user: 提供的汇编代码用C语言表示会是什么样子:

```asm
<bindresvport>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x28,%rsp
  mov    %edi,%r14d
  mov    %fs:0x28,%rax
  mov    %rax,0x18(%rsp)
  xor    %eax,%eax
  test   %rsi,%rsi
  je     L43
  mov    %rsi,%rbp
  mov    D124(%rip),%rax
  mov    (%rax),%rax
  cmp    %rax,(%rsi)
  jne    L151
L42:
  cmpw   $0x0,D97(%rip)
  je     L88
L128:
  mov    D51(%rip),%rax
  mov    (%rax),%r12d
  movswl D3(%rip),%eax
  lea    -0x1(%r12),%r13d
  sub    %eax,%r12d
  mov    $0xffffffff,%eax
  mov    $0x257,%r15d
  jmp    L32
L43:
  mov    %rsp,%rbp
  mov    $0x10,%esi
  mov    %rbp,%rdi
  call   <__bzero@plt>
  mov    D124(%rip),%rax
  mov    (%rax),%rax
  mov    %rax,(%rsp)
  jmp    L42
L151:
  mov    D84(%rip),%rax
  mov    (%rax),%edi
  call   <__set_errno@plt>
  mov    $0xffffffff,%eax
L120:
  mov    0x18(%rsp),%rdx
  sub    %fs:0x28,%rdx
  jne    L143
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L88:
  mov    $0x0,%eax
  call   <__getpid@plt>
  mov    D51(%rip),%rdx
  mov    (%rdx),%ecx
  sub    $0x258,%ecx
  cltd
  idiv   %ecx
  add    $0x258,%dx
  mov    %dx,D15(%rip)
  jmp    L128
L132:
  mov    $0x10,%edx
  mov    %rbp,%rsi
  mov    %r14d,%edi
  call   <__bind@plt>
  test   %eax,%eax
  jns    L37
  mov    D15(%rip),%rcx
  mov    D175(%rip),%rdx
  mov    (%rdx),%rsi
  cmp    %rsi,(%rcx)
  jne    L37
  add    $0x1,%ebx
  cmp    %ebx,%r12d
  je     L86
L105:
  movzwl D15(%rip),%edi
  lea    0x1(%rdi),%eax
  mov    %ax,D22(%rip)
  movswl %di,%edi
  call   <htons@plt>
  mov    %eax,0x8(%rbp)
  movswl D22(%rip),%eax
  cmp    %r13d,%eax
  jle    L132
  movzwl D3(%rip),%eax
  mov    %ax,D22(%rip)
  jmp    L132
L148:
  mov    $0x0,%ebx
L37:
  cmp    %ebx,%r12d
  jne    L120
L86:
  cmpw   $0x200,D3(%rip)
  je     L120
  movw   $0x200,D3(%rip)
  movzwl D22(%rip),%ecx
  movswl %cx,%edx
  imul   $0xba3,%edx,%edx
  sar    $0x12,%edx
  mov    %ecx,%esi
  sar    $0xf,%si
  sub    %esi,%edx
  lea    (%rdx,%rdx,4),%esi
  lea    (%rdx,%rsi,2),%edx
  shl    $0x3,%edx
  sub    %edx,%ecx
  add    $0x200,%cx
  mov    %cx,D22(%rip)
  mov    %r15d,%r13d
  mov    $0x58,%r12d
L32:
  test   %r12d,%r12d
  jle    L148
  mov    $0x0,%ebx
  jmp    L105
L143:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int bindresvport(int sd, struct sockaddr_in *sin) {
  static short port;
  struct sockaddr_in myaddr;
  int i;
  static short startport = 600;
  if (sin == (struct sockaddr_in *)0) {
    sin = &myaddr;
    __bzero(sin, sizeof(*sin));
    sin->sin_family = AF_INET;
  } else if (sin->sin_family != AF_INET) {
    __set_errno(EAFNOSUPPORT);
    return -1;
  }
  if (port == 0) {
    port = (__getpid() % ((IPPORT_RESERVED - 1) - 600 + 1)) + 600;
  }
  int res = -1;
  int nports = (IPPORT_RESERVED - 1) - startport + 1;
  int endport = (IPPORT_RESERVED - 1);
again:
  for (i = 0; i < nports; ++i) {
    sin->sin_port = htons(port++);
    if (port > endport)
      port = startport;
    res = __bind(sd, sin, sizeof(struct sockaddr_in));
    if (res >= 0 || errno != EADDRINUSE)
      break;
  }
  if (i == nports && startport != 512) {
    startport = 512;
    endport = 600 - 1;
    nports = 600 - 512;
    port = 512 + port % (600 - 512);
    goto again;
  }
  return res;
}
```