user: What is the c source code of the assembly code below?

```asm
<mul4>:
  endbr64
  sub    $0xd8,%rsp
  movsd  (%rsi),%xmm13
  xor    %eax,%eax
  movsd  0x8(%rsi),%xmm5
  movsd  (%rdx),%xmm11
  movsd  0x20(%rdx),%xmm4
  movapd %xmm13,%xmm0
  movapd %xmm5,%xmm1
  movsd  0x10(%rsi),%xmm3
  movsd  0x40(%rdx),%xmm2
  mulsd  %xmm4,%xmm1
  movsd  0x18(%rsi),%xmm12
  movsd  0x60(%rdx),%xmm10
  movapd %xmm5,%xmm6
  mulsd  %xmm11,%xmm0
  movsd  0x8(%rdx),%xmm9
  movsd  0x48(%rdx),%xmm8
  mov    %fs:0x28,%rcx
  mov    %rcx,0xc8(%rsp)
  xor    %ecx,%ecx
  movsd  0x68(%rdx),%xmm15
  movsd  0x50(%rdx),%xmm14
  movsd  %xmm15,0x20(%rsp)
  movsd  %xmm14,0x8(%rsp)
  addsd  %xmm1,%xmm0
  movapd %xmm3,%xmm1
  mulsd  %xmm2,%xmm1
  addsd  %xmm1,%xmm0
  movapd %xmm12,%xmm1
  mulsd  %xmm10,%xmm1
  movapd %xmm0,%xmm7
  movapd %xmm13,%xmm0
  mulsd  %xmm9,%xmm0
  addsd  %xmm1,%xmm7
  movsd  0x28(%rdx),%xmm1
  mulsd  %xmm1,%xmm6
  addsd  %xmm6,%xmm0
  movapd %xmm3,%xmm6
  mulsd  %xmm8,%xmm6
  addsd  %xmm6,%xmm0
  movapd %xmm15,%xmm6
  movsd  0x10(%rdx),%xmm15
  mulsd  %xmm12,%xmm6
  movsd  %xmm15,(%rsp)
  movsd  0x70(%rdx),%xmm15
  movsd  %xmm15,0x10(%rsp)
  addsd  %xmm6,%xmm0
  movsd  0x30(%rdx),%xmm6
  movsd  %xmm0,0x48(%rsp)
  movsd  (%rsp),%xmm0
  mulsd  %xmm13,%xmm0
  movapd %xmm0,%xmm14
  movapd %xmm5,%xmm0
  mulsd  %xmm6,%xmm0
  movapd %xmm0,%xmm15
  movsd  0x58(%rdx),%xmm0
  addsd  %xmm14,%xmm15
  movsd  0x8(%rsp),%xmm14
  movsd  %xmm0,0x18(%rsp)
  mulsd  %xmm3,%xmm14
  addsd  %xmm15,%xmm14
  movsd  0x10(%rsp),%xmm15
  mulsd  %xmm12,%xmm15
  addsd  %xmm15,%xmm14
  movsd  0x38(%rdx),%xmm15
  mulsd  %xmm15,%xmm5
  movsd  %xmm14,0x50(%rsp)
  movsd  0x18(%rdx),%xmm14
  movsd  0x78(%rdx),%xmm0
  mulsd  0x18(%rsp),%xmm3
  movsd  %xmm15,0x38(%rsp)
  mulsd  %xmm14,%xmm13
  movsd  %xmm0,0x28(%rsp)
  mulsd  %xmm0,%xmm12
  movapd %xmm11,%xmm0
  movsd  %xmm14,0x30(%rsp)
  addsd  %xmm13,%xmm5
  movsd  0x20(%rsi),%xmm13
  mulsd  %xmm13,%xmm0
  addsd  %xmm5,%xmm3
  movsd  0x28(%rsi),%xmm5
  addsd  %xmm12,%xmm3
  movsd  0x38(%rsi),%xmm12
  movapd %xmm0,%xmm14
  movapd %xmm4,%xmm0
  mulsd  %xmm5,%xmm0
  movsd  %xmm3,0x58(%rsp)
  movsd  0x30(%rsi),%xmm3
  movapd %xmm0,%xmm15
  movapd %xmm2,%xmm0
  mulsd  %xmm3,%xmm0
  addsd  %xmm14,%xmm15
  movapd %xmm0,%xmm14
  movapd %xmm10,%xmm0
  mulsd  %xmm12,%xmm0
  addsd  %xmm15,%xmm14
  addsd  %xmm0,%xmm14
  movapd %xmm9,%xmm0
  mulsd  %xmm13,%xmm0
  movsd  %xmm14,0x60(%rsp)
  movapd %xmm0,%xmm14
  movapd %xmm1,%xmm0
  mulsd  %xmm5,%xmm0
  movapd %xmm0,%xmm15
  movapd %xmm8,%xmm0
  mulsd  %xmm3,%xmm0
  addsd  %xmm14,%xmm15
  movapd %xmm0,%xmm14
  movsd  (%rsp),%xmm0
  addsd  %xmm15,%xmm14
  movsd  0x20(%rsp),%xmm15
  mulsd  %xmm13,%xmm0
  mulsd  %xmm12,%xmm15
  mulsd  0x30(%rsp),%xmm13
  addsd  %xmm15,%xmm14
  movsd  %xmm14,0x68(%rsp)
  movapd %xmm0,%xmm14
  movapd %xmm6,%xmm0
  mulsd  %xmm5,%xmm0
  mulsd  0x38(%rsp),%xmm5
  movapd %xmm0,%xmm15
  movapd %xmm11,%xmm0
  addsd  %xmm14,%xmm15
  movsd  0x8(%rsp),%xmm14
  addsd  %xmm13,%xmm5
  movsd  0x40(%rsi),%xmm13
  mulsd  %xmm3,%xmm14
  mulsd  0x18(%rsp),%xmm3
  mulsd  %xmm13,%xmm0
  addsd  %xmm15,%xmm14
  movsd  0x10(%rsp),%xmm15
  addsd  %xmm5,%xmm3
  movsd  0x48(%rsi),%xmm5
  mulsd  %xmm12,%xmm15
  mulsd  0x28(%rsp),%xmm12
  addsd  %xmm15,%xmm14
  addsd  %xmm12,%xmm3
  movsd  0x58(%rsi),%xmm12
  movsd  %xmm14,0x70(%rsp)
  movapd %xmm0,%xmm14
  movapd %xmm4,%xmm0
  mulsd  %xmm5,%xmm0
  movsd  %xmm3,0x78(%rsp)
  movsd  0x50(%rsi),%xmm3
  movapd %xmm0,%xmm15
  movapd %xmm2,%xmm0
  mulsd  %xmm3,%xmm0
  addsd  %xmm14,%xmm15
  movapd %xmm0,%xmm14
  movapd %xmm10,%xmm0
  mulsd  %xmm12,%xmm0
  addsd  %xmm15,%xmm14
  addsd  %xmm0,%xmm14
  movapd %xmm9,%xmm0
  mulsd  %xmm13,%xmm0
  movsd  %xmm14,0x80(%rsp)
  movapd %xmm0,%xmm14
  movapd %xmm1,%xmm0
  mulsd  %xmm5,%xmm0
  movapd %xmm0,%xmm15
  movapd %xmm8,%xmm0
  mulsd  %xmm3,%xmm0
  addsd  %xmm14,%xmm15
  movapd %xmm0,%xmm14
  movsd  (%rsp),%xmm0
  addsd  %xmm15,%xmm14
  movsd  0x20(%rsp),%xmm15
  mulsd  %xmm13,%xmm0
  mulsd  %xmm12,%xmm15
  addsd  %xmm15,%xmm14
  movsd  %xmm14,0x88(%rsp)
  movapd %xmm0,%xmm14
  movapd %xmm6,%xmm0
  mulsd  %xmm5,%xmm0
  movapd %xmm0,%xmm15
  addsd  %xmm14,%xmm15
  movsd  0x8(%rsp),%xmm14
  mulsd  %xmm3,%xmm14
  addsd  %xmm15,%xmm14
  movsd  0x10(%rsp),%xmm15
  mulsd  %xmm12,%xmm15
  addsd  %xmm15,%xmm14
  movsd  %xmm14,0x90(%rsp)
  mulsd  0x18(%rsp),%xmm3
  movsd  0x30(%rsp),%xmm14
  movsd  0x38(%rsp),%xmm15
  mulsd  0x28(%rsp),%xmm12
  mulsd  %xmm14,%xmm13
  movsd  (%rsp),%xmm0
  mulsd  %xmm15,%xmm5
  addsd  %xmm13,%xmm5
  movsd  0x60(%rsi),%xmm13
  mulsd  %xmm13,%xmm11
  addsd  %xmm5,%xmm3
  movsd  0x70(%rsi),%xmm5
  mulsd  %xmm13,%xmm9
  mulsd  %xmm13,%xmm0
  mulsd  %xmm5,%xmm2
  addsd  %xmm12,%xmm3
  movsd  0x68(%rsi),%xmm12
  mulsd  %xmm5,%xmm8
  mulsd  %xmm12,%xmm4
  movsd  %xmm3,0x98(%rsp)
  movsd  0x78(%rsi),%xmm3
  mulsd  %xmm12,%xmm1
  mulsd  %xmm12,%xmm6
  mulsd  %xmm3,%xmm10
  addsd  %xmm11,%xmm4
  addsd  %xmm9,%xmm1
  addsd  %xmm6,%xmm0
  addsd  %xmm4,%xmm2
  addsd  %xmm8,%xmm1
  addsd  %xmm10,%xmm2
  movsd  %xmm2,0xa0(%rsp)
  movsd  0x20(%rsp),%xmm2
  mulsd  %xmm3,%xmm2
  addsd  %xmm2,%xmm1
  movsd  %xmm1,0xa8(%rsp)
  movsd  0x8(%rsp),%xmm1
  mulsd  %xmm5,%xmm1
  addsd  %xmm1,%xmm0
  movsd  0x10(%rsp),%xmm1
  mulsd  %xmm3,%xmm1
  addsd  %xmm1,%xmm0
  movapd %xmm15,%xmm1
  mulsd  %xmm12,%xmm1
  movsd  %xmm0,0xb0(%rsp)
  movapd %xmm14,%xmm0
  mulsd  %xmm13,%xmm0
  addsd  %xmm1,%xmm0
  movsd  0x18(%rsp),%xmm1
  mulsd  %xmm5,%xmm1
  addsd  %xmm1,%xmm0
  movsd  0x28(%rsp),%xmm1
  mulsd  %xmm3,%xmm1
  addsd  %xmm1,%xmm0
  movsd  %xmm0,0xb8(%rsp)
  jmp    L26
  nopl   (%rax)
L9:
  movsd  0x40(%rsp,%rax,1),%xmm7
L26:
  movsd  %xmm7,(%rdi,%rax,1)
  add    $0x8,%rax
  cmp    $0x80,%rax
  jne    L9
  mov    0xc8(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L19
  add    $0xd8,%rsp
  ret
L19:
  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];
}
```