The X86 Microprocessors: Architecture and Programming (8086 to Pentium), 1st Edition

PROGRAMMING CONCEPTS  II 131

3.6 | Shift and Rotate Instructions

Table 3.8 gives the complete list of the shift and rotate instructions.

3.6.1 | Shift

Shift instructions do arithmetic or logical shifting.i)

 ey also shift right or left.ii)

Arithmetic shift is used for signed number operations, while logical shift caters to unsigned iii)

numbers.

Shifting right causes a divide by 2, for each bit position shifted, while shifting left corresponds iv)

to a multiplication by 2.

 e count means the number of bit positions, by which shifting is to be done.v)

If the count vi) >1, load it in CL, otherwise use ‘1’ in the immediate mode.

SAL/SHL – Shif ...