SX User’s Manual Rev. 3.1 116 © 2000 Scenix Semiconductor, Inc. All rights reserved. www.scenix.com Chapter 3 Instruction Set 3.6.46    RL fr Rotate fr Left through Carry Operation: fr = << fr Bits affected: C Opcode: 0011 011f ffff Description: This instruction rotates the bits of the specified file register left using the C bit. The
bits inside the register are shifted left by one bit position. C is shifted into the least
significant bit position and the most significant bit is shifted out into C, as shown in
the diagram below. Cycles: 1 Example 1: rl $18 This example rotates the bits of file register 18h. If the register initially contains 14h
and the C bit is set to 1, after executing this instruction, the register will contain 29h
and the C bit will be cleared to 0. Example 2: clrb $03.0 ;clear carry bit rl $18 ;rotate left, reg=reg*2 rl $18 ;rotate left, reg=reg*2 This example multiplies file register 18h by 4. The initial “clrb” instruction clears
the C bit, which ensures that 0 will be shifted into the least significant bit position.
The two “rl” instructions perform two successive multiply-by-2 operations. Figure 3-4 Rotate fr Left Through Carry File Register Carry Bit