05 More Instructions

Rotate¶

ROL/ROR

Data does not get lost

also, the value gets stored in carry flag

Shift¶

command is

• SAL/SHL
• SAR/SHR

Shift each bit count times

sal dest, count
shl dest, count

Multiplication¶

• Mul - unsigned
• Imul - signed

mul src

mul cx ; ax
mul cl ; al

Src times

• AL
• AX
• EAX

Source can be a register or memory location

• CF and OF are zero if MSB/MSW/MSD zero
• AF, PF, SF, ZF - undefined
• CBW/CWD

Conversion¶

• CBW converts byte to word
• CWD converts word to double word

When MSB is

• 0, 0s are added
• 1, 1s are added

Division¶

div¶

idiv¶

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