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Add partial support for the mouse move format in TWS files

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This commit is contained in:
Eevee (Evelyn Woods) 2024-04-24 03:21:14 -06:00
parent 097a4b04d8
commit df0ab43e70
1 changed files with 34 additions and 4 deletions
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38
js/format-tws.js
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@ -13,6 +13,7 @@ const TW_DIRECTION_TO_INPUT_BITS = [
INPUT_BITS.down | INPUT_BITS.right,
];
// doc: http://www.muppetlabs.com/~breadbox/software/tworld/tworldff.html#3
export function parse_solutions(bytes) {
let buf;
if (bytes.buffer) {
@ -82,10 +83,12 @@ export function parse_solutions(bytes) {
let q = p + 16;
while (q < p + len) {
// There are four formats for packing solutions, identified by the lowest two bits,
// except that format 3 is actually two formats, don't ask
// except that format 3 is actually two formats. Be aware that the documentation
// refers to them in a different order than suggested by the identifying nybble.
let fmt = bytes[q] & 0x3;
let fmt2 = (bytes[q] >> 4) & 0x1;
if (fmt === 0) {
// "Third format": three consecutive moves packed into one byte
let val = bytes[q];
q += 1;
let input1 = TW_DIRECTION_TO_INPUT_BITS[(val >> 2) & 0x3];
@ -98,6 +101,8 @@ export function parse_solutions(bytes) {
);
}
else if (fmt === 1 || fmt === 2 || (fmt === 3 && fmt2 === 0)) {
// "First format" and "second format": one, two, or four bytes containing a
// direction and a number of tics
let val;
if (fmt === 1) {
val = bytes[q];
@ -118,9 +123,34 @@ export function parse_solutions(bytes) {
}
inputs.push(input);
}
else { // 3-1
// variable-size and only needed for ms so let's just hope not
throw new Error;
else { // low nybble is 3, and bit 4 is set
// "Fourth format": 2 to 5 bytes, containing an exceptionally long direction
// field and time field, mostly used for MSCC mouse moves
let n = ((bytes[q] >> 2) & 0x3) + 2;
if (q + n - 1 >= bytes.length)
throw new Error(`Malformed TWS file: expected ${n} bytes starting at ${q}, but only found ${bytes.length - q}`);
// Up to 5 bytes is an annoying amount, but we can cut it down to 1-4 by
// extracting the direction first
let input = (bytes[q] >> 5) | ((bytes[q + 1] & 0x3f) << 3);
let duration = bytes[q + 1] >> 6;
for (let i = 3; i <= n; i++) {
duration |= bytes[q + i - 1] << (2 + (i - 3) * 8);
}
// Mouse moves are encoded as 16 + ((y + 9) * 19) + (x + 9), but I extremely do
// not support them at the moment (and may never), so replace them with blank
// input for now (and possibly forever)
if (input >= 16) {
input = 0;
}
// And now queue it up
for (let i = 0; i < duration; i++) {
inputs.push(input);
}
q += n;
}
}