user: Demonstrate the C code that generates the assembly output below:

```asm
<aes_decrypt>:
  endbr64
  push   %r15
  push   %r14
  xor    %r14d,%r14d
  push   %r13
  mov    %rdx,%r13
  push   %r12
  push   %rbp
  mov    %rcx,%rbp
  push   %rbx
  shr    $0x4,%rbp
  xor    %ebx,%ebx
  sub    $0x48,%rsp
  mov    %rdi,0x10(%rsp)
  mov    %rsi,0x8(%rsp)
  mov    %fs:0x28,%rax
  mov    %rax,0x38(%rsp)
  xor    %eax,%eax
  mov    %ecx,%eax
  and    $0xf,%eax
  mov    %eax,0x1c(%rsp)
  jmp    L271
  nopl   0x0(%rax)
L213:
  mov    0x1c(%rsp),%r15d
  test   %r15d,%r15d
  je     L5
  lea    0x20(%rsp),%r12
  mov    $0x10,%edx
  xor    %esi,%esi
  mov    %r12,%rdi
  call   <memset@plt>
L201:
  mov    0x8(%rsp),%rax
  shl    $0x4,%rbx
  mov    %r15d,%edx
  mov    %r12,%rdi
  lea    (%rax,%rbx,1),%rsi
  call   <memcpy@plt>
  mov    %r12,%rdi
  call   <decrypt@plt>
  mov    0x10(%rsp),%rax
  test   %r14d,%r14d
  je     L311
  lea    -0x1(%r14),%eax
  shl    $0x4,%rax
  add    0x8(%rsp),%rax
L311:
  lea    0x0(%r13,%rbx,1),%rdx
  lea    0x1(%rax),%r9
  mov    %rdx,%rdi
  lea    -0x1(%r15),%esi
  sub    %r9,%rdi
  cmp    $0xe,%rdi
  jbe    L282
  cmp    $0x6,%esi
  jbe    L282
  cmp    $0xf,%esi
  jne    L331
  movdqu (%rax),%xmm0
  pxor   0x20(%rsp),%xmm0
  movups %xmm0,(%rdx)
L207:
  lea    0x1(%r14),%ebx
  mov    %rbx,%r14
  cmp    %rbp,%rbx
  ja     L5
L271:
  cmp    %rbp,%rbx
  je     L213
  mov    $0x10,%r15d
  lea    0x20(%rsp),%r12
  jmp    L201
L331:
  movq   (%rax),%xmm0
  movq   0x20(%rsp),%xmm1
  pxor   %xmm1,%xmm0
  movq   %xmm0,(%rdx)
  cmp    $0x8,%r15d
  je     L207
  movzbl 0x8(%rax),%edx
  xor    0x28(%rsp),%dl
  mov    %dl,0x8(%r13,%rbx,1)
  cmp    $0x9,%r15d
  je     L207
  movzbl 0x9(%rax),%edx
  xor    0x29(%rsp),%dl
  mov    %dl,0x9(%r13,%rbx,1)
  cmp    $0xa,%r15d
  je     L207
  movzbl 0xa(%rax),%edx
  xor    0x2a(%rsp),%dl
  mov    %dl,0xa(%r13,%rbx,1)
  cmp    $0xb,%r15d
  je     L207
  movzbl 0xb(%rax),%edx
  xor    0x2b(%rsp),%dl
  mov    %dl,0xb(%r13,%rbx,1)
  cmp    $0xc,%r15d
  je     L207
  movzbl 0xc(%rax),%edx
  xor    0x2c(%rsp),%dl
  mov    %dl,0xc(%r13,%rbx,1)
  cmp    $0xd,%r15d
  je     L207
  movzbl 0xd(%rax),%edx
  xor    0x2d(%rsp),%dl
  mov    %dl,0xd(%r13,%rbx,1)
  cmp    $0xf,%r15d
  jne    L207
  movzbl 0xe(%rax),%eax
  xor    0x2e(%rsp),%al
  mov    %al,0xe(%r13,%rbx,1)
  lea    0x1(%r14),%ebx
  mov    %rbx,%r14
  cmp    %rbp,%rbx
  jbe    L271
L5:
  mov    0x38(%rsp),%rax
  sub    %fs:0x28,%rax
  jne    L245
  add    $0x48,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L282:
  movzbl (%rax),%esi
  xor    0x20(%rsp),%sil
  mov    %sil,(%rdx)
  cmp    $0x1,%r15d
  je     L207
  movzbl 0x1(%rax),%edx
  xor    0x21(%rsp),%dl
  mov    %dl,0x1(%r13,%rbx,1)
  cmp    $0x2,%r15d
  je     L207
  movzbl 0x2(%rax),%edx
  xor    0x22(%rsp),%dl
  mov    %dl,0x2(%r13,%rbx,1)
  cmp    $0x3,%r15d
  je     L207
  movzbl 0x3(%rax),%edx
  xor    0x23(%rsp),%dl
  mov    %dl,0x3(%r13,%rbx,1)
  cmp    $0x4,%r15d
  je     L207
  movzbl 0x4(%rax),%edx
  xor    0x24(%rsp),%dl
  mov    %dl,0x4(%r13,%rbx,1)
  cmp    $0x5,%r15d
  je     L207
  movzbl 0x5(%rax),%edx
  xor    0x25(%rsp),%dl
  mov    %dl,0x5(%r13,%rbx,1)
  cmp    $0x6,%r15d
  je     L207
  movzbl 0x6(%rax),%edx
  xor    0x26(%rsp),%dl
  mov    %dl,0x6(%r13,%rbx,1)
  cmp    $0x7,%r15d
  je     L207
  movzbl 0x7(%rax),%edx
  xor    0x27(%rsp),%dl
  mov    %dl,0x7(%r13,%rbx,1)
  cmp    $0x8,%r15d
  je     L207
  movzbl 0x8(%rax),%edx
  xor    0x28(%rsp),%dl
  mov    %dl,0x8(%r13,%rbx,1)
  cmp    $0x9,%r15d
  je     L207
  movzbl 0x9(%rax),%edx
  xor    0x29(%rsp),%dl
  mov    %dl,0x9(%r13,%rbx,1)
  cmp    $0xa,%r15d
  je     L207
  movzbl 0xa(%rax),%edx
  xor    0x2a(%rsp),%dl
  mov    %dl,0xa(%r13,%rbx,1)
  cmp    $0xb,%r15d
  je     L207
  movzbl 0xb(%rax),%edx
  xor    0x2b(%rsp),%dl
  mov    %dl,0xb(%r13,%rbx,1)
  cmp    $0xc,%r15d
  je     L207
  movzbl 0xc(%rax),%edx
  xor    0x2c(%rsp),%dl
  mov    %dl,0xc(%r13,%rbx,1)
  cmp    $0xd,%r15d
  je     L207
  movzbl 0xd(%rax),%edx
  xor    0x2d(%rsp),%dl
  mov    %dl,0xd(%r13,%rbx,1)
  cmp    $0xe,%r15d
  je     L207
  movzbl 0xe(%rax),%edx
  xor    0x2e(%rsp),%dl
  mov    %dl,0xe(%r13,%rbx,1)
  cmp    $0x10,%r15d
  jne    L207
  movzbl 0x2f(%rsp),%edx
  xor    0xf(%rax),%dl
  mov    %dl,0xf(%r13,%rbx,1)
  jmp    L207
L245:
  call   <__stack_chk_fail@plt>
```

assistant: ```c
void aes_decrypt(unsigned char *iv, unsigned char *inbuf, unsigned char *outbuf, unsigned long long len) {
  unsigned char block[16];
  unsigned int blockno = 0, i;
  for (blockno = 0; blockno <= (len / sizeof(block)); blockno++) {
    unsigned int fraction;
    if (blockno == (len / sizeof(block))) {
      fraction = len % sizeof(block);
      if (fraction == 0)
        break;
      memset(block, 0, sizeof(block));
    } else
      fraction = 16;
    memcpy(block, inbuf + blockno * sizeof(block), fraction);
    decrypt(block);
    unsigned char *ctext_ptr;
    if (blockno == 0)
      ctext_ptr = iv;
    else
      ctext_ptr = inbuf + (blockno - 1) * sizeof(block);
    for (i = 0; i < fraction; i++)
      outbuf[blockno * sizeof(block) + i] = ctext_ptr[i] ^ block[i];
  }
}
```