Assembly Language Logical Shift

This example uses a Logical Shift to perform multiplication. A Logical Shift Left will shift the binary pattern and add a zero at the least significant place value. For example the binary for 4 is '00100' a logical shift to the left of one place will give '01000' which is now 8. A logical shift to the left will multiply by 2. A logical shift of 2 places on '00100' will give '10000' which is 16.

Multiplication example

      INP R0,2
      INP R1,2
      MOV R2, R1
      MOV R3, R0
LOOP: LSL R3,R3,#1
      SUB R2,R2,#2
      CMP R2,#1
      BGT LOOP
      BLT END
      ADD R3,R3,R0
END:  OUT R3,4
      HALT