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

```asm
<strtoull>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    %edx,%ebx
  sub    $0x28,%rsp
  cmp    $0x1,%edx
  sete   %dl
  cmp    $0x24,%ebx
  mov    %rdi,0x8(%rsp)
  seta   %al
  mov    %rsi,0x10(%rsp)
  or     %al,%dl
  mov    %dl,0x1f(%rsp)
  je     L288
  test   %rsi,%rsi
  je     L191
  mov    %rdi,(%rsi)
L191:
  mov    D16(%rip),%rax
  xor    %r12d,%r12d
  mov    (%rax),%edx
  mov    D30(%rip),%rax
  mov    %edx,(%rax)
L237:
  add    $0x28,%rsp
  mov    %r12,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax)
L288:
  mov    0x8(%rsp),%r14
  nopl   (%rax)
L46:
  mov    %r14,%rbp
  movzbl (%r14),%r15d
  add    $0x1,%r14
  mov    %r15d,%edi
  call   <isspace@plt>
  test   %rax,%rax
  jne    L46
  cmp    $0x2d,%r15d
  je     L38
  cmp    $0x2b,%r15d
  je     L195
L137:
  test   $0xffffffef,%ebx
  jne    L89
  cmp    $0x30,%r15d
  je     L252
  test   %ebx,%ebx
  jne    L89
  movq   $0xa,(%rsp)
  mov    $0xa,%ebx
  jmp    L270
  nopl   0x0(%rax)
L89:
  movslq %ebx,%rax
  mov    %rax,(%rsp)
L270:
  mov    D1(%rip),%rax
  xor    %edx,%edx
  xor    %ebp,%ebp
  xor    %r12d,%r12d
  mov    (%rax),%rax
  divq   (%rsp)
  mov    %edx,0x18(%rsp)
  mov    %rax,%r13
  jmp    L224
  nopl   (%rax)
L72:
  cmp    %ecx,%ebx
  jle    L91
L235:
  cmp    $0xffffffff,%ebp
  je     L119
  cmp    %r13,%r12
  ja     L193
  jne    L127
  cmp    0x18(%rsp),%ecx
  jle    L127
L193:
  mov    D1(%rip),%rax
  mov    $0xffffffff,%ebp
  mov    (%rax),%r12
  mov    D37(%rip),%rax
  mov    (%rax),%edx
  mov    D30(%rip),%rax
  mov    %edx,(%rax)
L119:
  movzbl (%r14),%r15d
  add    $0x1,%r14
L224:
  mov    %r15d,%edi
  call   <isdigit@plt>
  lea    -0x30(%r15),%ecx
  test   %rax,%rax
  jne    L72
  mov    %r15d,%edi
  call   <isalpha@plt>
  test   %rax,%rax
  je     L91
  mov    %r15d,%edi
  call   <isupper@plt>
  mov    %r15d,%ecx
  cmp    $0x1,%rax
  sbb    %eax,%eax
  and    $0x20,%eax
  add    $0x37,%eax
  sub    %eax,%ecx
  cmp    %ecx,%ebx
  jg     L235
L91:
  test   %ebp,%ebp
  jle    L197
  cmpb   $0x0,0x1f(%rsp)
  je     L197
  neg    %r12
  cmpq   $0x0,0x10(%rsp)
  je     L237
L179:
  lea    -0x1(%r14),%rax
  mov    %rax,0x8(%rsp)
  jmp    L120
  nopw   0x0(%rax,%rax,1)
L127:
  imul   (%rsp),%r12
  movslq %ecx,%rcx
  mov    $0x1,%ebp
  add    %rcx,%r12
  jmp    L119
  nopl   (%rax)
L197:
  cmpq   $0x0,0x10(%rsp)
  je     L237
  test   %ebp,%ebp
  jne    L179
L120:
  mov    0x10(%rsp),%rax
  mov    0x8(%rsp),%rsi
  mov    %rsi,(%rax)
  jmp    L237
  nopw   0x0(%rax,%rax,1)
L195:
  movsbl (%r14),%r15d
  lea    0x2(%rbp),%r14
  jmp    L137
  nopl   (%rax)
L252:
  movzbl (%r14),%eax
  and    $0xffffffdf,%eax
  cmp    $0x58,%al
  je     L298
  test   %ebx,%ebx
  jne    L89
  movq   $0x8,(%rsp)
  mov    $0x8,%ebx
  jmp    L270
  nopl   (%rax)
L38:
  movsbl (%r14),%r15d
  movb   $0x1,0x1f(%rsp)
  lea    0x2(%rbp),%r14
  jmp    L137
L298:
  movsbl 0x1(%r14),%r15d
  mov    $0x10,%ebx
  add    $0x2,%r14
  movq   $0x10,(%rsp)
  jmp    L270
```

assistant: ```c
unsigned long long strtoull(const char *nptr, char **endptr, int base) {
  const char *s;
  unsigned long long acc, cutoff;
  int c;
  int neg, any, cutlim;
  if (base < 0 || base == 1 || base > 36) {
    if (endptr != 0)
      *endptr = (char *)nptr;
    errno = EINVAL;
    return 0;
  }
  s = nptr;
  do {
    c = (unsigned char)*s++;
  } while (isspace(c));
  if (c == '-') {
    neg = 1;
    c = *s++;
  } else {
    neg = 0;
    if (c == '+')
      c = *s++;
  }
  if ((base == 0 || base == 16) && c == '0' && (*s == 'x' || *s == 'X')) {
    c = s[1];
    s += 2;
    base = 16;
  }
  if (base == 0)
    base = c == '0' ? 8 : 10;
  cutoff = ULLONG_MAX / (unsigned long long)base;
  cutlim = ULLONG_MAX % (unsigned long long)base;
  for (acc = 0, any = 0;; c = (unsigned char)*s++) {
    if (isdigit(c))
      c -= '0';
    else if (isalpha(c))
      c -= isupper(c) ? 'A' - 10 : 'a' - 10;
    else
      break;
    if (c >= base)
      break;
    if (any < 0)
      continue;
    if (acc > cutoff || (acc == cutoff && c > cutlim)) {
      any = -1;
      acc = ULLONG_MAX;
      errno = ERANGE;
    } else {
      any = 1;
      acc *= (unsigned long long)base;
      acc += c;
    }
  }
  if (neg && any > 0)
    acc = -acc;
  if (endptr != 0)
    *endptr = (char *)(any ? s - 1 : nptr);
  return (acc);
}
```