Modest cleanups for DSi_NAND (#1714)

* Add a definition for TMD files

* Wrap TitleMetadata in a namespace

* Add a comment

* Remove TitleMetadataCertificate

- melonDS ignores it anyway

* Refactor the use of title metadata

- Move bitwise operations on the title ID into helper methods
- Use TitleMetadata objects instead of pointers to raw data

* Slight cleanup in DSi_NAND

- Replace some constants with sizeof
- Use an NDSHeader object instead of a raw array of bytes

* Add a DSi_NAND::ImportFile overload that loads a file from memory

* Split most of ImportTitle into InitTitleFileStructure

- It will be reused in the next commit

* Add ability to import title from memory

* Fix another potential issue

* Fix broken DSiWare installation

- The bytes of the title ID/category were being swapped in most places, but not all

* Add some logging calls

* Declare array sizes in DSi_TMD in decimal, not hex

* Add a space after the #endif

- To adhere to the style guide

* Assert the size of TitleMetadataContent

* Change the type of SignatureName

* Don't mark the TMD structs as packed

* Remove extraneous comments

* Cut down some newlines

1 files changed, 119 insertions, 0 deletions

diff --git a/src/DSi_TMD.h b/src/DSi_TMD.h
new file mode 100644
index 0000000..12226c5
--- /dev/null
+++ b/src/DSi_TMD.h
@@ -0,0 +1,119 @@
+/*
+    Copyright 2016-2023 melonDS team
+
+    This file is part of melonDS.
+
+    melonDS is free software: you can redistribute it and/or modify it under
+    the terms of the GNU General Public License as published by the Free
+    Software Foundation, either version 3 of the License, or (at your option)
+    any later version.
+
+    melonDS is distributed in the hope that it will be useful, but WITHOUT ANY
+    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+    FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with melonDS. If not, see http://www.gnu.org/licenses/.
+*/
+
+#ifndef DSI_TMD_H
+#define DSI_TMD_H
+
+#include "types.h"
+#include <array>
+
+namespace DSi_TMD
+{
+
+struct TitleMetadataContent {
+    u8 ContentId[4]; /// Content ID (00,00,00,vv) ;lowercase/hex ;"0000000vv.app"
+    u8 ContentIndex[2]; /// Content Index (00,00)
+    u8 ContentType[2]; /// Content Type (00,01) ;aka DSi .app
+    u8 ContentSize[8]; /// Content Size (00,00,00,00,00,19,E4,00)
+    u8 ContentSha1Hash[20]; /// Content SHA1 (on decrypted ".app" file)
+
+    [[nodiscard]] u32 GetVersion() const noexcept
+    {
+        return (ContentId[0] << 24) | (ContentId[1] << 16) | (ContentId[2] << 8) | ContentId[3];
+    }
+};
+
+static_assert(sizeof(TitleMetadataContent) == 36, "TitleMetadataContent is not 36 bytes!");
+
+/// Metadata for a DSiWare title.
+/// Used to install DSiWare titles to NAND.
+/// @see https://problemkaputt.de/gbatek.htm#dsisdmmcdsiwareticketsandtitlemetadata
+struct TitleMetadata
+{
+    u32 SignatureType;
+    u8 Signature[256];
+    u8 SignatureAlignment[60];
+    char SignatureName[64];
+
+    u8 TmdVersion;
+    u8 CaCrlVersion;
+    u8 SignerCrlVersion;
+    u8 Padding0;
+
+    u8 SystemVersion[8];
+    u8 TitleId[8];
+    u32 TitleType;
+    u8 GroupId[2];
+    u8 PublicSaveSize[4];
+    u8 PrivateSaveSize[4];
+    u8 Padding1[4];
+
+    u8 SrlFlag;
+    u8 Padding2[3];
+
+    u8 AgeRatings[16];
+    u8 Padding3[30];
+
+    u32 AccessRights;
+    u16 TitleVersion;
+
+    u16 NumberOfContents; /// There's always one or zero content entries in practice
+    u16 BootContentIndex;
+    u8 Padding4[2];
+
+    TitleMetadataContent Contents;
+
+    [[nodiscard]] bool HasPublicSaveData() const noexcept { return GetPublicSaveSize() != 0; }
+    [[nodiscard]] bool HasPrivateSaveData() const noexcept { return GetPrivateSaveSize() != 0; }
+
+    [[nodiscard]] u32 GetPublicSaveSize() const noexcept
+    {
+        return (PublicSaveSize[0] << 24) | (PublicSaveSize[1] << 16) | (PublicSaveSize[2] << 8) | PublicSaveSize[3];
+    }
+
+    [[nodiscard]] u32 GetPrivateSaveSize() const noexcept
+    {
+        return (PrivateSaveSize[0] << 24) | (PrivateSaveSize[1] << 16) | (PrivateSaveSize[2] << 8) | PrivateSaveSize[3];
+    }
+
+    [[nodiscard]] u32 GetCategory() const noexcept
+    {
+       return (TitleId[0] << 24) | (TitleId[1] << 16) | (TitleId[2] << 8) | TitleId[3];
+    }
+
+    [[nodiscard]] u32 GetCategoryNoByteswap() const noexcept
+    {
+        return reinterpret_cast<const u32&>(TitleId);
+    }
+
+    [[nodiscard]] u32 GetID() const noexcept
+    {
+        return (TitleId[4] << 24) | (TitleId[5] << 16) | (TitleId[6] << 8) | TitleId[7];
+    }
+
+    [[nodiscard]] u32 GetIDNoByteswap() const noexcept
+    {
+        return *reinterpret_cast<const u32*>(&TitleId[4]);
+    }
+};
+
+static_assert(sizeof(TitleMetadata) == 520, "TitleMetadata is not 520 bytes!");
+
+}
+
+#endif // DSI_TMD_H