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

```asm
<gf8_muladd_21>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %rdi,-0x68(%rbp)
  mov    %rsi,-0x70(%rbp)
  mov    %edx,-0x74(%rbp)
  mov    -0x70(%rbp),%rax
  mov    %rax,-0x10(%rbp)
  mov    -0x68(%rbp),%rax
  mov    %rax,-0x8(%rbp)
  movl   $0x0,-0x58(%rbp)
  jmp    L2
L0:
  mov    -0x8(%rbp),%rax
  mov    (%rax),%eax
  mov    %eax,-0x54(%rbp)
  mov    -0x74(%rbp),%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  mov    %eax,-0x50(%rbp)
  mov    -0x74(%rbp),%eax
  add    %eax,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  mov    %eax,-0x4c(%rbp)
  mov    -0x74(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  mov    %eax,-0x48(%rbp)
  mov    -0x74(%rbp),%eax
  shl    $0x2,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  mov    %eax,-0x44(%rbp)
  mov    -0x74(%rbp),%edx
  mov    %edx,%eax
  shl    $0x2,%eax
  add    %edx,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  mov    %eax,-0x40(%rbp)
  mov    -0x74(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  add    %eax,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  mov    %eax,-0x3c(%rbp)
  mov    -0x74(%rbp),%edx
  mov    %edx,%eax
  shl    $0x3,%eax
  sub    %edx,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x8(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  mov    %eax,-0x38(%rbp)
  mov    -0x50(%rbp),%eax
  xor    -0x44(%rbp),%eax
  mov    %eax,-0x34(%rbp)
  mov    -0x44(%rbp),%eax
  xor    -0x3c(%rbp),%eax
  mov    %eax,-0x30(%rbp)
  mov    -0x48(%rbp),%eax
  xor    -0x40(%rbp),%eax
  mov    %eax,-0x2c(%rbp)
  mov    -0x4c(%rbp),%eax
  xor    -0x3c(%rbp),%eax
  mov    %eax,-0x28(%rbp)
  mov    -0x54(%rbp),%eax
  xor    -0x48(%rbp),%eax
  xor    -0x38(%rbp),%eax
  mov    %eax,-0x24(%rbp)
  mov    -0x50(%rbp),%eax
  xor    -0x40(%rbp),%eax
  xor    -0x38(%rbp),%eax
  mov    %eax,-0x20(%rbp)
  mov    -0x30(%rbp),%eax
  xor    -0x38(%rbp),%eax
  mov    %eax,-0x1c(%rbp)
  mov    -0x30(%rbp),%eax
  xor    -0x54(%rbp),%eax
  mov    %eax,-0x18(%rbp)
  mov    -0x2c(%rbp),%eax
  xor    -0x4c(%rbp),%eax
  xor    -0x38(%rbp),%eax
  mov    %eax,-0x14(%rbp)
  mov    -0x10(%rbp),%rax
  mov    (%rax),%eax
  xor    -0x24(%rbp),%eax
  mov    %eax,%edx
  mov    -0x8(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x74(%rbp),%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x10(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  mov    -0x74(%rbp),%edx
  lea    0x0(,%rdx,4),%rcx
  mov    -0x8(%rbp),%rdx
  add    %rcx,%rdx
  xor    -0x34(%rbp),%eax
  mov    %eax,(%rdx)
  mov    -0x74(%rbp),%eax
  add    %eax,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x10(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  mov    -0x74(%rbp),%edx
  add    %edx,%edx
  mov    %edx,%edx
  lea    0x0(,%rdx,4),%rcx
  mov    -0x8(%rbp),%rdx
  add    %rcx,%rdx
  xor    -0x14(%rbp),%eax
  mov    %eax,(%rdx)
  mov    -0x74(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x10(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%edx
  mov    -0x74(%rbp),%ecx
  mov    %ecx,%eax
  add    %eax,%eax
  add    %ecx,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rcx
  mov    -0x8(%rbp),%rax
  add    %rax,%rcx
  mov    %edx,%eax
  xor    -0x1c(%rbp),%eax
  mov    %eax,(%rcx)
  mov    -0x74(%rbp),%eax
  shl    $0x2,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x10(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%eax
  mov    -0x74(%rbp),%edx
  shl    $0x2,%edx
  mov    %edx,%edx
  lea    0x0(,%rdx,4),%rcx
  mov    -0x8(%rbp),%rdx
  add    %rcx,%rdx
  xor    -0x2c(%rbp),%eax
  mov    %eax,(%rdx)
  mov    -0x74(%rbp),%edx
  mov    %edx,%eax
  shl    $0x2,%eax
  add    %edx,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x10(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%edx
  mov    -0x74(%rbp),%ecx
  mov    %ecx,%eax
  shl    $0x2,%eax
  add    %ecx,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rcx
  mov    -0x8(%rbp),%rax
  add    %rax,%rcx
  mov    %edx,%eax
  xor    -0x18(%rbp),%eax
  mov    %eax,(%rcx)
  mov    -0x74(%rbp),%edx
  mov    %edx,%eax
  add    %eax,%eax
  add    %edx,%eax
  add    %eax,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x10(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%edx
  mov    -0x74(%rbp),%ecx
  mov    %ecx,%eax
  add    %eax,%eax
  add    %ecx,%eax
  add    %eax,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rcx
  mov    -0x8(%rbp),%rax
  add    %rax,%rcx
  mov    %edx,%eax
  xor    -0x20(%rbp),%eax
  mov    %eax,(%rcx)
  mov    -0x74(%rbp),%edx
  mov    %edx,%eax
  shl    $0x3,%eax
  sub    %edx,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  mov    -0x10(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%edx
  mov    -0x74(%rbp),%ecx
  mov    %ecx,%eax
  shl    $0x3,%eax
  sub    %ecx,%eax
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rcx
  mov    -0x8(%rbp),%rax
  add    %rax,%rcx
  mov    %edx,%eax
  xor    -0x28(%rbp),%eax
  mov    %eax,(%rcx)
  addq   $0x4,-0x10(%rbp)
  addq   $0x4,-0x8(%rbp)
  addl   $0x1,-0x58(%rbp)
L2:
  mov    -0x58(%rbp),%eax
  cmp    -0x74(%rbp),%eax
  jb     L0
  nop
  nop
  pop    %rbp
  ret
```

assistant: ```c
void gf8_muladd_21(uint8_t *out, uint8_t *in, unsigned int width) {
  unsigned int i;
  uint64_t *in_ptr = (uint64_t *)in;
  uint64_t *out_ptr = (uint64_t *)out;
  for (i = 0; i < width; i++) {
    uint64_t out0, out1, out2, out3, out4, out5, out6, out7;
    uint64_t tmp0;
    uint64_t in0 = out_ptr[0];
    uint64_t in1 = out_ptr[width];
    uint64_t in2 = out_ptr[width * 2];
    uint64_t in3 = out_ptr[width * 3];
    uint64_t in4 = out_ptr[width * 4];
    uint64_t in5 = out_ptr[width * 5];
    uint64_t in6 = out_ptr[width * 6];
    uint64_t in7 = out_ptr[width * 7];
    out1 = in1 ^ in4;
    tmp0 = in4 ^ in6;
    out4 = in3 ^ in5;
    out7 = in2 ^ in6;
    out0 = in0 ^ in3 ^ in7;
    out6 = in1 ^ in5 ^ in7;
    out3 = tmp0 ^ in7;
    out5 = tmp0 ^ in0;
    out2 = out4 ^ in2 ^ in7;
    out_ptr[0] = out0 ^ in_ptr[0];
    out_ptr[width] = out1 ^ in_ptr[width];
    out_ptr[width * 2] = out2 ^ in_ptr[width * 2];
    out_ptr[width * 3] = out3 ^ in_ptr[width * 3];
    out_ptr[width * 4] = out4 ^ in_ptr[width * 4];
    out_ptr[width * 5] = out5 ^ in_ptr[width * 5];
    out_ptr[width * 6] = out6 ^ in_ptr[width * 6];
    out_ptr[width * 7] = out7 ^ in_ptr[width * 7];
    in_ptr++;
    out_ptr++;
  }
}
```