user: 请将以下的汇编代码转换成C语言代码：

```asm
<listen>:
  endbr64
  push   %r15
  push   %r14
  lea    0x1(%rdi),%r14d
  push   %r13
  push   %r12
  push   %rbp
  mov    %edi,%ebp
  push   %rbx
  sub    $0x448,%rsp
  mov    %rsi,0x8(%rsp)
  lea    0x24(%rsp),%rbx
  lea    0x28(%rsp),%r15
  mov    %rbx,%rdi
  mov    %fs:0x28,%rax
  mov    %rax,0x438(%rsp)
  xor    %eax,%eax
  call   <FD_ZERO@plt>
  movabs $0x88b8000000002,%rax
  mov    %rax,0x28(%rsp)
  lea    0x30(%rsp),%rax
  mov    %rax,(%rsp)
L104:
  mov    %rbx,%rsi
  mov    %ebp,%edi
  call   <FD_SET@plt>
  xor    %ecx,%ecx
  xor    %edx,%edx
  mov    %rbx,%rsi
  mov    %r14d,%edi
  mov    %r15,%r8
  call   <select@plt>
  mov    %rbx,%rsi
  mov    %ebp,%edi
  mov    %eax,%r12d
  call   <FD_ISSET@plt>
  test   %rax,%rax
  jne    L202
L103:
  test   %r12d,%r12d
  jne    L104
L136:
  mov    $0xffffffff,%r13d
L204:
  mov    0x438(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L72
  add    $0x448,%rsp
  mov    %r13d,%eax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopw   0x0(%rax,%rax,1)
L202:
  mov    (%rsp),%rsi
  mov    $0x400,%edx
  mov    %ebp,%edi
  call   <read@plt>
  mov    %eax,%r13d
  test   %eax,%eax
  jle    L103
  movzbl 0x30(%rsp),%ecx
  xor    %eax,%eax
  cmp    $0x18,%cl
  ja     L173
  mov    $0xfffffffffedfffbf,%rax
  sar    %cl,%rax
  and    $0x1,%eax
  xor    $0x1,%eax
L173:
  cmp    $0xa5,%cl
  je     L170
  test   %al,%al
  je     L103
L170:
  mov    (%rsp),%rsi
  mov    0x8(%rsp),%rdi
  mov    %r13d,%edx
  call   <memcpy@plt>
  test   %r12d,%r12d
  je     L136
  mov    0x8(%rsp),%rax
  movzbl (%rax),%eax
  cmp    $0x18,%al
  ja     L122
  mov    $0xfffffffffedfffbf,%rdx
  bt     %rax,%rdx
  jb     L122
  mov    $0x1,%r13d
  jmp    L204
  nopw   0x0(%rax,%rax,1)
L122:
  cmp    $0x5,%r13d
  jg     L209
  mov    %rbx,%rdi
  call   <FD_ZERO@plt>
  movabs $0x88b8000000002,%rax
  mov    %rax,0x28(%rsp)
L142:
  mov    0x8(%rsp),%rax
  add    $0x2,%rax
  mov    %rax,0x10(%rsp)
  jmp    L194
  nopl   0x0(%rax)
L199:
  cmp    $0x5,%r13d
  jg     L197
L169:
  test   %r12d,%r12d
  je     L75
L194:
  mov    %rbx,%rsi
  mov    %ebp,%edi
  call   <FD_SET@plt>
  xor    %ecx,%ecx
  xor    %edx,%edx
  mov    %rbx,%rsi
  mov    %r14d,%edi
  mov    %r15,%r8
  call   <select@plt>
  mov    %rbx,%rsi
  mov    %ebp,%edi
  mov    %eax,%r12d
  call   <FD_ISSET@plt>
  test   %rax,%rax
  je     L199
  mov    (%rsp),%rsi
  mov    $0x400,%edx
  mov    %ebp,%edi
  call   <read@plt>
  mov    %eax,%edx
  test   %eax,%eax
  jle    L199
  mov    (%rsp),%rsi
  movslq %r13d,%rdi
  add    0x8(%rsp),%rdi
  mov    %eax,0x1c(%rsp)
  call   <memcpy@plt>
  mov    0x1c(%rsp),%edx
  add    %edx,%r13d
  cmp    $0x5,%r13d
  jle    L169
  nopl   (%rax)
L197:
  mov    0x10(%rsp),%rdi
  call   <getint@plt>
  lea    -0x6(%r13),%edx
  cmp    %eax,%edx
  jne    L169
L75:
  mov    0x8(%rsp),%rdi
  mov    %r13d,%esi
  call   <checksum@plt>
  cmp    $0x1,%eax
  mov    $0xfffffffe,%eax
  cmovne %eax,%r13d
  jmp    L204
  nopl   0x0(%rax)
L209:
  mov    0x8(%rsp),%rax
  lea    0x2(%rax),%rdi
  call   <getint@plt>
  mov    %rbx,%rdi
  mov    %eax,%r12d
  call   <FD_ZERO@plt>
  movabs $0x88b8000000002,%rax
  mov    %rax,0x28(%rsp)
  lea    -0x6(%r13),%eax
  cmp    %r12d,%eax
  jne    L142
  jmp    L75
L72:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int listen(int fd, unsigned char *pak) {
  unsigned char buf[1024];
  fd_set readfs;
  struct timeval tout;
  int ret, res, STOP, TIMEOUT;
  int maxfd = fd + 1;
  int len = 0;
  STOP = 0;
  TIMEOUT = 0;
  FD_ZERO(&readfs);
  tout.tv_sec = 2;
  tout.tv_usec = 560000;
  while (STOP == 0) {
    FD_SET(fd, &readfs);
    ret = select(maxfd, &readfs, NULL, NULL, &tout);
    if (FD_ISSET(fd, &readfs)) {
      res = read(fd, buf, 1024);
      if (res > 0) {
        if (buf[0] == 0x06 || buf[0] == 0x15 || buf[0] == 0x18 || buf[0] == 0xa5) {
          STOP = 1;
          memcpy(pak, buf, res);
          len += res;
        }
      }
    }
    if (ret == 0) {
      STOP = 1;
      TIMEOUT = 1;
    }
  }
  if (TIMEOUT == 1)
    return -1;
  if (pak[0] == 0x06 || pak[0] == 0x15 || pak[0] == 0x18)
    return 1;
  STOP = 0;
  if (len >= 6 && (len - 6) == getint(&pak[2]))
    STOP = 1;
  TIMEOUT = 0;
  FD_ZERO(&readfs);
  tout.tv_sec = 2;
  tout.tv_usec = 560000;
  while (STOP == 0) {
    FD_SET(fd, &readfs);
    ret = select(maxfd, &readfs, NULL, NULL, &tout);
    if (FD_ISSET(fd, &readfs)) {
      res = read(fd, buf, 1024);
      if (res > 0) {
        memcpy(&pak[len], buf, res);
        len += res;
      }
    }
    if (ret == 0) {
      STOP = 1;
      TIMEOUT = 1;
    }
    if (len >= 6 && (len - 6) == getint(&pak[2]))
      STOP = 1;
  }
  if (checksum(pak, len) == 1)
    return len;
  else
    return -2;
}
```