mirror of
https://github.com/codedread/bitjs
synced 2025-10-04 18:19:15 +02:00
Whitespace and a couple arrow functions
This commit is contained in:
codedread
parent
0d27e9d9c0
commit
d2a4329893
5 changed files with 302 additions and 317 deletions
608
archive/unzip.js
608
archive/unzip.js
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@ -61,7 +61,7 @@ class ZipLocalFile {
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// takes a ByteStream and parses out the local file information
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constructor(bstream) {
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if (typeof bstream != typeof {} || !bstream.readNumber || typeof bstream.readNumber != typeof function(){}) {
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return null;
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return null;
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}
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bstream.readNumber(4); // swallow signature
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@ -78,7 +78,7 @@ class ZipLocalFile {
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this.filename = null;
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if (this.fileNameLength > 0) {
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this.filename = bstream.readString(this.fileNameLength);
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this.filename = bstream.readString(this.fileNameLength);
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}
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info("Zip Local File Header:");
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@ -96,14 +96,14 @@ class ZipLocalFile {
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this.extraField = null;
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if (this.extraFieldLength > 0) {
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this.extraField = bstream.readString(this.extraFieldLength);
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info(" extra field=" + this.extraField);
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this.extraField = bstream.readString(this.extraFieldLength);
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info(" extra field=" + this.extraField);
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}
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// read in the compressed data
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this.fileData = null;
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if (this.compressedSize > 0) {
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this.fileData = new Uint8Array(bstream.readBytes(this.compressedSize));
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this.fileData = new Uint8Array(bstream.readBytes(this.compressedSize));
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}
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// TODO: deal with data descriptor if present (we currently assume no data descriptor!)
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@ -111,9 +111,9 @@ class ZipLocalFile {
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// But how do you figure out how big the file data is if you don't know the compressedSize
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// from the header?!?
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if ((this.generalPurpose & BIT[3]) != 0) {
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this.crc32 = bstream.readNumber(4);
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this.compressedSize = bstream.readNumber(4);
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this.uncompressedSize = bstream.readNumber(4);
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this.crc32 = bstream.readNumber(4);
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this.compressedSize = bstream.readNumber(4);
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this.uncompressedSize = bstream.readNumber(4);
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}
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}
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@ -154,97 +154,95 @@ const unzip = function(arrayBuffer) {
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const bstream = new bitjs.io.ByteStream(arrayBuffer);
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// detect local file header signature or return null
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if (bstream.peekNumber(4) == zLocalFileHeaderSignature) {
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const localFiles = [];
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// loop until we don't see any more local files
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while (bstream.peekNumber(4) == zLocalFileHeaderSignature) {
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const oneLocalFile = new ZipLocalFile(bstream);
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// this should strip out directories/folders
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if (oneLocalFile && oneLocalFile.uncompressedSize > 0 && oneLocalFile.fileData) {
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localFiles.push(oneLocalFile);
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totalUncompressedBytesInArchive += oneLocalFile.uncompressedSize;
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}
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}
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totalFilesInArchive = localFiles.length;
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const localFiles = [];
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// loop until we don't see any more local files
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while (bstream.peekNumber(4) == zLocalFileHeaderSignature) {
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const oneLocalFile = new ZipLocalFile(bstream);
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// this should strip out directories/folders
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if (oneLocalFile && oneLocalFile.uncompressedSize > 0 && oneLocalFile.fileData) {
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localFiles.push(oneLocalFile);
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totalUncompressedBytesInArchive += oneLocalFile.uncompressedSize;
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}
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}
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totalFilesInArchive = localFiles.length;
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// got all local files, now sort them
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localFiles.sort(function(a,b) {
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return a.filename > b.filename ? 1 : -1;
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});
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// got all local files, now sort them
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localFiles.sort((a,b) => a.filename > b.filename ? 1 : -1);
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// archive extra data record
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if (bstream.peekNumber(4) == zArchiveExtraDataSignature) {
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info(" Found an Archive Extra Data Signature");
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// archive extra data record
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if (bstream.peekNumber(4) == zArchiveExtraDataSignature) {
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info(" Found an Archive Extra Data Signature");
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// skipping this record for now
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bstream.readNumber(4);
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const archiveExtraFieldLength = bstream.readNumber(4);
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bstream.readString(archiveExtraFieldLength);
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}
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// skipping this record for now
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bstream.readNumber(4);
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const archiveExtraFieldLength = bstream.readNumber(4);
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bstream.readString(archiveExtraFieldLength);
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}
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// central directory structure
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// TODO: handle the rest of the structures (Zip64 stuff)
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if (bstream.peekNumber(4) == zCentralFileHeaderSignature) {
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info(" Found a Central File Header");
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// central directory structure
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// TODO: handle the rest of the structures (Zip64 stuff)
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if (bstream.peekNumber(4) == zCentralFileHeaderSignature) {
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info(" Found a Central File Header");
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// read all file headers
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while (bstream.peekNumber(4) == zCentralFileHeaderSignature) {
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bstream.readNumber(4); // signature
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bstream.readNumber(2); // version made by
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bstream.readNumber(2); // version needed to extract
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bstream.readNumber(2); // general purpose bit flag
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bstream.readNumber(2); // compression method
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bstream.readNumber(2); // last mod file time
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bstream.readNumber(2); // last mod file date
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bstream.readNumber(4); // crc32
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bstream.readNumber(4); // compressed size
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bstream.readNumber(4); // uncompressed size
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const fileNameLength = bstream.readNumber(2); // file name length
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const extraFieldLength = bstream.readNumber(2); // extra field length
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const fileCommentLength = bstream.readNumber(2); // file comment length
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bstream.readNumber(2); // disk number start
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bstream.readNumber(2); // internal file attributes
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bstream.readNumber(4); // external file attributes
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bstream.readNumber(4); // relative offset of local header
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// read all file headers
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while (bstream.peekNumber(4) == zCentralFileHeaderSignature) {
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bstream.readNumber(4); // signature
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bstream.readNumber(2); // version made by
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bstream.readNumber(2); // version needed to extract
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bstream.readNumber(2); // general purpose bit flag
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bstream.readNumber(2); // compression method
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bstream.readNumber(2); // last mod file time
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bstream.readNumber(2); // last mod file date
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bstream.readNumber(4); // crc32
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bstream.readNumber(4); // compressed size
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bstream.readNumber(4); // uncompressed size
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const fileNameLength = bstream.readNumber(2); // file name length
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const extraFieldLength = bstream.readNumber(2); // extra field length
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const fileCommentLength = bstream.readNumber(2); // file comment length
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bstream.readNumber(2); // disk number start
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bstream.readNumber(2); // internal file attributes
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bstream.readNumber(4); // external file attributes
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bstream.readNumber(4); // relative offset of local header
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bstream.readString(fileNameLength); // file name
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bstream.readString(extraFieldLength); // extra field
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bstream.readString(fileCommentLength); // file comment
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}
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}
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bstream.readString(fileNameLength); // file name
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bstream.readString(extraFieldLength); // extra field
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bstream.readString(fileCommentLength); // file comment
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}
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}
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// digital signature
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if (bstream.peekNumber(4) == zDigitalSignatureSignature) {
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info(" Found a Digital Signature");
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// digital signature
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if (bstream.peekNumber(4) == zDigitalSignatureSignature) {
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info(" Found a Digital Signature");
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bstream.readNumber(4);
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const sizeOfSignature = bstream.readNumber(2);
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bstream.readString(sizeOfSignature); // digital signature data
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}
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bstream.readNumber(4);
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const sizeOfSignature = bstream.readNumber(2);
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bstream.readString(sizeOfSignature); // digital signature data
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}
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// report # files and total length
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if (localFiles.length > 0) {
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postProgress();
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}
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// report # files and total length
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if (localFiles.length > 0) {
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postProgress();
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}
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// now do the unzipping of each file
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for (let i = 0; i < localFiles.length; ++i) {
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const localfile = localFiles[i];
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// now do the unzipping of each file
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for (let i = 0; i < localFiles.length; ++i) {
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const localfile = localFiles[i];
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// update progress
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currentFilename = localfile.filename;
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currentFileNumber = i;
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currentBytesUnarchivedInFile = 0;
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// update progress
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currentFilename = localfile.filename;
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currentFileNumber = i;
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currentBytesUnarchivedInFile = 0;
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// actually do the unzipping
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localfile.unzip();
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// actually do the unzipping
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localfile.unzip();
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if (localfile.fileData != null) {
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postMessage(new bitjs.archive.UnarchiveExtractEvent(localfile));
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postProgress();
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}
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}
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if (localfile.fileData != null) {
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postMessage(new bitjs.archive.UnarchiveExtractEvent(localfile));
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postProgress();
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postMessage(new bitjs.archive.UnarchiveFinishEvent());
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}
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}
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postProgress();
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postMessage(new bitjs.archive.UnarchiveFinishEvent());
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}
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}
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@ -252,58 +250,57 @@ const unzip = function(arrayBuffer) {
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// each entry's index is its code and its value is a JavaScript object
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// containing {length: 6, symbol: X}
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function getHuffmanCodes(bitLengths) {
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// ensure bitLengths is an array containing at least one element
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if (typeof bitLengths != typeof [] || bitLengths.length < 1) {
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err("Error! getHuffmanCodes() called with an invalid array");
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return null;
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// ensure bitLengths is an array containing at least one element
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if (typeof bitLengths != typeof [] || bitLengths.length < 1) {
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err("Error! getHuffmanCodes() called with an invalid array");
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return null;
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}
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// Reference: http://tools.ietf.org/html/rfc1951#page-8
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const numLengths = bitLengths.length;
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const bl_count = [];
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let MAX_BITS = 1;
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// Step 1: count up how many codes of each length we have
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for (let i = 0; i < numLengths; ++i) {
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const length = bitLengths[i];
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// test to ensure each bit length is a positive, non-zero number
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if (typeof length != typeof 1 || length < 0) {
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err("bitLengths contained an invalid number in getHuffmanCodes(): " + length + " of type " + (typeof length));
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return null;
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}
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// increment the appropriate bitlength count
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if (bl_count[length] == undefined) bl_count[length] = 0;
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// a length of zero means this symbol is not participating in the huffman coding
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if (length > 0) bl_count[length]++;
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if (length > MAX_BITS) MAX_BITS = length;
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}
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// Reference: http://tools.ietf.org/html/rfc1951#page-8
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const numLengths = bitLengths.length;
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const bl_count = [];
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let MAX_BITS = 1;
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// Step 2: Find the numerical value of the smallest code for each code length
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const next_code = [];
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let code = 0;
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for (let bits = 1; bits <= MAX_BITS; ++bits) {
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const length = bits-1;
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// ensure undefined lengths are zero
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if (bl_count[length] == undefined) bl_count[length] = 0;
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code = (code + bl_count[bits-1]) << 1;
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next_code[bits] = code;
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}
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// Step 1: count up how many codes of each length we have
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for (let i = 0; i < numLengths; ++i) {
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const length = bitLengths[i];
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// test to ensure each bit length is a positive, non-zero number
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if (typeof length != typeof 1 || length < 0) {
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err("bitLengths contained an invalid number in getHuffmanCodes(): " + length + " of type " + (typeof length));
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return null;
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}
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// increment the appropriate bitlength count
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if (bl_count[length] == undefined) bl_count[length] = 0;
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// a length of zero means this symbol is not participating in the huffman coding
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if (length > 0) bl_count[length]++;
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if (length > MAX_BITS) MAX_BITS = length;
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// Step 3: Assign numerical values to all codes
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const table = {};
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let tableLength = 0;
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for (let n = 0; n < numLengths; ++n) {
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const len = bitLengths[n];
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if (len != 0) {
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table[next_code[len]] = { length: len, symbol: n }; //, bitstring: binaryValueToString(next_code[len],len) };
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tableLength++;
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next_code[len]++;
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}
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}
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table.maxLength = tableLength;
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// Step 2: Find the numerical value of the smallest code for each code length
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const next_code = [];
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let code = 0;
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for (let bits = 1; bits <= MAX_BITS; ++bits) {
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const length = bits-1;
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// ensure undefined lengths are zero
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if (bl_count[length] == undefined) bl_count[length] = 0;
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code = (code + bl_count[bits-1]) << 1;
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next_code[bits] = code;
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}
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// Step 3: Assign numerical values to all codes
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const table = {};
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let tableLength = 0;
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for (let n = 0; n < numLengths; ++n) {
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const len = bitLengths[n];
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if (len != 0) {
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table[next_code[len]] = { length: len, symbol: n }; //, bitstring: binaryValueToString(next_code[len],len) };
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tableLength++;
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next_code[len]++;
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}
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}
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table.maxLength = tableLength;
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return table;
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return table;
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}
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/*
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@ -341,42 +338,42 @@ function getFixedLiteralTable() {
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}
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function getFixedDistanceTable() {
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// create once
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if (!fixedHCtoDistance) {
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const bitlengths = new Array(32);
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for (let i = 0; i < 32; ++i) { bitlengths[i] = 5; }
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// create once
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if (!fixedHCtoDistance) {
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const bitlengths = new Array(32);
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for (let i = 0; i < 32; ++i) { bitlengths[i] = 5; }
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// get huffman code table
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fixedHCtoDistance = getHuffmanCodes(bitlengths);
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}
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return fixedHCtoDistance;
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// get huffman code table
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fixedHCtoDistance = getHuffmanCodes(bitlengths);
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}
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return fixedHCtoDistance;
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}
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// extract one bit at a time until we find a matching Huffman Code
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// then return that symbol
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function decodeSymbol(bstream, hcTable) {
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let code = 0;
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let len = 0;
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let match = false;
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let code = 0;
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let len = 0;
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let match = false;
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// loop until we match
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for (;;) {
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// read in next bit
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const bit = bstream.readBits(1);
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code = (code<<1) | bit;
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++len;
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// loop until we match
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for (;;) {
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// read in next bit
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const bit = bstream.readBits(1);
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code = (code<<1) | bit;
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++len;
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// check against Huffman Code table and break if found
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if (hcTable.hasOwnProperty(code) && hcTable[code].length == len) {
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break;
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}
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if (len > hcTable.maxLength) {
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err("Bit stream out of sync, didn't find a Huffman Code, length was " + len +
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" and table only max code length of " + hcTable.maxLength);
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break;
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}
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// check against Huffman Code table and break if found
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if (hcTable.hasOwnProperty(code) && hcTable[code].length == len) {
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break;
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}
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return hcTable[code].symbol;
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if (len > hcTable.maxLength) {
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err("Bit stream out of sync, didn't find a Huffman Code, length was " + len +
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" and table only max code length of " + hcTable.maxLength);
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break;
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}
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}
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return hcTable[code].symbol;
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}
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@ -441,67 +438,65 @@ const DistLookupTable = [
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];
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function inflateBlockData(bstream, hcLiteralTable, hcDistanceTable, buffer) {
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/*
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loop (until end of block code recognized)
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decode literal/length value from input stream
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if value < 256
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copy value (literal byte) to output stream
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otherwise
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if value = end of block (256)
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break from loop
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otherwise (value = 257..285)
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decode distance from input stream
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/*
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loop (until end of block code recognized)
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decode literal/length value from input stream
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if value < 256
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copy value (literal byte) to output stream
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otherwise
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if value = end of block (256)
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break from loop
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otherwise (value = 257..285)
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decode distance from input stream
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move backwards distance bytes in the output
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stream, and copy length bytes from this
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position to the output stream.
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*/
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let numSymbols = 0;
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let blockSize = 0;
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for (;;) {
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const symbol = decodeSymbol(bstream, hcLiteralTable);
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++numSymbols;
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if (symbol < 256) {
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// copy literal byte to output
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buffer.insertByte(symbol);
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blockSize++;
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move backwards distance bytes in the output
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stream, and copy length bytes from this
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position to the output stream.
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*/
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let numSymbols = 0;
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let blockSize = 0;
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for (;;) {
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const symbol = decodeSymbol(bstream, hcLiteralTable);
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++numSymbols;
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if (symbol < 256) {
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// copy literal byte to output
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buffer.insertByte(symbol);
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blockSize++;
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} else {
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// end of block reached
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if (symbol == 256) {
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break;
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} else {
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const lengthLookup = LengthLookupTable[symbol - 257];
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let length = lengthLookup[1] + bstream.readBits(lengthLookup[0]);
|
||||
const distLookup = DistLookupTable[decodeSymbol(bstream, hcDistanceTable)];
|
||||
let distance = distLookup[1] + bstream.readBits(distLookup[0]);
|
||||
|
||||
// now apply length and distance appropriately and copy to output
|
||||
|
||||
// TODO: check that backward distance < data.length?
|
||||
|
||||
// http://tools.ietf.org/html/rfc1951#page-11
|
||||
// "Note also that the referenced string may overlap the current
|
||||
// position; for example, if the last 2 bytes decoded have values
|
||||
// X and Y, a string reference with <length = 5, distance = 2>
|
||||
// adds X,Y,X,Y,X to the output stream."
|
||||
//
|
||||
// loop for each character
|
||||
let ch = buffer.ptr - distance;
|
||||
blockSize += length;
|
||||
if(length > distance) {
|
||||
const data = buffer.data;
|
||||
while (length--) {
|
||||
buffer.insertByte(data[ch++]);
|
||||
}
|
||||
} else {
|
||||
buffer.insertBytes(buffer.data.subarray(ch, ch + length))
|
||||
}
|
||||
else {
|
||||
// end of block reached
|
||||
if (symbol == 256) {
|
||||
break;
|
||||
}
|
||||
else {
|
||||
const lengthLookup = LengthLookupTable[symbol - 257];
|
||||
let length = lengthLookup[1] + bstream.readBits(lengthLookup[0]);
|
||||
const distLookup = DistLookupTable[decodeSymbol(bstream, hcDistanceTable)];
|
||||
let distance = distLookup[1] + bstream.readBits(distLookup[0]);
|
||||
|
||||
// now apply length and distance appropriately and copy to output
|
||||
|
||||
// TODO: check that backward distance < data.length?
|
||||
|
||||
// http://tools.ietf.org/html/rfc1951#page-11
|
||||
// "Note also that the referenced string may overlap the current
|
||||
// position; for example, if the last 2 bytes decoded have values
|
||||
// X and Y, a string reference with <length = 5, distance = 2>
|
||||
// adds X,Y,X,Y,X to the output stream."
|
||||
//
|
||||
// loop for each character
|
||||
let ch = buffer.ptr - distance;
|
||||
blockSize += length;
|
||||
if(length > distance) {
|
||||
const data = buffer.data;
|
||||
while (length--) {
|
||||
buffer.insertByte(data[ch++]);
|
||||
}
|
||||
} else {
|
||||
buffer.insertBytes(buffer.data.subarray(ch, ch + length))
|
||||
}
|
||||
} // length-distance pair
|
||||
} // length-distance pair or end-of-block
|
||||
} // loop until we reach end of block
|
||||
return blockSize;
|
||||
} // length-distance pair
|
||||
} // length-distance pair or end-of-block
|
||||
} // loop until we reach end of block
|
||||
return blockSize;
|
||||
}
|
||||
|
||||
// {Uint8Array} compressedData A Uint8Array of the compressed file data.
|
||||
|
|
@ -520,101 +515,96 @@ function inflate(compressedData, numDecompressedBytes) {
|
|||
// block format: http://tools.ietf.org/html/rfc1951#page-9
|
||||
let bFinal = 0;
|
||||
do {
|
||||
bFinal = bstream.readBits(1);
|
||||
let bType = bstream.readBits(2);
|
||||
blockSize = 0;
|
||||
++numBlocks;
|
||||
// no compression
|
||||
if (bType == 0) {
|
||||
// skip remaining bits in this byte
|
||||
while (bstream.bitPtr != 0) bstream.readBits(1);
|
||||
const len = bstream.readBits(16);
|
||||
const nlen = bstream.readBits(16);
|
||||
// TODO: check if nlen is the ones-complement of len?
|
||||
if (len > 0) buffer.insertBytes(bstream.readBytes(len));
|
||||
blockSize = len;
|
||||
bFinal = bstream.readBits(1);
|
||||
let bType = bstream.readBits(2);
|
||||
blockSize = 0;
|
||||
++numBlocks;
|
||||
// no compression
|
||||
if (bType == 0) {
|
||||
// skip remaining bits in this byte
|
||||
while (bstream.bitPtr != 0) bstream.readBits(1);
|
||||
const len = bstream.readBits(16);
|
||||
const nlen = bstream.readBits(16);
|
||||
// TODO: check if nlen is the ones-complement of len?
|
||||
if (len > 0) buffer.insertBytes(bstream.readBytes(len));
|
||||
blockSize = len;
|
||||
}
|
||||
// fixed Huffman codes
|
||||
else if(bType == 1) {
|
||||
blockSize = inflateBlockData(bstream, getFixedLiteralTable(), getFixedDistanceTable(), buffer);
|
||||
}
|
||||
// dynamic Huffman codes
|
||||
else if(bType == 2) {
|
||||
const numLiteralLengthCodes = bstream.readBits(5) + 257;
|
||||
const numDistanceCodes = bstream.readBits(5) + 1;
|
||||
const numCodeLengthCodes = bstream.readBits(4) + 4;
|
||||
|
||||
// populate the array of code length codes (first de-compaction)
|
||||
const codeLengthsCodeLengths = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0];
|
||||
for (let i = 0; i < numCodeLengthCodes; ++i) {
|
||||
codeLengthsCodeLengths[ CodeLengthCodeOrder[i] ] = bstream.readBits(3);
|
||||
}
|
||||
|
||||
// get the Huffman Codes for the code lengths
|
||||
const codeLengthsCodes = getHuffmanCodes(codeLengthsCodeLengths);
|
||||
|
||||
// now follow this mapping
|
||||
/*
|
||||
0 - 15: Represent code lengths of 0 - 15
|
||||
16: Copy the previous code length 3 - 6 times.
|
||||
The next 2 bits indicate repeat length
|
||||
(0 = 3, ... , 3 = 6)
|
||||
Example: Codes 8, 16 (+2 bits 11),
|
||||
16 (+2 bits 10) will expand to
|
||||
12 code lengths of 8 (1 + 6 + 5)
|
||||
17: Repeat a code length of 0 for 3 - 10 times.
|
||||
(3 bits of length)
|
||||
18: Repeat a code length of 0 for 11 - 138 times
|
||||
(7 bits of length)
|
||||
*/
|
||||
// to generate the true code lengths of the Huffman Codes for the literal
|
||||
// and distance tables together
|
||||
const literalCodeLengths = [];
|
||||
let prevCodeLength = 0;
|
||||
while (literalCodeLengths.length < numLiteralLengthCodes + numDistanceCodes) {
|
||||
const symbol = decodeSymbol(bstream, codeLengthsCodes);
|
||||
if (symbol <= 15) {
|
||||
literalCodeLengths.push(symbol);
|
||||
prevCodeLength = symbol;
|
||||
} else if (symbol == 16) {
|
||||
let repeat = bstream.readBits(2) + 3;
|
||||
while (repeat--) {
|
||||
literalCodeLengths.push(prevCodeLength);
|
||||
}
|
||||
} else if (symbol == 17) {
|
||||
let repeat = bstream.readBits(3) + 3;
|
||||
while (repeat--) {
|
||||
literalCodeLengths.push(0);
|
||||
}
|
||||
} else if (symbol == 18) {
|
||||
let repeat = bstream.readBits(7) + 11;
|
||||
while (repeat--) {
|
||||
literalCodeLengths.push(0);
|
||||
}
|
||||
}
|
||||
// fixed Huffman codes
|
||||
else if(bType == 1) {
|
||||
blockSize = inflateBlockData(bstream, getFixedLiteralTable(), getFixedDistanceTable(), buffer);
|
||||
}
|
||||
// dynamic Huffman codes
|
||||
else if(bType == 2) {
|
||||
const numLiteralLengthCodes = bstream.readBits(5) + 257;
|
||||
const numDistanceCodes = bstream.readBits(5) + 1;
|
||||
const numCodeLengthCodes = bstream.readBits(4) + 4;
|
||||
}
|
||||
|
||||
// populate the array of code length codes (first de-compaction)
|
||||
const codeLengthsCodeLengths = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0];
|
||||
for (let i = 0; i < numCodeLengthCodes; ++i) {
|
||||
codeLengthsCodeLengths[ CodeLengthCodeOrder[i] ] = bstream.readBits(3);
|
||||
}
|
||||
// now split the distance code lengths out of the literal code array
|
||||
const distanceCodeLengths = literalCodeLengths.splice(numLiteralLengthCodes, numDistanceCodes);
|
||||
|
||||
// get the Huffman Codes for the code lengths
|
||||
const codeLengthsCodes = getHuffmanCodes(codeLengthsCodeLengths);
|
||||
// now generate the true Huffman Code tables using these code lengths
|
||||
const hcLiteralTable = getHuffmanCodes(literalCodeLengths);
|
||||
const hcDistanceTable = getHuffmanCodes(distanceCodeLengths);
|
||||
blockSize = inflateBlockData(bstream, hcLiteralTable, hcDistanceTable, buffer);
|
||||
} else { // error
|
||||
err("Error! Encountered deflate block of type 3");
|
||||
return null;
|
||||
}
|
||||
|
||||
// now follow this mapping
|
||||
/*
|
||||
0 - 15: Represent code lengths of 0 - 15
|
||||
16: Copy the previous code length 3 - 6 times.
|
||||
The next 2 bits indicate repeat length
|
||||
(0 = 3, ... , 3 = 6)
|
||||
Example: Codes 8, 16 (+2 bits 11),
|
||||
16 (+2 bits 10) will expand to
|
||||
12 code lengths of 8 (1 + 6 + 5)
|
||||
17: Repeat a code length of 0 for 3 - 10 times.
|
||||
(3 bits of length)
|
||||
18: Repeat a code length of 0 for 11 - 138 times
|
||||
(7 bits of length)
|
||||
*/
|
||||
// to generate the true code lengths of the Huffman Codes for the literal
|
||||
// and distance tables together
|
||||
const literalCodeLengths = [];
|
||||
let prevCodeLength = 0;
|
||||
while (literalCodeLengths.length < numLiteralLengthCodes + numDistanceCodes) {
|
||||
const symbol = decodeSymbol(bstream, codeLengthsCodes);
|
||||
if (symbol <= 15) {
|
||||
literalCodeLengths.push(symbol);
|
||||
prevCodeLength = symbol;
|
||||
}
|
||||
else if (symbol == 16) {
|
||||
let repeat = bstream.readBits(2) + 3;
|
||||
while (repeat--) {
|
||||
literalCodeLengths.push(prevCodeLength);
|
||||
}
|
||||
}
|
||||
else if (symbol == 17) {
|
||||
let repeat = bstream.readBits(3) + 3;
|
||||
while (repeat--) {
|
||||
literalCodeLengths.push(0);
|
||||
}
|
||||
}
|
||||
else if (symbol == 18) {
|
||||
let repeat = bstream.readBits(7) + 11;
|
||||
while (repeat--) {
|
||||
literalCodeLengths.push(0);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// now split the distance code lengths out of the literal code array
|
||||
const distanceCodeLengths = literalCodeLengths.splice(numLiteralLengthCodes, numDistanceCodes);
|
||||
|
||||
// now generate the true Huffman Code tables using these code lengths
|
||||
const hcLiteralTable = getHuffmanCodes(literalCodeLengths);
|
||||
const hcDistanceTable = getHuffmanCodes(distanceCodeLengths);
|
||||
blockSize = inflateBlockData(bstream, hcLiteralTable, hcDistanceTable, buffer);
|
||||
}
|
||||
// error
|
||||
else {
|
||||
err("Error! Encountered deflate block of type 3");
|
||||
return null;
|
||||
}
|
||||
|
||||
// update progress
|
||||
currentBytesUnarchivedInFile += blockSize;
|
||||
currentBytesUnarchived += blockSize;
|
||||
postProgress();
|
||||
// update progress
|
||||
currentBytesUnarchivedInFile += blockSize;
|
||||
currentBytesUnarchived += blockSize;
|
||||
postProgress();
|
||||
} while (bFinal != 1);
|
||||
// we are done reading blocks if the bFinal bit was set for this block
|
||||
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue