user: 这段汇编代码用C语言表示是什么样的:

```asm
<to8bit>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x10,%rsp
  jmp    L138
L155:
  andl   $0xff,-0x4(%rbp)
  cmpl   $0x5c,-0x4(%rbp)
  je     L69
  mov    -0x4(%rbp),%eax
  mov    %eax,%edi
  call   <putchar@plt>
  jmp    L138
L69:
  mov    $0x0,%eax
  call   <getchar@plt>
  mov    %eax,-0x4(%rbp)
  cmpl   $0x80,-0x4(%rbp)
  je     L31
  cmpl   $0x80,-0x4(%rbp)
  jg     L68
  cmpl   $0x78,-0x4(%rbp)
  je     L404
  cmpl   $0x78,-0x4(%rbp)
  jg     L68
  cmpl   $0x37,-0x4(%rbp)
  jg     L372
  cmpl   $0x30,-0x4(%rbp)
  jge    L35
  jmp    L68
L372:
  cmpl   $0x58,-0x4(%rbp)
  je     L404
  jmp    L68
L31:
  mov    $0x5c,%edi
  call   <putchar@plt>
  jmp    L337
L404:
  mov    -0x4(%rbp),%eax
  mov    %eax,-0x8(%rbp)
  mov    $0x0,%eax
  call   <getchar@plt>
  mov    %eax,-0x4(%rbp)
  cmpl   $0x2f,-0x4(%rbp)
  jle    L273
  cmpl   $0x39,-0x4(%rbp)
  jg     L273
  mov    -0x4(%rbp),%eax
  sub    $0x30,%eax
  mov    %eax,-0x8(%rbp)
  jmp    L322
L273:
  cmpl   $0x60,-0x4(%rbp)
  jle    L83
  cmpl   $0x66,-0x4(%rbp)
  jg     L83
  mov    -0x4(%rbp),%eax
  sub    $0x57,%eax
  mov    %eax,-0x8(%rbp)
  jmp    L322
L83:
  cmpl   $0x40,-0x4(%rbp)
  jle    L132
  cmpl   $0x46,-0x4(%rbp)
  jg     L132
  mov    -0x4(%rbp),%eax
  sub    $0x37,%eax
  mov    %eax,-0x8(%rbp)
  jmp    L322
L132:
  mov    $0x5c,%edi
  call   <putchar@plt>
  mov    -0x8(%rbp),%eax
  mov    %eax,%edi
  call   <putchar@plt>
  mov    -0x4(%rbp),%eax
  mov    %eax,%edi
  call   <putchar@plt>
  jmp    L138
L322:
  mov    $0x0,%eax
  call   <getchar@plt>
  mov    %eax,-0x4(%rbp)
  cmpl   $0x2f,-0x4(%rbp)
  jle    L187
  cmpl   $0x39,-0x4(%rbp)
  jg     L187
  mov    -0x8(%rbp),%eax
  shl    $0x4,%eax
  mov    %eax,%edx
  mov    -0x4(%rbp),%eax
  sub    $0x30,%eax
  or     %edx,%eax
  mov    %eax,-0x8(%rbp)
  jmp    L97
L187:
  cmpl   $0x60,-0x4(%rbp)
  jle    L29
  cmpl   $0x66,-0x4(%rbp)
  jg     L29
  mov    -0x4(%rbp),%eax
  shl    $0x4,%eax
  sub    $0x57,%eax
  mov    %eax,-0x8(%rbp)
  jmp    L97
L29:
  cmpl   $0x40,-0x4(%rbp)
  jle    L120
  cmpl   $0x46,-0x4(%rbp)
  jg     L120
  mov    -0x4(%rbp),%eax
  shl    $0x4,%eax
  sub    $0x37,%eax
  mov    %eax,-0x8(%rbp)
  jmp    L97
L120:
  mov    -0x8(%rbp),%eax
  mov    %eax,%edi
  call   <putchar@plt>
  mov    -0x4(%rbp),%eax
  mov    %eax,%edi
  call   <putchar@plt>
  jmp    L138
L97:
  mov    -0x8(%rbp),%eax
  mov    %eax,%edi
  call   <putchar@plt>
  jmp    L138
L35:
  mov    -0x4(%rbp),%eax
  sub    $0x30,%eax
  mov    %eax,-0x8(%rbp)
  mov    $0x0,%eax
  call   <getchar@plt>
  mov    %eax,-0x4(%rbp)
  cmpl   $0x2f,-0x4(%rbp)
  jle    L202
  cmpl   $0x37,-0x4(%rbp)
  jg     L202
  mov    -0x8(%rbp),%eax
  lea    0x0(,%rax,8),%edx
  mov    -0x4(%rbp),%eax
  sub    $0x30,%eax
  or     %edx,%eax
  mov    %eax,-0x8(%rbp)
  mov    $0x0,%eax
  call   <getchar@plt>
  mov    %eax,-0x4(%rbp)
  cmpl   $0x2f,-0x4(%rbp)
  jg     L64
  jmp    L342
L202:
  mov    -0x8(%rbp),%eax
  mov    %eax,%edi
  call   <putchar@plt>
  mov    -0x4(%rbp),%eax
  mov    %eax,%edi
  call   <putchar@plt>
  jmp    L138
L64:
  cmpl   $0x37,-0x4(%rbp)
  jg     L342
  mov    -0x8(%rbp),%eax
  lea    0x0(,%rax,8),%edx
  mov    -0x4(%rbp),%eax
  sub    $0x30,%eax
  or     %edx,%eax
  mov    %eax,-0x8(%rbp)
  mov    -0x8(%rbp),%eax
  mov    %eax,%edi
  call   <putchar@plt>
  jmp    L138
L342:
  mov    -0x8(%rbp),%eax
  mov    %eax,%edi
  call   <putchar@plt>
  mov    -0x4(%rbp),%eax
  mov    %eax,%edi
  call   <putchar@plt>
  jmp    L138
L68:
  mov    $0x5c,%edi
  call   <putchar@plt>
  mov    -0x4(%rbp),%eax
  mov    %eax,%edi
  call   <putchar@plt>
  nop
L138:
  mov    $0x0,%eax
  call   <getchar@plt>
  mov    %eax,-0x4(%rbp)
  cmpl   $0x80,-0x4(%rbp)
  jne    L155
L337:
  leave
  ret
```

assistant: ```c
void to8bit() {
  int backch;
  int ch;
  while ((ch = getchar()) != EOF) {
    ch &= 0xFF;
    if (ch != '\\')
      (void)putchar(ch);
    else {
      ch = getchar();
      switch (ch) {
      case EOF:
        (void)putchar('\\');
        return;
      case 'x':
      case 'X':
        backch = ch;
        ch = getchar();
        if (ch >= '0' && ch <= '9')
          backch = ch - '0';
        else if (ch >= 'a' && ch <= 'f')
          backch = ch - 'a' + 0xA;
        else if (ch >= 'A' && ch <= 'F')
          backch = ch - 'A' + 0xA;
        else {
          (void)putchar('\\');
          (void)putchar(backch);
          (void)putchar(ch);
          break;
        }
        ch = getchar();
        if (ch >= '0' && ch <= '9')
          backch = (backch << 4) | (ch - '0');
        else if (ch >= 'a' && ch <= 'f')
          backch = (ch << 4) - 'a' + 0xA;
        else if (ch >= 'A' && ch <= 'F')
          backch = (ch << 4) - 'A' + 0xA;
        else {
          (void)putchar(backch);
          (void)putchar(ch);
          break;
        }
        (void)putchar(backch);
        break;
      case '0':
      case '1':
      case '2':
      case '3':
      case '4':
      case '5':
      case '6':
      case '7':
        backch = ch - '0';
        ch = getchar();
        if (ch >= '0' && ch <= '7')
          backch = (backch << 3) | (ch - '0');
        else {
          (void)putchar(backch);
          (void)putchar(ch);
          break;
        }
        ch = getchar();
        if (ch >= '0' && ch <= '7')
          backch = (backch << 3) | (ch - '0');
        else {
          (void)putchar(backch);
          (void)putchar(ch);
          break;
        }
        (void)putchar(backch);
        break;
        break;
      default:
        (void)putchar('\\');
        (void)putchar(ch);
        break;
      }
    }
  }
}
```