コード例 #1
0
 /// <summary>
 /// Writes the binary file header.
 /// </summary>
 /// <param name="binaryHeader">The binary file header to write.</param>
 public void Write(SegyFileHeader binaryHeader)
 {
     // write binary file header
     binaryHeader.DataSampleFormatCode = (short)FormatCode.IbmFloatingPoint4;
     _writer.BaseStream.Position       = TextHeaderSize;
     _writer.Write(binaryHeader.GetBytes());
 }
コード例 #2
0
        /// <summary>
        /// Ctor
        /// </summary>
        /// <param name="filepath">The path string of the file</param>
        public SegyReader(string filepath)
        {
            CodeContract.Requires(!string.IsNullOrEmpty(filepath));
            CodeContract.Requires <FileNotFoundException>(File.Exists(filepath), $"File {filepath} was not found.");

            _filepath = filepath;
            _stream   = new FileStream(filepath, FileMode.OpenOrCreate, FileAccess.Read, FileShare.Write);
            _reader   = new BinaryReader(_stream);
            FileInfo  = new FileInfo(filepath);

            //
            // Data Endianess
            //
            _reader.BaseStream.Seek(3224, SeekOrigin.Begin);
            var formatBytes = _reader.ReadBytes(2);

            var  lilEndianFormatCode = BitConverter.ToInt16(formatBytes, 0);
            var  bigEndianFormatCode = IbmConverter.ToInt16(formatBytes, 0);
            bool endianessSuccess    = false;

            for (var i = 0; i <= 8; i++)
            {
                if (bigEndianFormatCode == i)
                {
                    IsLittleEndian = false; endianessSuccess = true;
                }
                if (lilEndianFormatCode == i)
                {
                    IsLittleEndian = true; endianessSuccess = true;
                }
            }
            if (endianessSuccess == false)
            {
                throw new SegyEndianessException("Cannot infer endianess from format code. format code value is not within range 0 - 8 in either endianess");
            }

            //
            // File Binary Header
            //
            _reader.BaseStream.Seek(TextHeaderBytesCount, SeekOrigin.Begin);
            byte[] binaryHeaderBytes = _reader.ReadBytes(BinaryHeaderBytesCount);
            FileBinaryHeader      = SegyFileHeader.From(binaryHeaderBytes, IsLittleEndian);
            FileBinaryHeaderBytes = binaryHeaderBytes;

            //
            // File Textual Headers
            //
            _stream.Seek(0, SeekOrigin.Begin);

            List <string> textFileHeaders = new List <string>();

            byte[] bytes      = _reader.ReadBytes(TextHeaderBytesCount);
            string textHeader = bytes[0] == 'C'
                ? Encoding.Default.GetString(bytes)
                : _textHeaderEncoding.GetString(bytes);

            textFileHeaders.Add(textHeader);

            // as per rev 1, all data values are assumed big endian
            var binaryFileHeader = FileBinaryHeader;

            _stream.Seek(3600, SeekOrigin.Begin);
            byte[] extendedFileHeaders = binaryFileHeader.ExtendedTextHeadersCount < 0
                ? new byte[0]
                : _reader.ReadBytes(binaryFileHeader.ExtendedTextHeadersCount * 3200);

            for (int i = 0; i < binaryFileHeader.ExtendedTextHeadersCount; i++)
            {
                var extTextHeaderBytes = new byte[3200];
                Buffer.BlockCopy(extendedFileHeaders, i * 3200, bytes, 0, 3200);
                var extendedHeader = bytes[0] == 'C'
                    ? Encoding.Default.GetString(extTextHeaderBytes)
                    : _textHeaderEncoding.GetString(extTextHeaderBytes);
                textFileHeaders.Add(extendedHeader);
            }
            FileTextualHeaders = textFileHeaders.ToArray();

            //
            //Trace Count
            //
            var sampleformat = (FormatCode)FileBinaryHeader.DataSampleFormatCode;

            var dataStartIndex = TextHeaderBytesCount + BinaryHeaderBytesCount + TextHeaderBytesCount * (FileTextualHeaders.Length - 1);
            var dataEndIndex   = _stream.Length;
            var sampleSz       = SizeFrom(sampleformat);

            var fileSz      = _stream.Length;
            var nsamples    = FileBinaryHeader.SamplesPerTraceOfFile;
            var extTxtHdrCt = FileTextualHeaders.Length - 1;

            TraceCount = (fileSz - (3600 + (extTxtHdrCt * 3200))) / (240 + (nsamples * sampleSz));
        }