user: 请从给定的汇编指令推导出C源代码：

```asm
<getop>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x20,%rsp
  mov    %rdi,-0x18(%rbp)
  nop
L67:
  mov    $0x0,%eax
  call   <getch@plt>
  mov    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  mov    %dl,(%rax)
  mov    -0x18(%rbp),%rax
  movzbl (%rax),%eax
  cmp    $0x20,%al
  je     L67
  cmpl   $0x9,-0x4(%rbp)
  je     L67
  mov    -0x18(%rbp),%rax
  add    $0x1,%rax
  movb   $0x0,(%rax)
  movl   $0x0,-0x8(%rbp)
  mov    -0x4(%rbp),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isalpha@plt>
  test   %rax,%rax
  je     L32
  nop
L96:
  mov    $0x0,%eax
  call   <getch@plt>
  mov    %eax,-0x4(%rbp)
  addl   $0x1,-0x8(%rbp)
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  mov    -0x4(%rbp),%edx
  mov    %dl,(%rax)
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isalpha@plt>
  test   %rax,%rax
  jne    L96
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  mov    D15(%rip),%rax
  mov    (%rax),%eax
  cmp    %eax,-0x4(%rbp)
  je     L50
  mov    -0x4(%rbp),%eax
  mov    %eax,%edi
  call   <ungetch@plt>
L50:
  mov    $0x66,%eax
  jmp    L30
L32:
  mov    -0x4(%rbp),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  jne    L124
  cmpl   $0x2e,-0x4(%rbp)
  je     L124
  mov    -0x4(%rbp),%eax
  jmp    L30
L124:
  movl   $0x0,-0x8(%rbp)
  mov    -0x4(%rbp),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  je     L21
  nop
L6:
  mov    $0x0,%eax
  call   <getch@plt>
  mov    %eax,-0x4(%rbp)
  addl   $0x1,-0x8(%rbp)
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  mov    -0x4(%rbp),%edx
  mov    %dl,(%rax)
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  jne    L6
L21:
  cmpl   $0x2e,-0x4(%rbp)
  jne    L10
  nop
L16:
  mov    $0x0,%eax
  call   <getch@plt>
  mov    %eax,-0x4(%rbp)
  addl   $0x1,-0x8(%rbp)
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  mov    -0x4(%rbp),%edx
  mov    %dl,(%rax)
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  jne    L16
L10:
  mov    -0x8(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  mov    D15(%rip),%rax
  mov    (%rax),%eax
  cmp    %eax,-0x4(%rbp)
  je     L60
  mov    -0x4(%rbp),%eax
  mov    %eax,%edi
  call   <ungetch@plt>
L60:
  mov    $0x30,%eax
L30:
  leave
  ret
```

assistant: ```c
int getop(char s[]) {
  int i, c;
  while ((s[0] = c = getch()) == ' ' || c == '\t') {
    ;
  }
  s[1] = '\0';
  i = 0;
  if (isalpha(c)) {
    while (isalpha(s[++i] = c = getch())) {
      ;
    }
    s[i] = '\0';
    if (c != EOF) {
      ungetch(c);
    }
    return 'f';
  }
  if (!isdigit(c) && c != '.') {
    return c;
  }
  i = 0;
  if (isdigit(c)) {
    while (isdigit(s[++i] = c = getch())) {
      ;
    }
  }
  if (c == '.') {
    while (isdigit(s[++i] = c = getch())) {
      ;
    }
  }
  s[i] = '\0';
  if (c != EOF) {
    ungetch(c);
  }
  return '0';
}
```