user: Please show me the C implementation that matches the assembly code listed below:

```asm
<backSubstitution>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x38,%rsp
  mov    %edi,%ebx
  mov    %rsi,%r12
  mov    %rdx,%rbp
  call   <zeros@plt>
  mov    %rax,%r10
  lea    -0x1(%rbx),%eax
  mov    %eax,0x24(%rsp)
  test   %eax,%eax
  jle    L64
  mov    %eax,%r11d
  lea    -0x2(%rbx),%eax
  mov    %rax,0x10(%rsp)
  movslq %ebx,%rax
  mov    %rax,0x8(%rsp)
  lea    0x0(,%rax,8),%r9
  mov    %ebx,%r15d
  mov    $0x0,%r14d
  mov    $0x1,%r13d
  mov    $0x0,%r8d
  lea    0x8(%r12),%rax
  mov    %rax,0x18(%rsp)
  mov    %r10,0x28(%rsp)
  jmp    L95
L76:
  mov    %rax,%r8
L95:
  cmp    %r13d,%ebx
  jle    L77
  movslq %r14d,%rdx
  lea    (%rdx,%r8,1),%rax
  lea    (%r12,%rax,8),%r10
  movslq %r15d,%rcx
  lea    (%rcx,%r8,1),%rax
  lea    (%r12,%rax,8),%rdi
  sub    %rcx,%rdx
  mov    %r11d,%eax
  add    %rcx,%rax
  add    %r8,%rax
  mov    0x18(%rsp),%rsi
  lea    (%rsi,%rax,8),%rcx
  mov    %r13,%rsi
L61:
  movsd  (%rdi),%xmm2
  divsd  (%r10),%xmm2
  cmp    %r8d,%ebx
  jle    L22
  mov    %rdi,%rax
L16:
  movapd %xmm2,%xmm1
  mulsd  (%rax,%rdx,8),%xmm1
  movsd  (%rax),%xmm0
  subsd  %xmm1,%xmm0
  movsd  %xmm0,(%rax)
  add    $0x8,%rax
  cmp    %rcx,%rax
  jne    L16
L22:
  mulsd  0x0(%rbp,%r8,8),%xmm2
  movsd  0x0(%rbp,%rsi,8),%xmm0
  subsd  %xmm2,%xmm0
  movsd  %xmm0,0x0(%rbp,%rsi,8)
  add    $0x1,%rsi
  add    %r9,%rdi
  sub    0x8(%rsp),%rdx
  add    %r9,%rcx
  cmp    %esi,%ebx
  jg     L61
L77:
  lea    0x1(%r8),%rax
  add    $0x1,%r13
  add    %ebx,%r14d
  add    %ebx,%r15d
  sub    $0x1,%r11d
  cmp    0x10(%rsp),%r8
  jne    L76
  mov    0x28(%rsp),%r10
L64:
  movslq %ebx,%rsi
  lea    0x0(,%rsi,8),%rcx
  mov    0x24(%rsp),%r11d
  mov    %r11d,%eax
  imul   %ebx,%eax
  movslq %eax,%rdx
  add    %rsi,%rdx
  movsd  -0x8(%rbp,%rcx,1),%xmm0
  divsd  -0x8(%r12,%rdx,8),%xmm0
  movsd  %xmm0,-0x8(%r10,%rcx,1)
  mov    %ebx,%edi
  sub    $0x2,%edi
  js     L96
  mov    %r11d,%ecx
  mov    %ebx,%edx
  neg    %edx
  movslq %edx,%rdx
  lea    -0x8(,%rdx,8),%r9
  movslq %edi,%rsi
  sub    %ebx,%eax
  cltq
  add    %rsi,%rax
  lea    (%r12,%rax,8),%r8
  imul   %ebx,%edi
  shl    $0x3,%rsi
L12:
  movsd  0x0(%rbp,%rsi,1),%xmm1
  cmp    %ecx,%ebx
  jle    L50
  movslq %ecx,%rax
  movslq %edi,%rdx
  lea    (%r12,%rdx,8),%rdx
L97:
  movsd  (%rdx,%rax,8),%xmm0
  mulsd  (%r10,%rax,8),%xmm0
  subsd  %xmm0,%xmm1
  add    $0x1,%rax
  cmp    %eax,%ebx
  jg     L97
L50:
  divsd  (%r8),%xmm1
  movsd  %xmm1,(%r10,%rsi,1)
  add    %r9,%r8
  sub    %ebx,%edi
  sub    $0x8,%rsi
  sub    $0x1,%ecx
  jne    L12
L96:
  mov    %r10,%rax
  add    $0x38,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
double *backSubstitution(int n, double *matrix, double b[]) {
  int i, j, k;
  double aux, temp;
  double *x = zeros(n);
  for (i = 0; i < (n - 1); i++) {
    for (j = (i + 1); j < n; j++) {
      aux = *(matrix + n * j + i) / *(matrix + n * i + i);
      for (k = i; k < n; k++) {
        *(matrix + n * j + k) -= (aux * (*(matrix + n * i + k)));
      }
      b[j] -= (aux * b[i]);
    }
  }
  x[n - 1] = b[n - 1] / *(matrix + n * (n - 1) + n - 1);
  for (i = (n - 2); i >= 0; i--) {
    temp = b[i];
    for (j = (i + 1); j < n; j++) {
      temp -= (*(matrix + n * i + j) * x[j]);
    }
    x[i] = temp / *(matrix + n * i + i);
  }
  return x;
}
```