user: 请将这段汇编代码片段转换成等效的C代码:

```asm
<stime_darg>:
  endbr64
  push   %r13
  push   %r12
  push   %rbp
  mov    %rdi,%rbp
  push   %rbx
  mov    %rsi,%rbx
  sub    $0x18,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0x8(%rsp)
  xor    %eax,%eax
  movq   $0x0,0x8(%rsi)
  mov    $0xffffffff,%eax
  mov    $0x3a,%esi
  mov    %rax,(%rsp)
  call   <strchr@plt>
  test   %rax,%rax
  je     L68
  lea    0x1(%rax),%rdi
  mov    $0x3a,%esi
  call   <strchr@plt>
  test   %rax,%rax
  je     L68
  mov    %rbp,%rdi
  mov    $0x54,%esi
  mov    %rsp,%r12
  call   <strchr@plt>
  lea    D2(%rip),%rsi
  mov    %rbp,%rdi
  mov    %r12,%rdx
  test   %rax,%rax
  lea    D26(%rip),%rax
  cmove  %rax,%rsi
  call   <strptime@plt>
  mov    %rax,%rbp
  test   %rax,%rax
  je     L68
  movzbl (%rax),%eax
  mov    %eax,%edx
  and    $0xfffffffd,%edx
  cmp    $0x2c,%dl
  je     L7
L52:
  cmp    $0x5a,%al
  je     L127
  test   %al,%al
  jne    L68
  mov    %r12,%rdi
  call   <mktime@plt>
L44:
  mov    %eax,(%rbx)
  movdqu (%rbx),%xmm0
  movups %xmm0,0x10(%rbx)
  jmp    L6
  nopl   0x0(%rax,%rax,1)
L68:
  lea    D14(%rip),%rsi
  mov    $0x1,%edi
  call   <errx@plt>
L6:
  mov    0x8(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L49
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
L127:
  cmpb   $0x0,0x1(%rbp)
  jne    L68
  mov    %r12,%rdi
  call   <timegm@plt>
  jmp    L44
L7:
  movzbl 0x1(%rbp),%edi
  call   <isdigit@plt>
  test   %rax,%rax
  je     L12
  add    $0x1,%rbp
  mov    $0x5f5e100,%r13d
  jmp    L120
  nopw   0x0(%rax,%rax,1)
L31:
  movsbl 0x0(%rbp),%eax
  mov    %r13d,%edx
  add    $0x1,%rbp
  sar    $0x1f,%edx
  sub    $0x30,%eax
  imul   %r13d,%eax
  cltq
  add    %rax,0x8(%rbx)
  movslq %r13d,%rax
  imul   $0x66666667,%rax,%rax
  sar    $0x22,%rax
  sub    %edx,%eax
  mov    %eax,%r13d
L120:
  movzbl 0x0(%rbp),%edi
  call   <isdigit@plt>
  test   %rax,%rax
  jne    L31
L12:
  movzbl 0x0(%rbp),%eax
  jmp    L52
L49:
  call   <__stack_chk_fail@plt>
```

tool_calls: name: unpack_data
arguments: tag: D2
type_guessed: string
name: unpack_data
arguments: tag: D26
type_guessed: string
name: unpack_data
arguments: tag: D14
type_guessed: string

tool: D2: %Y-%m-%dT%H:%M:%S

tool: D26: %Y-%m-%d %H:%M:%S

tool: D14: out of range or illegal time specification: YYYY-MM-DDThh:mm:SS[.frac][tz]

assistant: ```c
void stime_darg(const char *arg, struct timespec *tvp) {
  struct tm t = {.tm_sec = 0};
  const char *fmt, *colon;
  char *p;
  int val, isutc = 0;
  tvp[0].tv_nsec = 0;
  t.tm_isdst = -1;
  colon = strchr(arg, ':');
  if (colon == NULL || strchr(colon + 1, ':') == NULL)
    goto bad;
  fmt = strchr(arg, 'T') != NULL ? "%Y-%m-%dT%H:%M:%S" : "%Y-%m-%d %H:%M:%S";
  p = strptime(arg, fmt, &t);
  if (p == NULL)
    goto bad;
  if ((*p == '.' || *p == ',') && isdigit((unsigned char)p[1])) {
    p++;
    val = 100000000;
    while (isdigit((unsigned char)*p)) {
      tvp[0].tv_nsec += val * (*p - '0');
      p++;
      val /= 10;
    }
  }
  if (*p == 'Z') {
    isutc = 1;
    p++;
  }
  if (*p != '\0')
    goto bad;
  tvp[0].tv_sec = isutc ? timegm(&t) : mktime(&t);
  tvp[1] = tvp[0];
  return;
bad:
  errx(1, "out of range or illegal time specification: YYYY-MM-DDThh:mm:SS[.frac][tz]");
}
```