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

```asm
<offtout>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  mov    %edi,-0x14(%rbp)
  mov    %rsi,-0x20(%rbp)
  cmpl   $0x0,-0x14(%rbp)
  jns    L3
  mov    -0x14(%rbp),%eax
  neg    %eax
  mov    %eax,-0x4(%rbp)
  jmp    L14
L3:
  mov    -0x14(%rbp),%eax
  mov    %eax,-0x4(%rbp)
L14:
  mov    -0x4(%rbp),%eax
  cltd
  shr    $0x18,%edx
  add    %edx,%eax
  movzbl %al,%eax
  sub    %edx,%eax
  mov    %eax,%edx
  mov    -0x20(%rbp),%rax
  mov    %edx,(%rax)
  mov    -0x20(%rbp),%rax
  mov    (%rax),%eax
  sub    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  lea    0xff(%rax),%edx
  test   %eax,%eax
  cmovs  %edx,%eax
  sar    $0x8,%eax
  mov    %eax,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  lea    0x4(%rax),%rdx
  mov    -0x4(%rbp),%eax
  mov    %eax,%ecx
  sar    $0x1f,%ecx
  shr    $0x18,%ecx
  add    %ecx,%eax
  movzbl %al,%eax
  sub    %ecx,%eax
  mov    %eax,(%rdx)
  mov    -0x20(%rbp),%rax
  add    $0x4,%rax
  mov    (%rax),%eax
  sub    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  lea    0xff(%rax),%edx
  test   %eax,%eax
  cmovs  %edx,%eax
  sar    $0x8,%eax
  mov    %eax,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  lea    0x8(%rax),%rdx
  mov    -0x4(%rbp),%eax
  mov    %eax,%ecx
  sar    $0x1f,%ecx
  shr    $0x18,%ecx
  add    %ecx,%eax
  movzbl %al,%eax
  sub    %ecx,%eax
  mov    %eax,(%rdx)
  mov    -0x20(%rbp),%rax
  add    $0x8,%rax
  mov    (%rax),%eax
  sub    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  lea    0xff(%rax),%edx
  test   %eax,%eax
  cmovs  %edx,%eax
  sar    $0x8,%eax
  mov    %eax,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  lea    0xc(%rax),%rdx
  mov    -0x4(%rbp),%eax
  mov    %eax,%ecx
  sar    $0x1f,%ecx
  shr    $0x18,%ecx
  add    %ecx,%eax
  movzbl %al,%eax
  sub    %ecx,%eax
  mov    %eax,(%rdx)
  mov    -0x20(%rbp),%rax
  add    $0xc,%rax
  mov    (%rax),%eax
  sub    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  lea    0xff(%rax),%edx
  test   %eax,%eax
  cmovs  %edx,%eax
  sar    $0x8,%eax
  mov    %eax,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  lea    0x10(%rax),%rdx
  mov    -0x4(%rbp),%eax
  mov    %eax,%ecx
  sar    $0x1f,%ecx
  shr    $0x18,%ecx
  add    %ecx,%eax
  movzbl %al,%eax
  sub    %ecx,%eax
  mov    %eax,(%rdx)
  mov    -0x20(%rbp),%rax
  add    $0x10,%rax
  mov    (%rax),%eax
  sub    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  lea    0xff(%rax),%edx
  test   %eax,%eax
  cmovs  %edx,%eax
  sar    $0x8,%eax
  mov    %eax,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  lea    0x14(%rax),%rdx
  mov    -0x4(%rbp),%eax
  mov    %eax,%ecx
  sar    $0x1f,%ecx
  shr    $0x18,%ecx
  add    %ecx,%eax
  movzbl %al,%eax
  sub    %ecx,%eax
  mov    %eax,(%rdx)
  mov    -0x20(%rbp),%rax
  add    $0x14,%rax
  mov    (%rax),%eax
  sub    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  lea    0xff(%rax),%edx
  test   %eax,%eax
  cmovs  %edx,%eax
  sar    $0x8,%eax
  mov    %eax,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  lea    0x18(%rax),%rdx
  mov    -0x4(%rbp),%eax
  mov    %eax,%ecx
  sar    $0x1f,%ecx
  shr    $0x18,%ecx
  add    %ecx,%eax
  movzbl %al,%eax
  sub    %ecx,%eax
  mov    %eax,(%rdx)
  mov    -0x20(%rbp),%rax
  add    $0x18,%rax
  mov    (%rax),%eax
  sub    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  lea    0xff(%rax),%edx
  test   %eax,%eax
  cmovs  %edx,%eax
  sar    $0x8,%eax
  mov    %eax,-0x4(%rbp)
  mov    -0x20(%rbp),%rax
  lea    0x1c(%rax),%rdx
  mov    -0x4(%rbp),%eax
  mov    %eax,%ecx
  sar    $0x1f,%ecx
  shr    $0x18,%ecx
  add    %ecx,%eax
  movzbl %al,%eax
  sub    %ecx,%eax
  mov    %eax,(%rdx)
  cmpl   $0x0,-0x14(%rbp)
  jns    L12
  mov    -0x20(%rbp),%rax
  add    $0x1c,%rax
  mov    (%rax),%edx
  mov    -0x20(%rbp),%rax
  add    $0x1c,%rax
  or     $0x80,%dl
  mov    %edx,(%rax)
L12:
  nop
  pop    %rbp
  ret
```

assistant: ```c
void offtout(off_t x, u_char *buf) {
  off_t y;
  if (x < 0)
    y = -x;
  else
    y = x;
  buf[0] = (u_char)(y % 256);
  y -= buf[0];
  y = y / 256;
  buf[1] = (u_char)(y % 256);
  y -= buf[1];
  y = y / 256;
  buf[2] = (u_char)(y % 256);
  y -= buf[2];
  y = y / 256;
  buf[3] = (u_char)(y % 256);
  y -= buf[3];
  y = y / 256;
  buf[4] = (u_char)(y % 256);
  y -= buf[4];
  y = y / 256;
  buf[5] = (u_char)(y % 256);
  y -= buf[5];
  y = y / 256;
  buf[6] = (u_char)(y % 256);
  y -= buf[6];
  y = y / 256;
  buf[7] = (u_char)(y % 256);
  if (x < 0)
    buf[7] |= 0x80;
}
```