/// <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());
}
/// <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));
}