user: 提供的汇编代码用C语言表示会是什么样子：

```asm
<__dns_decodename>:
  endbr64
  mov    %rdi,%r11
  mov    %esi,%edi
  push   %r15
  mov    %rdx,%r9
  push   %r14
  mov    %rdi,%rax
  add    %r11,%rdi
  push   %r13
  push   %r12
  push   %rbp
  mov    %ecx,%ebp
  push   %rbx
  add    %rdx,%rbp
  mov    %rdi,%rbx
  test   %ecx,%ecx
  je     L223
  xor    %ecx,%ecx
  nopw   0x0(%rax,%rax,1)
L20:
  movzbl (%rdi),%edx
  test   %dl,%dl
  je     L34
L82:
  cmp    %r8,%rdi
  jae    L160
  mov    %edx,%ecx
  shr    $0x6,%cl
  cmp    $0x3,%cl
  jne    L133
  movzbl 0x1(%rdi),%ecx
  shl    $0x8,%edx
  and    $0x3f00,%edx
  or     %ecx,%edx
  cmp    %edx,%eax
  jbe    L160
  add    $0x2,%rdi
  cmp    %rdi,%rbx
  cmovb  %rdi,%rbx
  lea    (%r11,%rdx,1),%rdi
  xor    %ecx,%ecx
  movzbl (%rdi),%edx
  test   %dl,%dl
  jne    L82
L34:
  cmp    $0x1,%ecx
  adc    $0xffffffffffffffff,%r9
L223:
  mov    %ebx,%eax
  movb   $0x0,(%r9)
  pop    %rbx
  sub    %r11d,%eax
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax)
L133:
  test   %cl,%cl
  jne    L160
  lea    0x1(%rdx),%ecx
  movzbl %cl,%ecx
  lea    (%r9,%rcx,1),%rsi
  cmp    %rsi,%rbp
  jb     L160
  add    %rdi,%rcx
  cmp    %rcx,%r8
  jbe    L160
  lea    0x2(%rdi),%rsi
  mov    %r9,%rcx
  movzbl %dl,%r13d
  sub    %rsi,%rcx
  lea    -0x1(%r13),%r12d
  cmp    $0xe,%rcx
  jbe    L158
  cmp    $0x6,%r12d
  jbe    L158
  cmp    $0xe,%r12d
  jbe    L14
  lea    -0x10(%r13),%r10d
  xor    %ecx,%ecx
  xor    %esi,%esi
  shr    $0x4,%r10d
  add    $0x1,%r10d
  nop
L69:
  movdqu 0x1(%rdi,%rcx,1),%xmm0
  add    $0x1,%esi
  movups %xmm0,(%r9,%rcx,1)
  add    $0x10,%rcx
  cmp    %esi,%r10d
  ja     L69
  shl    $0x4,%r10d
  mov    %r13d,%ecx
  mov    %r10d,%r15d
  sub    %r10d,%ecx
  lea    (%r9,%r15,1),%rsi
  lea    (%rdi,%r15,1),%r14
  cmp    %r10d,%r13d
  je     L110
  lea    -0x1(%rcx),%r10d
  mov    %ecx,%r13d
  cmp    $0x6,%r10d
  jbe    L194
L275:
  mov    0x1(%rdi,%r15,1),%r10
  mov    %r10,(%r9,%r15,1)
  mov    %r13d,%r10d
  and    $0xfffffff8,%r10d
  mov    %r10d,%r15d
  sub    %r10d,%ecx
  add    %r15,%rsi
  add    %r15,%r14
  cmp    %r10d,%r13d
  je     L110
  lea    -0x1(%rcx),%r10d
L194:
  movzbl 0x1(%r14),%r13d
  mov    %r13b,(%rsi)
  test   %r10d,%r10d
  je     L110
  movzbl 0x2(%r14),%r10d
  mov    %r10b,0x1(%rsi)
  cmp    $0x2,%ecx
  je     L110
  movzbl 0x3(%r14),%r10d
  mov    %r10b,0x2(%rsi)
  cmp    $0x3,%ecx
  je     L110
  movzbl 0x4(%r14),%r10d
  mov    %r10b,0x3(%rsi)
  cmp    $0x4,%ecx
  je     L110
  movzbl 0x5(%r14),%r10d
  mov    %r10b,0x4(%rsi)
  cmp    $0x5,%ecx
  je     L110
  movzbl 0x6(%r14),%r10d
  mov    %r10b,0x5(%rsi)
  cmp    $0x6,%ecx
  je     L110
  movzbl 0x7(%r14),%ecx
  mov    %cl,0x6(%rsi)
L110:
  add    $0x2,%r12
  lea    (%rdi,%rdx,1),%rsi
  add    %r9,%rdx
  mov    $0x1,%ecx
  add    %r12,%rdi
  movb   $0x2e,(%rdx)
  add    %r12,%r9
  cmp    %rdi,%rbx
  jae    L20
  cmpb   $0x0,0x1(%rsi)
  mov    %rdi,%rbx
  jne    L20
  lea    0x2(%rsi),%rbx
  jmp    L20
  nopw   0x0(%rax,%rax,1)
L158:
  xor    %ecx,%ecx
  nopw   0x0(%rax,%rax,1)
L259:
  movzbl 0x1(%rdi,%rcx,1),%esi
  mov    %sil,(%r9,%rcx,1)
  add    $0x1,%rcx
  cmp    %rdx,%rcx
  jne    L259
  jmp    L110
  nopl   0x0(%rax)
L160:
  pop    %rbx
  mov    $0xffffffff,%eax
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L14:
  mov    %r13d,%ecx
  mov    %rdi,%r14
  mov    %r9,%rsi
  xor    %r15d,%r15d
  jmp    L275
```

assistant: ```c
int __dns_decodename(const unsigned char *packet, unsigned int offset, unsigned char *dest, unsigned int maxlen, const unsigned char *behindpacket) {
  const unsigned char *tmp;
  const unsigned char *max = dest + maxlen;
  const unsigned char *after = packet + offset;
  int ok = 0;
  for (tmp = after; maxlen > 0 && *tmp;) {
    if (tmp >= behindpacket)
      return -1;
    if ((*tmp >> 6) == 3) {
      unsigned int ofs = ((unsigned int)(*tmp & 0x3f) << 8) | *(tmp + 1);
      if (ofs >= (unsigned int)offset)
        return -1;
      if (after < tmp + 2)
        after = tmp + 2;
      tmp = packet + ofs;
      ok = 0;
    } else if ((*tmp >> 6) == 0) {
      unsigned int duh;
      if (dest + *tmp + 1 > max)
        return -1;
      if (tmp + *tmp + 1 >= behindpacket)
        return -1;
      for (duh = *tmp; duh > 0; --duh)
        *dest++ = *++tmp;
      *dest++ = '.';
      ok = 1;
      ++tmp;
      if (tmp > after) {
        after = tmp;
        if (!*tmp)
          ++after;
      }
    } else
      return -1;
  }
  if (ok)
    --dest;
  *dest = 0;
  return after - packet;
}
```