It was hand-written for a system without multi-bit shift instructions. 8086 shifts were 1 bit at a time (2 cycles for a register shift.) or using cl for the co

It was hand-written for a system without multi-bit shift instructions. 8086 shifts were 1 bit at a time (2 cycles for a register shift.) or using cl for the count (8 cycles + 4 cycles/bit for a register shift). constant multi-bit shifts were added in the 80186.