user: 请显示与下面列出的汇编代码相匹配的C语言实现:

```asm
<conv_expand>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x8,%rsp
  mov    %rdi,%rbx
  mov    D29(%rip),%rdi
  test   %rdi,%rdi
  je     L149
  call   <free@plt>
L149:
  mov    %rbx,%rdi
  call   <strlen@plt>
  lea    0x1(,%rax,4),%edi
  call   <malloc@plt>
  mov    %rax,%r15
  mov    %rax,D0(%rip)
  test   %rax,%rax
  je     L80
  lea    0x1(%rbx),%r12
  movzbl (%rbx),%ebp
  movzbl %bpl,%r13d
  test   %r13d,%r13d
  je     L35
  mov    %rax,%rbx
  lea    D0(%rip),%r14
  jmp    L198
  mov    $0x27,%eax
  jmp    L130
  mov    $0x61,%eax
L130:
  movb   $0x5c,(%rbx)
  mov    %al,0x1(%rbx)
  lea    0x2(%rbx),%rbx
L216:
  add    $0x1,%r12
  movzbl -0x1(%r12),%ebp
  movzbl %bpl,%r13d
  test   %r13d,%r13d
  je     L173
L198:
  lea    -0x7(%rbp),%eax
  cmp    $0x55,%al
  ja     L33
  movzbl %al,%eax
  movslq (%r14,%rax,4),%rax
  add    %r14,%rax
  notrack jmp *%rax
  mov    $0x62,%eax
  jmp    L130
  mov    $0x65,%eax
  jmp    L130
  mov    $0x66,%eax
  jmp    L130
  mov    $0x6e,%eax
  jmp    L130
  mov    $0x72,%eax
  jmp    L130
  mov    $0x74,%eax
  jmp    L130
  mov    $0x76,%eax
  jmp    L130
L33:
  mov    %r13d,%edi
  call   <isprint@plt>
  test   %eax,%eax
  jne    L95
  movb   $0x5c,(%rbx)
  lea    0x1(%rbx),%rax
  test   %bpl,%bpl
  js     L189
L85:
  cmp    $0x7f,%r13d
  je     L199
  cmp    $0x1f,%r13d
  jg     L125
  movb   $0x5e,(%rax)
  lea    0x2(%rax),%rbx
  or     $0x40,%r13d
  mov    %r13b,0x1(%rax)
  jmp    L216
L95:
  mov    %bpl,(%rbx)
  lea    0x1(%rbx),%rbx
  jmp    L216
L189:
  lea    0x2(%rbx),%rax
  movb   $0x4d,0x1(%rbx)
  and    $0x7f,%r13b
  jmp    L85
L199:
  movb   $0x5e,(%rax)
  lea    0x2(%rax),%rbx
  movb   $0x3f,0x1(%rax)
  jmp    L216
L125:
  movb   $0x2d,(%rax)
  lea    0x2(%rax),%rbx
  mov    %r13b,0x1(%rax)
  jmp    L216
  mov    $0x5c,%eax
  jmp    L130
  mov    $0x22,%eax
  jmp    L130
L35:
  mov    %rax,%rbx
L173:
  movb   $0x0,(%rbx)
L218:
  mov    %r15,%rax
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L80:
  lea    D11(%rip),%r15
  jmp    L218
```

assistant: ```c
char *conv_expand(const char *str) {
  static char *conv_str;
  static char no_memory[] = "<no memory>";
  char *cp;
  int ch;
  if (conv_str)
    free(conv_str);
  conv_str = malloc(4 * strlen(str) + 1);
  if (!conv_str)
    return no_memory;
  cp = conv_str;
  while ((ch = *(const unsigned char *)str++) != '\0') {
    switch (ch) {
    case '\\':
      ch = '\\';
      break;
    case '\'':
      ch = '\'';
      break;
    case '"':
      ch = '"';
      break;
    case '\a':
      ch = 'a';
      break;
    case '\b':
      ch = 'b';
      break;
    case '\e':
      ch = 'e';
      break;
    case '\f':
      ch = 'f';
      break;
    case '\n':
      ch = 'n';
      break;
    case '\r':
      ch = 'r';
      break;
    case '\t':
      ch = 't';
      break;
    case '\v':
      ch = 'v';
      break;
    default:
      if (isprint(ch)) {
        *cp++ = ch;
        continue;
      }
      *cp++ = '\\';
      if (ch & 0200) {
        *cp++ = 'M';
        ch &= ~0200;
      }
      if (ch == 0177) {
        *cp++ = '^';
        *cp++ = '?';
        continue;
      }
      if (ch < 040) {
        *cp++ = '^';
        *cp++ = ch | 0100;
        continue;
      }
      *cp++ = '-';
      *cp++ = ch;
      continue;
    }
    *cp++ = '\\';
    *cp++ = ch;
  }
  *cp = 0;
  return conv_str;
}
```