user: What would the C source look like for the assembly code provided here?

```asm
<update_r>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x20,%rsp
  mov    %edi,-0x4(%rbp)
  mov    %esi,-0x8(%rbp)
  mov    %edx,-0xc(%rbp)
  mov    %ecx,-0x10(%rbp)
  mov    %r8d,-0x14(%rbp)
  mov    -0x14(%rbp),%ecx
  mov    -0x8(%rbp),%edx
  mov    -0x4(%rbp),%eax
  mov    %eax,%esi
  mov    $0x0,%edi
  call   <update@plt>
  mov    -0x14(%rbp),%eax
  neg    %eax
  mov    %eax,%ecx
  mov    -0x10(%rbp),%eax
  lea    0x1(%rax),%edx
  mov    -0x4(%rbp),%eax
  mov    %eax,%esi
  mov    $0x0,%edi
  call   <update@plt>
  mov    -0x14(%rbp),%eax
  neg    %eax
  mov    %eax,%edx
  mov    -0xc(%rbp),%eax
  lea    0x1(%rax),%esi
  mov    -0x8(%rbp),%eax
  mov    %edx,%ecx
  mov    %eax,%edx
  mov    $0x0,%edi
  call   <update@plt>
  mov    -0x10(%rbp),%eax
  lea    0x1(%rax),%edx
  mov    -0xc(%rbp),%eax
  lea    0x1(%rax),%esi
  mov    -0x14(%rbp),%eax
  mov    %eax,%ecx
  mov    $0x0,%edi
  call   <update@plt>
  mov    $0x1,%eax
  sub    -0x8(%rbp),%eax
  imul   -0x14(%rbp),%eax
  mov    %eax,%ecx
  mov    -0x8(%rbp),%edx
  mov    -0x4(%rbp),%eax
  mov    %eax,%esi
  mov    $0x1,%edi
  call   <update@plt>
  mov    -0x14(%rbp),%eax
  imul   -0x10(%rbp),%eax
  mov    %eax,%edx
  mov    -0x10(%rbp),%eax
  lea    0x1(%rax),%esi
  mov    -0x4(%rbp),%eax
  mov    %edx,%ecx
  mov    %esi,%edx
  mov    %eax,%esi
  mov    $0x1,%edi
  call   <update@plt>
  mov    -0x8(%rbp),%eax
  sub    $0x1,%eax
  imul   -0x14(%rbp),%eax
  mov    %eax,%edx
  mov    -0xc(%rbp),%eax
  lea    0x1(%rax),%esi
  mov    -0x8(%rbp),%eax
  mov    %edx,%ecx
  mov    %eax,%edx
  mov    $0x1,%edi
  call   <update@plt>
  mov    -0x14(%rbp),%eax
  neg    %eax
  imul   -0x10(%rbp),%eax
  mov    -0x10(%rbp),%edx
  add    $0x1,%edx
  mov    -0xc(%rbp),%ecx
  lea    0x1(%rcx),%esi
  mov    %eax,%ecx
  mov    $0x1,%edi
  call   <update@plt>
  mov    $0x1,%eax
  sub    -0x4(%rbp),%eax
  imul   -0x14(%rbp),%eax
  mov    %eax,%ecx
  mov    -0x8(%rbp),%edx
  mov    -0x4(%rbp),%eax
  mov    %eax,%esi
  mov    $0x2,%edi
  call   <update@plt>
  mov    -0x4(%rbp),%eax
  sub    $0x1,%eax
  imul   -0x14(%rbp),%eax
  mov    %eax,%edx
  mov    -0x10(%rbp),%eax
  lea    0x1(%rax),%esi
  mov    -0x4(%rbp),%eax
  mov    %edx,%ecx
  mov    %esi,%edx
  mov    %eax,%esi
  mov    $0x2,%edi
  call   <update@plt>
  mov    -0x14(%rbp),%eax
  imul   -0xc(%rbp),%eax
  mov    %eax,%edx
  mov    -0xc(%rbp),%eax
  lea    0x1(%rax),%esi
  mov    -0x8(%rbp),%eax
  mov    %edx,%ecx
  mov    %eax,%edx
  mov    $0x2,%edi
  call   <update@plt>
  mov    -0xc(%rbp),%eax
  neg    %eax
  imul   -0x14(%rbp),%eax
  mov    -0x10(%rbp),%edx
  add    $0x1,%edx
  mov    -0xc(%rbp),%ecx
  lea    0x1(%rcx),%esi
  mov    %eax,%ecx
  mov    $0x2,%edi
  call   <update@plt>
  mov    -0x4(%rbp),%eax
  lea    -0x1(%rax),%edx
  mov    -0x8(%rbp),%eax
  sub    $0x1,%eax
  imul   %edx,%eax
  imul   -0x14(%rbp),%eax
  mov    %eax,%ecx
  mov    -0x8(%rbp),%edx
  mov    -0x4(%rbp),%eax
  mov    %eax,%esi
  mov    $0x3,%edi
  call   <update@plt>
  mov    -0x10(%rbp),%eax
  neg    %eax
  mov    %eax,%edx
  mov    -0x4(%rbp),%eax
  sub    $0x1,%eax
  imul   %edx,%eax
  imul   -0x14(%rbp),%eax
  mov    %eax,%edx
  mov    -0x10(%rbp),%eax
  lea    0x1(%rax),%esi
  mov    -0x4(%rbp),%eax
  mov    %edx,%ecx
  mov    %esi,%edx
  mov    %eax,%esi
  mov    $0x3,%edi
  call   <update@plt>
  mov    -0xc(%rbp),%eax
  neg    %eax
  mov    %eax,%edx
  mov    -0x8(%rbp),%eax
  sub    $0x1,%eax
  imul   %edx,%eax
  imul   -0x14(%rbp),%eax
  mov    %eax,%edx
  mov    -0xc(%rbp),%eax
  lea    0x1(%rax),%esi
  mov    -0x8(%rbp),%eax
  mov    %edx,%ecx
  mov    %eax,%edx
  mov    $0x3,%edi
  call   <update@plt>
  mov    -0xc(%rbp),%eax
  imul   -0x10(%rbp),%eax
  imul   -0x14(%rbp),%eax
  mov    -0x10(%rbp),%edx
  add    $0x1,%edx
  mov    -0xc(%rbp),%ecx
  lea    0x1(%rcx),%esi
  mov    %eax,%ecx
  mov    $0x3,%edi
  call   <update@plt>
  nop
  leave
  ret
```

assistant: ```c
void update_r(int x1, int y1, int x2, int y2, int val) {
  update(0, x1, y1, val);
  update(0, x1, y2 + 1, -val);
  update(0, x2 + 1, y1, -val);
  update(0, x2 + 1, y2 + 1, val);
  update(1, x1, y1, val * (1 - y1));
  update(1, x1, y2 + 1, val * y2);
  update(1, x2 + 1, y1, val * (y1 - 1));
  update(1, x2 + 1, y2 + 1, -val * y2);
  update(2, x1, y1, val * (1 - x1));
  update(2, x1, y2 + 1, (x1 - 1) * val);
  update(2, x2 + 1, y1, val * x2);
  update(2, x2 + 1, y2 + 1, -x2 * val);
  update(3, x1, y1, (x1 - 1) * (y1 - 1) * val);
  update(3, x1, y2 + 1, -y2 * (x1 - 1) * val);
  update(3, x2 + 1, y1, -x2 * (y1 - 1) * val);
  update(3, x2 + 1, y2 + 1, x2 * y2 * val);
}
```