[Spotpass] Add ACNL spotpass documentation

Spotpass/Checksum.cpp

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+
+static const u32 crcTable[256] = { //Polynomial: 0x1EDC6F41, 0xFFFFFFFF initial value, 0xFFFFFFFF xor, Input Reflection, Output Reflection
+    0x00000000, 0xF26B8303, 0xE13B70F7, 0x1350F3F4, 0xC79A971F,
+    0x35F1141C, 0x26A1E7E8, 0xD4CA64EB, 0x8AD958CF, 0x78B2DBCC,
+    0x6BE22838, 0x9989AB3B, 0x4D43CFD0, 0xBF284CD3, 0xAC78BF27,
+    0x5E133C24, 0x105EC76F, 0xE235446C, 0xF165B798, 0x30E349B,
+    0xD7C45070, 0x25AFD373, 0x36FF2087, 0xC494A384, 0x9A879FA0,
+    0x68EC1CA3, 0x7BBCEF57, 0x89D76C54, 0x5D1D08BF, 0xAF768BBC,
+    0xBC267848, 0x4E4DFB4B, 0x20BD8EDE, 0xD2D60DDD, 0xC186FE29,
+    0x33ED7D2A, 0xE72719C1, 0x154C9AC2, 0x061C6936, 0xF477EA35,
+    0xAA64D611, 0x580F5512, 0x4B5FA6E6, 0xB93425E5, 0x6DFE410E,
+    0x9F95C20D, 0x8CC531F9, 0x7EAEB2FA, 0x30E349B1, 0xC288CAB2,
+    0xD1D83946, 0x23B3BA45, 0xF779DEAE, 0x05125DAD, 0x1642AE59,
+    0xE4292D5A, 0xBA3A117E, 0x4851927D, 0x5B016189, 0xA96AE28A,
+    0x7DA08661, 0x8FCB0562, 0x9C9BF696, 0x6EF07595, 0x417B1DBC,
+    0xB3109EBF, 0xA0406D4B, 0x522BEE48, 0x86E18AA3, 0x748A09A0,
+    0x67DAFA54, 0x95B17957, 0xCBA24573, 0x39C9C670, 0x2A993584,
+    0xD8F2B687, 0x0C38D26C, 0xFE53516F, 0xED03A29B, 0x1F682198,
+    0x5125DAD3, 0xA34E59D0, 0xB01EAA24, 0x42752927, 0x96BF4DCC,
+    0x64D4CECF, 0x77843D3B, 0x85EFBE38, 0xDBFC821C, 0x2997011F,
+    0x3AC7F2EB, 0xC8AC71E8, 0x1C661503, 0xEE0D9600, 0xFD5D65F4,
+    0x0F36E6F7, 0x61C69362, 0x93AD1061, 0x80FDE395, 0x72966096,
+    0xA65C047D, 0x5437877E, 0x4767748A, 0xB50CF789, 0xEB1FCBAD,
+    0x197448AE, 0x0A24BB5A, 0xF84F3859, 0x2C855CB2, 0xDEEEDFB1,
+    0xCDBE2C45, 0x3FD5AF46, 0x7198540D, 0x83F3D70E, 0x90A324FA,
+    0x62C8A7F9, 0xB602C312, 0x44694011, 0x5739B3E5, 0xA55230E6,
+    0xFB410CC2, 0x092A8FC1, 0x1A7A7C35, 0xE811FF36, 0x3CDB9BDD,
+    0xCEB018DE, 0xDDE0EB2A, 0x2F8B6829, 0x82F63B78, 0x709DB87B,
+    0x63CD4B8F, 0x91A6C88C, 0x456CAC67, 0xB7072F64, 0xA457DC90,
+    0x563C5F93, 0x082F63B7, 0xFA44E0B4, 0xE9141340, 0x1B7F9043,
+    0xCFB5F4A8, 0x3DDE77AB, 0x2E8E845F, 0xDCE5075C, 0x92A8FC17,
+    0x60C37F14, 0x73938CE0, 0x81F80FE3, 0x55326B08, 0xA759E80B,
+    0xB4091BFF, 0x466298FC, 0x1871A4D8, 0xEA1A27DB, 0xF94AD42F,
+    0x0B21572C, 0xDFEB33C7, 0x2D80B0C4, 0x3ED04330, 0xCCBBC033,
+    0xA24BB5A6, 0x502036A5, 0x4370C551, 0xB11B4652, 0x65D122B9,
+    0x97BAA1BA, 0x84EA524E, 0x7681D14D, 0x2892ED69, 0xDAF96E6A,
+    0xC9A99D9E, 0x3BC21E9D, 0xEF087A76, 0x1D63F975, 0x0E330A81,
+    0xFC588982, 0xB21572C9, 0x407EF1CA, 0x532E023E, 0xA145813D,
+    0x758FE5D6, 0x87E466D5, 0x94B49521, 0x66DF1622, 0x38CC2A06,
+    0xCAA7A905, 0xD9F75AF1, 0x2B9CD9F2, 0xFF56BD19, 0x0D3D3E1A,
+    0x1E6DCDEE, 0xEC064EED, 0xC38D26C4, 0x31E6A5C7, 0x22B65633,
+    0xD0DDD530, 0x0417B1DB, 0xF67C32D8, 0xE52CC12C, 0x1747422F,
+    0x49547E0B, 0xBB3FFD08, 0xA86F0EFC, 0x5A048DFF, 0x8ECEE914,
+    0x7CA56A17, 0x6FF599E3, 0x9D9E1AE0, 0xD3D3E1AB, 0x21B862A8,
+    0x32E8915C, 0xC083125F, 0x144976B4, 0xE622F5B7, 0xF5720643,
+    0x07198540, 0x590AB964, 0xAB613A67, 0xB831C993, 0x4A5A4A90,
+    0x9E902E7B, 0x6CFBAD78, 0x7FAB5E8C, 0x8DC0DD8F, 0xE330A81A,
+    0x115B2B19, 0x020BD8ED, 0xF0605BEE, 0x24AA3F05, 0xD6C1BC06,
+    0xC5914FF2, 0x37FACCF1, 0x69E9F0D5, 0x9B8273D6, 0x88D28022,
+    0x7AB90321, 0xAE7367CA, 0x5C18E4C9, 0x4F48173D, 0xBD23943E,
+    0xF36E6F75, 0x0105EC76, 0x12551F82, 0xE03E9C81, 0x34F4F86A,
+    0xC69F7B69, 0xD5CF889D, 0x27A40B9E, 0x79B737BA, 0x8BDCB4B9,
+    0x988C474D, 0x6AE7C44E, 0xBE2DA0A5, 0x4C4623A6, 0x5F16D052,
+    0xAD7D5351
+};
+
+//This CRC32 function is used for most checksums in the save, and also the checksums in Spotpass structs
+u32 CalculateCRC32Reflected(u8* buf, u32 size) {
+    u32 crc = 0xFFFFFFFF;
+    while (size-- != 0) {
+        crc = crcTable[(crc ^ *buf) & 0xFF] ^ (crc >> 8);
+        buf++;
+    }
+    return ~crc;
+}

Spotpass/README.md

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+# Spotpass in ACNL
+
+ACNL has a variety of Spotpass features.
+
+* Letters
+* Happy Home Showcase Houses
+* Presents/'Distributed Items'
+* RVs
+
+Each of these features have been utilised at some point in ACNL's lifespan.
+
+The Spotpass RVs was a new feature added in the Welcome Amiibo update. Unfortunately, this feature has only ever been used in Japan for distrubuting `Holden` and `Filly` RVs. It has never been used in Europe or the USA.
+
+In this repo I have provided some documentation on Spotpass files, and have also provided some sample Spotpass files. Unforunately, most of these are handcrafted and do not pass the checks Nintendo has put in place to ensure the Spotpass file was created by them. Thus, CFW is needed as it disables these checks. Spotpass files are also region and version locked, due to each version ACNL having it's own TitleID.
+
+*However*, I have managed to capture one RV file. This file is specifically for the original Japanese version of ACNL. It is a capture of a 7-11 `Filly` event. This file was created by Nintendo, and so should also pass the checks and theoretically doesn't require CFW.

Spotpass/Structures.cpp

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+struct Spotpass_RV //Content Datatype in Payload Content Header must be 0x00010010; Size of this struct: 0x8; Filename: camp_p.dat
+{
+    u32 Checksum; //This is over the next 4 bytes (see Checksum.cpp for algorithm)
+    u8  Magic;    //Has to be 0x1
+    u8  Padding; //Always 0
+    u16 VillagerID; //No restrictions
+};
+
+union IndexForItemArray
+{
+    u32     raw;
+    struct
+    {
+        u16     ID;
+        u16     Flags;
+    };
+};
+
+struct Spotpass_Present //Content Datatype in Payload Content Header must be 0x00010002; Size of this struct: 0xC; Filename: FGONLYT
+{
+    u32 Checksum; //This is over the next 8 bytes (see Checksum.cpp for algorithm)
+    u8  Magic; //Has to be 0x2
+    u8  Padding; //Always 0
+    u16 PresentID; //This is used to ensure the player can't get the gift twice
+    IndexForItemArray idx; //Game does (ID & 0xE000) && ID < 0x11AD, then gets WA item ID from g_ValidSpotpassGiftItems Array
+};