MOV #$0$x$9,$ R$6$ ; R$6=0$b$1001=9,$ bit pattern to search for ; Check for $\text{'}1001\text{'}$ pattern in R$5,2-$bit separation ; We need to check if $1001$XXXXX$1001$ exists in R$5,$ where X is any $2$ bits. ; Step $1$: Mask for the first occurrence of $\text{'}1001\text{'}$ MOV R$5,$ R$4$ ; Copy R$5$ to R$4$ for manipulation AND #$0$xF$000,$ R$4$ ; Mask the upper $4$ bits of R$4($bit $15$ to $12)$ CMP R$4,$ R$6$ ; Compare with $\text{'}1001\text{'}(0$x$9)$ JNE skip$\_$check$\_1$ ; If not equal, skip to next check ; Step $2$: Check for $\text{'}1001\text{'}$ after $2$ bits $($i$.$e$.,$ bits $7$ to $4)$ MOV R$5,$ R$4$ ; Copy R$5$ to R$4$ for manipulation again RRA R$4$ ; Shift right by $1$ bit to align bit positions RRA R$4$ ; Shift right by another bit $($total $2-$bit shift$)$ AND #$0$x$00$F$0,$ R$4$ ; Mask bits $7$ to $4$ of R$4$ CMP R$4,$ R$6$ ; Compare with $\text{'}1001\text{'}$ JNE no$\_$match ; If not equal, no match is found ; If both conditions are met, clear R$5$ CLR R$5$ ; Clear register R$5($set it to $0)$ JMP done ; Jump to end no$\_$match: ; If the pattern does not match, set R$5$ to all $1\text{'}$s MOV #$0$xFFFF$,$ R$5$ ; Set R$5$ to $0$xFFFF $($all $1\text{'}$s$)$ skip$\_$check$\_1$: ; Additional checks for $\text{'}1001\text{'}$ pattern in other positions can be added here. done: ; Restore the original state of registers POP R$6$ ; Restore R$6$ POP R$4$ ; Restore R$4$ RET ; Return from subroutine