From b76c923ff4dd8ad25fa6cd2f6aede40a2fa42b1a Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Mon, 22 Mar 2021 19:53:51 -0400
Subject: [PATCH] Adds detection of Spectrum-bootable disks.

---
 Analyser/Static/AmstradCPC/StaticAnalyser.cpp |  4 +-
 Analyser/Static/StaticAnalyser.cpp            |  2 +-
 Analyser/Static/ZXSpectrum/StaticAnalyser.cpp | 37 +++++++++++++++++++
 3 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/Analyser/Static/AmstradCPC/StaticAnalyser.cpp b/Analyser/Static/AmstradCPC/StaticAnalyser.cpp
index 500e3ce55..2ca6924b6 100644
--- a/Analyser/Static/AmstradCPC/StaticAnalyser.cpp
+++ b/Analyser/Static/AmstradCPC/StaticAnalyser.cpp
@@ -11,12 +11,12 @@
 #include <algorithm>
 #include <cstring>
 
-#include "Target.hpp"
-
 #include "../../../Storage/Disk/Parsers/CPM.hpp"
 #include "../../../Storage/Disk/Encodings/MFM/Parser.hpp"
 #include "../../../Storage/Tape/Parsers/Spectrum.hpp"
 
+#include "Target.hpp"
+
 namespace {
 
 bool strcmp_insensitive(const char *a, const char *b) {
diff --git a/Analyser/Static/StaticAnalyser.cpp b/Analyser/Static/StaticAnalyser.cpp
index 28cfc894e..7fe020af2 100644
--- a/Analyser/Static/StaticAnalyser.cpp
+++ b/Analyser/Static/StaticAnalyser.cpp
@@ -128,7 +128,7 @@ static Media GetMediaAndPlatforms(const std::string &file_name, TargetPlatform::
 	Format(	"dsk",
 			result.disks,
 			Disk::DiskImageHolder<Storage::Disk::CPCDSK>,
-			TargetPlatform::AmstradCPC | TargetPlatform::Oric)													// DSK (Amstrad CPC)
+			TargetPlatform::AmstradCPC | TargetPlatform::Oric | TargetPlatform::ZXSpectrum)						// DSK (Amstrad CPC, etc)
 	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::AppleDSK>, TargetPlatform::DiskII)			// DSK (Apple II)
 	Format("dsk", result.disks, Disk::DiskImageHolder<Storage::Disk::MacintoshIMG>, TargetPlatform::Macintosh)	// DSK (Macintosh, floppy disk)
 	Format("dsk", result.mass_storage_devices, MassStorage::HFV, TargetPlatform::Macintosh)						// DSK (Macintosh, hard disk)
diff --git a/Analyser/Static/ZXSpectrum/StaticAnalyser.cpp b/Analyser/Static/ZXSpectrum/StaticAnalyser.cpp
index 637a106a2..cb3e0f687 100644
--- a/Analyser/Static/ZXSpectrum/StaticAnalyser.cpp
+++ b/Analyser/Static/ZXSpectrum/StaticAnalyser.cpp
@@ -8,7 +8,9 @@
 
 #include "StaticAnalyser.hpp"
 
+#include "../../../Storage/Disk/Encodings/MFM/Parser.hpp"
 #include "../../../Storage/Tape/Parsers/Spectrum.hpp"
+
 #include "Target.hpp"
 
 namespace {
@@ -30,6 +32,28 @@ bool IsSpectrumTape(const std::shared_ptr<Storage::Tape::Tape> &tape) {
 	return false;
 }
 
+bool IsSpectrumDisk(const std::shared_ptr<Storage::Disk::Disk> &disk) {
+	Storage::Encodings::MFM::Parser parser(true, disk);
+
+	// Get logical sector 1; the Spectrum appears to support various physical
+	// sectors as sector 1.
+	Storage::Encodings::MFM::Sector *boot_sector = nullptr;
+	uint8_t sector_mask = 0;
+	while(!boot_sector) {
+		boot_sector = parser.get_sector(0, 0, sector_mask + 1);
+		sector_mask += 0x40;
+		if(!sector_mask) break;
+	}
+	if(!boot_sector) return false;
+
+	// Test that the contents of the boot sector sum to 3, modulo 256.
+	uint8_t byte_sum = 0;
+	for(auto byte: boot_sector->samples[0]) {
+		byte_sum += byte;
+	}
+	return byte_sum == 3;
+}
+
 }
 
 Analyser::Static::TargetList Analyser::Static::ZXSpectrum::GetTargets(const Media &media, const std::string &, TargetPlatform::IntType) {
@@ -48,6 +72,19 @@ Analyser::Static::TargetList Analyser::Static::ZXSpectrum::GetTargets(const Medi
 		}
 	}
 
+	if(!media.disks.empty()) {
+		bool has_spectrum_disk = false;
+
+		for(auto &disk: media.disks) {
+			has_spectrum_disk |= IsSpectrumDisk(disk);
+		}
+
+		if(has_spectrum_disk) {
+			target->media.disks = media.disks;
+			target->model = Target::Model::Plus3;
+		}
+	}
+
 	// If any media survived, add the target.
 	if(!target->media.empty())
 		destination.push_back(std::move(target));