public static bool TryParse(ReadOnlySequence <byte> buffer, bool metadataOnly, out JpegFrameHeader frameHeader, out int bytesConsumed)
{
if (buffer.IsSingleSegment)
{
return(TryParse(buffer.First.Span, metadataOnly, out frameHeader, out bytesConsumed));
}
bytesConsumed = 0;
if (buffer.Length < 6)
{
frameHeader = default;
return(false);
}
Span <byte> local = stackalloc byte[6];
buffer.Slice(0, 6).CopyTo(local);
byte numberOfComponenets = local[5];
ushort samplesPerLine = (ushort)(local[4] | (local[3] << 8));
ushort numberOfLines = (ushort)(local[2] | (local[1] << 8));
byte precision = local[0];
buffer = buffer.Slice(6);
bytesConsumed += 6;
if (buffer.Length < 3 * numberOfComponenets)
{
frameHeader = default;
return(false);
}
if (metadataOnly)
{
bytesConsumed += 3 * numberOfComponenets;
frameHeader = new JpegFrameHeader(precision, numberOfLines, samplesPerLine, numberOfComponenets, null);
return(true);
}
JpegFrameComponentSpecificationParameters[] components = new JpegFrameComponentSpecificationParameters[numberOfComponenets];
for (int i = 0; i < components.Length; i++)
{
if (!JpegFrameComponentSpecificationParameters.TryParse(buffer, out components[i]))
{
frameHeader = default;
return(false);
}
buffer = buffer.Slice(3);
bytesConsumed += 3;
}
frameHeader = new JpegFrameHeader(precision, numberOfLines, samplesPerLine, numberOfComponenets, components);
return(true);
}
public static bool TryParse(ReadOnlySpan <byte> buffer, bool metadataOnly, out JpegFrameHeader frameHeader, out int bytesConsumed)
{
bytesConsumed = 0;
if (buffer.Length < 6)
{
frameHeader = default;
return(false);
}
byte numberOfComponenets = buffer[5];
ushort samplesPerLine = (ushort)(buffer[4] | (buffer[3] << 8));
ushort numberOfLines = (ushort)(buffer[2] | (buffer[1] << 8));
byte precision = buffer[0];
buffer = buffer.Slice(6);
bytesConsumed += 6;
if (buffer.Length < 3 * numberOfComponenets)
{
frameHeader = default;
return(false);
}
if (metadataOnly)
{
bytesConsumed += 3 * numberOfComponenets;
frameHeader = new JpegFrameHeader(precision, numberOfLines, samplesPerLine, numberOfComponenets, null);
return(true);
}
JpegFrameComponentSpecificationParameters[] components = new JpegFrameComponentSpecificationParameters[numberOfComponenets];
for (int i = 0; i < components.Length; i++)
{
if (!JpegFrameComponentSpecificationParameters.TryParse(buffer, out components[i]))
{
frameHeader = default;
return(false);
}
buffer = buffer.Slice(3);
bytesConsumed += 3;
}
frameHeader = new JpegFrameHeader(precision, numberOfLines, samplesPerLine, numberOfComponenets, components);
return(true);
}