user: Converte this assembly snippet into its equivalent C code:

```asm
<flip_C4>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x30,%rsp
  mov    %rdi,-0x28(%rbp)
  mov    %rsi,-0x30(%rbp)
  mov    -0x28(%rbp),%rax
  shr    $0x9,%rax
  and    -0x30(%rbp),%rax
  movabs $0x400000000000,%rdx
  and    %rdx,%rax
  mov    %rax,-0x20(%rbp)
  mov    -0x28(%rbp),%rax
  shl    $0x7,%rax
  and    -0x30(%rbp),%rax
  and    $0x40000000,%eax
  or     %rax,-0x20(%rbp)
  mov    -0x28(%rbp),%rax
  shr    %rax
  and    -0x30(%rbp),%rax
  movabs $0x4000000000,%rdx
  and    %rdx,%rax
  or     %rax,-0x20(%rbp)
  mov    -0x28(%rbp),%rax
  and    $0x80402,%eax
  mov    %rax,-0x18(%rbp)
  mov    -0x30(%rbp),%rax
  and    $0x10080400,%eax
  mov    %rax,%rdx
  movabs $0x1feff7f800,%rax
  or     %rdx,%rax
  mov    %rax,-0x10(%rbp)
  mov    -0x18(%rbp),%rax
  shl    $0x9,%rax
  mov    %rax,%rdx
  mov    -0x10(%rbp),%rax
  add    %rax,%rdx
  movabs $0x2000000000,%rax
  and    %rdx,%rax
  mov    %rax,-0x8(%rbp)
  cmpq   $0x0,-0x8(%rbp)
  je     L26
  mov    -0x18(%rbp),%rax
  mov    %rax,%rdi
  call   <last_bit@plt>
  mov    $0x2,%edx
  mov    %eax,%ecx
  shl    %cl,%rdx
  movabs $0x2000000000,%rax
  sub    %rdx,%rax
  and    $0x10080400,%eax
  or     %rax,-0x20(%rbp)
L26:
  mov    -0x28(%rbp),%rax
  and    $0x202020,%eax
  mov    %rax,-0x18(%rbp)
  mov    -0x30(%rbp),%rax
  and    $0x20202000,%eax
  mov    %rax,%rdx
  movabs $0x1fdfdfc000,%rax
  or     %rdx,%rax
  mov    %rax,-0x10(%rbp)
  mov    -0x18(%rbp),%rax
  shl    $0x8,%rax
  mov    %rax,%rdx
  mov    -0x10(%rbp),%rax
  add    %rax,%rdx
  movabs $0x2000000000,%rax
  and    %rdx,%rax
  mov    %rax,-0x8(%rbp)
  cmpq   $0x0,-0x8(%rbp)
  je     L2
  mov    -0x18(%rbp),%rax
  mov    %rax,%rdi
  call   <last_bit@plt>
  mov    $0x2,%edx
  mov    %eax,%ecx
  shl    %cl,%rdx
  movabs $0x2000000000,%rax
  sub    %rdx,%rax
  and    $0x20202000,%eax
  or     %rax,-0x20(%rbp)
L2:
  movabs $0xf00000000,%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 $0x2000000000,%rax
  and    %rdx,%rax
  mov    %rax,-0x8(%rbp)
  cmpq   $0x0,-0x8(%rbp)
  je     L3
  mov    -0x18(%rbp),%rax
  mov    %rax,%rdi
  call   <last_bit@plt>
  mov    $0x2,%edx
  mov    %eax,%ecx
  shl    %cl,%rdx
  movabs $0x2000000000,%rax
  sub    %rdx,%rax
  or     %rax,-0x20(%rbp)
L3:
  movabs $0x408000000000000,%rax
  and    -0x28(%rbp),%rax
  mov    %rax,-0x18(%rbp)
  movabs $0x8100000000000,%rax
  and    -0x30(%rbp),%rax
  movabs $0x3f7e00000000000,%rdx
  or     %rdx,%rax
  mov    %rax,-0x10(%rbp)
  movabs $0x100000000000,%rdx
  mov    -0x10(%rbp),%rax
  add    %rdx,%rax
  and    -0x18(%rbp),%rax
  mov    %rax,-0x8(%rbp)
  cmpq   $0x0,-0x8(%rbp)
  je     L30
  mov    -0x8(%rbp),%rax
  lea    -0x1(%rax),%rdx
  movabs $0x8100000000000,%rax
  and    %rdx,%rax
  or     %rax,-0x20(%rbp)
L30:
  movabs $0x2020000000000000,%rax
  and    -0x28(%rbp),%rax
  mov    %rax,-0x18(%rbp)
  movabs $0x20200000000000,%rax
  and    -0x30(%rbp),%rax
  movabs $0x1fdfc00000000000,%rdx
  or     %rdx,%rax
  mov    %rax,-0x10(%rbp)
  movabs $0x200000000000,%rdx
  mov    -0x10(%rbp),%rax
  add    %rdx,%rax
  and    -0x18(%rbp),%rax
  mov    %rax,-0x8(%rbp)
  cmpq   $0x0,-0x8(%rbp)
  je     L18
  mov    -0x8(%rbp),%rax
  lea    -0x1(%rax),%rdx
  movabs $0x20200000000000,%rax
  and    %rdx,%rax
  or     %rax,-0x20(%rbp)
L18:
  mov    -0x20(%rbp),%rax
  leave
  ret
```

assistant: ```c
unsigned long long flip_C4(const unsigned long long discs_player, const unsigned long long discs_opponent) {
  unsigned long long my_discs, opp_discs, r;
  unsigned long long flipped = (discs_opponent & 0X0000400000000000ULL) & (discs_player >> 9);
  flipped |= (discs_opponent & 0X0000000040000000ULL) & (discs_player << 7);
  flipped |= (discs_opponent & 0X0000004000000000ULL) & (discs_player >> 1);
  my_discs = discs_player & 0X0000000000080402ULL;
  opp_discs = (discs_opponent & 0X0000000010080400ULL) | 0X0000001FEFF7F800ULL;
  r = ((my_discs << 9) + opp_discs) & 0X0000002000000000ULL;
  if (r != 0) {
    flipped |= (0X0000002000000000ULL - (0X2ULL << last_bit(my_discs))) & 0X0000000010080400ULL;
  }
  my_discs = discs_player & 0X0000000000202020ULL;
  opp_discs = (discs_opponent & 0X0000000020202000ULL) | 0X0000001FDFDFC000ULL;
  r = ((my_discs << 8) + opp_discs) & 0X0000002000000000ULL;
  if (r != 0) {
    flipped |= (0X0000002000000000ULL - (0X2ULL << last_bit(my_discs))) & 0X0000000020202000ULL;
  }
  my_discs = discs_player & 0X0000000F00000000ULL;
  r = ((my_discs << 1) + discs_opponent) & 0X0000002000000000ULL;
  if (r != 0) {
    flipped |= 0X0000002000000000ULL - (0X2ULL << last_bit(my_discs));
  }
  my_discs = discs_player & 0X0408000000000000ULL;
  opp_discs = (discs_opponent & 0X0008100000000000ULL) | 0X03F7E00000000000ULL;
  r = (opp_discs + 0X0000100000000000ULL) & my_discs;
  if (r != 0) {
    flipped |= (r - 1) & 0X0008100000000000ULL;
  }
  my_discs = discs_player & 0X2020000000000000ULL;
  opp_discs = (discs_opponent & 0X0020200000000000ULL) | 0X1FDFC00000000000ULL;
  r = (opp_discs + 0X0000200000000000ULL) & my_discs;
  if (r != 0) {
    flipped |= (r - 1) & 0X0020200000000000ULL;
  }
  return flipped;
}
```