1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
|
/*
* sym_word
* Check if a word is symmetric (oh, you call that palindrome...)
* x86 assembler demonstration program
*
* written by Jan Engelhardt, 2003-2007
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the WTF Public License version 2 or
* (at your option) any later version.
*/
.intel_syntax noprefix;
.section .rodata;
.L_LC0:
.string "\"%s\" is symmetric\n";
.L_LC1:
.string "\"%s\" is not symmetric\n";
.text;
.global main;
.type main, @function;
main:
push ebp;
mov ebp, esp;
jmp .L_main_cond;
.L_main_procloop:
push ebx;
call isSymmetric;
add esp, 4;
test eax, eax;
je .L_main_nosym;
push ebx;
push offset flat:.L_LC0;
call printf;
add esp, 4;
jmp .L_main_cond;
.L_main_nosym:
push ebx;
push offset flat:.L_LC1;
call printf;
add esp, 4;
.L_main_cond:
add dword ptr [ebp+12], 4;
mov ebx, dword ptr [ebp+12];
mov ebx, dword ptr [ebx];
cmp ebx, 0;
jne .L_main_procloop;
mov eax, 0;
leave;
ret;
.globl isSymmetric;
.type isSymmetric, @function;
isSymmetric:
push ebp;
mov ebp, esp;
/* ecx = strlen(cp1); */
mov esi, dword ptr [ebp+8];
push esi;
call strlen;
add esp, 4;
mov ecx, eax;
/* cp2 = cp1 + strlen(ecx) - 1; */
mov edi, esi;
add edi, ecx;
dec edi;
/* ecx >>= 1; */
shr ecx, 1;
inc ecx; /* loop = while (--ecx) rather than ecx-- */
jmp .L_isSymmetric_cond;
.L_isSymmetric_loop:
/* if (*cp1++ != *cp2--) */
mov al, byte ptr [esi];
mov ah, byte ptr [edi];
inc esi;
dec edi;
cmp al, ah;
jne .L_isSymmetric_NO;
.L_isSymmetric_cond:
/* while (ecx--) */
loop .L_isSymmetric_loop;
mov eax, 1;
leave;
ret;
.L_isSymmetric_NO:
mov eax, 0;
leave;
ret;
|
