Slide 16.6: ROR instruction Home

RCL and RCR Instructions

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The RCL (rotate carry left) instruction shifts each bit to the left, copies the Carry flag to the least significant bit (LSB), and copies the most significant bit (MSB) into the Carry flag.

RCL — Rotate Through Carry Left

Usage: rcl dest, count Flag O D I S Z A P C Result *             * Rotates the bits in the destination to the left “count” times with all data pushed out the left side re-entering on the right. The Carry flag holds the last bit rotated out. Clocks Operands 286 386 486 Size Bytes reg, 1 2 9 3 2 mem, 1 7 10 4 2–4 reg, CL 5+n 9 8–30 2 mem, CL 8+n 10 9–31 2-4 reg, immed8 5+n 9 8–30 3 mem, immed8 8+n 10 9–31 3-5

RCR Instruction

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The RCR (rotate carry right) instruction shifts each bit to the right, copies the Carry flag to the MSB, and copies the LSB into the Carry flag.

RCR — Rotate Through Carry Right

Usage: rcr dest, count Flag O D I S Z A P C Result *             * Rotates the bits in the destination to the right “count” times with all data pushed out the right side re-entering on the left. The Carry flag holds the last bit rotated out. Clocks Operands 286 386 486 Size Bytes reg, 1 2 9 3 2 mem, 1 7 10 4 2–4 reg, CL 5+n 9 8–30 2 mem, CL 8+n 10 9–31 2-4 reg, immed8 5+n 9 8–30 3 mem, immed8 8+n 10 9–31 3-5