user: Converte this assembly snippet into its equivalent C code:

```asm
<oo__strtimetosint64>:
  endbr64
  push   %rbp
  push   %rbx
  sub    $0x28,%rsp
  mov    %rdi,%rbx
  mov    %fs:0x28,%rax
  mov    %rax,0x18(%rsp)
  xor    %eax,%eax
  movzbl (%rdi),%eax
  cmp    $0x4e,%al
  je     L262
  sub    $0x31,%eax
  mov    $0x0,%edx
  cmp    $0x1,%al
  jbe    L267
L79:
  mov    0x18(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L166
  mov    %rdx,%rax
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  ret
L262:
  mov    $0x0,%edx
  cmpb   $0x4f,0x1(%rdi)
  jne    L79
  cmpb   $0x57,0x2(%rdi)
  jne    L79
  movzbl 0x3(%rdi),%eax
  sub    $0x2b,%eax
  test   $0xfd,%al
  jne    L79
  movzbl 0x4(%rdi),%edi
  call   <isdigit@plt>
  mov    $0x0,%edx
  test   %eax,%eax
  je     L79
  lea    0x4(%rbx),%rbp
  cmpb   $0x2b,0x3(%rbx)
  je     L114
  lea    0x3(%rbx),%rbp
L114:
  mov    $0x0,%edi
  call   <time@plt>
  mov    %rax,%rbx
  mov    %rbp,%rdi
  call   <oo__strtosint64@plt>
  lea    (%rbx,%rax,1),%rdx
  jmp    L79
L267:
  movzbl 0x1(%rdi),%edi
  call   <isdigit@plt>
  mov    $0x0,%edx
  test   %eax,%eax
  je     L79
  movzbl 0x2(%rbx),%edi
  call   <isdigit@plt>
  mov    $0x0,%edx
  test   %eax,%eax
  je     L79
  movzbl 0x3(%rbx),%edi
  call   <isdigit@plt>
  mov    $0x0,%edx
  test   %eax,%eax
  je     L79
  cmpb   $0x2d,0x4(%rbx)
  jne    L79
  movzbl 0x5(%rbx),%edi
  call   <isdigit@plt>
  mov    $0x0,%edx
  test   %eax,%eax
  je     L79
  movzbl 0x6(%rbx),%edi
  call   <isdigit@plt>
  mov    $0x0,%edx
  test   %eax,%eax
  je     L79
  cmpb   $0x2d,0x7(%rbx)
  jne    L79
  movzbl 0x8(%rbx),%edi
  call   <isdigit@plt>
  mov    $0x0,%edx
  test   %eax,%eax
  je     L79
  movzbl 0x9(%rbx),%edi
  call   <isdigit@plt>
  test   %eax,%eax
  je     L77
  mov    $0x0,%edx
  cmpb   $0x54,0xa(%rbx)
  jne    L79
  movzbl 0xb(%rbx),%edi
  call   <isdigit@plt>
  mov    $0x0,%edx
  test   %eax,%eax
  je     L79
  movzbl 0xc(%rbx),%edi
  call   <isdigit@plt>
  test   %eax,%eax
  je     L80
  mov    $0x0,%edx
  cmpb   $0x3a,0xd(%rbx)
  jne    L79
  movzbl 0xe(%rbx),%edi
  call   <isdigit@plt>
  mov    $0x0,%edx
  test   %eax,%eax
  je     L79
  movzbl 0xf(%rbx),%edi
  call   <isdigit@plt>
  test   %eax,%eax
  je     L302
  mov    $0x0,%edx
  cmpb   $0x3a,0x10(%rbx)
  jne    L79
  movzbl 0x11(%rbx),%edi
  call   <isdigit@plt>
  mov    $0x0,%edx
  test   %eax,%eax
  je     L79
  movzbl 0x12(%rbx),%edi
  call   <isdigit@plt>
  test   %eax,%eax
  je     L308
  mov    $0x0,%edx
  cmpb   $0x5a,0x13(%rbx)
  jne    L79
  movq   $0x0,0x8(%rsp)
  movsbl (%rbx),%edx
  sub    $0x30,%edx
  mov    $0xffffffe8,%ecx
  mov    %edx,%eax
  imul   %ecx,%eax
  mov    %eax,%edx
  movzbl 0x3(%rbx),%eax
  lea    0x64(%rdx,%rax,1),%edx
  movsbl 0x1(%rbx),%eax
  sub    $0x30,%eax
  mov    $0x64,%ecx
  imul   %ecx,%eax
  add    %eax,%edx
  movsbl 0x2(%rbx),%eax
  sub    $0x30,%eax
  mov    $0xa,%ecx
  imul   %ecx,%eax
  add    %eax,%edx
  mov    %dl,(%rsp)
  movsbl 0x5(%rbx),%eax
  sub    $0x30,%eax
  imul   %ecx,%eax
  movzbl 0x6(%rbx),%edx
  lea    -0x31(%rax,%rdx,1),%eax
  mov    %al,0x1(%rsp)
  movsbl 0x8(%rbx),%eax
  sub    $0x30,%eax
  imul   %ecx,%eax
  movzbl 0x9(%rbx),%edx
  lea    -0x30(%rax,%rdx,1),%eax
  mov    %al,0x2(%rsp)
  movsbl 0xb(%rbx),%eax
  sub    $0x30,%eax
  imul   %ecx,%eax
  movzbl 0xc(%rbx),%edx
  lea    -0x30(%rax,%rdx,1),%eax
  mov    %al,0x3(%rsp)
  movsbl 0xe(%rbx),%eax
  sub    $0x30,%eax
  imul   %ecx,%eax
  movzbl 0xf(%rbx),%edx
  lea    -0x30(%rax,%rdx,1),%eax
  mov    %al,0x4(%rsp)
  movsbl 0x11(%rbx),%eax
  sub    $0x30,%eax
  imul   %ecx,%eax
  movzbl 0x12(%rbx),%edx
  lea    -0x30(%rax,%rdx,1),%eax
  mov    %al,0x5(%rsp)
  mov    %rsp,%rdi
  call   <timegm@plt>
  mov    %rax,%rdx
  jmp    L79
L77:
  mov    $0x0,%edx
  jmp    L79
L80:
  mov    $0x0,%edx
  jmp    L79
L302:
  mov    $0x0,%edx
  jmp    L79
L308:
  mov    $0x0,%edx
  jmp    L79
L166:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int64_t oo__strtimetosint64(const char *s) {
  if (s[0] == 'N') {
    if (s[1] != 'O' || s[2] != 'W' || (s[3] != '+' && s[3] != '-') || !isdigit((unsigned char)(s[4])))
      return 0;
    s += 3;
    if (*s == '+')
      s++;
    return time(NULL) + oo__strtosint64(s);
  }
  if ((s[0] != '1' && s[0] != '2') || !isdigit((unsigned char)(s[1])) || !isdigit((unsigned char)(s[2])) || !isdigit((unsigned char)(s[3])) || s[4] != '-' || !isdigit((unsigned char)(s[5])) || !isdigit((unsigned char)(s[6])) || s[7] != '-' || !isdigit((unsigned char)(s[8])) || !isdigit((unsigned char)(s[9])) || s[10] != 'T' || !isdigit((unsigned char)(s[11])) || !isdigit((unsigned char)(s[12])) || s[13] != ':' || !isdigit((unsigned char)(s[14])) || !isdigit((unsigned char)(s[15])) || s[16] != ':' || !isdigit((unsigned char)(s[17])) || !isdigit((unsigned char)(s[18])) || s[19] != 'Z')
    return 0;
  {
    struct tm tm;
    tm.tm_isdst = 0;
    tm.tm_year = (s[0] - '0') * 1000 + (s[1] - '0') * 100 + (s[2] - '0') * 10 + (s[3] - '0') - 1900;
    tm.tm_mon = (s[5] - '0') * 10 + s[6] - '0' - 1;
    tm.tm_mday = (s[8] - '0') * 10 + s[9] - '0';
    tm.tm_hour = (s[11] - '0') * 10 + s[12] - '0';
    tm.tm_min = (s[14] - '0') * 10 + s[15] - '0';
    tm.tm_sec = (s[17] - '0') * 10 + s[18] - '0';
    return timegm(&tm);
  }
}
```