user: Demonstrate the C code that generates the assembly output below:

```asm
<neuralops_omp_caffe_maxpool2d_bwd>:
  endbr64
  push   %r15
  mov    %rdi,%rax
  mov    %rsi,%r15
  push   %r14
  imul   %rdx,%r15
  mov    %rsi,%r14
  push   %r13
  mov    %rdx,%r13
  push   %r12
  mov    %rcx,%r12
  imul   %r12,%rax
  push   %rbp
  mov    %r9,%rbp
  push   %rbx
  mov    %r8,%rbx
  imul   %r15,%rax
  sub    $0x58,%rsp
  mov    %rdi,0x30(%rsp)
  mov    0xa0(%rsp),%rcx
  test   %rax,%rax
  je     L69
  mov    %rcx,%rdi
  lea    0x0(,%rax,4),%rdx
  xor    %esi,%esi
  call   <memset@plt>
  mov    %rax,%rcx
L69:
  cmpq   $0x0,0x30(%rsp)
  je     L32
  mov    %rbx,%rdx
  mov    %r12,%rax
  mov    %rcx,0x28(%rsp)
  shl    $0x2,%r15
  imul   %rbp,%rdx
  lea    0x0(,%rbx,8),%r10
  movq   $0x0,0x10(%rsp)
  lea    0x0(,%rbx,4),%r9
  imul   %rdx,%rax
  lea    0x0(,%rdx,8),%rdi
  mov    %rdi,(%rsp)
  lea    0x0(,%rdx,4),%rdi
  mov    %r13,%rdx
  imul   %r12,%rdx
  mov    %rdi,0x8(%rsp)
  imul   %r14,%rdx
  lea    0x0(,%rdx,4),%rdi
  mov    %rdi,0x48(%rsp)
  lea    0x0(,%rax,8),%rdi
  shl    $0x2,%rax
  mov    %rdi,0x40(%rsp)
  mov    0x90(%rsp),%rdi
  mov    %rax,0x38(%rsp)
  mov    0x98(%rsp),%rax
  mov    %rdi,0x20(%rsp)
  mov    %rax,0x18(%rsp)
L11:
  mov    0x28(%rsp),%rdi
  mov    0x20(%rsp),%r14
  xor    %r11d,%r11d
  mov    0x18(%rsp),%r13
  test   %r12,%r12
  je     L54
  xchg   %ax,%ax
L56:
  test   %rbp,%rbp
  je     L25
  mov    %r14,%rsi
  mov    %r13,%rcx
  xor    %r8d,%r8d
  xchg   %ax,%ax
L1:
  xor    %eax,%eax
  test   %rbx,%rbx
  je     L7
  nopw   0x0(%rax,%rax,1)
L77:
  mov    (%rsi,%rax,8),%rdx
  lea    (%rdi,%rdx,4),%rdx
  movss  (%rdx),%xmm0
  addss  (%rcx,%rax,4),%xmm0
  add    $0x1,%rax
  movss  %xmm0,(%rdx)
  cmp    %rax,%rbx
  jne    L77
L7:
  add    $0x1,%r8
  add    %r10,%rsi
  add    %r9,%rcx
  cmp    %r8,%rbp
  jne    L1
L25:
  add    $0x1,%r11
  add    %r15,%rdi
  add    (%rsp),%r14
  add    0x8(%rsp),%r13
  cmp    %r11,%r12
  jne    L56
L54:
  mov    0x48(%rsp),%rsi
  addq   $0x1,0x10(%rsp)
  add    %rsi,0x28(%rsp)
  mov    0x38(%rsp),%rcx
  mov    0x40(%rsp),%rsi
  add    %rcx,0x18(%rsp)
  add    %rsi,0x20(%rsp)
  mov    0x10(%rsp),%rax
  cmp    %rax,0x30(%rsp)
  jne    L11
L32:
  add    $0x58,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void neuralops_omp_caffe_maxpool2d_bwd(size_t batch_sz, size_t in_width, size_t in_height, size_t chan, size_t out_width, size_t out_height, const uint32_t *mask_buf, const float *out_grad, float *in_grad, size_t kernel_w_, size_t kernel_h_, size_t stride_w_, size_t stride_h_, size_t pad_w_, size_t pad_h_) {
  size_t bottom_count = in_width * in_height * chan * batch_sz;
#pragma omp parallel for
  for (size_t i = 0; i < bottom_count; i++) {
    in_grad[i] = 0.0f;
  }
#pragma omp parallel for private(in_grad)
  for (size_t n = 0; n < batch_sz; n++) {
    float *bottom_diff = in_grad + n * in_width * in_height * chan;
    const uint32_t *top_mask = mask_buf + n * out_width * out_height * chan;
    const float *top_diff = out_grad + n * out_width * out_height * chan;
    for (size_t c = 0; c < chan; ++c) {
      for (size_t ph = 0; ph < out_height; ++ph) {
        for (size_t pw = 0; pw < out_width; ++pw) {
          size_t index = ph * out_width + pw;
          uint32_t bottom_index = top_mask[index];
          bottom_diff[bottom_index] += top_diff[index];
        }
      }
      bottom_diff += in_width * in_height;
      top_mask += out_width * out_height;
      top_diff += out_width * out_height;
    }
  }
}
```