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Implements RWTS acceleration.

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This commit is contained in:
Thomas Harte 2018-06-10 17:58:16 -04:00
parent e0b75b6e3d
commit af54666c23
1 changed files with 50 additions and 11 deletions
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61
Machines/AppleII/AppleII.cpp
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@ -28,6 +28,9 @@
#include "../../Analyser/Static/AppleII/Target.hpp"
#include "../../Storage/Disk/Track/TrackSerialiser.hpp"
#include "../../Storage/Disk/Encodings/AppleGCR/SegmentParser.hpp"
#include <algorithm>
#include <array>
#include <memory>
@ -258,7 +261,7 @@ class ConcreteMachine:
if(should_load_quickly_) {
// Check for a prima facie entry into RWTS.
if(operation == CPU::MOS6502::BusOperation::ReadOpcode && address == 0xb7b5) {
if(operation == CPU::MOS6502::BusOperation::ReadOpcode && (address&0xff) == ram_[0x3da] && (address >> 8) == ram_[0x3db]) {
// Grab the IO control block address for inspection.
uint16_t io_control_block_address =
static_cast<uint16_t>(
@ -274,27 +277,63 @@ class ConcreteMachine:
ram_[io_control_block_address+0x02] > 0 && ram_[io_control_block_address+0x02] < 3 &&
ram_[io_control_block_address+0x0c] < 2
) {
printf("RWTS %d: %d %d [%d]\n", ram_[io_control_block_address+0x0c], ram_[io_control_block_address+4], ram_[io_control_block_address+5], ram_[0x478]);
const uint8_t iob_track = ram_[io_control_block_address+4];
const uint8_t iob_sector = ram_[io_control_block_address+5];
const uint8_t iob_drive = ram_[io_control_block_address+2] - 1;
// Get the track identified and store the new head position.
auto track = diskii_card()->get_drive(ram_[io_control_block_address+0x02] - 1).step_to(Storage::Disk::HeadPosition(ram_[io_control_block_address+4]));
auto track = diskii_card()->get_drive(iob_drive).step_to(Storage::Disk::HeadPosition(iob_track));
// DOS 3.3 keeps the current track (unspecified drive) in 0x478; the current track for drive 1 and drive 2
// is also kept in that Disk II card's screen hole.
ram_[0x478] = ram_[io_control_block_address+4];
ram_[0x478] = iob_track;
if(ram_[io_control_block_address+0x02] == 1) {
ram_[0x47e] = ram_[io_control_block_address+4];
ram_[0x47e] = iob_track;
} else {
ram_[0x4fe] = ram_[io_control_block_address+4];
ram_[0x4fe] = iob_track;
}
// Check whether this is a read, not merely a seek.
// if(ram_[io_control_block_address+0x0c] == 1) {
// // Read logical sector at [5], write [b] bytes (where 0 is 256) to [8]/[9]
// }
if(ram_[io_control_block_address+0x0c] == 1) {
// Apple the DOS 3.3 formula to map the requested logical sector to a physical sector.
const int physical_sector = (iob_sector == 15) ? 15 : ((iob_sector * 13) % 15);
// Force an RTS.
// *value = 0x60;
// Parse the entire track. TODO: cache these.
auto sector_map = Storage::Encodings::AppleGCR::sectors_from_segment(
Storage::Disk::track_serialisation(*track, Storage::Time(1, 50000)));
bool found_sector = false;
for(const auto &pair: sector_map) {
if(pair.second.address.sector == physical_sector) {
found_sector = true;
// Copy the sector contents to their destination.
uint16_t target = static_cast<uint16_t>(
ram_[io_control_block_address+8] |
(ram_[io_control_block_address+9] << 8)
);
for(size_t c = 0; c < 256; ++c) {
ram_[target] = pair.second.data[c];
++target;
}
// Set no error encountered.
ram_[io_control_block_address + 0xd] = 0;
break;
}
}
if(found_sector) {
// Set no error in the flags register too, and RTS.
m6502_.set_value_of_register(CPU::MOS6502::Register::Flags, m6502_.get_value_of_register(CPU::MOS6502::Register::Flags) & ~1);
*value = 0x60;
}
} else {
// No error encountered; RTS.
m6502_.set_value_of_register(CPU::MOS6502::Register::Flags, m6502_.get_value_of_register(CPU::MOS6502::Register::Flags) & ~1);
*value = 0x60;
}
}
}
}