Update to v094r09 release.

byuu says:

This will easily be the biggest diff in the history of higan. And not in
a good way.

* target-higan and target-loki have been blown away completely
* nall and ruby massively updated
* phoenix replaced with hiro (pretty near a total rewrite)
* target-higan restarted using hiro (just a window for now)
* all emulation cores updated to compile again
* installation changed to not require root privileges (installs locally)

For the foreseeable future (maybe even permanently?), the new higan UI
will only build under Linux/BSD with GTK+ 2.20+. Probably the most
likely route for Windows/OS X will be to try and figure out how to build
hiro/GTK on those platforms, as awful as that would be. The other
alternative would be to produce new UIs for those platforms ... which
would actually be a good opportunity to make something much more user
friendly.

Being that I just started on this a few hours ago, that means that for
at least a few weeks, don't expect to be able to actually play any
games. Right now, you can pretty much just compile the binary and that's
it. It's quite possible that some nall changes didn't produce
compilation errors, but will produce runtime errors. So until the UI can
actually load games, we won't know if anything is broken. But we should
mostly be okay. It was mostly just trim<1> -> trim changes, moving to
Hash::SHA256 (much cleaner), and patching some reckless memory copy
functions enough to compile.

Progress isn't going to be like it was before: I'm now dividing my time
much thinner between studying and other hobbies.

My aim this time is not to produce a binary for everyone to play games
on. Rather, it's to keep the emulator alive. I want to be able to apply
critical patches again. And I would also like the base of the emulator
to live on, for use in other emulator frontends that utilize higan.

nall/string/allocator/copy-on-write.hpp

@@ -1,102 +1,90 @@
 #ifdef NALL_STRING_INTERNAL_HPP
 
-/*
-copy on write (COW) allocator
-sizeof(string) == 24 (amd64)
-
-utilizes a shared_ptr to reference count strings
-allows string copies to execute as fast as string moves
-requires extra computations, which will be slower for all string sizes
-
-pros:
-* lower memory usage
-* pass-by-value does not require heap allocation; obviates pass-by-const-reference
-
-cons:
-* added overhead to fetch data()
-* added heap allocation for reference-count pool
-* no potential for in-place resize (always copies)
-* larger sizeof(string)
-
-*/
-
 namespace nall {
 
-char* string::data() {
-  if(!_data.unique()) _copy();
-  return _data.get();
+string::string() : _data(nullptr), _refs(nullptr), _capacity(0), _size(0) {
 }
 
-const char* string::data() const {
-  if(!_data) return "";
-  return _data.get();
+auto string::pointer() -> char* {
+  static char _null[] = "";
+  if(!_data) return _null;
+  if(*_refs > 1) _data = _copy();  //make unique for write operations
+  return _data;
 }
 
-//copy _data (to make unique or to grow in size)
-void string::_copy() {
-  auto copy = new char[_capacity + 1];
-  if(_data.get()) memcpy(copy, _data.get(), min(_capacity, _size));
-  copy[_size] = 0;
-  copy[_capacity] = 0;
-  _data.reset(copy);
+auto string::data() const -> const char* {
+  static const char _null[] = "";
+  if(!_data) return _null;
+  return _data;
 }
 
-//amortize growth to O(log n)
-//allocate one extra byte to always store null-terminator for libc usage
-void string::reserve(unsigned capacity) {
-  if(capacity > _capacity) {
-    _capacity = bit::round(capacity + 1) - 1;
-    _copy();
+auto string::reset() -> type& {
+  if(_data && !--*_refs) {
+    memory::free(_data);
+    _data = nullptr;  //_refs = nullptr; is unnecessary
   }
-}
-
-void string::resize(unsigned size) {
-  reserve(size);
-  data()[_size = size] = 0;
-}
-
-void string::reset() {
-  _data.reset();
   _capacity = 0;
   _size = 0;
-}
-
-string& string::operator=(const string& source) {
-  if(&source == this) return *this;
-  reset();
-  _data = source._data;
-  _capacity = source._capacity;
-  _size = source._size;
   return *this;
 }
 
-string& string::operator=(string&& source) {
+auto string::reserve(unsigned capacity) -> type& {
+  if(capacity > _capacity) {
+    _capacity = bit::round(max(31u, capacity) + 1) - 1;
+    _data = _data ? _copy() : _allocate();
+  }
+  return *this;
+}
+
+auto string::resize(unsigned size) -> type& {
+  reserve(size);
+  pointer()[_size = size] = 0;
+  return *this;
+}
+
+auto string::operator=(const string& source) -> string& {
   if(&source == this) return *this;
   reset();
-  _data = std::move(source._data);
+  if(source._data) {
+    _data = source._data;
+    _refs = source._refs;
+    _capacity = source._capacity;
+    _size = source._size;
+    ++*_refs;
+  }
+  return *this;
+}
+
+auto string::operator=(string&& source) -> string& {
+  if(&source == this) return *this;
+  reset();
+  _data = source._data;
+  _refs = source._refs;
   _capacity = source._capacity;
   _size = source._size;
+  source._data = nullptr;
+  source._refs = nullptr;
   source._capacity = 0;
   source._size = 0;
   return *this;
 }
 
-template<typename T, typename... Args> string::string(T&& source, Args&&... args) {
-  construct();
-  sprint(*this, std::forward<T>(source), std::forward<Args>(args)...);
+auto string::_allocate() -> char* {
+  auto _temp = (char*)memory::allocate(_capacity + 1 + sizeof(unsigned));
+  *_temp = 0;
+  _refs = (unsigned*)(_temp + _capacity + 1);  //this will always be aligned by 32 via reserve()
+  *_refs = 1;
+  return _temp;
 }
 
-string::string() {
-  construct();
-}
-
-string::~string() {
-  reset();
-}
-
-void string::construct() {
-  _capacity = 0;
-  _size = 0;
+auto string::_copy() -> char* {
+  auto _temp = (char*)memory::allocate(_capacity + 1 + sizeof(unsigned));
+  memory::copy(_temp, _data, _size = min(_capacity, _size));
+  _temp[_size] = 0;
+  --*_refs;
+  _refs = (unsigned*)(_temp + _capacity + 1);
+  *_refs = 1;
+  return _temp;
 }
 
 }