user: 提供的汇编代码用C语言表示会是什么样子：

```asm
<submask_sub>:
  endbr64
  push   %r12
  push   %rbp
  mov    %rdi,%rbp
  push   %rbx
  sub    $0x20,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0x18(%rsp)
  xor    %eax,%eax
  cmpb   $0x2e,(%rdi)
  movl   $0x0,0x14(%rsp)
  je     L130
  cmpb   $0x2e,0x1(%rdi)
  je     L177
  cmpb   $0x2e,0x2(%rbp)
  je     L76
L387:
  cmpb   $0x2e,0x3(%rbp)
  je     L358
L47:
  cmpb   $0x2e,0x4(%rbp)
  je     L303
L397:
  cmpb   $0x2e,0x5(%rbp)
  je     L185
  cmpb   $0x2e,0x6(%rbp)
  je     L348
L327:
  cmpb   $0x2e,0x7(%rbp)
  je     L80
L420:
  cmpb   $0x2e,0x8(%rbp)
  je     L599
L320:
  cmpb   $0x2e,0x9(%rbp)
  je     L437
L513:
  cmpb   $0x2e,0xa(%rbp)
  je     L132
L393:
  cmpb   $0x2e,0xb(%rbp)
  je     L564
L251:
  cmpb   $0x2e,0xc(%rbp)
  je     L546
L125:
  cmpb   $0x2e,0xd(%rbp)
  je     L590
L383:
  cmpb   $0x2e,0xe(%rbp)
  je     L398
L438:
  cmpb   $0x2e,0xf(%rbp)
  jne    L49
  cltq
  movl   $0xf,0x8(%rsp,%rax,4)
  nopl   0x0(%rax)
L49:
  cmp    $0x1,%esi
  je     L405
  cmp    $0x2,%esi
  je     L31
  mov    0x10(%rsp),%r12d
  cmp    $0x3,%esi
  je     L116
  mov    %rbp,%rdi
  lea    0x1(%r12),%ebx
  call   <strlen@plt>
  cmp    %eax,%ebx
  jge    L499
  movslq %ebx,%rbx
  mov    %rbp,%rdi
  movzbl 0x0(%rbp,%rbx,1),%eax
  lea    0x2(%r12),%ebx
  mov    %al,0x14(%rsp)
  call   <strlen@plt>
  cmp    %eax,%ebx
  jge    L499
  movslq %ebx,%rbx
  mov    %rbp,%rdi
  movzbl 0x0(%rbp,%rbx,1),%eax
  lea    0x3(%r12),%ebx
  mov    %al,0x15(%rsp)
  call   <strlen@plt>
  cmp    %eax,%ebx
  jge    L499
  movslq %ebx,%rax
  mov    %rbp,%rdi
  lea    0x4(%r12),%ebx
  movzbl 0x0(%rbp,%rax,1),%eax
  mov    %al,0x16(%rsp)
  call   <strlen@plt>
  cmp    %eax,%ebx
  jge    L499
  movslq %ebx,%rbx
  movzbl 0x0(%rbp,%rbx,1),%eax
  mov    %al,0x17(%rsp)
L499:
  lea    0x14(%rsp),%rdi
L198:
  call   <atoi@plt>
L58:
  mov    0x18(%rsp),%rdx
  sub    %fs:0x28,%rdx
  jne    L413
  add    $0x20,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  ret
  nopl   0x0(%rax,%rax,1)
L185:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0x5,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  je     L49
  cmpb   $0x2e,0x6(%rbp)
  jne    L327
  jmp    L348
  nopl   0x0(%rax,%rax,1)
L405:
  mov    %rbp,%rdi
  call   <atoi@plt>
  jmp    L58
  nopw   0x0(%rax,%rax,1)
L348:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0x6,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  je     L49
  cmpb   $0x2e,0x7(%rbp)
  jne    L420
L80:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0x7,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  je     L49
  cmpb   $0x2e,0x8(%rbp)
  jne    L320
  jmp    L599
  nop
L177:
  xor    %eax,%eax
L595:
  movslq %eax,%rdx
  add    $0x1,%eax
  cmpb   $0x2e,0x2(%rbp)
  movl   $0x1,0x8(%rsp,%rdx,4)
  jne    L387
L76:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0x2,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  je     L49
  cmpb   $0x2e,0x3(%rbp)
  jne    L47
L358:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0x3,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  je     L49
  cmpb   $0x2e,0x4(%rbp)
  jne    L397
L303:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0x4,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  jne    L397
  jmp    L49
  nopl   0x0(%rax,%rax,1)
L599:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0x8,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  je     L49
  cmpb   $0x2e,0x9(%rbp)
  jne    L513
L437:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0x9,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  je     L49
  cmpb   $0x2e,0xa(%rbp)
  jne    L393
  jmp    L132
  nopl   0x0(%rax)
L130:
  cmpb   $0x2e,0x1(%rdi)
  movl   $0x0,0x8(%rsp)
  mov    $0x1,%eax
  je     L595
  cmpb   $0x2e,0x2(%rdi)
  mov    $0x1,%eax
  jne    L387
  movl   $0x2,0xc(%rsp)
  mov    $0x2,%eax
  jmp    L387
L31:
  mov    0x8(%rsp),%esi
  mov    0xc(%rsp),%eax
  lea    0x14(%rsp),%rdi
  lea    0x1(%rsi),%ecx
  cmp    %ecx,%eax
  jle    L198
  lea    -0x2(%rax),%edx
  movslq %ecx,%rcx
  mov    %edx,%eax
  sub    %esi,%eax
  lea    0x0(%rbp,%rcx,1),%rsi
  lea    0x1(%rax),%rdx
  call   <memcpy@plt>
  mov    %rax,%rdi
  jmp    L198
  nopl   0x0(%rax,%rax,1)
L132:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0xa,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  je     L49
  cmpb   $0x2e,0xb(%rbp)
  jne    L251
L564:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0xb,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  je     L49
  cmpb   $0x2e,0xc(%rbp)
  jne    L125
L546:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0xc,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  je     L49
  cmpb   $0x2e,0xd(%rbp)
  jne    L383
L590:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0xd,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  je     L49
  cmpb   $0x2e,0xe(%rbp)
  jne    L438
L398:
  movslq %eax,%rdx
  add    $0x1,%eax
  movl   $0xe,0x8(%rsp,%rdx,4)
  cmp    $0x3,%eax
  jne    L438
  jmp    L49
L116:
  mov    0xc(%rsp),%ecx
  lea    0x1(%rcx),%eax
  cmp    %r12d,%eax
  jge    L499
  lea    -0x2(%r12),%edx
  cltq
  lea    0x14(%rsp),%rdi
  mov    %edx,%ebx
  lea    0x0(%rbp,%rax,1),%rsi
  sub    %ecx,%ebx
  lea    0x1(%rbx),%rdx
  call   <memcpy@plt>
  mov    %rax,%rdi
  jmp    L198
L413:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int submask_sub(char ip[16], int n) {
  int daoat[3];
  char ippart[4] = "";
  int i = 0;
  int j = 0;
  for (i = 0, j = 0; i < 16; i++) {
    if (ip[i] == '.') {
      daoat[j] = i;
      j++;
    }
    if (j == 3) {
      break;
    }
  }
  if (n == 1) {
    return atoi(ip);
  } else if (n == 2) {
    for (j = 0, i = 1 + daoat[0]; i < daoat[1]; i++, j++) {
      ippart[j] = ip[i];
    }
  } else if (n == 3) {
    for (j = 0, i = 1 + daoat[1]; i < daoat[2]; i++, j++) {
      ippart[j] = ip[i];
    }
  } else {
    for (j = 0, i = 1 + daoat[2]; i < (int)strlen(ip); i++, j++) {
      ippart[j] = ip[i];
    }
  }
  return atoi(ippart);
}
```