Binary Frame Version 2

[timotheeg]

Context

As player skills skyrocketed (See Cheez's 2.3M score), the built-in limits of Nestrischamps have been reached.

The limiters of Nestrischamps were its compact binary frame format. Specifically the limitations of the frame format were as follows:

• level: 6 bits (max 62) -> nearly broken! (Cheez's game pieces reached 61)
• lines: 9 bits (max 510) -> broken! (Cheez's game pieces reached 551)
• piece counters: 8 bits each (max 254) -> almost broken! (Cheez's game pieces reached 218 - S)
• score: 21 bits (max 2,097,150) -> Safe! because score in UI will never be more than 1.6M even, with Game Genie code

To support such high level play, Nestrischamps must be able to transmit what it sees on screen.

Approach

This PR introduces a binary format version 2. The format consumes 2 more bytes per frame with the following changes:

• lines: 9 bits -> 12 bits (+3) (max 4094) (i.e. can handle up display FFE)
• level: 6 bits -> 8 bits (+2) (max 254)
• piece counters: 8 bits -> 9 bits (+1 x7) (each piece can get to 510)
• score: 21 bits -> 24 bits (+3) (unnecessary expansion for byte alignment)

To accommodate bit and byte boundaries, the field order of the binary frame format have been changed as well.

The change is backward compatible. All replays should be able to handle .ngf files containing either v1 frames and v2 frames (although of course a .ngf file should NOT have multiple versions of frames therein).

The layout of a given game frame now looks like this:

Fiel	Content	Size in bits	Range
1	version	3	7
2	game type	2	4
3	player num	3	7
4	game id	16	65,535
5	client time	28	268,435,455 (in ms; i.e. ~74h)
6	lines	12	4094
7	level	8	254
8	score	24	16,777,215
9	instant das	5	30
10	preview	3	7
11	cur piece das	5	30
12	cur piece	3	7
13	T	9	510
14	J	9	510
15	Z	9	510
16	O	9	510
17	S	9	510
18	L	9	510
19	I	9	510
20	field	400	2 bits x 10 columns x 20 lines