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Merge remote-tracking branch 'upstream/master' into dish-fix

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This commit is contained in:
n1073645 2019-12-13 16:11:48 +00:00
commit 6e411c9dd9
10 changed files with 2085 additions and 1298 deletions
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8
src/core/Chef.mjs
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@ -73,10 +73,10 @@ class Chef {
// The threshold is specified in KiB.
const threshold = (options.ioDisplayThreshold || 1024) * 1024;
const returnType =
this.dish.size > threshold ?
Dish.ARRAY_BUFFER :
this.dish.type === Dish.HTML ?
Dish.HTML :
this.dish.type === Dish.HTML ?
Dish.HTML :
this.dish.size > threshold ?
Dish.ARRAY_BUFFER :
Dish.STRING;
return {

38
src/core/Utils.mjs
View file

@ -591,6 +591,44 @@ class Utils {
return utf8 ? Utils.byteArrayToUtf8(arr) : Utils.byteArrayToChars(arr);
}
/**
* Calculates the Shannon entropy for a given set of data.
*
* @param {Uint8Array|ArrayBuffer} input
* @returns {number}
*/
static calculateShannonEntropy(data) {
if (data instanceof ArrayBuffer) {
data = new Uint8Array(data);
}
const prob = [],
occurrences = new Array(256).fill(0);
// Count occurrences of each byte in the input
let i;
for (i = 0; i < data.length; i++) {
occurrences[data[i]]++;
}
// Store probability list
for (i = 0; i < occurrences.length; i++) {
if (occurrences[i] > 0) {
prob.push(occurrences[i] / data.length);
}
}
// Calculate Shannon entropy
let entropy = 0,
p;
for (i = 0; i < prob.length; i++) {
p = prob[i];
entropy += p * Math.log(p) / Math.log(2);
}
return -entropy;
}
/**
* Parses CSV data and returns it as a two dimensional array or strings.