aspect_ratio) override {
@ -69,6 +64,28 @@ class ConcreteMachine:
return true;
}
void page_memory(uint8_t value) {
for(int c = 0; c < 4; ++c) {
read_pointers_[c] = unpopulated_;
write_pointers_[c] = scratch_;
}
switch(value&3) {
case 0: read_pointers_[0] = main_.data(); break;
case 2: read_pointers_[0] = write_pointers_[0] = &ram_[0]; break;
}
switch((value >> 2)&3) {
case 0: read_pointers_[1] = basic_.data(); break;
case 2: read_pointers_[1] = write_pointers_[1] = &ram_[16384]; break;
}
switch((value >> 4)&3) {
case 2: read_pointers_[2] = write_pointers_[2] = &ram_[32768]; break;
}
switch((value >> 6)&3) {
case 2: read_pointers_[3] = write_pointers_[3] = &ram_[49152]; break;
}
}
HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
uint16_t address = cycle.address ? *cycle.address : 0x0000;
switch(cycle.operation) {
@ -171,6 +188,31 @@ class ConcreteMachine:
}
private:
class i8255PortHandler: public Intel::i8255::PortHandler {
public:
i8255PortHandler(ConcreteMachine &machine) : machine_(machine) {}
void set_value(int port, uint8_t value) {
switch(port) {
case 0: machine_.page_memory(value); break;
case 2:
printf("?? Select keyboard row, etc: %02x\n", value);
break;
default: break;
}
}
uint8_t get_value(int port) {
if(port == 1) {
printf("?? Read keyboard\n");
}
return 0xff;
}
private:
ConcreteMachine &machine_;
};
CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
std::unique_ptr<TI::TMS9918> vdp_;
Intel::i8255::i8255<i8255PortHandler> i8255_;
@ -183,6 +225,7 @@ class ConcreteMachine:
uint8_t *write_pointers_[4];
uint8_t ram_[65536];
uint8_t scratch_[16384];
uint8_t unpopulated_[16384];
std::vector<uint8_t> basic_, main_;
HalfCycles time_since_vdp_update_;