user: Demonstrate the C code that generates the assembly output below:

```asm
<teredo_cksum>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %r13
  push   %r12
  push   %rbx
  sub    $0x78,%rsp
  mov    %rdi,-0x68(%rbp)
  mov    %rsi,-0x70(%rbp)
  mov    %rdx,-0x78(%rbp)
  mov    %rcx,-0x80(%rbp)
  mov    %r8,-0x88(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x28(%rbp)
  xor    %eax,%eax
  mov    %rsp,%rax
  mov    %rax,%rbx
  mov    -0x88(%rbp),%rax
  add    $0x3,%rax
  mov    %rax,%rdx
  sub    $0x1,%rdx
  mov    %rdx,-0x50(%rbp)
  mov    %rax,%r12
  mov    $0x0,%r13d
  mov    %rax,%r10
  mov    $0x0,%r11d
  shl    $0x4,%rax
  mov    %rax,%rdx
  mov    $0x10,%eax
  sub    $0x1,%rax
  add    %rdx,%rax
  mov    $0x10,%edi
  mov    $0x0,%edx
  div    %rdi
  imul   $0x10,%rax,%rax
  mov    %rax,%rcx
  and    $0xfffffffffffff000,%rcx
  mov    %rsp,%rdx
  sub    %rcx,%rdx
L37:
  cmp    %rdx,%rsp
  je     L4
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  jmp    L37
L4:
  mov    %rax,%rdx
  and    $0xfff,%edx
  sub    %rdx,%rsp
  mov    %rax,%rdx
  and    $0xfff,%edx
  test   %rdx,%rdx
  je     L34
  and    $0xfff,%eax
  sub    $0x8,%rax
  add    %rsp,%rax
  orq    $0x0,(%rax)
L34:
  mov    %rsp,%rax
  add    $0x7,%rax
  shr    $0x3,%rax
  shl    $0x3,%rax
  mov    %rax,-0x48(%rbp)
  movq   $0x0,-0x60(%rbp)
  movq   $0x0,-0x58(%rbp)
  jmp    L56
L33:
  mov    -0x58(%rbp),%rax
  shl    $0x4,%rax
  mov    %rax,%rdx
  mov    -0x80(%rbp),%rax
  add    %rdx,%rax
  mov    -0x58(%rbp),%rdx
  add    $0x3,%rdx
  mov    0x8(%rax),%rax
  mov    -0x48(%rbp),%rcx
  shl    $0x4,%rdx
  add    %rcx,%rdx
  add    $0x8,%rdx
  mov    %rax,(%rdx)
  mov    -0x58(%rbp),%rax
  shl    $0x4,%rax
  mov    %rax,%rdx
  mov    -0x80(%rbp),%rax
  add    %rax,%rdx
  mov    -0x58(%rbp),%rax
  add    $0x3,%rax
  mov    (%rdx),%rdx
  mov    -0x48(%rbp),%rcx
  mov    %rax,%rsi
  shl    $0x4,%rsi
  add    %rsi,%rcx
  mov    %rdx,(%rcx)
  mov    -0x48(%rbp),%rdx
  shl    $0x4,%rax
  add    %rdx,%rax
  mov    (%rax),%rax
  add    %rax,-0x60(%rbp)
  addq   $0x1,-0x58(%rbp)
L56:
  mov    -0x58(%rbp),%rax
  cmp    -0x88(%rbp),%rax
  jb     L33
  movq   $0x0,-0x40(%rbp)
  movq   $0x0,-0x38(%rbp)
  mov    -0x60(%rbp),%rax
  mov    %rax,%rdi
  call   <htonl@plt>
  mov    %eax,-0x40(%rbp)
  mov    -0x78(%rbp),%rax
  mov    %rax,%rdi
  call   <htonl@plt>
  mov    %eax,-0x3c(%rbp)
  mov    -0x48(%rbp),%rax
  mov    -0x68(%rbp),%rdx
  mov    %rdx,0x8(%rax)
  mov    -0x48(%rbp),%rax
  movq   $0x10,(%rax)
  mov    -0x48(%rbp),%rax
  mov    -0x70(%rbp),%rdx
  mov    %rdx,0x18(%rax)
  mov    -0x48(%rbp),%rax
  movq   $0x10,0x10(%rax)
  mov    -0x48(%rbp),%rax
  lea    -0x40(%rbp),%rdx
  mov    %rdx,0x28(%rax)
  mov    -0x48(%rbp),%rax
  movq   $0x8,0x20(%rax)
  mov    -0x88(%rbp),%rax
  add    $0x3,%eax
  mov    %eax,%edx
  mov    -0x48(%rbp),%rax
  mov    %edx,%esi
  mov    %rax,%rdi
  call   <in_cksum@plt>
  mov    %rbx,%rsp
  mov    -0x28(%rbp),%rdx
  sub    %fs:0x28,%rdx
  je     L57
  call   <__stack_chk_fail@plt>
L57:
  lea    -0x18(%rbp),%rsp
  pop    %rbx
  pop    %r12
  pop    %r13
  pop    %rbp
  ret
```

assistant: ```c
uint16_t teredo_cksum(const void *src, const void *dst, uint8_t protocol, const struct iovec *data, size_t n) {
  struct iovec iov[3 + n];
  size_t plen = 0;
  for (size_t i = 0; i < n; i++) {
    iov[3 + i].iov_base = data[i].iov_base;
    plen += (iov[3 + i].iov_len = data[i].iov_len);
  }
  uint32_t pseudo[4] = {htonl(plen), htonl(protocol)};
  iov[0].iov_base = (void *)src;
  iov[0].iov_len = 16;
  iov[1].iov_base = (void *)dst;
  iov[1].iov_len = 16;
  iov[2].iov_base = pseudo;
  iov[2].iov_len = 8;
  return in_cksum(iov, 3 + n);
}
```