user: 提供的汇编代码用C语言表示会是什么样子：

```asm
<revbin_permute>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x50,%rsp
  mov    %rdi,-0x48(%rbp)
  mov    %rsi,-0x50(%rbp)
  cmpq   $0x40,-0x50(%rbp)
  ja     L33
  mov    -0x50(%rbp),%rdx
  mov    -0x48(%rbp),%rax
  mov    %rdx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <revbin_permute_leq_64@plt>
  jmp    L50
L33:
  mov    -0x50(%rbp),%rax
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <ld@plt>
  cltq
  mov    %rax,-0x28(%rbp)
  mov    -0x50(%rbp),%rax
  shr    %rax
  mov    %rax,-0x20(%rbp)
  mov    -0x50(%rbp),%rax
  sub    $0x1,%rax
  mov    %rax,-0x18(%rbp)
  mov    -0x20(%rbp),%rax
  sub    $0x2,%rax
  mov    %rax,-0x10(%rbp)
  mov    -0x18(%rbp),%rax
  sub    -0x10(%rbp),%rax
  mov    %rax,-0x8(%rbp)
  movq   $0x0,-0x38(%rbp)
  movq   $0x0,-0x30(%rbp)
  jmp    L62
L35:
  mov    -0x30(%rbp),%rax
  cmp    -0x38(%rbp),%rax
  jbe    L24
  mov    -0x30(%rbp),%rdx
  mov    -0x38(%rbp),%rcx
  mov    -0x48(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <idx_swap@plt>
  mov    -0x18(%rbp),%rax
  xor    -0x30(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x18(%rbp),%rax
  xor    -0x38(%rbp),%rax
  mov    %rax,%rcx
  mov    -0x48(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <idx_swap@plt>
  mov    -0x10(%rbp),%rax
  xor    -0x30(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x10(%rbp),%rax
  xor    -0x38(%rbp),%rax
  mov    %rax,%rcx
  mov    -0x48(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <idx_swap@plt>
  mov    -0x8(%rbp),%rax
  xor    -0x30(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x8(%rbp),%rax
  xor    -0x38(%rbp),%rax
  mov    %rax,%rcx
  mov    -0x48(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <idx_swap@plt>
L24:
  addq   $0x1,-0x38(%rbp)
  mov    -0x20(%rbp),%rax
  xor    %rax,-0x30(%rbp)
  mov    -0x30(%rbp),%rax
  cmp    -0x38(%rbp),%rax
  jbe    L64
  mov    -0x30(%rbp),%rdx
  mov    -0x38(%rbp),%rcx
  mov    -0x48(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <idx_swap@plt>
  mov    -0x18(%rbp),%rax
  xor    -0x30(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x18(%rbp),%rax
  xor    -0x38(%rbp),%rax
  mov    %rax,%rcx
  mov    -0x48(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <idx_swap@plt>
L64:
  addq   $0x1,-0x38(%rbp)
  mov    -0x28(%rbp),%rdx
  mov    -0x38(%rbp),%rax
  mov    %rdx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <revbin@plt>
  cltq
  mov    %rax,-0x30(%rbp)
  mov    -0x30(%rbp),%rax
  cmp    -0x38(%rbp),%rax
  jbe    L32
  mov    -0x30(%rbp),%rdx
  mov    -0x38(%rbp),%rcx
  mov    -0x48(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <idx_swap@plt>
  mov    -0x18(%rbp),%rax
  xor    -0x30(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x18(%rbp),%rax
  xor    -0x38(%rbp),%rax
  mov    %rax,%rcx
  mov    -0x48(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <idx_swap@plt>
L32:
  addq   $0x1,-0x38(%rbp)
  mov    -0x20(%rbp),%rax
  xor    %rax,-0x30(%rbp)
  mov    -0x30(%rbp),%rax
  cmp    -0x38(%rbp),%rax
  jbe    L16
  mov    -0x30(%rbp),%rdx
  mov    -0x38(%rbp),%rcx
  mov    -0x48(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <idx_swap@plt>
  mov    -0x10(%rbp),%rax
  xor    -0x30(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x10(%rbp),%rax
  xor    -0x38(%rbp),%rax
  mov    %rax,%rcx
  mov    -0x48(%rbp),%rax
  mov    %rcx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <idx_swap@plt>
L16:
  addq   $0x1,-0x38(%rbp)
  mov    -0x28(%rbp),%rdx
  mov    -0x38(%rbp),%rax
  mov    %rdx,%rsi
  mov    %rax,%rdi
  mov    $0x0,%eax
  call   <revbin@plt>
  cltq
  mov    %rax,-0x30(%rbp)
L62:
  mov    -0x50(%rbp),%rax
  shr    $0x2,%rax
  cmp    %rax,-0x38(%rbp)
  jb     L35
L50:
  leave
  ret
```

assistant: ```c
void revbin_permute(double _Complex *f, unsigned long n) {
  if (n <= 64) {
    revbin_permute_leq_64(f, n);
    return;
  }
  const unsigned long ldn = ld(n);
  const unsigned long nh = (n >> 1);
  const unsigned long n1 = n - 1;
  const unsigned long nx1 = nh - 2;
  const unsigned long nx2 = n1 - nx1;
  unsigned long k = 0, r = 0;
  while (k < (n / 4)) {
    if (r > k) {
      idx_swap(f, k, r);
      idx_swap(f, n1 ^ k, n1 ^ r);
      idx_swap(f, nx1 ^ k, nx1 ^ r);
      idx_swap(f, nx2 ^ k, nx2 ^ r);
    }
    ++k;
    r ^= nh;
    if (r > k) {
      idx_swap(f, k, r);
      idx_swap(f, n1 ^ k, n1 ^ r);
    }
    ++k;
    r = revbin(k, ldn);
    if (r > k) {
      idx_swap(f, k, r);
      idx_swap(f, n1 ^ k, n1 ^ r);
    }
    ++k;
    r ^= nh;
    if (r > k) {
      idx_swap(f, k, r);
      idx_swap(f, nx1 ^ k, nx1 ^ r);
    }
    ++k;
    r = revbin(k, ldn);
  }
}
```