user: 请显示与下面列出的汇编代码相匹配的C语言实现:

```asm
<loggerGetFileExt>:
  endbr64
  push   %r13
  push   %r12
  push   %rbp
  mov    %esi,%ebp
  xor    %esi,%esi
  push   %rbx
  sub    $0x8,%rsp
  call   <loggerGetFileName@plt>
  mov    %rax,%r12
  test   %rax,%rax
  je     L66
  mov    $0x2e,%esi
  mov    %rax,%rdi
  call   <strrchr@plt>
  mov    %rax,%rbx
  test   %rax,%rax
  je     L129
  lea    0x1(%rax),%rdi
  call   <strlen@plt>
  lea    0x1(%rax),%edx
  movslq %edx,%rdx
  test   %rdx,%rdx
  je     L66
  test   %ebp,%ebp
  jne    L122
  lea    0x2(%rbx),%rdi
  mov    %r12,%rsi
  lea    -0x1(%rdx),%rcx
  sub    %rdi,%rsi
  cmp    $0xe,%rsi
  jbe    L184
  cmp    $0x6,%rcx
  jbe    L184
  cmp    $0xe,%rcx
  mov    %rdx,%rcx
  jbe    L97
  and    $0xfffffffffffffff0,%rcx
  xor    %eax,%eax
  nopl   0x0(%rax)
L30:
  movdqu 0x1(%rbx,%rax,1),%xmm0
  movups %xmm0,(%r12,%rax,1)
  add    $0x10,%rax
  cmp    %rcx,%rax
  jne    L30
  mov    %rdx,%rax
  and    $0xfffffffffffffff0,%rax
  test   $0xf,%dl
  je     L66
  mov    %rdx,%rcx
  sub    %rax,%rcx
  lea    -0x1(%rcx),%rsi
  cmp    $0x6,%rsi
  jbe    L86
L12:
  mov    0x1(%rbx,%rax,1),%rsi
  mov    %rsi,(%r12,%rax,1)
  mov    %rcx,%rsi
  and    $0xfffffffffffffff8,%rsi
  add    %rsi,%rax
  cmp    %rsi,%rcx
  je     L66
L86:
  movzbl 0x1(%rbx,%rax,1),%ecx
  mov    %cl,(%r12,%rax,1)
  lea    0x1(%rax),%rcx
  cmp    %rcx,%rdx
  jbe    L66
  movzbl 0x2(%rbx,%rax,1),%ecx
  mov    %cl,0x1(%r12,%rax,1)
  lea    0x2(%rax),%rcx
  cmp    %rcx,%rdx
  jbe    L66
  movzbl 0x3(%rbx,%rax,1),%ecx
  mov    %cl,0x2(%r12,%rax,1)
  lea    0x3(%rax),%rcx
  cmp    %rcx,%rdx
  jbe    L66
  movzbl 0x4(%rbx,%rax,1),%ecx
  mov    %cl,0x3(%r12,%rax,1)
  lea    0x4(%rax),%rcx
  cmp    %rcx,%rdx
  jbe    L66
  movzbl 0x5(%rbx,%rax,1),%ecx
  mov    %cl,0x4(%r12,%rax,1)
  lea    0x5(%rax),%rcx
  cmp    %rcx,%rdx
  jbe    L66
  movzbl 0x6(%rbx,%rax,1),%ecx
  mov    %cl,0x5(%r12,%rax,1)
  lea    0x6(%rax),%rcx
  cmp    %rcx,%rdx
  jbe    L66
  movzbl 0x7(%rbx,%rax,1),%edx
  mov    %dl,0x6(%r12,%rax,1)
L66:
  add    $0x8,%rsp
  mov    %r12,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
  nopl   (%rax)
L122:
  movslq %eax,%r13
  xor    %ebp,%ebp
  nopl   (%rax)
L213:
  movsbl 0x1(%rbx,%rbp,1),%edi
  call   <tolower@plt>
  mov    %al,(%r12,%rbp,1)
  mov    %rbp,%rax
  add    $0x1,%rbp
  cmp    %r13,%rax
  jne    L213
  add    $0x8,%rsp
  mov    %r12,%rax
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
L184:
  cltq
  xor    %edx,%edx
  nopl   0x0(%rax)
L207:
  movzbl 0x1(%rbx,%rdx,1),%ecx
  mov    %cl,(%r12,%rdx,1)
  mov    %rdx,%rcx
  add    $0x1,%rdx
  cmp    %rcx,%rax
  jne    L207
  jmp    L66
L129:
  mov    %r12,%rdi
  xor    %r12d,%r12d
  call   <free@plt>
  jmp    L66
L97:
  xor    %eax,%eax
  jmp    L12
```

assistant: ```c
char *loggerGetFileExt(const char *path_, int tolower_) {
  size_t i;
  size_t size;
  const char *ext;
  char *fname = loggerGetFileName(path_, 0);
  if (!fname) {
    return NULL;
  }
  ext = strrchr(fname, '.');
  if (!ext) {
    free(fname);
    return NULL;
  }
  ++ext;
  size = strlen(ext) + 1;
  for (i = 0; i < size; ++i) {
    if (tolower_) {
      fname[i] = tolower(ext[i]);
    } else {
      fname[i] = ext[i];
    }
  }
  return fname;
}
```