user: 提供的汇编代码用C语言表示会是什么样子：

```asm
<sendData>:
  endbr64
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x50,%rsp
  mov    %fs:0x28,%rax
  mov    %rax,0x48(%rsp)
  xor    %eax,%eax
  lea    -0x1(%rdx),%eax
  cmp    $0xff,%eax
  ja     L58
  lea    -0x1(%rdx),%ecx
  mov    %edi,%r12d
  mov    %rsi,%rbp
  mov    %edx,%ebx
  mov    %cl,0x46(%rsp)
  cmp    $0xe,%eax
  jbe    L39
  mov    %edx,%eax
  movdqu (%rsi),%xmm0
  shr    $0x4,%eax
  cmp    $0x1,%eax
  je     L255
  movdqu 0x10(%rsi),%xmm2
  pxor   %xmm2,%xmm0
  cmp    $0x2,%eax
  je     L255
  movdqu 0x20(%rsi),%xmm3
  pxor   %xmm3,%xmm0
  cmp    $0x3,%eax
  je     L255
  movdqu 0x30(%rsi),%xmm4
  pxor   %xmm4,%xmm0
  cmp    $0x4,%eax
  je     L255
  movdqu 0x40(%rsi),%xmm5
  pxor   %xmm5,%xmm0
  cmp    $0x5,%eax
  je     L255
  movdqu 0x50(%rsi),%xmm6
  pxor   %xmm6,%xmm0
  cmp    $0x6,%eax
  je     L255
  movdqu 0x60(%rsi),%xmm7
  pxor   %xmm7,%xmm0
  cmp    $0x7,%eax
  je     L255
  movdqu 0x70(%rsi),%xmm7
  pxor   %xmm7,%xmm0
  cmp    $0x8,%eax
  je     L255
  movdqu 0x80(%rsi),%xmm6
  pxor   %xmm6,%xmm0
  cmp    $0x9,%eax
  je     L255
  movdqu 0x90(%rsi),%xmm5
  pxor   %xmm5,%xmm0
  cmp    $0xa,%eax
  je     L255
  movdqu 0xa0(%rsi),%xmm4
  pxor   %xmm4,%xmm0
  cmp    $0xb,%eax
  je     L255
  movdqu 0xb0(%rsi),%xmm7
  pxor   %xmm7,%xmm0
  cmp    $0xc,%eax
  je     L255
  movdqu 0xc0(%rsi),%xmm6
  pxor   %xmm6,%xmm0
  cmp    $0xd,%eax
  je     L255
  movdqu 0xd0(%rsi),%xmm5
  pxor   %xmm5,%xmm0
  cmp    $0xe,%eax
  je     L255
  movdqu 0xe0(%rsi),%xmm3
  pxor   %xmm3,%xmm0
  cmp    $0x10,%eax
  jne    L255
  movdqu 0xf0(%rsi),%xmm4
  pxor   %xmm4,%xmm0
  movdqa %xmm0,%xmm1
  psrldq $0x8,%xmm1
  pxor   %xmm1,%xmm0
  movdqa %xmm0,%xmm1
  psrldq $0x4,%xmm1
  pxor   %xmm1,%xmm0
  movdqa %xmm0,%xmm1
  psrldq $0x2,%xmm1
  pxor   %xmm1,%xmm0
  movdqa %xmm0,%xmm1
  psrldq $0x1,%xmm1
  pxor   %xmm1,%xmm0
  movd   %xmm0,%eax
  xor    %eax,%ecx
  nopl   0x0(%rax,%rax,1)
L306:
  lea    0x46(%rsp),%rsi
  mov    $0x1,%edx
  mov    %r12d,%edi
  mov    %cl,0x47(%rsp)
  call   <write@plt>
  cmp    $0x1,%eax
  jne    L58
  mov    %ebx,%edx
  mov    %rbp,%rsi
  mov    %r12d,%edi
  call   <write@plt>
  cmp    %ebx,%eax
  jne    L58
  lea    0x47(%rsp),%rsi
  mov    $0x1,%edx
  mov    %r12d,%edi
  call   <write@plt>
  cmp    $0x1,%eax
  jne    L58
  mov    %r12d,%edi
  call   <readAck@plt>
  neg    %rax
  sbb    %eax,%eax
L131:
  mov    0x48(%rsp),%rdx
  sub    %fs:0x28,%rdx
  jne    L117
  add    $0x50,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  ret
  nopl   0x0(%rax)
L255:
  movdqa %xmm0,%xmm1
  mov    %ebx,%esi
  psrldq $0x8,%xmm1
  and    $0xfffffff0,%esi
  pxor   %xmm1,%xmm0
  movdqa %xmm0,%xmm1
  psrldq $0x4,%xmm1
  pxor   %xmm1,%xmm0
  movdqa %xmm0,%xmm1
  psrldq $0x2,%xmm1
  pxor   %xmm1,%xmm0
  movdqa %xmm0,%xmm1
  psrldq $0x1,%xmm1
  pxor   %xmm1,%xmm0
  movd   %xmm0,%eax
  xor    %eax,%ecx
  test   $0xf,%bl
  je     L306
L47:
  mov    %ebx,%edi
  sub    %esi,%edi
  lea    -0x1(%rdi),%eax
  cmp    $0x6,%eax
  jbe    L170
  mov    %esi,%eax
  mov    0x0(%rbp,%rax,1),%rax
  movzbl %ah,%edx
  mov    %rax,0x38(%rsp)
  mov    %rdx,%r8
  mov    %eax,%edx
  mov    %rax,0x30(%rsp)
  xor    %r8d,%edx
  mov    %rax,0x28(%rsp)
  xor    %ecx,%edx
  mov    %rax,%rcx
  mov    %rax,0x20(%rsp)
  shr    $0x10,%rcx
  mov    %rax,0x18(%rsp)
  xor    %ecx,%edx
  mov    %rax,%rcx
  mov    %rax,0x10(%rsp)
  shr    $0x18,%rcx
  mov    %rax,0x8(%rsp)
  xor    %ecx,%edx
  mov    %rax,%rcx
  mov    %rax,(%rsp)
  shr    $0x20,%rcx
  xor    %ecx,%edx
  mov    %rax,%rcx
  shr    $0x28,%rcx
  xor    %ecx,%edx
  mov    %rax,%rcx
  shr    $0x30,%rcx
  xor    %ecx,%edx
  mov    %rax,%rcx
  mov    %edi,%eax
  shr    $0x38,%rcx
  and    $0xfffffff8,%eax
  xor    %edx,%ecx
  add    %eax,%esi
  cmp    %eax,%edi
  je     L306
L170:
  mov    %esi,%eax
  xor    0x0(%rbp,%rax,1),%cl
  lea    0x1(%rsi),%eax
  cmp    %eax,%ebx
  jbe    L306
  xor    0x0(%rbp,%rax,1),%cl
  lea    0x2(%rsi),%eax
  cmp    %ebx,%eax
  jae    L306
  xor    0x0(%rbp,%rax,1),%cl
  lea    0x3(%rsi),%eax
  cmp    %eax,%ebx
  jbe    L306
  xor    0x0(%rbp,%rax,1),%cl
  lea    0x4(%rsi),%eax
  cmp    %eax,%ebx
  jbe    L306
  xor    0x0(%rbp,%rax,1),%cl
  lea    0x5(%rsi),%eax
  cmp    %eax,%ebx
  jbe    L306
  add    $0x6,%esi
  xor    0x0(%rbp,%rax,1),%cl
  cmp    %esi,%ebx
  jbe    L306
  xor    0x0(%rbp,%rsi,1),%cl
  jmp    L306
  nopl   (%rax)
L58:
  mov    $0xffffffff,%eax
  jmp    L131
  nopw   0x0(%rax,%rax,1)
L39:
  xor    %esi,%esi
  jmp    L47
L117:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
int sendData(int fd, void *ptr, unsigned len) {
  unsigned char x;
  unsigned char check;
  unsigned char *data = ptr;
  unsigned n;
  if ((len < 1) || (len > 256))
    return -1;
  check = x = (len - 1);
  for (n = 0; n < len; n++) {
    check ^= data[n];
  }
  if (write(fd, &x, 1) != 1)
    return -1;
  if (write(fd, data, len) != len)
    return -1;
  if (write(fd, &check, 1) != 1)
    return -1;
  if (readAck(fd))
    return -1;
  return 0;
}
```