Assembly Language Questions Long
In Assembly Language, logical shifts refer to the operation of shifting the bits of a binary number to the left or right. These shifts are called logical because they do not consider the sign bit or carry bit during the shifting process. Logical shifts are commonly used for various purposes such as multiplication or division by powers of 2, extracting or inserting specific bits, and manipulating data in bitwise operations.
There are two types of logical shifts: logical left shift (LSL) and logical right shift (LSR).
1. Logical Left Shift (LSL):
In a logical left shift, the bits of a binary number are shifted towards the left, and zeros are filled in from the right side. Each bit is shifted one position to the left, and the leftmost bit is discarded. This operation effectively multiplies the number by 2 for each shift.
For example, let's consider the binary number 10101010. If we perform a logical left shift by 2 positions, the result will be 101010000. The two rightmost bits are discarded, and two zeros are added on the left side.
Logical left shifts are commonly used for multiplication by powers of 2. For instance, if we want to multiply a number by 8, we can perform a logical left shift by 3 positions.
2. Logical Right Shift (LSR):
In a logical right shift, the bits of a binary number are shifted towards the right, and zeros are filled in from the left side. Each bit is shifted one position to the right, and the rightmost bit is discarded. This operation effectively divides the number by 2 for each shift.
For example, let's consider the binary number 10101010. If we perform a logical right shift by 2 positions, the result will be 00101010. The two leftmost bits are discarded, and two zeros are added on the right side.
Logical right shifts are commonly used for division by powers of 2. For instance, if we want to divide a number by 4, we can perform a logical right shift by 2 positions.
It is important to note that logical shifts do not consider the sign bit or carry bit, which means that the shifted bits are simply replaced with zeros. This behavior is different from arithmetic shifts, where the sign bit is preserved during the shifting process.
In conclusion, logical shifts in Assembly Language involve shifting the bits of a binary number to the left or right, filling in zeros from the opposite side. These shifts are used for various purposes such as multiplication or division by powers of 2 and manipulating data in bitwise operations. Logical shifts do not consider the sign bit or carry bit, and they are commonly performed using the logical left shift (LSL) and logical right shift (LSR) instructions.