user: 提供的汇编代码用C语言表示会是什么样子：

```asm
<main>:
  endbr64
  push   %r12
  push   %rbp
  push   %rbx
  mov    %rsi,%rbx
  sub    $0xe0,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0xd8(%rsp)
  xor    %eax,%eax
  cmp    $0x1,%edi
  mov    %rsp,%rbp
  lea    0x70(%rsp),%r12
  setg   %dil
  movzbl %dil,%edi
  call   <assert@plt>
  mov    $0x64,%edx
  mov    $0x6f,%esi
  mov    %rbp,%rdi
  call   <memset@plt>
  mov    $0x64,%edx
  mov    $0x6f,%esi
  mov    %r12,%rdi
  call   <memset@plt>
  mov    0x8(%rbx),%rax
  movzbl (%rax),%eax
  sub    $0x61,%eax
  cmp    $0x8,%al
  ja     10c0 <main.cold>
  lea    D8(%rip),%rdx
  movzbl %al,%eax
  movslq (%rdx,%rax,4),%rax
  add    %rdx,%rax
  notrack jmp *%rax
  mov    $0xc8,%edx
  mov    %r12,%rsi
  mov    %rbp,%rdi
  movb   $0x0,0x63(%rsp)
  call   <strncasecmp@plt>
  xor    %edi,%edi
  test   %eax,%eax
  setne  %dil
  call   <assert@plt>
  xor    %eax,%eax
  nopl   0x0(%rax,%rax,1)
L52:
  mov    0xd8(%rsp),%rdx
  sub    %fs:0x28,%rdx
  jne    L94
  add    $0xe0,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  ret
  mov    $0xc8,%edx
  mov    %r12,%rsi
  mov    %rbp,%rdi
  movb   $0x0,0xd3(%rsp)
  call   <strncasecmp@plt>
  xor    %edi,%edi
  test   %eax,%eax
  setne  %dil
  call   <assert@plt>
  xor    %eax,%eax
  jmp    L52
  movb   $0x7a,0x63(%rsp)
  xor    %ebx,%ebx
  movb   $0x78,0xd3(%rsp)
  nopl   0x0(%rax,%rax,1)
L34:
  mov    %rbx,%rdx
  mov    %r12,%rsi
  mov    %rbp,%rdi
  call   <strncasecmp@plt>
  test   %eax,%eax
  setne  %dil
  cmp    $0x63,%rbx
  setbe  %al
  add    $0x1,%rbx
  xor    %eax,%edi
  movzbl %dil,%edi
  call   <assert@plt>
  cmp    $0x65,%rbx
  jne    L34
  mov    $0xc8,%edx
  mov    %r12,%rsi
  mov    %rbp,%rdi
  movb   $0x0,0x63(%rsp)
  movb   $0x0,0xd3(%rsp)
  call   <strncasecmp@plt>
  xor    %edi,%edi
  test   %eax,%eax
  sete   %dil
  call   <assert@plt>
  xor    %eax,%eax
  jmp    L52
  lea    -0x1(%rsp),%rdi
  mov    $0x1,%edx
  mov    %r12,%rsi
  call   <strncasecmp@plt>
  jmp    L52
  lea    0x6f(%rsp),%rsi
  mov    $0x1,%edx
  mov    %rbp,%rdi
  call   <strncasecmp@plt>
  jmp    L52
  lea    0x64(%rsp),%rdi
  mov    $0x1,%edx
  mov    %r12,%rsi
  call   <strncasecmp@plt>
  jmp    L52
  lea    0xd4(%rsp),%rsi
  mov    $0x1,%edx
  mov    %rbp,%rdi
  call   <strncasecmp@plt>
  jmp    L52
  lea    0x1(%rsp),%rdi
  mov    $0x64,%edx
  mov    %r12,%rsi
  call   <strncasecmp@plt>
  jmp    L52
  lea    0x71(%rsp),%rsi
  mov    $0x64,%edx
  mov    %rbp,%rdi
  call   <strncasecmp@plt>
  jmp    L52
L94:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int main(int argc, char **argv) {
  assert(argc >= 2);
  const size_t size = 100;
  char fill = 'o';
  char s1[size];
  char s2[size];
  memset(s1, fill, size);
  memset(s2, fill, size);
  switch (argv[1][0]) {
  case 'a':
    s1[size - 1] = 'z';
    s2[size - 1] = 'x';
    for (int i = 0; i <= size; ++i)
      assert((strncasecmp(s1, s2, i) == 0) == (i < size));
    s1[size - 1] = '\0';
    s2[size - 1] = '\0';
    assert(strncasecmp(s1, s2, 2 * size) == 0);
    break;
  case 'b':
    return strncasecmp(s1 - 1, s2, 1);
  case 'c':
    return strncasecmp(s1, s2 - 1, 1);
  case 'd':
    return strncasecmp(s1 + size, s2, 1);
  case 'e':
    return strncasecmp(s1, s2 + size, 1);
  case 'f':
    return strncasecmp(s1 + 1, s2, size);
  case 'g':
    return strncasecmp(s1, s2 + 1, size);
  case 'h':
    s1[size - 1] = '\0';
    assert(strncasecmp(s1, s2, 2 * size) != 0);
    break;
  case 'i':
    s2[size - 1] = '\0';
    assert(strncasecmp(s1, s2, 2 * size) != 0);
    break;
  }
  return 0;
}
```