16 bit Assembly
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ROL - Roll Left Instruction
The ROL instruction is used to rotate the bits to the left.
This command has 3 part the Instruction, A Register or memory address, and the number of bits to rotate left.
As each bit is rotated it passes in to the Carry flag, where it can be assessed using a conditional jump JC or JNC.
As each bit moves off the highest bit it is inserted in the lowest bit.
| Assembly Sample | Description | 16 bit Machine Code |
|---|---|---|
| ROL AL, 1 | ; Rotate AL left by 1 bit | D0 C0 |
| ROL AL, CL | ; Rotate AL left by value of CL | D2 C0 |
| ROL AL, 0x03 | ; Rotate AL left by 8 bit immediate | C0 C0 03 |
| ROL AX, 1 | ; Rotate AX left by 1 bit | D1 C0 |
| ROL AX, CL | ; Rotate AX left by value of CL | D3 C0 |
| ROL AX, 0x03 | ; Rotate AX left by 8 bit immediate | C1 C0 03 |
| ROL [BX], 1 | ; Rotate memory address left by 1 bit | D0 07 |
| ROL [BX], CL | ; Rotate memory address left by value of CL | D2 07 |
| ROL [BX], 0x03 | ; Rotate memory address left by 8 bit immediate | C0 07 03 |
| ROL [BX+2], 1 | ; Rotate memory address left by 1 bit | D0 47 02 |
| ROL [BX+2], CL | ; Rotate memory address left by value of CL | D2 47 02 |
| ROL [BX+2], 0x03 | ; Rotate memory address left by 8 bit immediate | C0 47 02 03 |
Last Update 11/02/2023