Assembly Language for Beginners

1.9. SCANF()

Listing 1.82: MSVC 2012 x64

_DATA SEGMENT
$SG2924 DB 'Enter X:', 0aH, 00H
$SG2926 DB '%d', 00H
$SG2927 DB 'You entered %d...', 0aH, 00H
$SG2929 DB 'What you entered? Huh?', 0aH, 00H
_DATA ENDS

_TEXT SEGMENT
x$ = 32
main PROC
$LN5:
sub rsp, 56
lea rcx, OFFSET FLAT:$SG2924 ; 'Enter X:'
call printf
lea rdx, QWORD PTR x$[rsp]
lea rcx, OFFSET FLAT:$SG2926 ; '%d'
call scanf
cmp eax, 1
jne SHORT $LN2@main
mov edx, DWORD PTR x$[rsp]
lea rcx, OFFSET FLAT:$SG2927 ; 'You entered %d...'
call printf
jmp SHORT $LN1@main
$LN2@main:
lea rcx, OFFSET FLAT:$SG2929 ; 'What you entered? Huh?'
call printf
$LN1@main:
; return 0
xor eax, eax
add rsp, 56
ret 0
main ENDP
_TEXT ENDS
END

ARM

ARM: Optimizing Keil 6/2013 (Thumb mode)

Listing 1.83: Optimizing Keil 6/2013 (Thumb mode)

var_8 = -8

PUSH {R3,LR}

ADR R0, aEnterX ; "Enter X:\n"

BL __2printf

MOV R1, SP

ADR R0, aD ; "%d"

BL __0scanf

CMP R0, #1

BEQ loc_1E

ADR R0, aWhatYouEntered ; "What you entered? Huh?\n"

BL __2printf

loc_1A ; CODE XREF: main+26
MOVS R0, #0
POP {R3,PC}

loc_1E ; CODE XREF: main+12
LDR R1, [SP,#8+var_8]
ADR R0, aYouEnteredD_ ; "You entered %d...\n"
BL 2printf
B loc_1A