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Attempts to rationalise Apple II address decoding.

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This commit is contained in:
Thomas Harte 2018-05-05 20:24:03 -04:00
parent 9ff34d90f4
commit 4c4ab25d0e
1 changed files with 77 additions and 58 deletions
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135
Machines/AppleII/AppleII.cpp
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@ -72,7 +72,6 @@ class ConcreteMachine:
uint8_t ram_[48*1024]; uint8_t ram_[48*1024];
std::vector<uint8_t> apple2_rom_, apple2plus_rom_, rom_; std::vector<uint8_t> apple2_rom_, apple2plus_rom_, rom_;
std::vector<uint8_t> character_rom_; std::vector<uint8_t> character_rom_;
uint16_t rom_start_address_;
uint8_t keyboard_input_ = 0x00; uint8_t keyboard_input_ = 0x00;
Concurrency::DeferringAsyncTaskQueue audio_queue_; Concurrency::DeferringAsyncTaskQueue audio_queue_;
@ -85,6 +84,11 @@ class ConcreteMachine:
Cycles cycles_since_card_update_; Cycles cycles_since_card_update_;
int stretched_cycles_since_card_update_ = 0; int stretched_cycles_since_card_update_ = 0;
struct MemoryBlock {
uint8_t *read_pointer = nullptr;
uint8_t *write_pointer = nullptr;
} memory_blocks_[4]; // The IO page isn't included.
public: public:
ConcreteMachine(): ConcreteMachine():
m6502_(*this), m6502_(*this),
@ -129,72 +133,82 @@ class ConcreteMachine:
++ cycles_since_card_update_; ++ cycles_since_card_update_;
cycles_since_audio_update_ += Cycles(7); cycles_since_audio_update_ += Cycles(7);
switch(address) { /*
default: There are five distinct zones of memory on an Apple II:
if(isReadOperation(operation)) {
if(address < sizeof(ram_)) { 0000 — 0200 : the zero and stack pages, which can be paged independently on a IIe
*value = ram_[address]; 0200 — c000 : the main block of RAM, which can be paged on a IIe
} else if(address >= rom_start_address_) { c000 — d000 : the IO area, including card ROMs
*value = rom_[address - rom_start_address_]; d000 — e000 : the low ROM area, which can contain indepdently-paged RAM with a language card
} else { e000 — : the rest of ROM, also potentially replaced with RAM by a language card
*/
MemoryBlock *block = nullptr;
if(address < 0x200) block = &memory_blocks_[0];
else if(address < 0xc000) {update_video(); block = &memory_blocks_[1]; address -= 0x200; }
else if(address < 0xd000) block = nullptr;
else if(address < 0xe000) {block = &memory_blocks_[2]; address -= 0xd000; }
else {block = &memory_blocks_[3]; address -= 0xe000; }
if(block) {
if(isReadOperation(operation)) *value = block->read_pointer[address];
else if(block->write_pointer) block->write_pointer[address] = *value;
} else {
switch(address) {
default:
if(isReadOperation(operation)) {
// Read-only switches.
switch(address) { switch(address) {
default: default: break;
// printf("Unknown access to %04x\n", address);
break;
case 0xc000: case 0xc000:
*value = keyboard_input_; *value = keyboard_input_;
break; break;
} }
} else {
// Write-only switches.
} }
} else { break;
if(address < sizeof(ram_)) {
if(address >= 0x400) {
// TODO: be more selective.
update_video();
}
ram_[address] = *value;
}
}
break;
case 0xc050: update_video(); video_->set_graphics_mode(); break; /* Read-write switches. */
case 0xc051: update_video(); video_->set_text_mode(); break; case 0xc050: update_video(); video_->set_graphics_mode(); break;
case 0xc052: update_video(); video_->set_mixed_mode(false); break; case 0xc051: update_video(); video_->set_text_mode(); break;
case 0xc053: update_video(); video_->set_mixed_mode(true); break; case 0xc052: update_video(); video_->set_mixed_mode(false); break;
case 0xc054: update_video(); video_->set_video_page(0); break; case 0xc053: update_video(); video_->set_mixed_mode(true); break;
case 0xc055: update_video(); video_->set_video_page(1); break; case 0xc054: update_video(); video_->set_video_page(0); break;
case 0xc056: update_video(); video_->set_low_resolution(); break; case 0xc055: update_video(); video_->set_video_page(1); break;
case 0xc057: update_video(); video_->set_high_resolution(); break; case 0xc056: update_video(); video_->set_low_resolution(); break;
case 0xc057: update_video(); video_->set_high_resolution(); break;
case 0xc010: case 0xc010:
keyboard_input_ &= 0x7f; keyboard_input_ &= 0x7f;
break; break;
case 0xc030: case 0xc030:
update_audio(); update_audio();
audio_toggle_.set_output(!audio_toggle_.get_output()); audio_toggle_.set_output(!audio_toggle_.get_output());
break; break;
}
if(address >= 0xc100 && address < 0xc800) {
/*
Decode the area conventionally used by cards for ROMs:
0xCn00 — 0xCnff: card n.
*/
const int card_number = (address - 0xc100) >> 8;
if(cards_[card_number]) {
update_cards();
cards_[card_number]->perform_bus_operation(operation, address & 0xff, value);
} }
} else if(address >= 0xc090 && address < 0xc100) {
/* if(address >= 0xc100 && address < 0xc800) {
Decode the area conventionally used by cards for registers: /*
C0n0--C0nF: card n - 8. Decode the area conventionally used by cards for ROMs:
*/ 0xCn00 — 0xCnff: card n.
const int card_number = (address - 0xc090) >> 4; */
if(cards_[card_number]) { const int card_number = (address - 0xc100) >> 8;
update_cards(); if(cards_[card_number]) {
cards_[card_number]->perform_bus_operation(operation, 0x100 | (address&0xf), value); update_cards();
cards_[card_number]->perform_bus_operation(operation, address & 0xff, value);
}
} else if(address >= 0xc090 && address < 0xc100) {
/*
Decode the area conventionally used by cards for registers:
C0n0--C0nF: card n - 8.
*/
const int card_number = (address - 0xc090) >> 4;
if(cards_[card_number]) {
update_cards();
cards_[card_number]->perform_bus_operation(operation, 0x100 | (address&0xf), value);
}
} }
} }
@ -283,7 +297,12 @@ class ConcreteMachine:
if(rom_.size() > 12*1024) { if(rom_.size() > 12*1024) {
rom_.erase(rom_.begin(), rom_.begin() + static_cast<off_t>(rom_.size()) - 12*1024); rom_.erase(rom_.begin(), rom_.begin() + static_cast<off_t>(rom_.size()) - 12*1024);
} }
rom_start_address_ = 0xd000;//static_cast<uint16_t>(0x10000 - rom_.size());
// Set up the default memory blocks.
memory_blocks_[0].read_pointer = memory_blocks_[0].write_pointer = ram_;
memory_blocks_[1].read_pointer = memory_blocks_[1].write_pointer = &ram_[0x200];
memory_blocks_[2].read_pointer = rom_.data();
memory_blocks_[3].read_pointer = rom_.data() + 0x1000;
insert_media(apple_target->media); insert_media(apple_target->media);
} }