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

```asm
<drawCircle>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x18,%rsp
  mov    %esi,%r13d
  mov    %edx,%ebp
  mov    %edx,%r12d
  mov    $0x1,%r14d
  sub    %edx,%r14d
  mov    %edx,%eax
  neg    %eax
  add    %eax,%eax
  mov    %ax,0xe(%rsp)
  movswl %cx,%ebx
  mov    %si,0xc(%rsp)
  mov    %edi,(%rsp)
  movswl (%rsp),%r15d
  lea    (%rdx,%rsi,1),%esi
  movswl %si,%esi
  mov    %ebx,%edx
  mov    %r15d,%edi
  call   <drawPixel@plt>
  mov    %r13d,%esi
  sub    %ebp,%esi
  movswl %si,%esi
  mov    %ebx,%edx
  mov    %r15d,%edi
  call   <drawPixel@plt>
  movswl %r13w,%r13d
  mov    (%rsp),%edi
  mov    %edi,%r15d
  mov    %edi,%eax
  lea    0x0(%rbp,%rax,1),%edi
  movswl %di,%edi
  mov    %ebx,%edx
  mov    %r13d,%esi
  call   <drawPixel@plt>
  movzwl (%rsp),%edi
  sub    %ebp,%edi
  movswl %di,%edi
  mov    %ebx,%edx
  mov    %r13d,%esi
  call   <drawPixel@plt>
  test   %bp,%bp
  jle    L6
  movw   $0x0,(%rsp)
  jmp    L20
L35:
  sub    $0x1,%r12d
  movzwl 0xe(%rsp),%eax
  add    $0x2,%eax
  mov    %ax,0xe(%rsp)
  add    %eax,%r14d
L17:
  movzwl (%rsp),%ebp
  add    $0x1,%ebp
  mov    %bp,(%rsp)
  lea    0x1(%r14,%rbp,2),%r14d
  movzwl 0xc(%rsp),%eax
  add    %r12d,%eax
  movswl %ax,%r13d
  lea    (%r15,%rbp,1),%eax
  movswl %ax,%ecx
  mov    %ebx,%edx
  mov    %r13d,%esi
  mov    %ecx,0x4(%rsp)
  mov    %ecx,%edi
  call   <drawPixel@plt>
  mov    %r15d,%eax
  sub    %ebp,%eax
  movswl %ax,%edx
  mov    %edx,%r8d
  mov    %ebx,%edx
  mov    %r13d,%esi
  mov    %r8d,0x8(%rsp)
  mov    %r8d,%edi
  call   <drawPixel@plt>
  movzwl 0xc(%rsp),%r13d
  sub    %r12d,%r13d
  movswl %r13w,%r13d
  mov    %ebx,%edx
  mov    %r13d,%esi
  mov    0x4(%rsp),%edi
  call   <drawPixel@plt>
  mov    %ebx,%edx
  mov    %r13d,%esi
  mov    0x8(%rsp),%edi
  call   <drawPixel@plt>
  movzwl 0xc(%rsp),%r13d
  lea    0x0(%r13,%rbp,1),%eax
  movswl %ax,%r13d
  lea    (%r15,%r12,1),%eax
  movswl %ax,%ecx
  mov    %ebx,%edx
  mov    %r13d,%esi
  mov    %ecx,0x4(%rsp)
  mov    %ecx,%edi
  call   <drawPixel@plt>
  mov    %r15d,%eax
  sub    %r12d,%eax
  movswl %ax,%esi
  mov    %esi,%r9d
  mov    %ebx,%edx
  mov    %r13d,%esi
  mov    %r9d,0x8(%rsp)
  mov    %r9d,%edi
  call   <drawPixel@plt>
  movzwl 0xc(%rsp),%r13d
  sub    %ebp,%r13d
  movswl %r13w,%r13d
  mov    %ebx,%edx
  mov    %r13d,%esi
  mov    0x4(%rsp),%edi
  call   <drawPixel@plt>
  mov    %ebx,%edx
  mov    %r13d,%esi
  mov    0x8(%rsp),%edi
  call   <drawPixel@plt>
  cmp    %bp,%r12w
  jle    L6
L20:
  test   %r14w,%r14w
  jns    L35
  jmp    L17
L6:
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void drawCircle(short x0, short y0, short r, short color) {
  short f = 1 - r;
  short ddF_x = 1;
  short ddF_y = -2 * r;
  short x = 0;
  short y = r;
  drawPixel(x0, y0 + r, color);
  drawPixel(x0, y0 - r, color);
  drawPixel(x0 + r, y0, color);
  drawPixel(x0 - r, y0, color);
  while (x < y) {
    if (f >= 0) {
      y--;
      ddF_y += 2;
      f += ddF_y;
    }
    x++;
    ddF_x += 2;
    f += ddF_x;
    drawPixel(x0 + x, y0 + y, color);
    drawPixel(x0 - x, y0 + y, color);
    drawPixel(x0 + x, y0 - y, color);
    drawPixel(x0 - x, y0 - y, color);
    drawPixel(x0 + y, y0 + x, color);
    drawPixel(x0 - y, y0 + x, color);
    drawPixel(x0 + y, y0 - x, color);
    drawPixel(x0 - y, y0 - x, color);
  }
}
```