Assembly Language for Beginners

3.11. INLINE FUNCTIONS

strcmp()

Listing 3.31: strcmp() example

bool is_bool (char *s)
{
if (strcmp (s, "true")==0)
return true;
if (strcmp (s, "false")==0)
return false;

assert(0);
};

Listing 3.32: Optimizing GCC 4.8.1

.LC0:
.string "true"
.LC1:
.string "false"
is_bool:
.LFB0:
push edi
mov ecx, 5
push esi
mov edi, OFFSET FLAT:.LC0
sub esp, 20
mov esi, DWORD PTR [esp+32]
repz cmpsb
je .L3
mov esi, DWORD PTR [esp+32]
mov ecx, 6
mov edi, OFFSET FLAT:.LC1
repz cmpsb
seta cl
setb dl
xor eax, eax
cmp cl, dl
jne .L8
add esp, 20
pop esi
pop edi
ret
.L8:
mov DWORD PTR [esp], 0
call assert
add esp, 20
pop esi
pop edi
ret
.L3:
add esp, 20
mov eax, 1
pop esi
pop edi
ret

Listing 3.33: Optimizing MSVC 2010

$SG3454 DB 'true', 00H
$SG3456 DB 'false', 00H

_s$ = 8 ; size = 4
?is_bool@@YA_NPAD@Z PROC ; is_bool
push esi
mov esi, DWORD PTR _s$[esp]
mov ecx, OFFSET $SG3454 ; 'true'
mov eax, esi
npad 4 ; align next label
$LL6@is_bool: