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

```asm
<divbwt>:
  endbr64
  push   %rbp
  mov    %rsp,%rbp
  sub    $0x50,%rsp
  mov    %rdi,-0x38(%rbp)
  mov    %rsi,-0x40(%rbp)
  mov    %rdx,-0x48(%rbp)
  mov    %ecx,-0x4c(%rbp)
  cmpq   $0x0,-0x38(%rbp)
  je     L38
  cmpq   $0x0,-0x40(%rbp)
  je     L38
  cmpl   $0x0,-0x4c(%rbp)
  jns    L45
L38:
  mov    $0xffffffff,%eax
  jmp    L21
L45:
  cmpl   $0x1,-0x4c(%rbp)
  jg     L80
  cmpl   $0x1,-0x4c(%rbp)
  jne    L30
  mov    -0x38(%rbp),%rax
  movzbl (%rax),%edx
  mov    -0x40(%rbp),%rax
  mov    %dl,(%rax)
L30:
  mov    -0x4c(%rbp),%eax
  jmp    L21
L80:
  mov    -0x48(%rbp),%rax
  mov    %rax,-0x18(%rbp)
  cmpq   $0x0,-0x18(%rbp)
  jne    L129
  mov    -0x4c(%rbp),%eax
  add    $0x1,%eax
  cltq
  shl    $0x2,%eax
  mov    %eax,%edi
  call   <malloc@plt>
  mov    %rax,-0x18(%rbp)
L129:
  mov    $0x400,%edi
  call   <malloc@plt>
  mov    %rax,-0x10(%rbp)
  mov    $0x40000,%edi
  call   <malloc@plt>
  mov    %rax,-0x8(%rbp)
  cmpq   $0x0,-0x18(%rbp)
  je     L142
  cmpq   $0x0,-0x10(%rbp)
  je     L142
  cmpq   $0x0,-0x8(%rbp)
  je     L142
  mov    -0x4c(%rbp),%edi
  mov    -0x8(%rbp),%rcx
  mov    -0x10(%rbp),%rdx
  mov    -0x18(%rbp),%rsi
  mov    -0x38(%rbp),%rax
  mov    %edi,%r8d
  mov    %rax,%rdi
  call   <sort_typeBstar@plt>
  mov    %eax,-0x1c(%rbp)
  mov    -0x1c(%rbp),%r8d
  mov    -0x4c(%rbp),%edi
  mov    -0x8(%rbp),%rcx
  mov    -0x10(%rbp),%rdx
  mov    -0x18(%rbp),%rsi
  mov    -0x38(%rbp),%rax
  mov    %r8d,%r9d
  mov    %edi,%r8d
  mov    %rax,%rdi
  call   <construct_BWT@plt>
  mov    %eax,-0x24(%rbp)
  mov    -0x4c(%rbp),%eax
  cltq
  lea    -0x1(%rax),%rdx
  mov    -0x38(%rbp),%rax
  add    %rdx,%rax
  movzbl (%rax),%edx
  mov    -0x40(%rbp),%rax
  mov    %dl,(%rax)
  movl   $0x0,-0x20(%rbp)
  jmp    L145
L86:
  mov    -0x20(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%edx
  mov    -0x20(%rbp),%eax
  cltq
  lea    0x1(%rax),%rcx
  mov    -0x40(%rbp),%rax
  add    %rcx,%rax
  mov    %dl,(%rax)
  addl   $0x1,-0x20(%rbp)
L145:
  mov    -0x20(%rbp),%eax
  cmp    -0x24(%rbp),%eax
  jl     L86
  addl   $0x1,-0x20(%rbp)
  jmp    L72
L117:
  mov    -0x20(%rbp),%eax
  cltq
  lea    0x0(,%rax,4),%rdx
  mov    -0x18(%rbp),%rax
  add    %rdx,%rax
  mov    (%rax),%edx
  mov    -0x20(%rbp),%eax
  movslq %eax,%rcx
  mov    -0x40(%rbp),%rax
  add    %rcx,%rax
  mov    %dl,(%rax)
  addl   $0x1,-0x20(%rbp)
L72:
  mov    -0x20(%rbp),%eax
  cmp    -0x4c(%rbp),%eax
  jl     L117
  addl   $0x1,-0x24(%rbp)
  jmp    L48
L142:
  movl   $0xfffffffe,-0x24(%rbp)
L48:
  mov    -0x8(%rbp),%rax
  mov    %rax,%rdi
  call   <free@plt>
  mov    -0x10(%rbp),%rax
  mov    %rax,%rdi
  call   <free@plt>
  cmpq   $0x0,-0x48(%rbp)
  jne    L107
  mov    -0x18(%rbp),%rax
  mov    %rax,%rdi
  call   <free@plt>
L107:
  mov    -0x24(%rbp),%eax
L21:
  leave
  ret
```

assistant: ```c
int divbwt(const unsigned char *T, unsigned char *U, int *A, int n) {
  int *B;
  int *bucket_A, *bucket_B;
  int m, pidx, i;
  if ((T == NULL) || (U == NULL) || (n < 0)) {
    return -1;
  } else if (n <= 1) {
    if (n == 1) {
      U[0] = T[0];
    }
    return n;
  }
  if ((B = A) == NULL) {
    B = (int *)malloc((size_t)(n + 1) * sizeof(int));
  }
  bucket_A = (int *)malloc(((256)) * sizeof(int));
  bucket_B = (int *)malloc(((256) * (256)) * sizeof(int));
  if ((B != NULL) && (bucket_A != NULL) && (bucket_B != NULL)) {
    m = sort_typeBstar(T, B, bucket_A, bucket_B, n);
    pidx = construct_BWT(T, B, bucket_A, bucket_B, n, m);
    U[0] = T[n - 1];
    for (i = 0; i < pidx; ++i) {
      U[i + 1] = (unsigned char)B[i];
    }
    for (i += 1; i < n; ++i) {
      U[i] = (unsigned char)B[i];
    }
    pidx += 1;
  } else {
    pidx = -2;
  }
  free(bucket_B);
  free(bucket_A);
  if (A == NULL) {
    free(B);
  }
  return pidx;
}
```