TestSlowForwardCopyOverrun tests the "expand the pattern" algorithm described in decode_amd64.s and its claim of a 10 byte overrun worst case.

decode writes the decoding of src to dst. It assumes that the varint-encoded length of the decompressed bytes has already been read, and that len(dst)

encodeBlock encodes a non-empty src to a guaranteed-large-enough dst. It assumes that the varint-encoded length of the decompressed bytes has already

extendMatch returns the largest k such that k <= len(src) and that src[i:i+k-j] and src[j:k] have the same contents. It assumes that: 0 <= i && i <