private static void ThrowIfError(ulong code)
{
if (Zstandard64NativeMethods.ZSTD_isError(code))
{
var errorPtr = Zstandard64NativeMethods.ZSTD_getErrorName(code);
var errorMsg = Marshal.PtrToStringAnsi(errorPtr);
throw new IOException(errorMsg);
}
}
public void Dispose()
{
switch (_compressionMode)
{
case CompressionMode.Compress:
Zstandard64NativeMethods.ZSTD_freeCStream(_zstreamPointer);
break;
case CompressionMode.Decompress:
Zstandard64NativeMethods.ZSTD_freeDStream(_zstreamPointer);
break;
}
}
private void InitializeIfNotAlreadyInitialized()
{
if (!_operationInitialized)
{
_operationInitialized = true;
switch (_compressionMode)
{
case CompressionMode.Compress:
Zstandard64NativeMethods.ZSTD_initCStream(_zstreamPointer, _compressionLevel); // start a new compression operation
break;
case CompressionMode.Decompress:
Zstandard64NativeMethods.ZSTD_initDStream(_zstreamPointer); // start a new decompression operation
break;
}
}
}
public void Decompress(
OperationContext operationContext,
int compressedOffset,
int inputCompressedSize,
int inputUncompressedSize,
out int compressedBytesProcessed,
out int uncompressedBytesProcessed)
{
Ensure.IsNotNull(operationContext, nameof(operationContext));
Ensure.That(_compressionMode == CompressionMode.Decompress, nameof(_compressionMode));
Ensure.IsGreaterThanOrEqualToZero(inputCompressedSize, nameof(inputCompressedSize));
Ensure.IsGreaterThanOrEqualToZero(inputUncompressedSize, nameof(inputUncompressedSize));
InitializeIfNotAlreadyInitialized();
// apply reading progress on CompressedPinnedBufferWalker
operationContext.CompressedPinnedBufferWalker.Offset = compressedOffset;
// compressed data
var inputNativeBuffer = CreateNativeBuffer(
inputCompressedSize <= 0 ? null : operationContext.CompressedPinnedBufferWalker,
inputCompressedSize <= 0 ? 0 : (ulong)inputCompressedSize);
// uncompressed data
var outputNativeBuffer = CreateNativeBuffer(
operationContext.UncompressedPinnedBufferWalker, // operation result
(ulong)inputUncompressedSize);
// decompress inputNativeBuffer to outputNativeBuffer
_ = Zstandard64NativeMethods.ZSTD_decompressStream(
_zstreamPointer,
outputNativeBuffer,
inputNativeBuffer);
uncompressedBytesProcessed = (int)outputNativeBuffer.Position; // because start Position is always 0
compressedBytesProcessed = (int)inputNativeBuffer.Position; // because start Position is always 0
operationContext.UncompressedPinnedBufferWalker.Offset += uncompressedBytesProcessed;
// CompressedPinnedBufferWalker.Offset will be calculated on stream side
}
public ZstandardNativeWrapper(CompressionMode compressionMode, int compressionLevel)
{
_compressionLevel = compressionLevel;
_compressionMode = compressionMode;
switch (_compressionMode)
{
case CompressionMode.Compress:
// calculate recommended size for input buffer
_recommendedZstreamInputSize = Zstandard64NativeMethods.ZSTD_CStreamInSize();
// calculate recommended size for output buffer. Guarantee to successfully flush at least one complete compressed block
_recommendedZstreamOutputSize = Zstandard64NativeMethods.ZSTD_CStreamOutSize();
_zstreamPointer = Zstandard64NativeMethods.ZSTD_createCStream(); // create resource
break;
case CompressionMode.Decompress:
// calculate recommended size for input buffer
_recommendedZstreamInputSize = Zstandard64NativeMethods.ZSTD_DStreamInSize();
// calculate recommended size for output buffer. Guarantee to successfully flush at least one complete block in all circumstances
_recommendedZstreamOutputSize = Zstandard64NativeMethods.ZSTD_DStreamOutSize();
_zstreamPointer = Zstandard64NativeMethods.ZSTD_createDStream(); // create resource
break;
}
}
public IEnumerable <int> StepwiseFlush(BufferInfo compressedBufferInfo)
{
if (_compressionMode != CompressionMode.Compress)
{
throw new InvalidDataException($"{nameof(StepwiseFlush)} must be called only from Compress mode.");
}
using (var operationContext = InitializeOperationContext(compressedBufferInfo))
{
yield return(ProcessCompressedOutput(operationContext, (zcs, buffer) => Zstandard64NativeMethods.ZSTD_flushStream(zcs, buffer)));
}
using (var operationContext = InitializeOperationContext(compressedBufferInfo))
{
yield return(ProcessCompressedOutput(operationContext, (zcs, buffer) => Zstandard64NativeMethods.ZSTD_endStream(zcs, buffer)));
}
int ProcessCompressedOutput(OperationContext context, Action <IntPtr, NativeBufferInfo> outputAction)
{
var outputNativeBuffer = CreateNativeBuffer(
context.CompressedPinnedBufferWalker,
_recommendedZstreamOutputSize);
outputAction(_zstreamPointer, outputNativeBuffer);
return((int)outputNativeBuffer.Position);
}
}
