Create head.md

Author: n123git

head.md

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+---
+parent: Save Docs!
+layout: default
+nav_order: 999
+title: Header Files
+---
+This page documents Header files (also known as `head.yw`). Note that each game has 3 save files (`game*.yw`) but ONE `head.yw` which has data for all three
+
+<sup>Disclaimer: **Most** changes to the `head.yw` only affect the preview you see before you enter the save file, NOT the actual save file (This is very important, dont forget :P). Exceptions to this rule include the save file names, and decryption seed.</sup>
+Most (known) parts of the `head.yw` are duplicated, with 3 versions corresponding to the 3 save files. An exception to this is the seed located in the head file.
+
+Here are some of the known elements
+
+
+## Fixed Elements (1 per head)
+
+| Offset | Length  | Description                                                                          |
+| ------ | ------- | ------------------------------------------------------------------------------------ |
+| `0x0C` | 0x04    | (Uint32) - A seed ran through a Xorshift-based pseudorandom number generator (PRNG) to derive an AES-128 encryption key, used in part of the decryption process for V2 save files. |
+
+
+## Save File Dependant (3 per head)
+Note that the `Offset` in this table assumes the Player name is at `0x00` instead of providing all 3 possible positions. A list of player name positions can be found below for reference.
+
+| Offset | Length  | Description                                                                          |
+| ------ | ------- | ------------------------------------------------------------------------------------ |
+| `0x00` | 0x08    | Player name (UTF-8 LE, fixed length 8 bytes, padded if shorter)                      |
+| `0x09` | 0x1A    | Unknown (18 bytes)                                                                   |
+| `0x1B` | 0x01    | Boolean Main Story Completion? (1 bytes, unverified)                                 |
+| `0x1C` | 0x24    | Unknown (10 bytes)                                                                   |
+| `0x25` | 0x01    | **Watch Rank** (`0x05 = S`, `0x04 = A`, `0x03 = B`, etc.)                            |
+| `0x26` | 0x43    | Unknown (67 bytes) — **still part of the 0x60 block total from 0x08–0x68**           |
+| `0x67` | 0x02    | Year (`UInt16`)                                                                      |
+| `0x6B` | 0x01    | Day (`LEB128` or `UInt8`)                                                            |
+| `0x6C` | 0x01    | Month (`LEB128` or `UInt8`)                                                          |
+| `0x6D` | 0x01    | Hour (`LEB128` or `UInt8`)                                                           |
+| `0x6E` | 0x01    | Minute (`LEB128` or `UInt8`)                                                         |
+| `0x6F` | 0x01`?` | (Optional) Seconds? (`LEB128` or `UInt8`, Not displayed but may be internally used)  |
+
+## Player Name Positions
+
+
+| Block # | Start Addr | End Addr | Size      |
+| ------- | ---------- | -------- | --------- |
+| 1       | `0x5390`   | `0x5417` | 136 bytes |
+| 2       | `0x5418`   | `0x549F` | 136 bytes |
+| 3       | `0x54A0`   | `0x5527` | 136 bytes |
+
+## Notes (IGNORE)
+The `head.yw` is especially tolerant of illegal values, it allows things like illegal names (disallowed unicode characters appear as a black-box), an hour value of 25 etc
+SECTIONID parse?????????????????????????
+TO;DO document save file play time, save file location, save file party, save file gender, save file version
+
+legacy:
+1-8 = Name (Length: 0x8 or 8) in UTF8-LE
+9-36 = Unknown
+37 = Save File Rank 05 = S, 04 = A etc
+38 - 104 Unknown (Length: 0x60 or 96)
+Then Int/Uint16 Year followed by LEB/ULEB128 Day, LEB/ULEB128 OR INT8/UINT8 Month (Identical in this case), then LEB/ULEB128 OR INT8/UINT8 Hour (Again, identical in this case), then LEB/ULEB128 OR INT8/UINT8 Minute (Again, identical in this case), then (this isn't shown, but is internally used) then LEB/ULEB128 OR INT8/UINT8 Seconds?
+
+53B8-53D2
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+53C0-53D0