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

```asm
<ellipse>:
  endbr64
  push   %r15
  mov    %edx,%r11d
  mov    %ecx,%r8d
  mov    %esi,%eax
  push   %r14
  sub    %edi,%r11d
  push   %r13
  push   %r12
  mov    %edi,%r12d
  mov    %r11d,%edi
  push   %rbp
  mov    %edx,%ebp
  push   %rbx
  sub    $0x28,%rsp
  neg    %edi
  cmovs  %r11d,%edi
  sub    %esi,%ecx
  mov    %ecx,%r13d
  mov    %ecx,0x8(%rsp)
  neg    %r13d
  cmovs  %ecx,%r13d
  mov    $0x1,%ecx
  sub    %edi,%ecx
  mov    %r13d,%esi
  imul   %r13d,%ecx
  mov    %r13d,0x18(%rsp)
  and    $0x1,%esi
  lea    0x1(%rsi),%edx
  imul   %edi,%edx
  imul   %r13d,%ecx
  mov    %edx,%r9d
  sub    %edi,%edx
  imul   %edi,%r9d
  shl    $0x2,%ecx
  imul   %edi,%edx
  movslq %ecx,%r13
  shl    $0x2,%r9d
  movslq %r9d,%r14
  movslq %edx,%rdx
  lea    0x0(%r13,%r14,1),%r10
  add    %r10,%rdx
  cmp    %r12d,%ebp
  jge    L28
  mov    %ebp,%r12d
  add    %edi,%ebp
L28:
  mov    0x18(%rsp),%ecx
  cmp    %eax,%r8d
  cmovle %r8d,%eax
  lea    0x1(%rcx),%r8d
  sar    %r8d
  lea    (%r8,%rax,1),%r15d
  mov    %r11d,%eax
  imul   %r11d,%eax
  mov    %r15d,%ebx
  sub    %esi,%ebx
  shl    $0x3,%eax
  mov    %eax,0x1c(%rsp)
  mov    0x8(%rsp),%eax
  imul   %eax,%eax
  shl    $0x3,%eax
  cltq
  mov    %rax,0x10(%rsp)
  jmp    L17
  nopl   (%rax)
L1:
  movslq 0x1c(%rsp),%rsi
  add    $0x1,%r15d
  sub    $0x1,%ebx
  add    %rsi,%r14
  add    %r14,%rdx
  cmp    %rax,%r13
  jle    L61
  lea    (%rdx,%rdx,1),%rax
  cmp    %r14,%rax
  jg     L61
  cmp    %ebp,%r12d
  jg     L39
L17:
  mov    %r15d,%esi
  mov    %ebp,%edi
  mov    %rdx,0x8(%rsp)
  call   <setPixel@plt>
  mov    %r15d,%esi
  mov    %r12d,%edi
  call   <setPixel@plt>
  mov    %ebx,%esi
  mov    %r12d,%edi
  call   <setPixel@plt>
  mov    %ebx,%esi
  mov    %ebp,%edi
  call   <setPixel@plt>
  mov    0x8(%rsp),%rdx
  lea    (%rdx,%rdx,1),%rax
  cmp    %rax,%r14
  jge    L1
L61:
  add    0x10(%rsp),%r13
  add    $0x1,%r12d
  sub    $0x1,%ebp
  add    %r13,%rdx
  cmp    %ebp,%r12d
  jle    L17
L39:
  mov    %r15d,%eax
  sub    %ebx,%eax
  cmp    %eax,0x18(%rsp)
  jle    L65
  sub    $0x1,%r12d
  add    $0x1,%ebp
  add    %ebx,%r15d
  nopl   0x0(%rax)
L63:
  mov    %r15d,%r14d
  mov    %r12d,%edi
  sub    %ebx,%r14d
  mov    %r14d,%esi
  call   <setPixel@plt>
  mov    %r14d,%esi
  mov    %ebp,%edi
  call   <setPixel@plt>
  mov    %ebx,%esi
  mov    %r12d,%edi
  call   <setPixel@plt>
  mov    %ebx,%esi
  mov    %ebp,%edi
  sub    $0x1,%ebx
  call   <setPixel@plt>
  lea    (%rbx,%rbx,1),%edx
  mov    %r15d,%eax
  sub    %edx,%eax
  cmp    %eax,0x18(%rsp)
  jg     L63
L65:
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void ellipse(int x0, int y0, int x1, int y1) {
  int a = abs(x1 - x0), b = abs(y1 - y0), b1 = b & 1;
  long dx = 4 * (1 - a) * b * b, dy = 4 * (b1 + 1) * a * a;
  long err = dx + dy + b1 * a * a, e2;
  if (x0 > x1) {
    x0 = x1;
    x1 += a;
  }
  if (y0 > y1)
    y0 = y1;
  y0 += (b + 1) / 2;
  y1 = y0 - b1;
  a *= 8 * a;
  b1 = 8 * b * b;
  do {
    setPixel(x1, y0);
    setPixel(x0, y0);
    setPixel(x0, y1);
    setPixel(x1, y1);
    e2 = 2 * err;
    if (e2 <= dy) {
      y0++;
      y1--;
      err += dy += a;
    }
    if (e2 >= dx || 2 * err > dy) {
      x0++;
      x1--;
      err += dx += b1;
    }
  } while (x0 <= x1);
  while (y0 - y1 < b) {
    setPixel(x0 - 1, y0);
    setPixel(x1 + 1, y0++);
    setPixel(x0 - 1, y1);
    setPixel(x1 + 1, y1--);
  }
}
```