Move C++ code into cpp/ dir (#941)

- Moved C++ code to cpp/ from src/raspberrypi
- Related updates to Makefile, easyinstall.sh, and the github build rules
- Removed the native X68k C code in src/x68k from the repo

cpp/devices/disk_cache.cpp

@@ -0,0 +1,198 @@
+//---------------------------------------------------------------------------
+//
+//	X68000 EMULATOR "XM6"
+//
+//	Copyright (C) 2001-2006 ＰＩ．(ytanaka@ipc-tokai.or.jp)
+//	Copyright (C) 2014-2020 GIMONS
+//
+//	XM6i
+//	Copyright (C) 2010-2015 isaki@NetBSD.org
+//	Copyright (C) 2010 Y.Sugahara
+//
+//	Imported sava's Anex86/T98Next image and MO format support patch.
+//  	Comments translated to english by akuker.
+//
+//---------------------------------------------------------------------------
+
+#include "os.h"
+#include "disk_track.h"
+#include "disk_cache.h"
+#include <cstdlib>
+#include <cassert>
+
+DiskCache::DiskCache(const string& path, int size, uint32_t blocks, off_t imgoff)
+	: sec_path(path), sec_size(size), sec_blocks(blocks), imgoffset(imgoff)
+{
+	assert(blocks > 0);
+	assert(imgoff >= 0);
+}
+
+bool DiskCache::Save() const
+{
+	// Save track
+	for (const cache_t& c : cache) {
+		// Save if this is a valid track
+		if (c.disktrk && !c.disktrk->Save(sec_path)) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
+shared_ptr<DiskTrack> DiskCache::GetTrack(uint32_t block)
+{
+	// Update first
+	UpdateSerialNumber();
+
+	// Calculate track (fixed to 256 sectors/track)
+	int track = block >> 8;
+
+	// Get track data
+	return Assign(track);
+}
+
+bool DiskCache::ReadSector(vector<BYTE>& buf, uint32_t block)
+{
+	shared_ptr<DiskTrack> disktrk = GetTrack(block);
+	if (disktrk == nullptr) {
+		return false;
+	}
+
+	// Read the track data to the cache
+	return disktrk->ReadSector(buf, block & 0xff);
+}
+
+bool DiskCache::WriteSector(const vector<BYTE>& buf, uint32_t block)
+{
+	shared_ptr<DiskTrack> disktrk = GetTrack(block);
+	if (disktrk == nullptr) {
+		return false;
+	}
+
+	// Write the data to the cache
+	return disktrk->WriteSector(buf, block & 0xff);
+}
+
+//---------------------------------------------------------------------------
+//
+//	Track Assignment
+//
+//---------------------------------------------------------------------------
+shared_ptr<DiskTrack> DiskCache::Assign(int track)
+{
+	assert(sec_size != 0);
+	assert(track >= 0);
+
+	// First, check if it is already assigned
+	for (cache_t& c : cache) {
+		if (c.disktrk && c.disktrk->GetTrack() == track) {
+			// Track match
+			c.serial = serial;
+			return c.disktrk;
+		}
+	}
+
+	// Next, check for empty
+	for (size_t i = 0; i < cache.size(); i++) {
+		if (cache[i].disktrk == nullptr) {
+			// Try loading
+			if (Load((int)i, track, nullptr)) {
+				// Success loading
+				cache[i].serial = serial;
+				return cache[i].disktrk;
+			}
+
+			// Load failed
+			return nullptr;
+		}
+	}
+
+	// Finally, find the youngest serial number and delete it
+
+	// Set index 0 as candidate c
+	uint32_t s = cache[0].serial;
+	size_t c = 0;
+
+	// Compare candidate with serial and update to smaller one
+	for (size_t i = 0; i < cache.size(); i++) {
+		assert(cache[i].disktrk);
+
+		// Compare and update the existing serial
+		if (cache[i].serial < s) {
+			s = cache[i].serial;
+			c = i;
+		}
+	}
+
+	// Save this track
+	if (!cache[c].disktrk->Save(sec_path)) {
+		return nullptr;
+	}
+
+	// Delete this track
+	shared_ptr<DiskTrack> disktrk = cache[c].disktrk;
+	cache[c].disktrk.reset();
+
+	if (Load((int)c, track, disktrk)) {
+		// Successful loading
+		cache[c].serial = serial;
+		return cache[c].disktrk;
+	}
+
+	// Load failed
+	return nullptr;
+}
+
+//---------------------------------------------------------------------------
+//
+//	Load cache
+//
+//---------------------------------------------------------------------------
+bool DiskCache::Load(int index, int track, shared_ptr<DiskTrack> disktrk)
+{
+	assert(index >= 0 && index < (int)cache.size());
+	assert(track >= 0);
+	assert(cache[index].disktrk == nullptr);
+
+	// Get the number of sectors on this track
+	int sectors = sec_blocks - (track << 8);
+	assert(sectors > 0);
+	if (sectors > 0x100) {
+		sectors = 0x100;
+	}
+
+	// Create a disk track
+	if (disktrk == nullptr) {
+		disktrk = make_shared<DiskTrack>();
+	}
+
+	// Initialize disk track
+	disktrk->Init(track, sec_size, sectors, cd_raw, imgoffset);
+
+	// Try loading
+	if (!disktrk->Load(sec_path)) {
+		// Failure
+		return false;
+	}
+
+	// Allocation successful, work set
+	cache[index].disktrk = disktrk;
+
+	return true;
+}
+
+void DiskCache::UpdateSerialNumber()
+{
+	// Update and do nothing except 0
+	serial++;
+	if (serial != 0) {
+		return;
+	}
+
+	// Clear serial of all caches
+	for (cache_t& c : cache) {
+		c.serial = 0;
+	}
+}
+