Byte-table leading-zero count ($L(0)=8,L(b)=7-\lfloor {\log }_{2}b\rfloor (b>0)$)

For leading-zero count, inspect a word's bytes from most significant to least significant. Every zero byte contributes eight; the first nonzero byte contributes its table value in the title. If all bytes are zero, a word of width $w$ contributes $w$. Defining the zero table entry explicitly makes the all-zero argument a regular case rather than an out-of-range logarithm.