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

```asm
<epr_str_tok_tok>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  mov    %rdx,%r13
  push   %r12
  mov    %rcx,%r12
  push   %rbp
  mov    %rdi,%rbp
  push   %rbx
  mov    %rsi,%rbx
  sub    $0x18,%rsp
  test   %rdi,%rdi
  setne  %dil
  movzbl %dil,%edi
  call   <assert@plt>
  mov    (%r12),%r14
  mov    %rbp,%rdi
  call   <strlen@plt>
  cmp    %rax,%r14
  jae    L67
  lea    0x0(%rbp,%r14,1),%rcx
  mov    %r14,%r15
  movsbl (%rcx),%esi
  mov    %rcx,0x8(%rsp)
  test   %sil,%sil
  jne    L63
  jmp    L149
  nopl   (%rax)
L133:
  add    $0x1,%r15
  movsbl 0x0(%rbp,%r15,1),%esi
  test   %sil,%sil
  je     L116
L63:
  mov    %rbx,%rdi
  call   <strchr@plt>
  test   %rax,%rax
  je     L109
  test   %r15,%r15
  je     L81
  movsbl 0x0(%rbp,%r15,1),%esi
  mov    %rbx,%rdi
  call   <strchr@plt>
  test   %rax,%rax
  je     L133
L30:
  movsbl -0x1(%rbp,%r15,1),%esi
  mov    %r13,%rdi
  call   <strchr@plt>
  test   %rax,%rax
  jne    L133
  lea    0x1(%r15),%rbx
  jmp    L146
  nopl   0x0(%rax)
L109:
  movsbl 0x0(%rbp,%r15,1),%esi
  mov    %rbx,%rdi
  call   <strchr@plt>
  test   %r15,%r15
  je     L133
  test   %rax,%rax
  jne    L30
  add    $0x1,%r15
  movsbl 0x0(%rbp,%r15,1),%esi
  test   %sil,%sil
  jne    L63
  nop
L116:
  mov    %rbp,%rdi
  call   <strlen@plt>
L149:
  test   %rax,%rax
  je     L67
  test   %r14,%r14
  jne    L107
  lea    0x1(%r15),%rdx
  mov    0x8(%rsp),%rdi
  mov    %rdx,(%r12)
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  jmp    10d0 <epr_clone_string@plt>
  nopw   0x0(%rax,%rax,1)
L81:
  mov    $0x1,%ebx
L146:
  sub    (%r12),%r15
  mov    %r15,%rdi
  call   <epr_create_string@plt>
  mov    (%r12),%rsi
  mov    %r15,%rdx
  mov    %rax,%r13
  mov    %rax,%rdi
  add    %rbp,%rsi
  call   <strncpy@plt>
  movb   $0x0,0x0(%r13,%r15,1)
  mov    %rbx,(%r12)
L33:
  add    $0x18,%rsp
  mov    %r13,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopw   0x0(%rax,%rax,1)
L67:
  xor    %r13d,%r13d
  jmp    L33
  nopl   (%rax)
L107:
  mov    %r15,%rbx
  sub    %r14,%rbx
  mov    %rbx,%rdi
  call   <epr_create_string@plt>
  mov    (%r12),%rsi
  mov    %rbx,%rdx
  mov    %rax,%r13
  mov    %rax,%rdi
  add    %rbp,%rsi
  call   <strncpy@plt>
  movb   $0x0,0x0(%r13,%rbx,1)
  mov    %rbp,%rdi
  call   <strlen@plt>
  cltq
  mov    %rax,(%r12)
  jmp    L33
```

assistant: ```c
char *epr_str_tok_tok(const char *str, const char *seps, const char *exceptions, uint *pos) {
  char *token = NULL;
  uint i, old_pos;
  uint token_len = 0;
  assert(str != NULL);
  if (*pos >= (uint)strlen(str))
    return NULL;
  old_pos = *pos;
  for (i = *pos; str[i] != '\0'; i++) {
    if (((strchr(seps, str[i]) != NULL) && (i == 0)) || ((strchr(seps, str[i]) != NULL) && (i > 0) && (strchr(exceptions, str[i - 1]) == NULL))) {
      token_len = i - *pos;
      token = epr_create_string(token_len);
      strncpy(token, str + *pos, token_len);
      token[token_len] = '\0';
      *pos = i + 1;
      return token;
    }
  }
  if (strlen(str) > 0) {
    if (old_pos == 0) {
      *pos = i + 1;
      token = epr_clone_string(str);
      return token;
    } else if (old_pos > 0) {
      token_len = i - old_pos;
      token = epr_create_string(token_len);
      strncpy(token, str + *pos, token_len);
      token[token_len] = '\0';
      *pos = (int)strlen(str);
      return token;
    }
  }
  return NULL;
}
```