static size_t ZSTD_decompressBlock_internal()

in csharp/src/ZStdDecompress.cs [1868:1909]

• 30 lines of code
• 12 McCabe index (conditional complexity)

		static size_t ZSTD_decompressBlock_internal(ZSTD_DCtx dctx,
									void* dst, size_t dstCapacity,
							  void* src, size_t srcSize, int frame)
		{   /* blockType == blockCompressed */
			BYTE* ip = (BYTE*)src;
			/* isLongOffset must be true if there are long offsets.
			 * Offsets are long if they are larger than 2^STREAM_ACCUMULATOR_MIN.
			 * We don't expect that to be the case in 64-bit mode.
			 * In block mode, window size is not known, so we have to be conservative. (note: but it could be evaluated from current-lowLimit)
			 */
			ZSTD_longOffset_e isLongOffset = (ZSTD_longOffset_e)(MEM_32bits() && (frame == 0 || dctx.fParams.windowSize > ((U64)1 << (int)STREAM_ACCUMULATOR_MIN)) ? 1 : 0);

			if (srcSize >= ZSTD_BLOCKSIZE_MAX) return ERROR(Error.srcSize_wrong);

			/* Decode literals section */
			{
				size_t litCSize = DecodeLiteralsBlock(dctx, src, srcSize);
				if (IsError(litCSize)) return litCSize;
				ip += litCSize;
				srcSize -= litCSize;
			}

			/* Build Decoding Tables */
			{
				int nbSeq;
				size_t seqHSize = DecodeSeqHeaders(dctx, &nbSeq, ip, srcSize);
				if (IsError(seqHSize)) return seqHSize;
				ip += seqHSize;
				srcSize -= seqHSize;

				if ((frame == 0 || dctx.fParams.windowSize > (1 << 24))
				  && (nbSeq > 0))
				{  /* could probably use a larger nbSeq limit */
					U32 shareLongOffsets = GetLongOffsetsShare(dctx.OFTptr);
					U32 minShare = MEM_64bits() ? (U32)7 : 20; /* heuristic values, correspond to 2.73% and 7.81% */
					if (shareLongOffsets >= minShare)
						return DecompressSequencesLong(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset);
				}

				return DecompressSequences(dctx, dst, dstCapacity, ip, srcSize, nbSeq, isLongOffset);
			}
		}