Refactor the core's handling of firmware and BIOS images to rely less on the file system (#1826)

* Introduce firmware-related structs

* Fix some indents

* Move the generated firmware identifier to a constant

* Document the WifiAccessPoint constructors

* Add some constants

* Remove a stray comment

* Implement Firmware::UserData

* Add Firmware::Mask

* Document Firmware::Buffer

* Add a Firmware constructor that uses a FileHandle

* Set the default username in UserData

* Update the UserData checksum

* Forgot to include Platform.h

* Remove some redundant assignments in the default Firmware constructor

* const-ify CRC16

* Replace the plain Firmware buffer with a Firmware object

- Remove some functions that were reimplemented in the Firmware constructors

* Fix some crashes due to undefined behavior

* Fix the user data initialization

- Initialize both user data objects to default
- Set both user data objects to the same touch screen calibration

* Follow the DS logic in determining which user data section is current

* Remove an unneeded include

* Remove another unneeded include

* Initialize FirmwareMask in Firmware::Firmware

* Use the DEFAULT_SSID constant

* Add SPI_Firmware::InstallFirmware and SPI_Firmware::RemoveFirmware

* Move a logging call to after the file is written

* Add a SaveManager for the firmware

* Touch up the SPI_Firmware::Firmware declaration

* Move all firmware loading and customization to the frontend

* Call Platform::WriteFirmware when it's time to write the firmware back to disk

* Fix some missing stuff

* Remove the Get* functions from SPI_Firmware in favor of GetFirmware()

* Implement SPI_Firmware::DeInit in terms of RemoveFirmware

* Add Firmware::UpdateChecksums

* Fix an incorrect length

* Update all checksums in the firmware after setting touch screen calibration data

* Use the Firmware object's Position methods

* Remove register fields from the Firmware object

* Install the firmware before seeing if direct boot is necessary

* Install the firmware before calling NDS::Reset in LoadROM

* Slight cleanup in ROMManager

* Fix the default access point name

* Shorten the various getters in Firmware

* Add qualifiers for certain uses of firmware types

- GCC can get picky if -fpermissive isn't defined

* Add an InstallFirmware overload that takes a unique_ptr

* Log when firmware is added or removed

* Don't clear the firmware in SPI_Firmware::Init

- The original code didn't, it just set the pointer to nullptr

* Fix a typo

* Write back the full firmware if it's not generated

* Move the FreeBIOS to an external file

* Load wfcsettings.bin into the correct part of the generated firmware blob

* Load BIOS files in the frontend, not in the core

* Fix logging the firmware ID

* Add some utility functions

* Mark Firmware's constructors as explicit

* Remove obsolete ConfigEntry values

* Include <locale> explicitly in ROMManager

* Fix up some includes

* Add Firmware::IsBootable()

* Add a newline to a log entry

- Whoops

* Log the number of bytes written out in SaveManager

* Mark FirmwareHeader's constructor as explicit

* Clean up GenerateDefaultFirmware and LoadFirmwareFromFile

- Now they return a pair instead of two by-ref values

* Refactor SaveManager a little bit

- Manage its buffers as unique_ptrs to mitigate leaks
- Reallocate the internal buffer if SetPath is asked to reload the file (and the new length is different)

* Remove some stray parens

* Fix some firmware-related bugs I introduced

- Firmware settings are now properly saved to disk (beforehand I misunderstood when the firmware blob was written)
- Firmware is no longer overwritten by contents of wfcsettings.bin

* Slight cleanup

src/Platform.h

@@ -24,6 +24,11 @@
 #include <functional>
 #include <string>
 
+namespace SPI_Firmware
+{
+    class Firmware;
+}
+
 namespace Platform
 {
 
@@ -102,13 +107,6 @@ enum ConfigEntry
 
     ExternalBIOSEnable,
 
-    BIOS9Path,
-    BIOS7Path,
-    FirmwarePath,
-
-    DSi_BIOS9Path,
-    DSi_BIOS7Path,
-    DSi_FirmwarePath,
     DSi_NANDPath,
 
     DLDI_Enable,
@@ -125,7 +123,7 @@ enum ConfigEntry
     DSiSD_FolderSync,
     DSiSD_FolderPath,
 
-    Firm_OverrideSettings,
+    Firm_OverrideSettings [[deprecated("Individual fields can now be overridden")]],
     Firm_Username,
     Firm_Language,
     Firm_BirthdayMonth,
@@ -333,6 +331,13 @@ void Sleep(u64 usecs);
 void WriteNDSSave(const u8* savedata, u32 savelen, u32 writeoffset, u32 writelen);
 void WriteGBASave(const u8* savedata, u32 savelen, u32 writeoffset, u32 writelen);
 
+/// Called when the firmware needs to be written back to storage,
+/// after one of the supported write commands finishes execution.
+/// @param firmware The firmware that was just written.
+/// @param writeoffset The offset of the first byte that was written to firmware.
+/// @param writelen The number of bytes that were written to firmware.
+void WriteFirmware(const SPI_Firmware::Firmware& firmware, u32 writeoffset, u32 writelen);
+
 
 // local multiplayer comm interface
 // packet type: DS-style TX header (12 bytes) + original 802.11 frame