user: 请将以下的汇编代码转换成C语言代码：

```asm
<flip_B4>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x30,%rsp
  mov    %rdi,-0x28(%rbp)
  mov    %rsi,-0x30(%rbp)
  movq   $0x0,-0x20(%rbp)
  movabs $0x1f00000000,%rax
  and    -0x28(%rbp),%rax
  mov    %rax,-0x18(%rbp)
  mov    -0x18(%rbp),%rax
  lea    (%rax,%rax,1),%rdx
  mov    -0x30(%rbp),%rax
  add    %rax,%rdx
  movabs $0x4000000000,%rax
  and    %rdx,%rax
  mov    %rax,-0x10(%rbp)
  cmpq   $0x0,-0x10(%rbp)
  je     L31
  mov    -0x18(%rbp),%rax
  mov    %rax,%rdi
  call   <last_bit@plt>
  mov    $0x2,%edx
  mov    %eax,%ecx
  shl    %cl,%rdx
  movabs $0x4000000000,%rax
  sub    %rdx,%rax
  or     %rax,-0x20(%rbp)
L31:
  movabs $0x810000000000000,%rax
  and    -0x28(%rbp),%rax
  mov    %rax,-0x18(%rbp)
  movabs $0x10200000000000,%rax
  and    -0x30(%rbp),%rax
  movabs $0x7efc00000000000,%rdx
  or     %rdx,%rax
  mov    %rax,-0x8(%rbp)
  movabs $0x200000000000,%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  and    -0x18(%rbp),%rax
  mov    %rax,-0x10(%rbp)
  cmpq   $0x0,-0x10(%rbp)
  je     L5
  mov    -0x10(%rbp),%rax
  lea    -0x1(%rax),%rdx
  movabs $0x10200000000000,%rax
  and    %rdx,%rax
  or     %rax,-0x20(%rbp)
L5:
  mov    -0x28(%rbp),%rax
  and    $0x100804,%eax
  mov    %rax,-0x18(%rbp)
  mov    -0x30(%rbp),%rax
  and    $0x20100800,%eax
  mov    %rax,%rdx
  movabs $0x3fdfeff000,%rax
  or     %rdx,%rax
  mov    %rax,-0x8(%rbp)
  mov    -0x18(%rbp),%rax
  shl    $0x9,%rax
  mov    %rax,%rdx
  mov    -0x8(%rbp),%rax
  add    %rax,%rdx
  movabs $0x4000000000,%rax
  and    %rdx,%rax
  mov    %rax,-0x10(%rbp)
  cmpq   $0x0,-0x10(%rbp)
  je     L43
  mov    -0x18(%rbp),%rax
  mov    %rax,%rdi
  call   <last_bit@plt>
  mov    $0x2,%edx
  mov    %eax,%ecx
  shl    %cl,%rdx
  movabs $0x4000000000,%rax
  sub    %rdx,%rax
  and    $0x20100800,%eax
  or     %rax,-0x20(%rbp)
L43:
  movabs $0x4040000000000000,%rax
  and    -0x28(%rbp),%rax
  mov    %rax,-0x18(%rbp)
  movabs $0x40400000000000,%rax
  and    -0x30(%rbp),%rax
  movabs $0x3fbf800000000000,%rdx
  or     %rdx,%rax
  mov    %rax,-0x8(%rbp)
  movabs $0x400000000000,%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  and    -0x18(%rbp),%rax
  mov    %rax,-0x10(%rbp)
  cmpq   $0x0,-0x10(%rbp)
  je     L38
  mov    -0x10(%rbp),%rax
  lea    -0x1(%rax),%rdx
  movabs $0x40400000000000,%rax
  and    %rdx,%rax
  or     %rax,-0x20(%rbp)
L38:
  mov    -0x28(%rbp),%rax
  and    $0x404040,%eax
  mov    %rax,-0x18(%rbp)
  mov    -0x30(%rbp),%rax
  and    $0x40404000,%eax
  mov    %rax,%rdx
  movabs $0x3fbfbf8000,%rax
  or     %rdx,%rax
  mov    %rax,-0x8(%rbp)
  mov    -0x18(%rbp),%rax
  shl    $0x8,%rax
  mov    %rax,%rdx
  mov    -0x8(%rbp),%rax
  add    %rax,%rdx
  movabs $0x4000000000,%rax
  and    %rdx,%rax
  mov    %rax,-0x10(%rbp)
  cmpq   $0x0,-0x10(%rbp)
  je     L19
  mov    -0x18(%rbp),%rax
  mov    %rax,%rdi
  call   <last_bit@plt>
  mov    $0x2,%edx
  mov    %eax,%ecx
  shl    %cl,%rdx
  movabs $0x4000000000,%rax
  sub    %rdx,%rax
  and    $0x40404000,%eax
  or     %rax,-0x20(%rbp)
L19:
  mov    -0x20(%rbp),%rax
  leave
  ret
```

assistant: ```c
unsigned long long flip_B4(const unsigned long long discs_player, const unsigned long long discs_opponent) {
  unsigned long long my_discs, opp_discs, r, flipped = 0ULL;
  my_discs = discs_player & 0X0000001F00000000ULL;
  r = ((my_discs << 1) + discs_opponent) & 0X0000004000000000ULL;
  if (r != 0) {
    flipped |= 0X0000004000000000ULL - (0X2ULL << last_bit(my_discs));
  }
  my_discs = discs_player & 0X0810000000000000ULL;
  opp_discs = (discs_opponent & 0X0010200000000000ULL) | 0X07EFC00000000000ULL;
  r = (opp_discs + 0X0000200000000000ULL) & my_discs;
  if (r != 0) {
    flipped |= (r - 1) & 0X0010200000000000ULL;
  }
  my_discs = discs_player & 0X0000000000100804ULL;
  opp_discs = (discs_opponent & 0X0000000020100800ULL) | 0X0000003FDFEFF000ULL;
  r = ((my_discs << 9) + opp_discs) & 0X0000004000000000ULL;
  if (r != 0) {
    flipped |= (0X0000004000000000ULL - (0X2ULL << last_bit(my_discs))) & 0X0000000020100800ULL;
  }
  my_discs = discs_player & 0X4040000000000000ULL;
  opp_discs = (discs_opponent & 0X0040400000000000ULL) | 0X3FBF800000000000ULL;
  r = (opp_discs + 0X0000400000000000ULL) & my_discs;
  if (r != 0) {
    flipped |= (r - 1) & 0X0040400000000000ULL;
  }
  my_discs = discs_player & 0X0000000000404040ULL;
  opp_discs = (discs_opponent & 0X0000000040404000ULL) | 0X0000003FBFBF8000ULL;
  r = ((my_discs << 8) + opp_discs) & 0X0000004000000000ULL;
  if (r != 0) {
    flipped |= (0X0000004000000000ULL - (0X2ULL << last_bit(my_discs))) & 0X0000000040404000ULL;
  }
  return flipped;
}
```