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Add T6RP documentation
author Thibaut Girka <thib@sitedethib.com>
date Tue, 23 Aug 2011 13:18:17 +0200
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children 9f0e37b7eeab
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7:2a7b9d62c0c4 8:c5b074b0abbd
1 <?xml version="1.0" encoding="utf-8"?>
2 <?xml-stylesheet type="text/css" href="../style.css"?>
3 <!DOCTYPE html>
4 <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
5 <head>
6 <title>T6RP format</title>
7 </head>
8 <body>
9 <h1>T6RP format</h1>
10 <p>The T6RP format is the replay format used by EoSD.</p>
11
12 <p>It is composed of a header and an "encrypted" data section, which is itself composed of a header, per-stage structures and lists of keystates.</p>
13
14
15 <h2>Header</h2>
16 <pre>
17 typedef struct {
18 char magic[4]; // T6RP
19 uint16_t unknown; //TODO: always 0x0102
20 // Seems to be a switch, if 0x0102 do something, else (whatever the value is), do something else
21 uint8_t player; // 0 = ReimuA, 1 = ReimuB, 2 = MarisaA, 3 = MarisaB
22 uint8_t rank; // 0 = Easy, 3 = Lunatic, 4 = Extra
23 uint32_t checksum; // (0x3f000318 + key + sum(c for c in decrypted_data)) % (2 ** 32)
24 uint16_t unknown2; //TODO: seems to be ignored by the game
25 uint8_t key;
26 char crypted_data[]; // crypted(a, i) = (a + key + 7*i) % 256
27 // decrypted(c, i) = (c - key - 7*i) % 256
28 } thrpy6_header_t;
29 </pre>
30
31 <h2>Decrypting the data section.</h2>
32 <p>As stated earlier, the data section is encrypted. Luckily, this encryption is quite simplistic, and encrypting/decrypting it is easy (see this snippet of python3 code):</p>
33 <pre>
34 def decrypt(key, data):
35 return bytes((c - key - 7 * i) % 256 for i, c in enumerate(data))
36
37 def encrypt(key, data):
38 return bytes((c + key + 7 * i) % 256 for i, c in enumerate(data))
39 </pre>
40
41 <h2>Encrypted header</h2>
42 <pre>
43 typedef struct {
44 uint8_t unknown; //TODO: seems to be ignored by the game
45 char date[9]; // null-terminated string
46 char name[9]; // null-terminated string
47 uint16_t unknown2; //TODO: seems to be ignored by the game
48 uint32_t score; //TODO: Total score. seems to be ignored by the game
49 uint32_t unknown3; //TODO: seems to be ignored by the game
50 float slowdown_rate; // As a percentage, not a proper rate
51 uint8_t unknwon[4]; //TODO: seems to have no effect
52 uint32_t stage1_offset; // Offset of a thrpy6_stage_t from the start of the file (including the unencrypted header)
53 uint32_t stage2_offset;
54 uint32_t stage3_offset;
55 uint32_t stage4_offset;
56 uint32_t stage5_offset;
57 uint32_t stage6_offset;
58 uint32_t stage7_offset;
59 } thrpy6_encrypted_header;
60 </pre>
61
62 <h2>Stage entry</h2>
63 <pre>
64 typedef struct {
65 uint32_t score;
66 uint16_t random_seed;
67 uint16_t unknown1; //TODO: seems to be ignored by the game
68 uint8_t power;
69 int8_t lives;
70 int8_t bombs;
71 uint8_t difficulty; //TODO: WARNING: This has a huge effect on the game!
72 // It is also called rank (but we use the term "difficulty" because "rank" is the official name for Easy/Normal/Hard/Lunatic/Extra)
73 // See: http://en.touhouwiki.net/wiki/Embodiment_of_Scarlet_Devil/Gameplay#Rank
74 uint8_t unknown3[3]; //TODO: seems to be ignored by the game. Padding?
75 thrpy6_keystate_t keystates[];
76 } thrpy6_stage_t;
77 </pre>
78
79 <h2>Keystates</h2>
80 <pre>
81 struct {
82 uint32_t time; // Time of the event, most probably exprimed in frames
83 uint16_t keys; // 1 = shoot, 2 = bomb, 4 = focus, 8 = ?, 16 = up, 32 = down, 64 = left, 128 = right
84 uint16_t unknown; //TODO: seems to be ignored by the game
85 } thrpy6_keystate_t;
86 </pre>
87 </body>
88 </html>