user: 提供的汇编代码用C语言表示会是什么样子:

```asm
<bn_sub_words>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x40,%rsp
  mov    %rdi,-0x28(%rbp)
  mov    %rsi,-0x30(%rbp)
  mov    %rdx,-0x38(%rbp)
  mov    %ecx,-0x3c(%rbp)
  movl   $0x0,-0x14(%rbp)
  mov    -0x3c(%rbp),%eax
  not    %eax
  shr    $0x1f,%eax
  movzbl %al,%eax
  mov    %eax,%edi
  call   <assert@plt>
  cmpl   $0x0,-0x3c(%rbp)
  jg     L127
  mov    $0x0,%eax
  jmp    L15
L127:
  mov    -0x30(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,-0x10(%rbp)
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,-0x8(%rbp)
  mov    -0x10(%rbp),%rax
  sub    -0x8(%rbp),%rax
  mov    -0x14(%rbp),%edx
  movslq %edx,%rcx
  sub    %rcx,%rax
  mov    %rax,%rdx
  mov    -0x28(%rbp),%rax
  mov    %rdx,(%rax)
  mov    -0x10(%rbp),%rax
  cmp    -0x8(%rbp),%rax
  je     L12
  mov    -0x10(%rbp),%rax
  cmp    -0x8(%rbp),%rax
  setb   %al
  movzbl %al,%eax
  mov    %eax,-0x14(%rbp)
L12:
  subl   $0x1,-0x3c(%rbp)
  cmpl   $0x0,-0x3c(%rbp)
  jle    L31
  mov    -0x30(%rbp),%rax
  mov    0x8(%rax),%rax
  mov    %rax,-0x10(%rbp)
  mov    -0x38(%rbp),%rax
  mov    0x8(%rax),%rax
  mov    %rax,-0x8(%rbp)
  mov    -0x10(%rbp),%rax
  sub    -0x8(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x28(%rbp),%rax
  add    $0x8,%rax
  sub    %rcx,%rdx
  mov    %rdx,(%rax)
  mov    -0x10(%rbp),%rax
  cmp    -0x8(%rbp),%rax
  je     L62
  mov    -0x10(%rbp),%rax
  cmp    -0x8(%rbp),%rax
  setb   %al
  movzbl %al,%eax
  mov    %eax,-0x14(%rbp)
L62:
  subl   $0x1,-0x3c(%rbp)
  cmpl   $0x0,-0x3c(%rbp)
  jle    L90
  mov    -0x30(%rbp),%rax
  mov    0x10(%rax),%rax
  mov    %rax,-0x10(%rbp)
  mov    -0x38(%rbp),%rax
  mov    0x10(%rax),%rax
  mov    %rax,-0x8(%rbp)
  mov    -0x10(%rbp),%rax
  sub    -0x8(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x28(%rbp),%rax
  add    $0x10,%rax
  sub    %rcx,%rdx
  mov    %rdx,(%rax)
  mov    -0x10(%rbp),%rax
  cmp    -0x8(%rbp),%rax
  je     L108
  mov    -0x10(%rbp),%rax
  cmp    -0x8(%rbp),%rax
  setb   %al
  movzbl %al,%eax
  mov    %eax,-0x14(%rbp)
L108:
  subl   $0x1,-0x3c(%rbp)
  cmpl   $0x0,-0x3c(%rbp)
  jle    L60
  mov    -0x30(%rbp),%rax
  mov    0x18(%rax),%rax
  mov    %rax,-0x10(%rbp)
  mov    -0x38(%rbp),%rax
  mov    0x18(%rax),%rax
  mov    %rax,-0x8(%rbp)
  mov    -0x10(%rbp),%rax
  sub    -0x8(%rbp),%rax
  mov    %rax,%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x28(%rbp),%rax
  add    $0x18,%rax
  sub    %rcx,%rdx
  mov    %rdx,(%rax)
  mov    -0x10(%rbp),%rax
  cmp    -0x8(%rbp),%rax
  je     L135
  mov    -0x10(%rbp),%rax
  cmp    -0x8(%rbp),%rax
  setb   %al
  movzbl %al,%eax
  mov    %eax,-0x14(%rbp)
L135:
  subl   $0x1,-0x3c(%rbp)
  cmpl   $0x0,-0x3c(%rbp)
  jle    L68
  addq   $0x20,-0x30(%rbp)
  addq   $0x20,-0x38(%rbp)
  addq   $0x20,-0x28(%rbp)
  jmp    L127
L31:
  nop
  jmp    L71
L90:
  nop
  jmp    L71
L60:
  nop
  jmp    L71
L68:
  nop
L71:
  mov    -0x14(%rbp),%eax
  cltq
L15:
  leave
  ret
```

assistant: ```c
unsigned long long bn_sub_words(unsigned long long *r, unsigned long long *a, unsigned long long *b, int n) {
  unsigned long long t1, t2;
  int c = 0;
  assert(n >= 0);
  if (n <= 0)
    return ((unsigned long long)0);
  for (;;) {
    t1 = a[0];
    t2 = b[0];
    r[0] = (t1 - t2 - c) & (0xffffffffffffffffLL);
    if (t1 != t2)
      c = (t1 < t2);
    if (--n <= 0)
      break;
    t1 = a[1];
    t2 = b[1];
    r[1] = (t1 - t2 - c) & (0xffffffffffffffffLL);
    if (t1 != t2)
      c = (t1 < t2);
    if (--n <= 0)
      break;
    t1 = a[2];
    t2 = b[2];
    r[2] = (t1 - t2 - c) & (0xffffffffffffffffLL);
    if (t1 != t2)
      c = (t1 < t2);
    if (--n <= 0)
      break;
    t1 = a[3];
    t2 = b[3];
    r[3] = (t1 - t2 - c) & (0xffffffffffffffffLL);
    if (t1 != t2)
      c = (t1 < t2);
    if (--n <= 0)
      break;
    a += 4;
    b += 4;
    r += 4;
  }
  return (c);
}
```