What is the difference between SAR and SHR?

SHR moves all bits of the binary number 1 or more positions to the right, so essentially diving by 2. SAR does the same but for signed numbers. It essentially keeps the sign bit of the number (that shows if the number is positive or negative) unaffected.

What is SHR instruction?

The SHR (shift right) instruction performs a logical right shift on the destination operand. The highest bit position is filled with a zero.

What is SAR instruction?

Description. The shr or sar instruction is used to shift the bits of the operand destination to the right, by the number of bits specified in the count operand. Bits shifted beyond the destination are first shifted into the CF flag.

Which of the flags are not affected by SAR instruction?

If the shift count is zero, the sar instruction doesn’t affect any flags. The carry flag contains the last bit shifted out of the L.O. bit of the operand. The overflow flag will contain zero if the shift count is one. The zero flag will be one if the shift produces a zero result.

How does CDQ work?

The CDQ instruction copies the sign (bit 31) of the value in the EAX register into every bit position in the EDX register. The CWD instruction is intended for use when the operand-size attribute is 16 and the CDQ instruction for when the operand-size attribute is 32.

What is the difference between SAL and SHL?

According to this, they are the same: The shift arithmetic left (SAL) and shift logical left (SHL) instructions perform the same operation; they shift the bits in the destination operand to the left (toward more significant bit locations).

Which instructions do not affect the flags?

As there is no arithmetic or logical operation being performed, no flags are affected by data transfer instructions. Arithmetic instruction: Arithmetic Instructions are the instructions that perform basic arithmetic operations such as addition, subtraction, and a few more.

Which instructions does affect carry flag?

The logical instructions that affect the carry flag during its execution are RL, RLC, RRC and RR. Explanation: The instruction, CPL Bit is used to complement or invert the bit of a bit addressable SFR or RAM.

What is Xlat instruction?

Description. XLAT changes the AL register from the table index to the table entry. AL should be the unsigned index into a table addressed by DS:BX (for an address-size attribute of 16 bits) or DS:EBX (for an address-size attribute of 32 bits). The operand to XLAT allows for the possibility of a segment override.