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Made a first attempt at implementing the Parker Bros pager within the emulation.

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This commit is contained in:
Thomas Harte 2017-03-11 12:43:12 -05:00
parent 8dbf9fd302
commit 2b5e3a600e
3 changed files with 35 additions and 19 deletions
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50
Machines/Atari2600/Atari2600.cpp
View File

@ -66,30 +66,42 @@ unsigned int Machine::perform_bus_operation(CPU6502::BusOperation operation, uin
cycles_since_6532_update_ += (cycles_run_for / 3);
if(operation != CPU6502::BusOperation::Ready) {
uint16_t masked_address = address & 0x1fff;
// check for a paging access
if(rom_size_ > 4096 && ((address & 0x1f00) == 0x1f00)) {
uint8_t *base_ptr = rom_pages_[0];
uint8_t first_paging_register = (uint8_t)(0xf8 - (rom_size_ >> 14)*2);
// check for potential paging
switch(paging_model_) {
default:
// check for an Atari paging access
if(rom_size_ > 4096 && ((address & 0x1f00) == 0x1f00)) {
uint8_t *base_ptr = rom_pages_[0];
uint8_t first_paging_register = (uint8_t)(0xf8 - (rom_size_ >> 14)*2);
const uint8_t paging_register = address&0xff;
if(paging_register >= first_paging_register) {
const uint16_t selected_page = paging_register - first_paging_register;
if(selected_page * 4096 < rom_size_) {
base_ptr = &rom_[selected_page * 4096];
const uint8_t paging_register = address&0xff;
if(paging_register >= first_paging_register) {
const uint16_t selected_page = paging_register - first_paging_register;
if(selected_page * 4096 < rom_size_) {
base_ptr = &rom_[selected_page * 4096];
}
}
if(base_ptr != rom_pages_[0]) {
rom_pages_[0] = base_ptr;
rom_pages_[1] = base_ptr + 1024;
rom_pages_[2] = base_ptr + 2048;
rom_pages_[3] = base_ptr + 3072;
}
}
}
if(base_ptr != rom_pages_[0]) {
rom_pages_[0] = base_ptr;
rom_pages_[1] = base_ptr + 1024;
rom_pages_[2] = base_ptr + 2048;
rom_pages_[3] = base_ptr + 3072;
}
break;
case StaticAnalyser::Atari2600PagingModel::ParkerBros:
if(masked_address >= 0x1fe0 && masked_address <= 0x1ff8) {
int slot = (masked_address - 0x1fe0) >> 3;
int target = masked_address & 7;
rom_pages_[slot] = &rom_[target * 1024];
}
break;
}
// check for a ROM read
uint16_t masked_address = address & 0x1fff;
if(address&0x1000)
{
// check for a RAM access
@ -305,6 +317,8 @@ void Machine::configure_as_target(const StaticAnalyser::Target &target)
ram_read_start_ = 0x1000;
break;
}
paging_model_ = target.atari.paging_model;
}
#pragma mark - Audio and Video

1
Machines/Atari2600/Atari2600.hpp
View File

@ -59,6 +59,7 @@ class Machine:
// ROM information
uint8_t *rom_, *rom_pages_[4];
size_t rom_size_;
StaticAnalyser::Atari2600PagingModel paging_model_;
// cartridge RAM expansion store
std::vector<uint8_t> ram_;

3
StaticAnalyser/Atari/StaticAnalyser.cpp
View File

@ -108,7 +108,8 @@ static void DeterminePagingFor8kCartridge(StaticAnalyser::Target &target, const
looks_like_parker_bros |= ((address & 0x1fff) >= 0x1fe0) && ((address & 0x1fff) < 0x1fe8);
}
printf("%s %s\n", looks_like_atari ? "a" : "-", looks_like_parker_bros ? "p" : "-");
if(looks_like_parker_bros) target.atari.paging_model = StaticAnalyser::Atari2600PagingModel::ParkerBros;
if(looks_like_atari) target.atari.paging_model = StaticAnalyser::Atari2600PagingModel::Atari8k;
}
static void DeterminePagingForCartridge(StaticAnalyser::Target &target, const Storage::Cartridge::Cartridge::Segment &segment)