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

```asm
<double_string>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %r12
  push   %rbx
  sub    $0x30,%rsp
  mov    %rdi,-0x38(%rbp)
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  sub    $0x30,%eax
  mov    %eax,-0x18(%rbp)
  movl   $0x0,-0x24(%rbp)
  cmpl   $0x5,-0x18(%rbp)
  je     L94
  cmpl   $0x6,-0x18(%rbp)
  je     L94
  cmpl   $0x7,-0x18(%rbp)
  je     L94
  cmpl   $0x8,-0x18(%rbp)
  je     L94
  cmpl   $0x9,-0x18(%rbp)
  jne    L125
L94:
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  lea    0x2(%rax),%edx
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rax
  mov    %edx,%esi
  mov    %rax,%rdi
  call   <realloc@plt>
  mov    -0x38(%rbp),%rdx
  mov    %rax,(%rdx)
  movl   $0x1,-0x24(%rbp)
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rbx
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  cltq
  add    $0x1,%rax
  add    %rax,%rbx
  movb   $0x0,(%rbx)
  mov    -0x38(%rbp),%rax
  mov    (%rax),%r12
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  cltq
  lea    (%r12,%rax,1),%rdx
  movzbl (%rbx),%eax
  mov    %al,(%rdx)
L125:
  movl   $0x0,-0x20(%rbp)
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %eax,-0x1c(%rbp)
  jmp    L87
L122:
  mov    -0x1c(%rbp),%eax
  sub    $0x1,%eax
  mov    %eax,-0x14(%rbp)
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rdx
  mov    -0x14(%rbp),%eax
  cltq
  add    %rdx,%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  sub    $0x30,%eax
  cmp    $0x9,%eax
  ja     L103
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  lea    D14(%rip),%rax
  mov    (%rdx,%rax,1),%eax
  cltq
  lea    D14(%rip),%rdx
  add    %rdx,%rax
  notrack jmp *%rax
  mov    -0x20(%rbp),%eax
  lea    0x30(%rax),%esi
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x24(%rbp),%eax
  cltq
  add    %rcx,%rax
  add    %rdx,%rax
  mov    %esi,%edx
  mov    %dl,(%rax)
  movl   $0x0,-0x20(%rbp)
  jmp    L103
  mov    -0x20(%rbp),%eax
  lea    0x32(%rax),%esi
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x24(%rbp),%eax
  cltq
  add    %rcx,%rax
  add    %rdx,%rax
  mov    %esi,%edx
  mov    %dl,(%rax)
  movl   $0x0,-0x20(%rbp)
  jmp    L103
  mov    -0x20(%rbp),%eax
  lea    0x34(%rax),%esi
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x24(%rbp),%eax
  cltq
  add    %rcx,%rax
  add    %rdx,%rax
  mov    %esi,%edx
  mov    %dl,(%rax)
  movl   $0x0,-0x20(%rbp)
  jmp    L103
  mov    -0x20(%rbp),%eax
  lea    0x36(%rax),%esi
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x24(%rbp),%eax
  cltq
  add    %rcx,%rax
  add    %rdx,%rax
  mov    %esi,%edx
  mov    %dl,(%rax)
  movl   $0x0,-0x20(%rbp)
  jmp    L103
  mov    -0x20(%rbp),%eax
  lea    0x38(%rax),%esi
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x24(%rbp),%eax
  cltq
  add    %rcx,%rax
  add    %rdx,%rax
  mov    %esi,%edx
  mov    %dl,(%rax)
  movl   $0x0,-0x20(%rbp)
  jmp    L103
  mov    -0x20(%rbp),%eax
  lea    0x30(%rax),%esi
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x24(%rbp),%eax
  cltq
  add    %rcx,%rax
  add    %rdx,%rax
  mov    %esi,%edx
  mov    %dl,(%rax)
  movl   $0x1,-0x20(%rbp)
  jmp    L103
  mov    -0x20(%rbp),%eax
  lea    0x32(%rax),%esi
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x24(%rbp),%eax
  cltq
  add    %rcx,%rax
  add    %rdx,%rax
  mov    %esi,%edx
  mov    %dl,(%rax)
  movl   $0x1,-0x20(%rbp)
  jmp    L103
  mov    -0x20(%rbp),%eax
  lea    0x34(%rax),%esi
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x24(%rbp),%eax
  cltq
  add    %rcx,%rax
  add    %rdx,%rax
  mov    %esi,%edx
  mov    %dl,(%rax)
  movl   $0x1,-0x20(%rbp)
  jmp    L103
  mov    -0x20(%rbp),%eax
  lea    0x36(%rax),%esi
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x24(%rbp),%eax
  cltq
  add    %rcx,%rax
  add    %rdx,%rax
  mov    %esi,%edx
  mov    %dl,(%rax)
  movl   $0x1,-0x20(%rbp)
  jmp    L103
  mov    -0x20(%rbp),%eax
  lea    0x38(%rax),%esi
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rdx
  mov    -0x14(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x24(%rbp),%eax
  cltq
  add    %rcx,%rax
  add    %rdx,%rax
  mov    %esi,%edx
  mov    %dl,(%rax)
  movl   $0x1,-0x20(%rbp)
  nop
L103:
  subl   $0x1,-0x1c(%rbp)
L87:
  cmpl   $0x0,-0x1c(%rbp)
  jg     L122
  cmpl   $0x0,-0x20(%rbp)
  je     L112
  mov    -0x20(%rbp),%eax
  lea    0x30(%rax),%edx
  mov    -0x38(%rbp),%rax
  mov    (%rax),%rax
  mov    %dl,(%rax)
  movl   $0x0,-0x20(%rbp)
L112:
  nop
  add    $0x30,%rsp
  pop    %rbx
  pop    %r12
  pop    %rbp
  ret
```

assistant: ```c
void double_string(char **in) {
  int first = **in - 48;
  int ra = 0;
  if ((first == 5) || (first == 6) || (first == 7) || (first == 8) || (first == 9)) {
    *in = realloc(*in, strlen(*in) + 2);
    ra = 1;
    *(*in + strlen(*in)) = *(*in + strlen(*in) + 1) = 0;
  }
  int carry = 0;
  int j;
  for (j = strlen(*in); j > 0; --j) {
    int i = j - 1;
    switch (*(*in + i) - 48) {
    case 0:
      *(*in + i + ra) = 0 + 48 + carry;
      carry = 0;
      break;
    case 1:
      *(*in + i + ra) = 2 + 48 + carry;
      carry = 0;
      break;
    case 2:
      *(*in + i + ra) = 4 + 48 + carry;
      carry = 0;
      break;
    case 3:
      *(*in + i + ra) = 6 + 48 + carry;
      carry = 0;
      break;
    case 4:
      *(*in + i + ra) = 8 + 48 + carry;
      carry = 0;
      break;
    case 5:
      *(*in + i + ra) = 0 + 48 + carry;
      carry = 1;
      break;
    case 6:
      *(*in + i + ra) = 2 + 48 + carry;
      carry = 1;
      break;
    case 7:
      *(*in + i + ra) = 4 + 48 + carry;
      carry = 1;
      break;
    case 8:
      *(*in + i + ra) = 6 + 48 + carry;
      carry = 1;
      break;
    case 9:
      *(*in + i + ra) = 8 + 48 + carry;
      carry = 1;
      break;
    }
  }
  if (carry) {
    **in = 0 + 48 + carry;
    carry = 0;
  }
}
```