public void DecodeNextMessage(Stream fitStream)
{
var br = new BinaryReader(fitStream);
byte nextByte = br.ReadByte();
// Is it a compressed timestamp mesg?
if ((nextByte & Fit.CompressedHeaderMask) == Fit.CompressedHeaderMask)
{
var mesgBuffer = new MemoryStream();
int timeOffset = nextByte & Fit.CompressedTimeMask;
timestamp += (uint)((timeOffset - lastTimeOffset) & Fit.CompressedTimeMask);
lastTimeOffset = timeOffset;
var timestampField = new Field(Profile.mesgs[Profile.RecordIndex].GetField("Timestamp"));
timestampField.SetValue(timestamp);
var localMesgNum = (byte)((nextByte & Fit.CompressedLocalMesgNumMask) >> 5);
mesgBuffer.WriteByte(localMesgNum);
if (localMesgDefs[localMesgNum] == null)
{
throw new FitException(
"Decode:DecodeNextMessage - FIT decode error: Missing message definition for local message number " + localMesgNum +
".");
}
int fieldsSize = localMesgDefs[localMesgNum].GetMesgSize() - 1;
try
{
mesgBuffer.Write(br.ReadBytes(fieldsSize), 0, fieldsSize);
}
catch (IOException e)
{
throw new FitException(
"Decode:DecodeNextMessage - Compressed Data Message unexpected end of file. Wanted " + fieldsSize +
" bytes at stream position " + fitStream.Position, e);
}
var newMesg = new Mesg(mesgBuffer, localMesgDefs[localMesgNum]);
newMesg.InsertField(0, timestampField);
if (MesgEvent != null)
{
MesgEvent(this, new MesgEventArgs(newMesg));
}
}
// Is it a mesg def?
else if ((nextByte & Fit.HeaderTypeMask) == Fit.MesgDefinitionMask)
{
var mesgDefBuffer = new MemoryStream();
// Figure out number of fields (length) of our defn and build buffer
mesgDefBuffer.WriteByte(nextByte);
mesgDefBuffer.Write(br.ReadBytes(4), 0, 4);
byte numfields = br.ReadByte();
mesgDefBuffer.WriteByte(numfields);
try
{
mesgDefBuffer.Write(br.ReadBytes(numfields*3), 0, numfields*3);
}
catch (IOException e)
{
throw new FitException(
"Decode:DecodeNextMessage - Defn Message unexpected end of file. Wanted " + (numfields*3) +
" bytes at stream position " + fitStream.Position, e);
}
var newMesgDef = new MesgDefinition(mesgDefBuffer);
localMesgDefs[newMesgDef.LocalMesgNum] = newMesgDef;
if (MesgDefinitionEvent != null)
{
MesgDefinitionEvent(this, new MesgDefinitionEventArgs(newMesgDef));
}
}
// Is it a data mesg?
else if ((nextByte & Fit.HeaderTypeMask) == Fit.MesgHeaderMask)
{
var mesgBuffer = new MemoryStream();
var localMesgNum = (byte) (nextByte & Fit.LocalMesgNumMask);
mesgBuffer.WriteByte(localMesgNum);
if (localMesgDefs[localMesgNum] == null)
{
throw new FitException(
"Decode:DecodeNextMessage - FIT decode error: Missing message definition for local message number " + localMesgNum +
".");
}
int fieldsSize = localMesgDefs[localMesgNum].GetMesgSize() - 1;
try
{
mesgBuffer.Write(br.ReadBytes(fieldsSize), 0, fieldsSize);
}
catch (Exception e)
{
throw new FitException(
"Decode:DecodeNextMessage - Data Message unexpected end of file. Wanted " + fieldsSize +
" bytes at stream position " + fitStream.Position, e);
}
var newMesg = new Mesg(mesgBuffer, localMesgDefs[localMesgNum]);
// If the new message contains a timestamp field, record the value to use as
// a reference for compressed timestamp headers
Field timestampField = newMesg.GetField("Timestamp");
if (timestampField != null)
{
timestamp = (uint) timestampField.GetValue();
lastTimeOffset = (int) timestamp & Fit.CompressedTimeMask;
}
// Now that the entire message is decoded we can evaluate subfields and expand any components
newMesg.ExpandComponents();
if (MesgEvent != null)
{
MesgEvent(this, new MesgEventArgs(newMesg));
}
}
else
{
throw new FitException("Decode:Read - FIT decode error: Unexpected Record Header Byte 0x" + nextByte.ToString("X"));
}
}
