ROR - M68K instruction reference

rorRotate right 
Rotates the bits of the destination operand to the right.
XNZVC –●●0●
● set from the result
0 always 0
– not changed
Forms  ror ,    Sizes .b .w .l, .w by default 
 ror    Size .w 
Operands <ea> An operand using one of the instruction’s supported addressing modes, such as d0, (a0)+ or 4(a1). It may name a register, memory or an immediate value. More
Dn A data register, d0 to d7. More
#imm An immediate rotate count from 1 to 8, for example #3. More
Two forms: (1) ro<d> Dx/Im, Dn rotates Dn by the count in Dx or immediate (1–8), any size. Defaults to word. (2) ro<d>.w (An) rotates a memory word by 1; .w is the only size accepted and may be omitted.
 * --- ROL: rotate left (bits wrap around) ---
move.w #$1234, d0
rol.w #8, d0 ; d0 = $3412

* --- ROR: rotate right ---
move.w #$1234, d1
ror.w #8, d1 ; d1 = $3412

* --- Single bit rotate ---
move.w #%10000000_00000001, d2
rol.w #1, d2 ; d2 = %00000000_00000011

* --- Memory form: rotates word at (a0) left by 1 ---
lea $1000, a0
move.w #%10000000_00000001, (a0)
rol (a0) ; (a0) = %00000000_00000011