cryptpadtab

commit

61ae74fb13e7c240aa6ff84713f85e87e1faae7b

parent

1213151e282ca143b92e47dcadf5ef0233d1e1a6

Author

Tobias Bengfort <tobias.bengfort@posteo.de>

Date

2024-05-29 13:05

Revert "lzw compression"

This reverts commit 61754d0f849c599bf90104a64f55bbe53e2d3ea7.

Diffstat

2 files changed, 2 insertions, 131 deletions

diff --git a/static/lzw.js b/static/lzw.js

@@ -1,128 +0,0 @@
    1    -1 class Buffer {
    2    -1 	constructor(bytes) {
    3    -1 		this.bytes = bytes;
    4    -1 		this.i_byte = 0;
    5    -1 		this.i_bit = 0;
    6    -1 	}
    7    -1 
    8    -1 	next() {
    9    -1 		if (this.i_bit < 7) {
   10    -1 			this.i_bit += 1;
   11    -1 		} else {
   12    -1 			this.i_byte += 1;
   13    -1 			this.i_bit = 0;
   14    -1 		}
   15    -1 	}
   16    -1 
   17    -1 	read(size) {
   18    -1 		var bits = 0;
   19    -1 		for (let i = 0; i < size; i++) {
   20    -1 			if (this.bytes.length <= this.i_byte) {
   21    -1 				throw new RangeError();
   22    -1 			}
   23    -1 			bits <<= 1;
   24    -1 			if (this.bytes[this.i_byte] & (1 << (7 - this.i_bit))) {
   25    -1 				bits |= 1;
   26    -1 			}
   27    -1 			this.next();
   28    -1 		}
   29    -1 		return bits;
   30    -1 	}
   31    -1 
   32    -1 	write(bits, size) {
   33    -1 		for (let i = 0; i < size; i++) {
   34    -1 			if (this.bytes.length <= this.i_byte) {
   35    -1 				this.bytes.push(0);
   36    -1 			}
   37    -1 			if (bits & (1 << (size - i - 1))) {
   38    -1 				this.bytes[this.i_byte] |= 1 << (7 - this.i_bit);
   39    -1 			}
   40    -1 			this.next();
   41    -1 		}
   42    -1 	}
   43    -1 }
   44    -1 
   45    -1 var sIndexOf = function(dict, value) {
   46    -1 	var s = value.toString();
   47    -1 	for (let i = 0; i < dict.length; i++) {
   48    -1 		if (s === dict[i].toString()) {
   49    -1 			return i;
   50    -1 		}
   51    -1 	}
   52    -1 	return -1;
   53    -1 };
   54    -1 
   55    -1 export var compress = function(bytes) {
   56    -1 	var result = [];
   57    -1 	var buf = new Buffer(result);
   58    -1 
   59    -1 	var field_size = 9;
   60    -1 	var dict = [];
   61    -1 	dict.push('end');
   62    -1 	for (let i = 0; i < 256; i++) {
   63    -1 		dict.push([i]);
   64    -1 	}
   65    -1 
   66    -1 	var win = [];
   67    -1 	var i = 0;
   68    -1 	while (i < bytes.length) {
   69    -1 		var tmp = [...win, bytes[i]];
   70    -1 		if (sIndexOf(dict, tmp) === -1) {
   71    -1 			buf.write(sIndexOf(dict, win), field_size);
   72    -1 			win = [];
   73    -1 			if (dict.length >> field_size) {
   74    -1 				field_size += 1;
   75    -1 			}
   76    -1 			dict.push(tmp);
   77    -1 		} else {
   78    -1 			win = tmp;
   79    -1 			i += 1;
   80    -1 		}
   81    -1 	}
   82    -1 	buf.write(sIndexOf(dict, win), field_size);
   83    -1 	buf.write(sIndexOf(dict, 'end'), field_size);
   84    -1 
   85    -1 	return new Uint8Array(result);
   86    -1 };
   87    -1 
   88    -1 export var decompress = function(bytes) {
   89    -1 	var result = [];
   90    -1 	var buf = new Buffer(bytes);
   91    -1 	var prev = null;
   92    -1 
   93    -1 	var field_size = 9;
   94    -1 	var dict = [];
   95    -1 	dict.push('end');
   96    -1 	for (let i = 0; i < 256; i++) {
   97    -1 		dict.push([i]);
   98    -1 	}
   99    -1 
  100    -1 	while (true) {
  101    -1 		var index = buf.read(field_size);
  102    -1 		var value = dict[index];
  103    -1 		if (dict.length >> field_size) {
  104    -1 			field_size += 1;
  105    -1 		}
  106    -1 
  107    -1 		if (value === 'end') {
  108    -1 			break;
  109    -1 		}
  110    -1 
  111    -1 		// push to dict with one cycle delay because we need the first
  112    -1 		// item from the next entry.
  113    -1 		//
  114    -1 		// If value is undefined, the next entry is the not-yet-pushed one.
  115    -1 		// Fortunately, we know that its first item is the same as in the entry
  116    -1 		// before that.
  117    -1 		if (!value) {
  118    -1 			value = [...prev, prev[0]];
  119    -1 		}
  120    -1 		result = result.concat(value);
  121    -1 		if (prev) {
  122    -1 			dict.push([...prev, value[0]]);
  123    -1 		}
  124    -1 		prev = value;
  125    -1 	}
  126    -1 
  127    -1 	return new Uint8Array(result);
  128    -1 };

diff --git a/static/main.js b/static/main.js

@@ -1,15 +1,14 @@
    1     1 import * as base64 from './base64.js';
    2    -1 import * as lzw from './lzw.js';
    3     2 
    4     3 var encode = function(text) {
    5     4 	var encoder = new TextEncoder();
    6     5 	var bytes = encoder.encode(text);
    7    -1 	return base64.encode(lzw.compress(bytes));
   -1     6 	return base64.encode(bytes);
    8     7 };
    9     8 
   10     9 var decode = function(string) {
   11    10 	var decoder = new TextDecoder();
   12    -1 	var bytes = lzw.decompress(base64.decode(string));
   -1    11 	var bytes = base64.decode(string);
   13    12 	return decoder.decode(bytes);
   14    13 };
   15    14