user: 请从给定的汇编指令推导出C源代码:

```asm
<dfs>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x40,%rsp
  mov    %rdi,-0x18(%rbp)
  mov    %rsi,-0x20(%rbp)
  mov    %rdx,-0x28(%rbp)
  mov    %ecx,-0x2c(%rbp)
  mov    %r8d,-0x30(%rbp)
  mov    %r9d,-0x34(%rbp)
  mov    -0x2c(%rbp),%eax
  cltq
  lea    0x0(,%rax,8),%rdx
  mov    -0x20(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%rdx
  mov    -0x30(%rbp),%eax
  cltq
  add    %rdx,%rax
  movzbl (%rax),%edx
  mov    -0x18(%rbp),%rax
  movzbl (%rax),%eax
  cmp    %al,%dl
  je     L105
  mov    $0x0,%eax
  jmp    L106
L105:
  mov    -0x2c(%rbp),%eax
  imul   0x10(%rbp),%eax
  mov    %eax,%edx
  mov    -0x30(%rbp),%eax
  add    %edx,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movl   $0x1,(%rax)
  mov    -0x18(%rbp),%rax
  add    $0x1,%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L116
  mov    $0x1,%eax
  jmp    L106
L116:
  movl   $0x0,-0x4(%rbp)
  cmpl   $0x0,-0x2c(%rbp)
  jle    L30
  mov    -0x2c(%rbp),%eax
  sub    $0x1,%eax
  imul   0x10(%rbp),%eax
  mov    %eax,%edx
  mov    -0x30(%rbp),%eax
  add    %edx,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  test   %eax,%eax
  jne    L30
  mov    -0x2c(%rbp),%eax
  lea    -0x1(%rax),%ecx
  mov    -0x18(%rbp),%rax
  lea    0x1(%rax),%rdi
  mov    -0x34(%rbp),%r9d
  mov    -0x30(%rbp),%r8d
  mov    -0x28(%rbp),%rdx
  mov    -0x20(%rbp),%rax
  sub    $0x8,%rsp
  mov    0x10(%rbp),%esi
  push   %rsi
  mov    %rax,%rsi
  call   <dfs>
  add    $0x10,%rsp
  mov    %eax,-0x4(%rbp)
L30:
  cmpl   $0x0,-0x4(%rbp)
  jne    L135
  mov    -0x34(%rbp),%eax
  sub    $0x1,%eax
  cmp    %eax,-0x2c(%rbp)
  jge    L135
  mov    -0x2c(%rbp),%eax
  add    $0x1,%eax
  imul   0x10(%rbp),%eax
  mov    %eax,%edx
  mov    -0x30(%rbp),%eax
  add    %edx,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  test   %eax,%eax
  jne    L135
  mov    -0x2c(%rbp),%eax
  lea    0x1(%rax),%ecx
  mov    -0x18(%rbp),%rax
  lea    0x1(%rax),%rdi
  mov    -0x34(%rbp),%r9d
  mov    -0x30(%rbp),%r8d
  mov    -0x28(%rbp),%rdx
  mov    -0x20(%rbp),%rax
  sub    $0x8,%rsp
  mov    0x10(%rbp),%esi
  push   %rsi
  mov    %rax,%rsi
  call   <dfs>
  add    $0x10,%rsp
  mov    %eax,-0x4(%rbp)
L135:
  cmpl   $0x0,-0x4(%rbp)
  jne    L86
  cmpl   $0x0,-0x30(%rbp)
  jle    L86
  mov    -0x2c(%rbp),%eax
  imul   0x10(%rbp),%eax
  mov    %eax,%edx
  mov    -0x30(%rbp),%eax
  add    %edx,%eax
  cltq
  shl    $0x2,%rax
  lea    -0x4(%rax),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  test   %eax,%eax
  jne    L86
  mov    -0x30(%rbp),%eax
  lea    -0x1(%rax),%r10d
  mov    -0x18(%rbp),%rax
  lea    0x1(%rax),%rdi
  mov    -0x34(%rbp),%r8d
  mov    -0x2c(%rbp),%ecx
  mov    -0x28(%rbp),%rdx
  mov    -0x20(%rbp),%rax
  sub    $0x8,%rsp
  mov    0x10(%rbp),%esi
  push   %rsi
  mov    %r8d,%r9d
  mov    %r10d,%r8d
  mov    %rax,%rsi
  call   <dfs>
  add    $0x10,%rsp
  mov    %eax,-0x4(%rbp)
L86:
  cmpl   $0x0,-0x4(%rbp)
  jne    L26
  mov    0x10(%rbp),%eax
  sub    $0x1,%eax
  cmp    %eax,-0x30(%rbp)
  jge    L26
  mov    -0x2c(%rbp),%eax
  imul   0x10(%rbp),%eax
  mov    %eax,%edx
  mov    -0x30(%rbp),%eax
  add    %edx,%eax
  cltq
  add    $0x1,%rax
  lea    0x0(,%rax,4),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  test   %eax,%eax
  jne    L26
  mov    -0x30(%rbp),%eax
  lea    0x1(%rax),%r10d
  mov    -0x18(%rbp),%rax
  lea    0x1(%rax),%rdi
  mov    -0x34(%rbp),%r8d
  mov    -0x2c(%rbp),%ecx
  mov    -0x28(%rbp),%rdx
  mov    -0x20(%rbp),%rax
  sub    $0x8,%rsp
  mov    0x10(%rbp),%esi
  push   %rsi
  mov    %r8d,%r9d
  mov    %r10d,%r8d
  mov    %rax,%rsi
  call   <dfs>
  add    $0x10,%rsp
  mov    %eax,-0x4(%rbp)
L26:
  mov    -0x2c(%rbp),%eax
  imul   0x10(%rbp),%eax
  mov    %eax,%edx
  mov    -0x30(%rbp),%eax
  add    %edx,%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x28(%rbp),%rax
  add    %rdx,%rax
  movl   $0x0,(%rax)
  mov    -0x4(%rbp),%eax
L106:
  leave
  ret
```

assistant: ```c
bool dfs(char *word, char **board, bool *used, int row, int col, int row_size, int col_size) {
  if (board[row][col] != *word) {
    return false;
  }
  used[row * col_size + col] = true;
  if (*(word + 1) == '\0') {
    return true;
  }
  bool result = false;
  if (row > 0 && !used[(row - 1) * col_size + col]) {
    result = dfs(word + 1, board, used, row - 1, col, row_size, col_size);
  }
  if (!result && row < row_size - 1 && !used[(row + 1) * col_size + col]) {
    result = dfs(word + 1, board, used, row + 1, col, row_size, col_size);
  }
  if (!result && col > 0 && !used[row * col_size + col - 1]) {
    result = dfs(word + 1, board, used, row, col - 1, row_size, col_size);
  }
  if (!result && col < col_size - 1 && !used[row * col_size + col + 1]) {
    result = dfs(word + 1, board, used, row, col + 1, row_size, col_size);
  }
  used[row * col_size + col] = false;
  return result;
}
```