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Add some CP/M smarts to +3 disk analysis.

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This commit is contained in:
Thomas Harte
2024-08-20 21:43:31 -04:00
parent 0de7057d6f
commit 69ba94e379
5 changed files with 108 additions and 26 deletions
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Analyser/Static/ZXSpectrum/StaticAnalyser.cpp
+63 -11
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@@ -8,6 +8,7 @@
#include "StaticAnalyser.hpp"
#include "../../../Storage/Disk/Parsers/CPM.hpp"
#include "../../../Storage/Disk/Encodings/MFM/Parser.hpp"
#include "../../../Storage/Tape/Parsers/Spectrum.hpp"
@@ -37,21 +38,72 @@ bool IsSpectrumTape(const std::shared_ptr<Storage::Tape::Tape> &tape) {
bool IsSpectrumDisk(const std::shared_ptr<Storage::Disk::Disk> &disk) {
Storage::Encodings::MFM::Parser parser(Storage::Encodings::MFM::Density::Double, disk);
// Get logical sector 1; the Spectrum appears to support various physical
// sectors as sector 1.
const Storage::Encodings::MFM::Sector *boot_sector = nullptr;
uint8_t sector_mask = 0;
while(!boot_sector) {
boot_sector = parser.sector(0, 0, sector_mask + 1);
sector_mask += 0x40;
if(!sector_mask) break;
}
// Grab absolutely any sector from the first track to determine general encoding.
const Storage::Encodings::MFM::Sector *any_sector = parser.any_sector(0, 0);
if(!any_sector) return false;
// Determine the sector base and get logical sector 1.
const uint8_t sector_base = any_sector->address.sector & 0xc0;
const Storage::Encodings::MFM::Sector *boot_sector = parser.sector(0, 0, sector_base + 1);
if(!boot_sector) return false;
// Test that the contents of the boot sector sum to 3, modulo 256.
Storage::Disk::CPM::ParameterBlock cpm_format{};
switch(sector_base) {
case 0x40: cpm_format = Storage::Disk::CPM::ParameterBlock::cpc_system_format(); break;
case 0xc0: cpm_format = Storage::Disk::CPM::ParameterBlock::cpc_data_format(); break;
default: {
// Check the first ten bytes of the first sector for the disk format; if these are all
// the same value then instead substitute a default format.
std::array<uint8_t, 10> format;
std::copy(boot_sector->samples[0].begin(), boot_sector->samples[0].begin() + 10, format.begin());
if(std::all_of(format.begin(), format.end(), [&](const uint8_t v) { return v == format[0]; })) {
format = {0x00, 0x00, 0x28, 0x09, 0x02, 0x01, 0x03, 0x02, 0x2a, 0x52};
}
// Parse those ten bytes as:
//
// Byte 0: disc type
// Byte 1: sidedness
// bits 0-6: arrangement
// 0 => single sided
// 1 => double sided, flip sides
// 2 => double sided, up and over
// bit 7: double-track
// Byte 2: number of tracks per side
// Byte 3: number of sectors per track
// Byte 4: Log2(sector size) - 7
// Byte 5: number of reserved tracks
// Byte 6: Log2(block size) - 7
// Byte 7: number of directory blocks
// Byte 8: gap length (read/write)
// Byte 9: gap length(format)
cpm_format.sectors_per_track = format[3];
cpm_format.tracks = format[2];
cpm_format.block_size = 128 << format[6];
cpm_format.first_sector = sector_base + 1;
cpm_format.reserved_tracks = format[5];
// i.e. bits set downward from 0x4000 for as many blocks as form the catalogue.
cpm_format.catalogue_allocation_bitmap = 0x8000 - (0x8000 >> format[7]);
} break;
}
// If the boot sector sums to 3 modulo 256 then this is a Spectrum disk.
const auto byte_sum = static_cast<uint8_t>(
std::accumulate(boot_sector->samples[0].begin(), boot_sector->samples[0].end(), 0));
return byte_sum == 3;
if(byte_sum == 3) {
return true;
}
// ... otherwise read a CPM directory and look for a BASIC program called "DISK".
const auto catalogue = Storage::Disk::CPM::GetCatalogue(disk, cpm_format);
if(!catalogue) return false;
const auto file = std::find_if(catalogue->files.begin(), catalogue->files.end(), [](const auto &file) { return file.name == "DISK "; });
if(file == catalogue->files.end()) return false;
// TODO: check out contents of "DISK"
return true;
}
}