nl_tokens: Parses a single SequenceRecord from the start of the ArrayBuffer . fileOffset is the position of this sequence within the 2bit file .
pl_tokens: function parseSequenceRecord ( buffer : ArrayBuffer , fileOffset : number ) : SequenceRecord { var jb = new jBinary ( <mask> , twoBitTypes . TYPE_SET ) ; var header = jb . read ( 'SequenceRecord' ) ; var dnaOffset = jb . tell ( ) + 8 * header . maskBlockCount + 4 ; return { numBases : header . dnaSize , unknownBlockStarts : header . nBlockStarts , unknownBlockLengths : header . nBlockSizes , numMaskBlocks : header . maskBlockCount , maskBlockStarts : [ ] , maskBlockLengths : [ ] , dnaOffsetFromHeader : dnaOffset , offset : fileOffset } ; }