Need help with Coding assignment in uVision using ARM Assembly:

Have a read$-$only array of eight bytes named Unpacked and a read$/$write integer named Packed. We'll be condensing the Unpacked array into a single integer called Packed where the four most significant bits $($bits $31,30,29,28)$ represent the first value in Unpacked, the next four bits $($bits $27,26,25,24)$ represent the second value in Unpacked, etc., down to the four least significant bits $(3,2,1,0)$ representing the final$/$eighth value in the Unpacked array. You'll achieve this by looping through the Unpacked array and placing the lower four bits of each of the byte values into register three $(r3)$ based upon the following criteria:

If the byte value is between decimal zero and nine, inclusive, just use the

lowest four bits

If the byte value is anything else, use $0$xF $(2\_1111)$ to represent it in $r3$

Each time through the loop, you'll need to shift r$3$ to make room for the "new" four

bits you'll be adding.

Once the looping is completed, store $r3$ as the Packed integer value.

Below are some example Unpacked arrays and their corresponding Packed integers.

Unpacked dcb $9,8,7,6,5,4,3,2$

; Packed will be $0$x$98765432$

Unpacked dcb $3,2,1,0,12,5,6,9$

; Packed will be $0$x$3210$F$569$

Unpacked dcb $4,13,7,8,10,2,9,-3$

; Packed will be $0$x$4$F$78$F$29$F

Posted below is the code I have tried thus far and has not been successful. Please Help.AREA RESET, CODE

THUMB

ENTRY

Main

LDR RO$,=$Unpacked ; Load the address of Unpacked array into RO

MOV Rl$,$ #$0$ ; Initialize Rl to $0($accumulator for Packed$)$

loop

LDR R$2,[$R$0],$ #$1$ ; Load byte from Unpacked into R$2,$ and increment the pointer

CMP R$2,$ #$9$ ; Compare the byte value with $9$

BLE unpacked$\_$value ; Branch if less than or equal to $9$

MOV R$2,$ #$0$xF ; Set R$2$ to OxF if byte value $>9$

unpacked$\_$value

AND $\frac{?}{\text{b}\text{a}\text{r}}(R)2,R2,$ #$0$xF ; Mask out only the lower $4$ bits of R$2$

ORR R$1,$ R$1,$ R$2,$ LSL #$28$; Shift R$2$ into position and OR with accumulator

LDR R$3,[$R$0,$ #$8]$

CMP RO$,$ R$3$ ;Compare RO with the end of Unpacked array

BLT loop ; Branch back to loop if R$0$ is less than $($Unpacked $+8)$

Store

LDR $RO,=$ Packed

STRB R$1,[$RO$]$ ; Store the final packed integer value

B$.$ ; Branch to end ; Infinite loop to stop execution

AREA HW$5,$ CODE, READONLY

Unpacked dcb $9,8,7,6,5,4,3,2$ ; Example Unpacked array

Packed dcd $0$

END