Это моё решение.
LDR R0,= A
LDR R3, [R0]
MOV R1, 0x000003ff ; mask for last 10 bits - 1111111111
AND R5, R3, R1 ; Place BitWise AND of R3 & R1 into R5
LSL R2, R1, #10 ; Shift left R1 ten times to capture 11th - 20th bit
AND R6, R3, R2 ; Place BitWise AND of R3 & R2 into R6
LSL R4, R2, #10 ; Further Shift R2 left 12 times to capture 21st - 32nd bit
AND R7, R3, R4 ; Place BitWise AND of R3 & R4 into R7
LDR R8,=0x20000014
MOV SP, R8
STMIA SP!, {R6, R5, R7}
A DCD 0x97D6E4 ; 9950948 - student ID excluding 00's
;--------------------------------------
stop B stop
END