user: 请显示与下面列出的汇编代码相匹配的C语言实现：

```asm
<itoa>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x90,%rsp
  mov    %rdi,-0x88(%rbp)
  mov    %esi,-0x8c(%rbp)
  mov    %fs:0x28,%rax
  mov    %rax,-0x8(%rbp)
  xor    %eax,%eax
  movl   $0x0,-0x80(%rbp)
  cmpl   $0x0,-0x8c(%rbp)
  jle    L87
  mov    $0x1,%eax
  jmp    L7
L87:
  mov    $0xffffffff,%eax
L7:
  mov    %eax,-0x78(%rbp)
  mov    -0x8c(%rbp),%eax
  mov    %eax,%edx
  neg    %edx
  cmovns %edx,%eax
  mov    %eax,-0x7c(%rbp)
  jmp    L2
L16:
  mov    -0x7c(%rbp),%edx
  movslq %edx,%rax
  imul   $0x66666667,%rax,%rax
  shr    $0x20,%rax
  sar    $0x2,%eax
  mov    %edx,%esi
  sar    $0x1f,%esi
  sub    %esi,%eax
  mov    %eax,%ecx
  mov    %ecx,%eax
  shl    $0x2,%eax
  add    %ecx,%eax
  add    %eax,%eax
  mov    %edx,%ecx
  sub    %eax,%ecx
  mov    %ecx,%eax
  add    $0x30,%eax
  mov    %eax,%edx
  mov    -0x80(%rbp),%eax
  cltq
  mov    %dl,-0x70(%rbp,%rax,1)
  mov    -0x7c(%rbp),%eax
  movslq %eax,%rdx
  imul   $0x66666667,%rdx,%rdx
  shr    $0x20,%rdx
  sar    $0x2,%edx
  sar    $0x1f,%eax
  mov    %eax,%ecx
  mov    %edx,%eax
  sub    %ecx,%eax
  mov    %eax,-0x7c(%rbp)
  addl   $0x1,-0x80(%rbp)
L2:
  cmpl   $0x0,-0x7c(%rbp)
  jne    L16
  mov    -0x80(%rbp),%eax
  cltq
  movb   $0x0,-0x70(%rbp,%rax,1)
  lea    -0x70(%rbp),%rax
  mov    %rax,%rdi
  call   <strlen@plt>
  mov    %eax,-0x74(%rbp)
  movl   $0x0,-0x80(%rbp)
  jmp    L50
L54:
  mov    -0x74(%rbp),%eax
  sub    $0x1,%eax
  sub    -0x80(%rbp),%eax
  cltq
  movzbl -0x70(%rbp,%rax,1),%eax
  movsbl %al,%eax
  mov    %eax,-0x7c(%rbp)
  mov    -0x74(%rbp),%eax
  sub    $0x1,%eax
  sub    -0x80(%rbp),%eax
  mov    %eax,%ecx
  mov    -0x80(%rbp),%eax
  cltq
  movzbl -0x70(%rbp,%rax,1),%edx
  movslq %ecx,%rax
  mov    %dl,-0x70(%rbp,%rax,1)
  mov    -0x7c(%rbp),%eax
  mov    %eax,%edx
  mov    -0x80(%rbp),%eax
  cltq
  mov    %dl,-0x70(%rbp,%rax,1)
  addl   $0x1,-0x80(%rbp)
L50:
  mov    -0x74(%rbp),%eax
  mov    %eax,%edx
  shr    $0x1f,%edx
  add    %edx,%eax
  sar    %eax
  cmp    %eax,-0x80(%rbp)
  jl     L54
  cmpl   $0xffffffff,-0x78(%rbp)
  jne    L94
  mov    -0x74(%rbp),%eax
  add    $0x1,%eax
  cltq
  movb   $0x0,-0x70(%rbp,%rax,1)
  mov    -0x74(%rbp),%eax
  mov    %eax,-0x80(%rbp)
  jmp    L98
L6:
  mov    -0x80(%rbp),%eax
  sub    $0x1,%eax
  cltq
  movzbl -0x70(%rbp,%rax,1),%edx
  mov    -0x80(%rbp),%eax
  cltq
  mov    %dl,-0x70(%rbp,%rax,1)
  subl   $0x1,-0x80(%rbp)
L98:
  cmpl   $0x0,-0x80(%rbp)
  jg     L6
  movb   $0x2d,-0x70(%rbp)
L94:
  lea    -0x70(%rbp),%rdx
  mov    -0x88(%rbp),%rax
  mov    %rdx,%rsi
  mov    %rax,%rdi
  call   <strcpy@plt>
  nop
  mov    -0x8(%rbp),%rax
  sub    %fs:0x28,%rax
  je     L53
  call   <__stack_chk_fail@plt>
L53:
  leave
  ret
```

assistant: ```c
void itoa(char *buf, int a) {
  char array[100];
  int i = 0, length;
  int temp, flag;
  flag = a > 0 ? 1 : (-1);
  temp = a > 0 ? a : -a;
  while (temp) {
    array[i] = temp % 10 + '0';
    temp /= 10;
    i++;
  }
  array[i] = '\0';
  length = strlen(array);
  for (i = 0; i < length / 2; i++) {
    temp = array[length - 1 - i];
    array[length - 1 - i] = array[i];
    array[i] = temp;
  }
  if (flag == -1) {
    array[length + 1] = '\0';
    for (i = length; i > 0; i--) {
      array[i] = array[i - 1];
    }
    array[0] = '-';
  }
  strcpy(buf, array);
}
```