user: 请从给定的汇编指令推导出C源代码:

```asm
<walk>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x30,%rsp
  mov    %rdi,-0x18(%rbp)
  mov    %esi,-0x1c(%rbp)
  mov    %edx,-0x20(%rbp)
  mov    %ecx,-0x24(%rbp)
  movl   $0x0,-0x4(%rbp)
  mov    -0x1c(%rbp),%eax
  cltq
  mov    %rax,%rdx
  shl    $0x5,%rdx
  add    %rax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x20(%rbp),%eax
  cltq
  movzbl (%rdx,%rax,1),%eax
  test   %al,%al
  jne    L32
  mov    -0x1c(%rbp),%eax
  cltq
  mov    %rax,%rdx
  shl    $0x5,%rdx
  add    %rax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x20(%rbp),%eax
  cltq
  movb   $0x2,(%rdx,%rax,1)
  mov    -0x24(%rbp),%eax
  sub    $0x1,%eax
  cmp    %eax,-0x1c(%rbp)
  jge    L72
  mov    -0x1c(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    %rdx,%rax
  shl    $0x5,%rax
  add    %rax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x20(%rbp),%eax
  cltq
  movzbl (%rdx,%rax,1),%eax
  cmp    $0x1,%al
  jne    L259
  addl   $0x1,-0x4(%rbp)
  jmp    L72
L259:
  mov    -0x1c(%rbp),%eax
  cltq
  lea    0x1(%rax),%rdx
  mov    %rdx,%rax
  shl    $0x5,%rax
  add    %rax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x20(%rbp),%eax
  cltq
  movzbl (%rdx,%rax,1),%eax
  test   %al,%al
  jne    L72
  mov    -0x1c(%rbp),%eax
  lea    0x1(%rax),%esi
  mov    -0x24(%rbp),%ecx
  mov    -0x20(%rbp),%edx
  mov    -0x18(%rbp),%rax
  mov    %rax,%rdi
  call   <walk>
  add    %eax,-0x4(%rbp)
L72:
  cmpl   $0x0,-0x1c(%rbp)
  jle    L45
  mov    -0x1c(%rbp),%eax
  cltq
  mov    %rax,%rdx
  shl    $0x5,%rdx
  add    %rdx,%rax
  lea    -0x21(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x20(%rbp),%eax
  cltq
  movzbl (%rdx,%rax,1),%eax
  cmp    $0x1,%al
  jne    L227
  addl   $0x1,-0x4(%rbp)
  jmp    L45
L227:
  mov    -0x1c(%rbp),%eax
  cltq
  mov    %rax,%rdx
  shl    $0x5,%rdx
  add    %rdx,%rax
  lea    -0x21(%rax),%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x20(%rbp),%eax
  cltq
  movzbl (%rdx,%rax,1),%eax
  test   %al,%al
  jne    L45
  mov    -0x1c(%rbp),%eax
  lea    -0x1(%rax),%esi
  mov    -0x24(%rbp),%ecx
  mov    -0x20(%rbp),%edx
  mov    -0x18(%rbp),%rax
  mov    %rax,%rdi
  call   <walk>
  add    %eax,-0x4(%rbp)
L45:
  mov    -0x24(%rbp),%eax
  sub    $0x1,%eax
  cmp    %eax,-0x20(%rbp)
  jge    L166
  mov    -0x1c(%rbp),%eax
  cltq
  mov    %rax,%rdx
  shl    $0x5,%rdx
  add    %rax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x20(%rbp),%eax
  add    $0x1,%eax
  cltq
  movzbl (%rdx,%rax,1),%eax
  cmp    $0x1,%al
  jne    L35
  addl   $0x1,-0x4(%rbp)
  jmp    L166
L35:
  mov    -0x1c(%rbp),%eax
  cltq
  mov    %rax,%rdx
  shl    $0x5,%rdx
  add    %rax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x20(%rbp),%eax
  add    $0x1,%eax
  cltq
  movzbl (%rdx,%rax,1),%eax
  test   %al,%al
  jne    L166
  mov    -0x20(%rbp),%eax
  lea    0x1(%rax),%edi
  mov    -0x24(%rbp),%edx
  mov    -0x1c(%rbp),%esi
  mov    -0x18(%rbp),%rax
  mov    %edx,%ecx
  mov    %edi,%edx
  mov    %rax,%rdi
  call   <walk>
  add    %eax,-0x4(%rbp)
L166:
  cmpl   $0x0,-0x20(%rbp)
  jle    L211
  mov    -0x1c(%rbp),%eax
  cltq
  mov    %rax,%rdx
  shl    $0x5,%rdx
  add    %rax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x20(%rbp),%eax
  sub    $0x1,%eax
  cltq
  movzbl (%rdx,%rax,1),%eax
  cmp    $0x1,%al
  jne    L204
  addl   $0x1,-0x4(%rbp)
  jmp    L211
L204:
  mov    -0x1c(%rbp),%eax
  cltq
  mov    %rax,%rdx
  shl    $0x5,%rdx
  add    %rax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rax,%rdx
  mov    -0x20(%rbp),%eax
  sub    $0x1,%eax
  cltq
  movzbl (%rdx,%rax,1),%eax
  test   %al,%al
  jne    L211
  mov    -0x20(%rbp),%eax
  lea    -0x1(%rax),%edi
  mov    -0x24(%rbp),%edx
  mov    -0x1c(%rbp),%esi
  mov    -0x18(%rbp),%rax
  mov    %edx,%ecx
  mov    %edi,%edx
  mov    %rax,%rdi
  call   <walk>
  add    %eax,-0x4(%rbp)
L211:
  cmpl   $0x0,-0x1c(%rbp)
  jne    L54
  cmpl   $0x0,-0x20(%rbp)
  je     L54
  addl   $0x1,-0x4(%rbp)
  jmp    L157
L54:
  mov    -0x24(%rbp),%eax
  sub    $0x1,%eax
  cmp    %eax,-0x1c(%rbp)
  jne    L157
  mov    -0x24(%rbp),%eax
  sub    $0x1,%eax
  cmp    %eax,-0x20(%rbp)
  je     L157
  addl   $0x1,-0x4(%rbp)
L157:
  cmpl   $0x0,-0x20(%rbp)
  jne    L25
  cmpl   $0x0,-0x1c(%rbp)
  je     L25
  addl   $0x1,-0x4(%rbp)
  jmp    L32
L25:
  mov    -0x24(%rbp),%eax
  sub    $0x1,%eax
  cmp    %eax,-0x20(%rbp)
  jne    L32
  mov    -0x24(%rbp),%eax
  sub    $0x1,%eax
  cmp    %eax,-0x1c(%rbp)
  je     L32
  addl   $0x1,-0x4(%rbp)
L32:
  mov    -0x4(%rbp),%eax
  leave
  ret
```

assistant: ```c
int walk(char maze[][33], int lin, int col, int n) {
  int walls = 0;
  if (!maze[lin][col]) {
    maze[lin][col] = 2;
    if (lin < n - 1) {
      if (maze[lin + 1][col] == 1)
        walls++;
      else if (!maze[lin + 1][col])
        walls += walk(maze, lin + 1, col, n);
    }
    if (lin > 0) {
      if (maze[lin - 1][col] == 1)
        walls++;
      else if (!maze[lin - 1][col])
        walls += walk(maze, lin - 1, col, n);
    }
    if (col < n - 1) {
      if (maze[lin][col + 1] == 1)
        walls++;
      else if (!maze[lin][col + 1])
        walls += walk(maze, lin, col + 1, n);
    }
    if (col > 0) {
      if (maze[lin][col - 1] == 1)
        walls++;
      else if (!maze[lin][col - 1])
        walls += walk(maze, lin, col - 1, n);
    }
    if (lin == 0 && col != 0)
      walls++;
    else if (lin == n - 1 && col != n - 1)
      walls++;
    if (col == 0 && lin != 0)
      walls++;
    else if (col == n - 1 && lin != n - 1)
      walls++;
  }
  return walls;
}
```