user: What is the c source code of the assembly code below?

```asm
<strtol>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x28,%rsp
  mov    %rdi,0x18(%rsp)
  mov    %rsi,0x10(%rsp)
  mov    %edx,%r14d
  mov    %rdi,%rbp
L245:
  mov    %rbp,%r13
  add    $0x1,%rbp
  movzbl -0x1(%rbp),%ebx
  mov    %ebx,%edi
  call   <isspace@plt>
  mov    %rax,%r12
  test   %rax,%rax
  jne    L245
  cmp    $0x2d,%ebx
  je     L244
  movl   $0x0,(%rsp)
  cmp    $0x2b,%ebx
  je     L94
L223:
  test   $0xffffffef,%r14d
  jne    L273
  cmp    $0x30,%ebx
  je     L217
L273:
  test   %r14d,%r14d
  jne    L291
  cmp    $0x30,%ebx
  setne  %r14b
  movzbl %r14b,%r14d
  lea    0x8(%r14,%r14,1),%r14d
L291:
  cmpl   $0x0,(%rsp)
  je     L43
  mov    D66(%rip),%rax
  mov    (%rax),%rax
  movslq %r14d,%rcx
  mov    %rcx,0x8(%rsp)
  cqto
  idiv   %rcx
  mov    %edx,%ecx
  mov    %rax,%r15
  test   %edx,%edx
  jle    L211
  sub    %r14d,%ecx
  lea    0x1(%rax),%r15
L211:
  neg    %ecx
  mov    %ecx,0x4(%rsp)
  jmp    L119
L244:
  movsbl 0x0(%rbp),%ebx
  lea    0x2(%r13),%rbp
  movl   $0x1,(%rsp)
  jmp    L223
L94:
  movsbl 0x0(%rbp),%ebx
  lea    0x2(%r13),%rbp
  jmp    L223
L217:
  movzbl 0x0(%rbp),%eax
  and    $0xffffffdf,%eax
  cmp    $0x58,%al
  jne    L270
  movsbl 0x1(%rbp),%ebx
  add    $0x2,%rbp
  mov    $0x10,%r14d
  jmp    L291
L270:
  mov    $0x30,%ebx
  jmp    L273
L43:
  mov    D78(%rip),%rax
  mov    (%rax),%rax
  movslq %r14d,%rsi
  mov    %rsi,0x8(%rsp)
  cqto
  idiv   %rsi
  mov    %edx,0x4(%rsp)
  mov    %rax,%r15
L119:
  mov    $0x0,%r13d
  jmp    L184
L15:
  mov    %ebx,%edi
  call   <isalpha@plt>
  test   %rax,%rax
  je     L18
  mov    %ebx,%edi
  call   <isupper@plt>
  cmp    $0x1,%rax
  sbb    %eax,%eax
  and    $0x20,%eax
  add    $0x37,%eax
  sub    %eax,%ebx
  jmp    L271
L224:
  mov    D66(%rip),%rax
  mov    (%rax),%r12
  mov    D23(%rip),%rax
  mov    (%rax),%edx
  mov    D21(%rip),%rax
  mov    %edx,(%rax)
  mov    $0xffffffff,%r13d
L269:
  add    $0x1,%rbp
  movzbl -0x1(%rbp),%ebx
L184:
  mov    %ebx,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  je     L15
  sub    $0x30,%ebx
L271:
  cmp    %ebx,%r14d
  jle    L18
  test   %r13d,%r13d
  js     L269
  cmpl   $0x0,(%rsp)
  je     L282
  cmp    %r15,%r12
  jl     L224
  jne    L152
  cmp    0x4(%rsp),%ebx
  jg     L224
L152:
  imul   0x8(%rsp),%r12
  movslq %ebx,%rbx
  sub    %rbx,%r12
  mov    (%rsp),%r13d
  jmp    L269
L282:
  cmp    %r15,%r12
  jg     L240
  jne    L207
  cmp    0x4(%rsp),%ebx
  jle    L207
L240:
  mov    D78(%rip),%rax
  mov    (%rax),%r12
  mov    D23(%rip),%rax
  mov    (%rax),%edx
  mov    D21(%rip),%rax
  mov    %edx,(%rax)
  mov    $0xffffffff,%r13d
  jmp    L269
L207:
  imul   0x8(%rsp),%r12
  movslq %ebx,%rbx
  add    %rbx,%r12
  mov    $0x1,%r13d
  jmp    L269
L18:
  mov    0x10(%rsp),%rax
  test   %rax,%rax
  je     L277
  sub    $0x1,%rbp
  test   %r13d,%r13d
  cmove  0x18(%rsp),%rbp
  mov    %rbp,(%rax)
L277:
  mov    %r12,%rax
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
long strtol(const char *nptr, char **endptr, int base) {
  const char *s;
  long acc, cutoff;
  int c;
  int neg, any, cutlim;
  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 = neg ? LONG_MIN : LONG_MAX;
  cutlim = cutoff % base;
  cutoff /= base;
  if (neg) {
    if (cutlim > 0) {
      cutlim -= base;
      cutoff += 1;
    }
    cutlim = -cutlim;
  }
  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 (neg) {
      if (acc < cutoff || (acc == cutoff && c > cutlim)) {
        any = -1;
        acc = LONG_MIN;
        errno = ERANGE;
      } else {
        any = 1;
        acc *= base;
        acc -= c;
      }
    } else {
      if (acc > cutoff || (acc == cutoff && c > cutlim)) {
        any = -1;
        acc = LONG_MAX;
        errno = ERANGE;
      } else {
        any = 1;
        acc *= base;
        acc += c;
      }
    }
  }
  if (endptr != 0)
    *endptr = (char *)(any ? s - 1 : nptr);
  return (acc);
}
```