CHAPTER 13. SWITCH()/CASE/DEFAULT CHAPTER 13. SWITCH()/CASE/DEFAULT
4
5 void f(int type)
6 {
7 int read=0, write=0;
8
9 switch (type)
10 {
11 case RW:
12 read=1;
13 case W:
14 write=1;
15 break;
16 case R:
17 read=1;
18 break;
19 default:
20 break;
21 };
22 printf ("read=%d, write=%d\n", read, write);
23 };
Iftype= 1(R),readis to be set to 1, iftype= 2(W),writeis to be set to 2. In case oftype= 3(RW), bothreadandwriteis
to be set to 1.The code at line 14 is executed in two cases: iftype=RWor iftype=W. There is no “break” for “case RW”x and that’s OK.13.4.1 MSVC x86
Listing 13.13: MSVC 2012
$SG1305 DB 'read=%d, write=%d', 0aH, 00H_write$ = -12 ; size = 4
_read$ = -8 ; size = 4
tv64 = -4 ; size = 4
_type$ = 8 ; size = 4
_f PROC
push ebp
mov ebp, esp
sub esp, 12
mov DWORD PTR _read$[ebp], 0
mov DWORD PTR _write$[ebp], 0
mov eax, DWORD PTR _type$[ebp]
mov DWORD PTR tv64[ebp], eax
cmp DWORD PTR tv64[ebp], 1 ; R
je SHORT $LN2@f
cmp DWORD PTR tv64[ebp], 2 ; W
je SHORT $LN3@f
cmp DWORD PTR tv64[ebp], 3 ; RW
je SHORT $LN4@f
jmp SHORT $LN5@f
$LN4@f: ; case RW:
mov DWORD PTR _read$[ebp], 1
$LN3@f: ; case W:
mov DWORD PTR _write$[ebp], 1
jmp SHORT $LN5@f
$LN2@f: ; case R:
mov DWORD PTR _read$[ebp], 1
$LN5@f: ; default
mov ecx, DWORD PTR _write$[ebp]
push ecx
mov edx, DWORD PTR _read$[ebp]
push edx
push OFFSET $SG1305 ; 'read=%d, write=%d'
call _printf
add esp, 12
mov esp, ebp
pop ebp
ret 0