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

```asm
<calc_relative_path>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %r15
  push   %r14
  mov    %rdi,%r14
  mov    %rsi,%rdi
  push   %r13
  push   %r12
  mov    %rdx,%r12
  push   %rbx
  sub    $0x18,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,-0x38(%rbp)
  xor    %eax,%eax
  mov    D0(%rip),%rax
  mov    %rsp,%rcx
  mov    %rsp,%r13
  movslq (%rax),%rax
  add    $0xf,%rax
  mov    %rax,%rsi
  mov    %rax,%rdx
  and    $0xfffffffffffff000,%rsi
  and    $0xfffffffffffffff0,%rdx
  sub    %rsi,%rcx
  cmp    %rcx,%rsp
  je     L256
L125:
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  cmp    %rcx,%rsp
  jne    L125
L256:
  and    $0xfff,%edx
  sub    %rdx,%rsp
  test   %rdx,%rdx
  jne    L252
L92:
  mov    %rax,%rdx
  mov    %rsp,%rcx
  and    $0xfffffffffffff000,%rax
  mov    %rsp,%rbx
  sub    %rax,%rcx
  and    $0xfffffffffffffff0,%rdx
  cmp    %rcx,%rsp
  je     L219
L120:
  sub    $0x1000,%rsp
  orq    $0x0,0xff8(%rsp)
  cmp    %rcx,%rsp
  jne    L120
L219:
  and    $0xfff,%edx
  sub    %rdx,%rsp
  test   %rdx,%rdx
  jne    L171
L83:
  mov    %rsp,%rsi
  mov    %rsp,%r15
  call   <realpath@plt>
  test   %eax,%eax
  je     L33
  test   %r14,%r14
  je     L33
  mov    %rbx,%rsi
  mov    %r14,%rdi
  call   <realpath@plt>
  test   %eax,%eax
  je     L33
  movzbl (%rsp),%ecx
  mov    %rsp,%rax
  mov    $0xffffffff,%r9d
  xor    %r8d,%r8d
  cmp    %cl,(%rbx)
  jne    L33
  nopw   0x0(%rax,%rax,1)
L147:
  mov    %rbx,%rdx
  mov    %rax,%rdi
  add    $0x1,%rbx
  add    $0x1,%rax
  cmp    $0x2f,%cl
  jne    L201
  add    $0x1,%r9d
  mov    %rax,%r8
L201:
  movzbl (%rbx),%esi
  movzbl (%rax),%ecx
  cmp    %cl,%sil
  je     L147
  test   %sil,%sil
  jne    L71
  cmp    $0x2f,%cl
  je     L49
L71:
  mov    $0x1,%ecx
L203:
  test   %r9d,%r9d
  jle    L33
  cmpb   $0x0,(%rbx)
  lea    0x2(%rdx),%rax
  je     L169
  nopw   0x0(%rax,%rax,1)
L126:
  movzbl (%rax),%edx
  add    $0x1,%rax
  cmp    $0x2f,%dl
  je     L121
  test   %dl,%dl
  jne    L126
L169:
  test   %ecx,%ecx
  je     L75
  movslq %ecx,%rcx
  lea    (%rcx,%rcx,2),%rax
  add    %r12,%rax
  nopw   0x0(%rax,%rax,1)
L212:
  movb   $0x2e,(%r12)
  add    $0x3,%r12
  movb   $0x2e,-0x2(%r12)
  movb   $0x2f,-0x1(%r12)
  cmp    %r12,%rax
  jne    L212
L75:
  mov    %r8,%rsi
  mov    %r12,%rdi
  call   <strcpy@plt>
  mov    %r13,%rsp
L106:
  mov    -0x38(%rbp),%rax
  sub    %fs:0x28,%rax
  jne    L186
  lea    -0x28(%rbp),%rsp
  pop    %rbx
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  pop    %rbp
  ret
  xchg   %ax,%ax
L252:
  orq    $0x0,-0x8(%rsp,%rdx,1)
  jmp    L92
  nopl   0x0(%rax,%rax,1)
L33:
  mov    %r15,%rsi
  mov    %r12,%rdi
  call   <strcpy@plt>
  mov    %r13,%rsp
  jmp    L106
L121:
  add    $0x1,%ecx
  jmp    L126
  nopl   0x0(%rax,%rax,1)
L49:
  add    $0x1,%r9d
  lea    0x2(%rdi),%r8
  xor    %ecx,%ecx
  jmp    L203
  nop
L171:
  orq    $0x0,-0x8(%rsp,%rdx,1)
  jmp    L83
L186:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void calc_relative_path(const char *from, const char *to, char *out) {
  char path_from[PATH_MAX];
  char path_to[PATH_MAX];
  if (!realpath(to, path_to) || !from || !realpath(from, path_from)) {
    strcpy(out, path_to);
    return;
  }
  char *ptr_from = path_from;
  char *ptr_to = path_to;
  char *ptr_match = NULL;
  int depth_match = -1;
  while (*ptr_from == *ptr_to) {
    ptr_from++;
    if (*ptr_to++ == '/') {
      ptr_match = ptr_to;
      depth_match++;
    }
  }
  int depth = 0;
  if (!(*ptr_from) && *ptr_to == '/') {
    ptr_match = ++ptr_to;
    depth_match++;
  } else {
    depth++;
  }
  if (depth_match <= 0) {
    strcpy(out, path_to);
    return;
  }
  while (*ptr_from++) {
    if (*ptr_from == '/')
      depth++;
  }
  if (*(ptr_from - 1) == '/')
    depth--;
  while (depth--) {
    *out++ = '.';
    *out++ = '.';
    *out++ = '/';
  }
  strcpy(out, ptr_match);
}
```