user: 下面的汇编指令对应的C源代码是什么：

```asm
<getop>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x20,%rsp
  mov    %rdi,-0x18(%rbp)
  nop
L137:
  mov    $0x0,%eax
  call   <getch@plt>
  mov    %eax,-0x8(%rbp)
  mov    -0x8(%rbp),%eax
  mov    %eax,%edx
  mov    -0x18(%rbp),%rax
  mov    %dl,(%rax)
  mov    -0x18(%rbp),%rax
  movzbl (%rax),%eax
  cmp    $0x20,%al
  je     L137
  cmpl   $0x9,-0x8(%rbp)
  je     L137
  mov    -0x8(%rbp),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  jne    L63
  cmpl   $0x2e,-0x8(%rbp)
  je     L63
  cmpl   $0x2d,-0x8(%rbp)
  jne    L9
  mov    $0x0,%eax
  call   <getch@plt>
  mov    %eax,-0x4(%rbp)
  mov    -0x4(%rbp),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  jne    L27
  cmpl   $0x2e,-0x4(%rbp)
  jne    L10
L27:
  mov    -0x4(%rbp),%eax
  mov    %eax,-0x8(%rbp)
  movl   $0x1,-0xc(%rbp)
  mov    -0x18(%rbp),%rax
  add    $0x1,%rax
  mov    -0x8(%rbp),%edx
  mov    %dl,(%rax)
  jmp    L0
L10:
  mov    D6(%rip),%rax
  mov    (%rax),%eax
  cmp    %eax,-0x4(%rbp)
  je     L129
  mov    -0x4(%rbp),%eax
  mov    %eax,%edi
  call   <ungetch@plt>
L129:
  mov    -0x18(%rbp),%rax
  add    $0x1,%rax
  movb   $0x0,(%rax)
  mov    -0x8(%rbp),%eax
  jmp    L149
L9:
  mov    -0x18(%rbp),%rax
  add    $0x1,%rax
  movb   $0x0,(%rax)
  mov    -0x8(%rbp),%eax
  jmp    L149
L63:
  movl   $0x0,-0xc(%rbp)
L0:
  mov    -0x8(%rbp),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  je     L136
  nop
L135:
  mov    $0x0,%eax
  call   <getch@plt>
  mov    %eax,-0x8(%rbp)
  addl   $0x1,-0xc(%rbp)
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  mov    -0x8(%rbp),%edx
  mov    %dl,(%rax)
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  jne    L135
L136:
  cmpl   $0x2e,-0x8(%rbp)
  jne    L73
  nop
L36:
  mov    $0x0,%eax
  call   <getch@plt>
  mov    %eax,-0x8(%rbp)
  addl   $0x1,-0xc(%rbp)
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  mov    -0x8(%rbp),%edx
  mov    %dl,(%rax)
  movzbl (%rax),%eax
  movsbl %al,%eax
  mov    %eax,%edi
  call   <isdigit@plt>
  test   %rax,%rax
  jne    L36
L73:
  mov    -0xc(%rbp),%eax
  movslq %eax,%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  movb   $0x0,(%rax)
  mov    D6(%rip),%rax
  mov    (%rax),%eax
  cmp    %eax,-0x8(%rbp)
  je     L132
  mov    -0x8(%rbp),%eax
  mov    %eax,%edi
  call   <ungetch@plt>
L132:
  mov    $0x30,%eax
L149:
  leave
  ret
```

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