user: What would the C source look like for the assembly code provided here:

```asm
<parse_qrels_line>:
  endbr64
  push   %r15
  mov    %rdx,%r15
  push   %r14
  mov    %rcx,%r14
  push   %r13
  mov    %rdi,%r13
  push   %r12
  push   %rbp
  mov    %rsi,%rbp
  push   %rbx
  sub    $0x8,%rsp
  mov    (%rdi),%rbx
  movsbl (%rbx),%edi
  cmp    $0xa,%dil
  jne    L139
  jmp    L213
  nopl   0x0(%rax)
L149:
  movsbl 0x1(%rbx),%edi
  add    $0x1,%rbx
  cmp    $0xa,%dil
  je     L213
L139:
  call   <isspace@plt>
  test   %rax,%rax
  jne    L149
L213:
  mov    %rbx,0x0(%rbp)
  jmp    L208
  xchg   %ax,%ax
L133:
  add    $0x1,%rbx
L208:
  movsbl (%rbx),%edi
  call   <isspace@plt>
  test   %rax,%rax
  je     L133
  cmpb   $0xa,(%rbx)
  je     L313
  movsbl 0x1(%rbx),%edi
  movb   $0x0,(%rbx)
  lea    0x1(%rbx),%r12
  cmp    $0xa,%dil
  jne    L164
  jmp    L130
  nopl   (%rax)
L46:
  movsbl 0x1(%r12),%edi
  add    $0x1,%r12
  cmp    $0xa,%dil
  je     L130
L164:
  call   <isspace@plt>
  test   %rax,%rax
  jne    L46
  movsbl (%r12),%edi
  call   <isspace@plt>
  test   %rax,%rax
  jne    L54
  nopl   0x0(%rax)
L323:
  add    $0x1,%r12
L130:
  movsbl (%r12),%edi
  call   <isspace@plt>
  test   %rax,%rax
  je     L323
L54:
  cmpb   $0xa,(%r12)
  je     L313
  movsbl 0x1(%r12),%edi
  lea    0x1(%r12),%rbp
  cmp    $0xa,%dil
  jne    L248
  jmp    L155
  nopl   0x0(%rax)
L261:
  movsbl 0x1(%rbp),%edi
  add    $0x1,%rbp
  cmp    $0xa,%dil
  je     L155
L248:
  call   <isspace@plt>
  test   %rax,%rax
  jne    L261
L155:
  mov    %rbp,(%r15)
  jmp    L85
  nopl   (%rax)
L109:
  add    $0x1,%rbp
L85:
  movsbl 0x0(%rbp),%edi
  call   <isspace@plt>
  test   %rax,%rax
  je     L109
  cmpb   $0xa,0x0(%rbp)
  je     L313
  movsbl 0x1(%rbp),%edi
  movb   $0x0,0x0(%rbp)
  lea    0x1(%rbp),%rbx
  cmp    $0xa,%dil
  jne    L32
  jmp    L313
  nopl   0x0(%rax,%rax,1)
L247:
  movsbl 0x1(%rbx),%edi
  add    $0x1,%rbx
  cmp    $0xa,%dil
  je     L313
L32:
  call   <isspace@plt>
  test   %rax,%rax
  jne    L247
  cmpb   $0xa,(%rbx)
  je     L313
  mov    %rbx,(%r14)
  nopl   0x0(%rax)
L66:
  movsbl (%rbx),%edi
  call   <isspace@plt>
  mov    %rbx,%rdx
  add    $0x1,%rbx
  test   %rax,%rax
  je     L66
  cmpb   $0xa,(%rdx)
  je     L206
  movsbl 0x1(%rdx),%edi
  movb   $0x0,(%rdx)
  cmp    $0xa,%dil
  jne    L256
  jmp    L44
L277:
  movsbl 0x1(%rbx),%edi
  add    $0x1,%rbx
  cmp    $0xa,%dil
  je     L44
L256:
  call   <isspace@plt>
  test   %rax,%rax
  jne    L277
  cmpb   $0xa,(%rbx)
  jne    L313
L44:
  mov    %rbx,%rdx
L206:
  movb   $0x0,(%rdx)
  add    $0x1,%rdx
  xor    %eax,%eax
  mov    %rdx,0x0(%r13)
L269:
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax)
L313:
  mov    $0xffffffff,%eax
  jmp    L269
```

assistant: ```c
int parse_qrels_line(char **start_ptr, char **qid_ptr, char **docno_ptr, char **rel_ptr) {
  char *ptr = *start_ptr;
  while (*ptr != '\n' && isspace(*ptr))
    ptr++;
  *qid_ptr = ptr;
  while (!isspace(*ptr))
    ptr++;
  if (*ptr == '\n')
    return (-1);
  *ptr++ = '\0';
  while (*ptr != '\n' && isspace(*ptr))
    ptr++;
  while (!isspace(*ptr))
    ptr++;
  if (*ptr == '\n')
    return (-1);
  ptr++;
  while (*ptr != '\n' && isspace(*ptr))
    ptr++;
  *docno_ptr = ptr;
  while (!isspace(*ptr))
    ptr++;
  if (*ptr == '\n')
    return (-1);
  *ptr++ = '\0';
  while (*ptr != '\n' && isspace(*ptr))
    ptr++;
  if (*ptr == '\n')
    return (-1);
  *rel_ptr = ptr;
  while (!isspace(*ptr))
    ptr++;
  if (*ptr != '\n') {
    *ptr++ = '\0';
    while (*ptr != '\n' && isspace(*ptr))
      ptr++;
    if (*ptr != '\n')
      return (-1);
  }
  *ptr++ = '\0';
  *start_ptr = ptr;
  return (0);
}
```