user: Translate the below assembly code into C programming language:

```asm
<dt_parse_iso_zone_lenient>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x18,%rsp
  test   %rsi,%rsi
  je     L271
  movzbl (%rdi),%eax
  mov    %rdi,%rbp
  mov    %rsi,%r12
  mov    %rdx,%r14
  cmp    $0x47,%al
  je     L315
  jbe    L185
  mov    %eax,%edx
  and    $0xffffffdf,%edx
  cmp    $0x5a,%dl
  je     L145
  cmp    $0x55,%al
  jne    L271
  cmp    $0x2,%rsi
  jbe    L271
  cmpb   $0x54,0x1(%rdi)
  je     L71
  nop
L271:
  xor    %r13d,%r13d
L267:
  add    $0x18,%rsp
  mov    %r13,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   (%rax)
L185:
  cmp    $0x2b,%al
  je     L194
  cmp    $0x2d,%al
  jne    L271
  mov    $0xffffffff,%r15d
L250:
  cmp    $0x1,%r12
  je     L271
  mov    %r12,%rdx
  mov    $0x1,%esi
  mov    %rbp,%rdi
  call   <count_digits@plt>
  cmp    $0x2,%eax
  je     L137
  cmp    $0x4,%eax
  je     L134
  cmp    $0x1,%eax
  jne    L271
  mov    $0x1,%esi
  mov    $0x1,%edx
  mov    %rbp,%rdi
  mov    $0x2,%r13d
  call   <parse_number@plt>
  mov    $0x3,%esi
  mov    %eax,%ebx
L233:
  xor    %edx,%edx
  xor    %eax,%eax
  cmp    %r12,%rsi
  ja     L338
  cmpb   $0x3a,0x0(%rbp,%r13,1)
  je     L188
L338:
  cmp    $0x17,%ebx
  jg     L271
  test   %dl,%dl
  jne    L271
  imul   $0x3c,%ebx,%ebx
  add    %ebx,%eax
  imul   %r15d,%eax
  jmp    L9
  nopw   0x0(%rax,%rax,1)
L194:
  mov    $0x1,%r15d
  jmp    L250
  nopl   0x0(%rax,%rax,1)
L145:
  mov    $0x1,%r13d
  xor    %eax,%eax
L9:
  test   %r14,%r14
  je     L267
  mov    %eax,(%r14)
  jmp    L267
  nopl   0x0(%rax)
L315:
  cmp    $0x2,%rsi
  jbe    L271
  cmpb   $0x4d,0x1(%rdi)
  jne    L271
  cmpb   $0x54,0x2(%rdi)
  jne    L271
L11:
  cmp    $0x3,%r12
  je     L99
  movzbl 0x3(%rbp),%eax
  sub    $0x2b,%eax
  test   $0xfd,%al
  jne    L99
  lea    -0x3(%r12),%rsi
  lea    0x3(%rbp),%rdi
  mov    %r14,%rdx
  call   <dt_parse_iso_zone_lenient>
  lea    0x3(%rax),%r13
  test   %rax,%rax
  jne    L267
  jmp    L271
  nopw   0x0(%rax,%rax,1)
L71:
  cmpb   $0x43,0x2(%rdi)
  jne    L271
  jmp    L11
  nopl   0x0(%rax)
L134:
  mov    $0x2,%edx
  mov    $0x1,%esi
  mov    %rbp,%rdi
  mov    $0x5,%r13d
  call   <parse_number@plt>
  mov    $0x2,%edx
  mov    $0x3,%esi
  mov    %rbp,%rdi
  mov    %eax,%ebx
  call   <parse_number@plt>
  cmp    $0x3b,%eax
  setg   %dl
  jmp    L338
  nopw   0x0(%rax,%rax,1)
L137:
  mov    $0x1,%esi
  mov    $0x2,%edx
  mov    %rbp,%rdi
  mov    $0x3,%r13d
  call   <parse_number@plt>
  mov    $0x4,%esi
  mov    %eax,%ebx
  jmp    L233
  nopl   0x0(%rax)
L99:
  mov    $0x3,%r13d
  xor    %eax,%eax
  jmp    L9
  nopl   (%rax)
L188:
  mov    %r12,%rdx
  mov    %rbp,%rdi
  mov    %rsi,0x8(%rsp)
  call   <count_digits@plt>
  mov    0x8(%rsp),%rsi
  cmp    $0x2,%eax
  jne    L271
  mov    $0x2,%edx
  mov    %rbp,%rdi
  add    $0x3,%r13
  call   <parse_number@plt>
  cmp    $0x3b,%eax
  setg   %dl
  jmp    L338
```

assistant: ```c
size_t dt_parse_iso_zone_lenient(const char *str, size_t len, int *op) {
  const unsigned char *p;
  int o, h, m, sign;
  size_t n;
  if (len < 1)
    return 0;
  p = (const unsigned char *)str;
  switch (*p) {
  case 'z':
  case 'Z':
    o = 0;
    n = 1;
    goto zulu;
  case 'G':
    if (len < 3 || p[1] != 'M' || p[2] != 'T')
      return 0;
    if (len > 3 && (p[3] == '+' || p[3] == '-')) {
      if (!(n = dt_parse_iso_zone_lenient(str + 3, len - 3, op)))
        return 0;
      return n + 3;
    }
    o = 0;
    n = 3;
    goto zulu;
  case 'U':
    if (len < 3 || p[1] != 'T' || p[2] != 'C')
      return 0;
    if (len > 3 && (p[3] == '+' || p[3] == '-')) {
      if (!(n = dt_parse_iso_zone_lenient(str + 3, len - 3, op)))
        return 0;
      return n + 3;
    }
    o = 0;
    n = 3;
    goto zulu;
  case '+':
    sign = 1;
    break;
  case '-':
    sign = -1;
    break;
  default:
    return 0;
  }
  if (len < 2)
    return 0;
  n = count_digits(p, 1, len);
  m = 0;
  switch (n) {
  case 1:
    h = parse_number(p, 1, 1);
    n = 2;
    break;
  case 2:
    h = parse_number(p, 1, 2);
    n = 3;
    break;
  case 4:
    h = parse_number(p, 1, 2);
    m = parse_number(p, 3, 2);
    n = 5;
    goto hm;
  default:
    return 0;
  }
  if (len < n + 1 || p[n] != ':')
    goto hm;
  if (count_digits(p, ++n, len) != 2)
    return 0;
  m = parse_number(p, n, 2);
  n += 2;
hm:
  if (h > 23 || m > 59)
    return 0;
  o = sign * (h * 60 + m);
zulu:
  if (op)
    *op = o;
  return n;
}
```