ZSTD_countLeadingZeros32
return ZSTD_countLeadingZeros32((U32)val) >> 3;
return 31 - ZSTD_countLeadingZeros32(val);
return 32 + ZSTD_countLeadingZeros32(leastSignificantWord);
return ZSTD_countLeadingZeros32(mostSignificantWord);