user: 提供的汇编代码用C语言表示会是什么样子:

```asm
<next_spec>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  push   %r12
  push   %rbx
  mov    %rdi,-0x18(%rbp)
  mov    %rsi,-0x20(%rbp)
  mov    -0x20(%rbp),%rbx
  mov    -0x18(%rbp),%r12
  jmp    L37
L114:
  movzbl (%r12),%eax
  test   %al,%al
  jne    L12
  movb   $0x0,(%rbx)
  mov    $0xffffffff,%eax
  jmp    L138
L12:
  mov    %r12,%rdx
  lea    0x1(%rdx),%r12
  mov    %rbx,%rax
  lea    0x1(%rax),%rbx
  movzbl (%rdx),%edx
  mov    %dl,(%rax)
L37:
  movzbl (%r12),%eax
  cmp    $0x25,%al
  jne    L114
  mov    %r12,%rdx
  lea    0x1(%rdx),%r12
  mov    %rbx,%rax
  lea    0x1(%rax),%rbx
  movzbl (%rdx),%edx
  mov    %dl,(%rax)
  jmp    L277
L81:
  movzbl (%r12),%eax
  movsbl %al,%eax
  cmp    $0x63,%eax
  jg     L205
  cmp    $0x20,%eax
  jge    L228
  jmp    L101
L88:
  sub    $0x64,%eax
  mov    $0x1,%edx
  mov    %eax,%ecx
  shl    %cl,%rdx
  mov    %rdx,%rax
  mov    %rax,%rdx
  and    $0x120801,%edx
  test   %rdx,%rdx
  setne  %dl
  test   %dl,%dl
  jne    L192
  mov    %rax,%rdx
  and    $0xe,%edx
  test   %rdx,%rdx
  setne  %dl
  test   %dl,%dl
  jne    L20
  and    $0x8000,%eax
  test   %rax,%rax
  setne  %al
  test   %al,%al
  jne    L216
  jmp    L101
L228:
  sub    $0x20,%eax
  cmp    $0x43,%eax
  ja     L101
  mov    %eax,%eax
  lea    0x0(,%rax,4),%rdx
  lea    D7(%rip),%rax
  mov    (%rdx,%rax,1),%eax
  cltq
  lea    D7(%rip),%rdx
  add    %rdx,%rax
  notrack jmp *%rax
L205:
  cmp    $0x78,%eax
  jg     L101
  cmp    $0x64,%eax
  jge    L88
  jmp    L101
  movb   $0x0,(%rbx)
  mov    $0xffffffff,%eax
  jmp    L138
L192:
  movb   $0x0,(%rbx)
  mov    $0x4,%eax
  jmp    L138
  movb   $0x0,(%rbx)
  mov    $0x0,%eax
  jmp    L138
L20:
  movb   $0x0,(%rbx)
  mov    $0x2,%eax
  jmp    L138
L216:
  movb   $0x0,(%rbx)
  mov    $0x5,%eax
  jmp    L138
  add    $0x1,%r12
  jmp    L226
L162:
  movzbl (%r12),%eax
  test   %al,%al
  jne    L150
  mov    $0xfffffffe,%eax
  jmp    L138
L150:
  mov    %r12,%rdx
  lea    0x1(%rdx),%r12
  mov    %rbx,%rax
  lea    0x1(%rax),%rbx
  movzbl (%rdx),%edx
  mov    %dl,(%rax)
L226:
  movzbl (%r12),%eax
  cmp    $0x5d,%al
  jne    L162
  mov    %rbx,%rax
  lea    0x1(%rax),%rbx
  movb   $0x5d,(%rax)
  movb   $0x0,(%rbx)
  mov    $0x5,%eax
  jmp    L138
L101:
  mov    $0xfffffffe,%eax
  jmp    L138
  nop
  add    $0x1,%r12
L277:
  mov    %rbx,%rax
  lea    0x1(%rax),%rbx
  movzbl (%r12),%edx
  mov    %dl,(%rax)
  movzbl (%rax),%eax
  test   %al,%al
  jne    L81
  mov    $0xfffffffe,%eax
L138:
  pop    %rbx
  pop    %r12
  pop    %rbp
  ret
```

assistant: ```c
int next_spec(specin, specout)
char *specin, *specout;
{
  register char *s = specout;
  register char *t = specin;
  for (; *t != '%'; *s++ = *t++) {
    if (*t == '\0') {
      *s = '\0';
      return (-1);
    }
  }
  *s++ = *t++;
  for (; *s++ = *t; t++) {
    switch (*t) {
    case '%':
      *s = '\0';
      return (-1);
    case 'd':
    case 'x':
    case 'o':
    case 'u':
      *s = '\0';
      return (4);
    case 'c':
      *s = '\0';
      return (0);
    case 'f':
    case 'e':
    case 'g':
      *s = '\0';
      return (2);
    case 's':
      *s = '\0';
      return (5);
    case '[':
      t += 1;
      while (*t != ']') {
        if (*t == '\0')
          return (-2);
        *s++ = *t++;
      }
      *s++ = ']';
      *s = '\0';
      return (5);
    case '#':
    case '-':
    case '+':
    case ' ':
    case '.':
    case '0':
    case '1':
    case '2':
    case '3':
    case '4':
    case '5':
    case '6':
    case '7':
    case '8':
    case '9':
      break;
    default:
      return (-2);
    }
  }
  return (-2);
}
```