mirror of
https://github.com/TomHarte/CLK.git
synced 2024-11-26 23:52:26 +00:00
120 lines
3.9 KiB
C++
120 lines
3.9 KiB
C++
//
|
|
// G64.cpp
|
|
// Clock Signal
|
|
//
|
|
// Created by Thomas Harte on 10/07/2016.
|
|
// Copyright © 2016 Thomas Harte. All rights reserved.
|
|
//
|
|
|
|
#include "G64.hpp"
|
|
|
|
#include <vector>
|
|
#include "../PCMTrack.hpp"
|
|
#include "../Encodings/CommodoreGCR.hpp"
|
|
|
|
using namespace Storage::Disk;
|
|
|
|
G64::G64(const char *file_name) :
|
|
Storage::FileHolder(file_name) {
|
|
// read and check the file signature
|
|
if(!check_signature("GCR-1541", 8)) throw ErrorNotG64;
|
|
|
|
// check the version number
|
|
int version = fgetc(file_);
|
|
if(version != 0) throw ErrorUnknownVersion;
|
|
|
|
// get the number of tracks and track size
|
|
number_of_tracks_ = (uint8_t)fgetc(file_);
|
|
maximum_track_size_ = fgetc16le();
|
|
}
|
|
|
|
unsigned int G64::get_head_position_count() {
|
|
// give at least 84 tracks, to yield the normal geometry but,
|
|
// if there are more, shove them in
|
|
return number_of_tracks_ > 84 ? number_of_tracks_ : 84;
|
|
}
|
|
|
|
std::shared_ptr<Track> G64::get_uncached_track_at_position(unsigned int head, unsigned int position) {
|
|
std::shared_ptr<Track> resulting_track;
|
|
|
|
// if there's definitely no track here, return the empty track
|
|
// (TODO: should be supplying one with an index hole?)
|
|
if(position >= number_of_tracks_) return resulting_track;
|
|
if(head >= 1) return resulting_track;
|
|
|
|
// seek to this track's entry in the track table
|
|
fseek(file_, (long)((position * 4) + 0xc), SEEK_SET);
|
|
|
|
// read the track offset
|
|
uint32_t track_offset;
|
|
track_offset = fgetc32le();
|
|
|
|
// if the track offset is zero, this track doesn't exist, so...
|
|
if(!track_offset) return resulting_track;
|
|
|
|
// seek to the track start
|
|
fseek(file_, (int)track_offset, SEEK_SET);
|
|
|
|
// get the real track length
|
|
uint16_t track_length;
|
|
track_length = fgetc16le();
|
|
|
|
// grab the byte contents of this track
|
|
std::vector<uint8_t> track_contents(track_length);
|
|
fread(&track_contents[0], 1, track_length, file_);
|
|
|
|
// seek to this track's entry in the speed zone table
|
|
fseek(file_, (long)((position * 4) + 0x15c), SEEK_SET);
|
|
|
|
// read the speed zone offsrt
|
|
uint32_t speed_zone_offset;
|
|
speed_zone_offset = fgetc32le();
|
|
|
|
// if the speed zone is not constant, create a track based on the whole table; otherwise create one that's constant
|
|
if(speed_zone_offset > 3) {
|
|
// seek to start of speed zone
|
|
fseek(file_, (int)speed_zone_offset, SEEK_SET);
|
|
|
|
uint16_t speed_zone_length = (track_length + 3) >> 2;
|
|
|
|
// read the speed zone bytes
|
|
uint8_t speed_zone_contents[speed_zone_length];
|
|
fread(speed_zone_contents, 1, speed_zone_length, file_);
|
|
|
|
// divide track into appropriately timed PCMSegments
|
|
std::vector<PCMSegment> segments;
|
|
unsigned int current_speed = speed_zone_contents[0] >> 6;
|
|
unsigned int start_byte_in_current_speed = 0;
|
|
for(unsigned int byte = 0; byte < track_length; byte ++) {
|
|
unsigned int byte_speed = speed_zone_contents[byte >> 2] >> (6 - (byte&3)*2);
|
|
if(byte_speed != current_speed || byte == (track_length-1)) {
|
|
unsigned int number_of_bytes = byte - start_byte_in_current_speed;
|
|
|
|
PCMSegment segment;
|
|
segment.number_of_bits = number_of_bytes * 8;
|
|
segment.length_of_a_bit = Encodings::CommodoreGCR::length_of_a_bit_in_time_zone(current_speed);
|
|
segment.data.resize(number_of_bytes);
|
|
memcpy(&segment.data[0], &track_contents[start_byte_in_current_speed], number_of_bytes);
|
|
segments.push_back(std::move(segment));
|
|
|
|
current_speed = byte_speed;
|
|
start_byte_in_current_speed = byte;
|
|
}
|
|
}
|
|
|
|
resulting_track.reset(new PCMTrack(std::move(segments)));
|
|
} else {
|
|
PCMSegment segment;
|
|
segment.number_of_bits = track_length * 8;
|
|
segment.length_of_a_bit = Encodings::CommodoreGCR::length_of_a_bit_in_time_zone((unsigned int)speed_zone_offset);
|
|
segment.data = std::move(track_contents);
|
|
|
|
resulting_track.reset(new PCMTrack(std::move(segment)));
|
|
}
|
|
|
|
// TODO: find out whether it's possible for a G64 to supply only a partial track. I don't think it is, which would make the
|
|
// above correct but supposing I'm wrong, the above would produce some incorrectly clocked tracks
|
|
|
|
return resulting_track;
|
|
}
|