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

```asm
<mul4>:
  endbr64
  sub    $0x138,%rsp
  movupd 0x60(%rsi),%xmm3
  movupd 0x30(%rsi),%xmm5
  mov    %fs:0x28,%rax
  mov    %rax,0x128(%rsp)
  xor    %eax,%eax
  movupd 0x50(%rsi),%xmm15
  movupd (%rsi),%xmm2
  movaps %xmm5,(%rsp)
  movapd %xmm3,%xmm5
  movupd 0x70(%rsi),%xmm14
  movupd 0x20(%rdx),%xmm7
  unpcklpd %xmm3,%xmm5
  unpckhpd %xmm3,%xmm3
  movapd %xmm2,%xmm13
  movupd (%rdx),%xmm10
  movaps %xmm5,0x40(%rsp)
  movupd 0x70(%rdx),%xmm5
  unpcklpd %xmm2,%xmm13
  movupd 0x40(%rsi),%xmm4
  movaps %xmm3,0x60(%rsp)
  movapd (%rsp),%xmm3
  unpckhpd %xmm2,%xmm2
  movupd 0x10(%rsi),%xmm6
  movapd %xmm4,%xmm0
  movaps %xmm5,0x90(%rsp)
  movupd 0x50(%rdx),%xmm9
  movupd 0x10(%rdx),%xmm11
  movapd %xmm3,%xmm5
  unpcklpd %xmm4,%xmm0
  unpckhpd %xmm4,%xmm4
  movupd 0x30(%rdx),%xmm8
  unpcklpd %xmm3,%xmm5
  movaps %xmm0,0x30(%rsp)
  movupd 0x40(%rdx),%xmm0
  movupd 0x20(%rsi),%xmm1
  movapd %xmm5,%xmm3
  movapd %xmm15,%xmm5
  movaps %xmm4,0x50(%rsp)
  movapd %xmm6,%xmm4
  unpcklpd %xmm15,%xmm5
  unpckhpd %xmm15,%xmm15
  unpcklpd %xmm6,%xmm4
  movaps %xmm9,0x80(%rsp)
  movaps %xmm5,0x10(%rsp)
  movapd %xmm14,%xmm5
  movupd 0x60(%rdx),%xmm9
  unpckhpd %xmm6,%xmm6
  unpcklpd %xmm14,%xmm5
  unpckhpd %xmm14,%xmm14
  movapd %xmm1,%xmm12
  movaps %xmm5,0x70(%rsp)
  movapd (%rsp),%xmm5
  unpcklpd %xmm1,%xmm12
  unpckhpd %xmm1,%xmm1
  movaps %xmm15,(%rsp)
  movapd %xmm7,%xmm15
  movaps %xmm14,0x20(%rsp)
  movapd %xmm13,%xmm14
  unpckhpd %xmm5,%xmm5
  mulpd  %xmm10,%xmm14
  mulpd  %xmm2,%xmm15
  mulpd  %xmm11,%xmm13
  mulpd  %xmm8,%xmm2
  addpd  %xmm14,%xmm15
  movapd %xmm0,%xmm14
  mulpd  %xmm4,%xmm14
  addpd  %xmm13,%xmm2
  addpd  %xmm15,%xmm14
  movapd %xmm9,%xmm15
  mulpd  %xmm6,%xmm15
  addpd  %xmm15,%xmm14
  movaps %xmm14,0xa0(%rsp)
  movapd 0x80(%rsp),%xmm13
  movapd 0x90(%rsp),%xmm15
  movups %xmm14,(%rdi)
  mulpd  %xmm13,%xmm4
  mulpd  %xmm15,%xmm6
  addpd  %xmm2,%xmm4
  movapd %xmm12,%xmm2
  mulpd  %xmm10,%xmm2
  mulpd  %xmm11,%xmm12
  addpd  %xmm4,%xmm6
  movapd %xmm2,%xmm4
  movapd %xmm7,%xmm2
  movaps %xmm6,0xb0(%rsp)
  mulpd  %xmm1,%xmm2
  movups %xmm6,0x10(%rdi)
  mulpd  %xmm8,%xmm1
  addpd  %xmm4,%xmm2
  movapd %xmm0,%xmm4
  mulpd  %xmm3,%xmm4
  addpd  %xmm12,%xmm1
  movapd %xmm13,%xmm12
  mulpd  %xmm13,%xmm3
  movapd %xmm15,%xmm13
  addpd  %xmm2,%xmm4
  movapd %xmm9,%xmm2
  mulpd  %xmm5,%xmm2
  addpd  %xmm1,%xmm3
  mulpd  %xmm15,%xmm5
  movapd 0x50(%rsp),%xmm15
  addpd  %xmm4,%xmm2
  movapd 0x30(%rsp),%xmm4
  addpd  %xmm3,%xmm5
  movapd %xmm15,%xmm3
  mulpd  %xmm7,%xmm3
  movapd %xmm4,%xmm1
  mulpd  %xmm10,%xmm1
  movaps %xmm2,0xc0(%rsp)
  mulpd  %xmm11,%xmm4
  movaps %xmm5,0xd0(%rsp)
  movups %xmm2,0x20(%rdi)
  movups %xmm5,0x30(%rdi)
  addpd  %xmm1,%xmm3
  movapd 0x10(%rsp),%xmm1
  mulpd  %xmm0,%xmm1
  addpd  %xmm3,%xmm1
  movapd (%rsp),%xmm3
  mulpd  %xmm9,%xmm3
  mulpd  0x20(%rsp),%xmm9
  addpd  %xmm3,%xmm1
  movapd %xmm4,%xmm3
  movapd %xmm15,%xmm4
  movapd 0x60(%rsp),%xmm15
  mulpd  %xmm8,%xmm4
  mulpd  %xmm15,%xmm7
  mulpd  %xmm15,%xmm8
  movaps %xmm1,0xe0(%rsp)
  movups %xmm1,0x40(%rdi)
  addpd  %xmm3,%xmm4
  movapd 0x10(%rsp),%xmm3
  mulpd  %xmm12,%xmm3
  addpd  %xmm4,%xmm3
  movapd (%rsp),%xmm4
  mulpd  %xmm13,%xmm4
  mulpd  0x20(%rsp),%xmm13
  addpd  %xmm3,%xmm4
  movapd 0x40(%rsp),%xmm3
  mulpd  %xmm3,%xmm10
  mulpd  %xmm11,%xmm3
  movaps %xmm4,0xf0(%rsp)
  movups %xmm4,0x50(%rdi)
  addpd  %xmm10,%xmm7
  movapd 0x70(%rsp),%xmm10
  addpd  %xmm8,%xmm3
  mulpd  %xmm10,%xmm0
  addpd  %xmm7,%xmm0
  movapd %xmm12,%xmm7
  mulpd  %xmm10,%xmm7
  addpd  %xmm9,%xmm0
  addpd  %xmm7,%xmm3
  movaps %xmm0,0x100(%rsp)
  movups %xmm0,0x60(%rdi)
  addpd  %xmm13,%xmm3
  movaps %xmm3,0x110(%rsp)
  movups %xmm3,0x70(%rdi)
  mov    0x128(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L9
  add    $0x138,%rsp
  ret
L9:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void mul4(double *Out, const double A[4][4], const double B[4][4]) {
  unsigned n;
  double Res[16];
  Res[0] = A[0][0] * B[0][0] + A[0][1] * B[1][0] + A[0][2] * B[2][0] + A[0][3] * B[3][0];
  Res[1] = A[0][0] * B[0][1] + A[0][1] * B[1][1] + A[0][2] * B[2][1] + A[0][3] * B[3][1];
  Res[2] = A[0][0] * B[0][2] + A[0][1] * B[1][2] + A[0][2] * B[2][2] + A[0][3] * B[3][2];
  Res[3] = A[0][0] * B[0][3] + A[0][1] * B[1][3] + A[0][2] * B[2][3] + A[0][3] * B[3][3];
  Res[4] = A[1][0] * B[0][0] + A[1][1] * B[1][0] + A[1][2] * B[2][0] + A[1][3] * B[3][0];
  Res[5] = A[1][0] * B[0][1] + A[1][1] * B[1][1] + A[1][2] * B[2][1] + A[1][3] * B[3][1];
  Res[6] = A[1][0] * B[0][2] + A[1][1] * B[1][2] + A[1][2] * B[2][2] + A[1][3] * B[3][2];
  Res[7] = A[1][0] * B[0][3] + A[1][1] * B[1][3] + A[1][2] * B[2][3] + A[1][3] * B[3][3];
  Res[8] = A[2][0] * B[0][0] + A[2][1] * B[1][0] + A[2][2] * B[2][0] + A[2][3] * B[3][0];
  Res[9] = A[2][0] * B[0][1] + A[2][1] * B[1][1] + A[2][2] * B[2][1] + A[2][3] * B[3][1];
  Res[10] = A[2][0] * B[0][2] + A[2][1] * B[1][2] + A[2][2] * B[2][2] + A[2][3] * B[3][2];
  Res[11] = A[2][0] * B[0][3] + A[2][1] * B[1][3] + A[2][2] * B[2][3] + A[2][3] * B[3][3];
  Res[12] = A[3][0] * B[0][0] + A[3][1] * B[1][0] + A[3][2] * B[2][0] + A[3][3] * B[3][0];
  Res[13] = A[3][0] * B[0][1] + A[3][1] * B[1][1] + A[3][2] * B[2][1] + A[3][3] * B[3][1];
  Res[14] = A[3][0] * B[0][2] + A[3][1] * B[1][2] + A[3][2] * B[2][2] + A[3][3] * B[3][2];
  Res[15] = A[3][0] * B[0][3] + A[3][1] * B[1][3] + A[3][2] * B[2][3] + A[3][3] * B[3][3];
  for (n = 0; n < 16; ++n)
    Out[n] = Res[n];
}
```