Question

Given the following pseudo code:

int result; (result is 1 byte)

int count; (count is 1 byte)

for (result= 10, count= -10; count < result ; count++) {

if(count > 2) result--;

else result ++;

}

1) write an assembly language program that will implement this pseudo code using a while construct.

2) write an assembly language program that will implement this pseudo code using a do-until construct

Note: For both 1) and 2), do not forget to include the data section in your program. count and result are 1-byte variables to be implemented in memory, not in registers. Your assembly program must match the pseudo code 1-to-1 (this also means that you should use a conditional branch that correctly implements the loop condition; BNE or BEQ branches are not allowed). Use labels such as IF, ENDIF, WHILE, ENDWHILE, DO, ENDDO, to show where your If/While/Do-Until constructs are. Do not forget the data section.

Answer 1

1. Assembly language using while construct:

Section .data

result DB 0 // one byte memory variable

count DB 0

section .text

start:

mov result, #10 // initialisation

mov count, #-10

WHILE: cmp count,result   

BGE ENDWHILE // if count greater than -//or equal to result end while

IF: cmp count, #2   

BLE ELSE // branch to else if count less //than or equal to 2

DEC [result]
jmp BOTH

ELSE: INC [result]
BOTH: INC [count]. // increasing loop //counter
JMP WHILE // jumping to while

ENDWHILE: end start

2. Using do-until

Section .data

result DB 0

count DB 0

section .text

start:

mov result, #10

mov count, #-10

DO:

IF: cmp count, #2

BLE ELSE

DEC [result]
jmp BOTH

ELSE: INC [result]

BOTH: INC [count]

CMP count,result
BLE DO // branch if count less than or //equal to result

end start