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

```asm
<regexp_infx2postfx>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x680,%rsp
  mov    %rdi,-0x678(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  movq   $0x0,-0x670(%rbp)
  movq   $0x0,-0x668(%rbp)
  lea    D2(%rip),%rax
  mov    %rax,-0x660(%rbp)
  lea    -0x650(%rbp),%rax
  mov    %rax,-0x658(%rbp)
  mov    -0x678(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  cmp    $0xfff,%eax
  jle    L251
  mov    $0x0,%eax
  jmp    L31
L107:
  mov    -0x678(%rbp),%rax
  movzbl (%rax),%eax
  movsbl %al,%eax
  cmp    $0x7c,%eax
  je     L188
  cmp    $0x7c,%eax
  jg     L137
  cmp    $0x3f,%eax
  je     L252
  cmp    $0x3f,%eax
  jg     L137
  cmp    $0x2b,%eax
  jg     L137
  cmp    $0x2a,%eax
  jge    L252
  cmp    $0x28,%eax
  je     L42
  cmp    $0x29,%eax
  je     L240
  jmp    L137
L42:
  cmpq   $0x1,-0x668(%rbp)
  jbe    L236
  subq   $0x1,-0x668(%rbp)
  mov    -0x660(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x660(%rbp)
  movb   $0x10,(%rax)
L236:
  lea    -0x650(%rbp),%rax
  add    $0x640,%rax
  cmp    %rax,-0x658(%rbp)
  jb     L69
  mov    $0x0,%eax
  jmp    L31
L69:
  mov    -0x658(%rbp),%rax
  mov    -0x670(%rbp),%rdx
  mov    %rdx,(%rax)
  mov    -0x658(%rbp),%rax
  mov    -0x668(%rbp),%rdx
  mov    %rdx,0x8(%rax)
  addq   $0x10,-0x658(%rbp)
  movq   $0x0,-0x670(%rbp)
  movq   $0x0,-0x668(%rbp)
  jmp    L89
L240:
  lea    -0x650(%rbp),%rax
  cmp    %rax,-0x658(%rbp)
  jne    L246
  mov    $0x0,%eax
  jmp    L31
L246:
  cmpq   $0x0,-0x668(%rbp)
  jne    L301
  mov    $0x0,%eax
  jmp    L31
L303:
  mov    -0x660(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x660(%rbp)
  movb   $0x10,(%rax)
L301:
  subq   $0x1,-0x668(%rbp)
  cmpq   $0x0,-0x668(%rbp)
  jne    L303
  jmp    L372
L314:
  mov    -0x660(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x660(%rbp)
  movb   $0x7c,(%rax)
  subq   $0x1,-0x670(%rbp)
L372:
  cmpq   $0x0,-0x670(%rbp)
  jne    L314
  subq   $0x10,-0x658(%rbp)
  mov    -0x658(%rbp),%rax
  mov    (%rax),%rax
  mov    %rax,-0x670(%rbp)
  mov    -0x658(%rbp),%rax
  mov    0x8(%rax),%rax
  mov    %rax,-0x668(%rbp)
  addq   $0x1,-0x668(%rbp)
  jmp    L89
L188:
  cmpq   $0x0,-0x668(%rbp)
  jne    L76
  mov    $0x0,%eax
  jmp    L31
L306:
  mov    -0x660(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x660(%rbp)
  movb   $0x10,(%rax)
L76:
  subq   $0x1,-0x668(%rbp)
  cmpq   $0x0,-0x668(%rbp)
  jne    L306
  addq   $0x1,-0x670(%rbp)
  jmp    L89
L252:
  cmpq   $0x0,-0x668(%rbp)
  jne    L122
  mov    $0x0,%eax
  jmp    L31
L122:
  mov    -0x660(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x660(%rbp)
  mov    -0x678(%rbp),%rdx
  movzbl (%rdx),%edx
  mov    %dl,(%rax)
  jmp    L89
L137:
  cmpq   $0x1,-0x668(%rbp)
  jbe    L29
  subq   $0x1,-0x668(%rbp)
  mov    -0x660(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x660(%rbp)
  movb   $0x10,(%rax)
L29:
  mov    -0x660(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x660(%rbp)
  mov    -0x678(%rbp),%rdx
  movzbl (%rdx),%edx
  mov    %dl,(%rax)
  addq   $0x1,-0x668(%rbp)
  nop
L89:
  addq   $0x1,-0x678(%rbp)
L251:
  mov    -0x678(%rbp),%rax
  movzbl (%rax),%eax
  test   %al,%al
  jne    L107
  lea    -0x650(%rbp),%rax
  cmp    %rax,-0x658(%rbp)
  je     L289
  mov    $0x0,%eax
  jmp    L31
L346:
  mov    -0x660(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x660(%rbp)
  movb   $0x10,(%rax)
L289:
  subq   $0x1,-0x668(%rbp)
  cmpq   $0x0,-0x668(%rbp)
  jne    L346
  jmp    L37
L148:
  mov    -0x660(%rbp),%rax
  lea    0x1(%rax),%rdx
  mov    %rdx,-0x660(%rbp)
  movb   $0x7c,(%rax)
  subq   $0x1,-0x670(%rbp)
L37:
  cmpq   $0x0,-0x670(%rbp)
  jne    L148
  mov    -0x660(%rbp),%rax
  movb   $0x0,(%rax)
  lea    D2(%rip),%rax
L31:
  mov    -0x8(%rbp),%rdx
  sub    %fs:0x28,%rdx
  je     L93
  call   <__stack_chk_fail@plt>
L93:
  leave
  ret
```

assistant: ```c
char *regexp_infx2postfx(char *infx) {
  size_t alternate_cnt = 0, atomic_cnt = 0;
  static char buffer[8192];
  char *dest = buffer;
  struct {
    size_t alternate_cnt;
    size_t atomic_cnt;
  } subexpr_stack[100], *stack_ptr;
  stack_ptr = subexpr_stack;
  if (strlen(infx) >= 8192 / 2) {
    return NULL;
  }
  for (; *infx; infx++) {
    switch (*infx) {
    case '(':
      if (atomic_cnt > 1) {
        atomic_cnt--;
        *dest++ = 16;
      }
      if (stack_ptr >= subexpr_stack + 100) {
        return NULL;
      }
      stack_ptr->alternate_cnt = alternate_cnt;
      stack_ptr->atomic_cnt = atomic_cnt;
      stack_ptr++;
      alternate_cnt = 0;
      atomic_cnt = 0;
      break;
    case ')':
      if (stack_ptr == subexpr_stack) {
        return NULL;
      }
      if (atomic_cnt == 0) {
        return NULL;
      }
      while (--atomic_cnt > 0) {
        *dest++ = 16;
      }
      for (; alternate_cnt > 0; alternate_cnt--) {
        *dest++ = '|';
      }
      stack_ptr--;
      alternate_cnt = stack_ptr->alternate_cnt;
      atomic_cnt = stack_ptr->atomic_cnt;
      atomic_cnt++;
      break;
    case '|':
      if (atomic_cnt == 0) {
        return NULL;
      }
      while (--atomic_cnt > 0) {
        *dest++ = 16;
      }
      alternate_cnt++;
      break;
    case '*':
    case '+':
    case '?':
      if (atomic_cnt == 0) {
        return NULL;
      }
      *dest++ = *infx;
      break;
    default:
      if (atomic_cnt > 1) {
        atomic_cnt--;
        *dest++ = 16;
      }
      *dest++ = *infx;
      atomic_cnt++;
      break;
    }
  }
  if (stack_ptr != subexpr_stack) {
    return NULL;
  }
  while (--atomic_cnt > 0) {
    *dest++ = 16;
  }
  for (; alternate_cnt > 0; alternate_cnt--) {
    *dest++ = '|';
  }
  *dest = 0;
  return buffer;
}
```