user: 请从给定的汇编指令推导出C源代码:

```asm
<entab>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x18,%rsp
  mov    %rdi,%r13
  lea    0x1(%rsi),%edi
  call   <malloc@plt>
  mov    %rax,%r14
  mov    %r13,%rsi
  mov    %rax,%rdi
  call   <strcpy@plt>
  movzbl (%r14),%eax
  test   %al,%al
  je     L107
  mov    $0x0,%ebp
  mov    $0x0,%r12d
  lea    0x1(%r13),%rdi
  mov    %rdi,0x8(%rsp)
  jmp    L124
L6:
  movslq %r12d,%rax
  add    %r14,%rax
  mov    %r12d,%ebx
L9:
  mov    %ebx,%r15d
  add    $0x1,%ebx
  movzbl (%rax),%edx
  add    $0x1,%rax
  cmp    $0x20,%dl
  je     L9
  mov    %r12d,%edi
  call   <getStop@plt>
  cmp    %eax,%ebx
  jge    L158
  sub    %r12d,%ebx
  mov    %ebx,%eax
  sar    $0x1f,%eax
  shr    $0x1d,%eax
  add    %eax,%ebx
  and    $0x7,%ebx
  sub    %eax,%ebx
  cmp    $0x1,%ebx
  jle    L16
  movslq %ebp,%rdx
  lea    0x0(%r13,%rdx,1),%rax
  add    0x8(%rsp),%rdx
  lea    -0x2(%rbx),%ecx
  add    %rcx,%rdx
L72:
  movb   $0x20,(%rax)
  add    $0x1,%rax
  cmp    %rdx,%rax
  jne    L72
  lea    -0x1(%rbp,%rbx,1),%ebp
  mov    %r15d,%r12d
L85:
  movslq %r12d,%rax
  movzbl (%r14,%rax,1),%eax
  test   %al,%al
  je     L65
L124:
  cmp    $0x20,%al
  je     L6
  add    $0x1,%r12d
  movslq %ebp,%rdx
  mov    %al,0x0(%r13,%rdx,1)
  lea    0x1(%rbp),%ebp
  jmp    L85
L158:
  mov    %eax,%edx
L157:
  add    $0x8,%edx
  cmp    %edx,%ebx
  jge    L157
  mov    %ebx,%edx
  sub    %eax,%edx
  mov    %edx,%ecx
  shr    $0x3,%ecx
  and    $0xfffffff8,%edx
  lea    0x8(%rax,%rdx,1),%edi
  movslq %ebp,%rsi
  add    %r13,%rsi
  mov    %rsi,%rax
L71:
  movb   $0x9,(%rax)
  add    $0x1,%rax
  mov    %eax,%edx
  sub    %esi,%edx
  sub    $0x1,%edx
  cmp    %edx,%ecx
  jg     L71
  test   %ecx,%ecx
  mov    $0x0,%eax
  cmovs  %eax,%ecx
  lea    0x1(%rbp,%rcx,1),%ebp
  sub    %edi,%ebx
  cmp    $0xfffffff9,%ebx
  jl     L108
  movslq %ebp,%rcx
  lea    0x0(%r13,%rcx,1),%rax
  lea    0x7(%rbx),%edx
  add    0x8(%rsp),%rdx
  add    %rcx,%rdx
L51:
  movb   $0x20,(%rax)
  add    $0x1,%rax
  cmp    %rdx,%rax
  jne    L51
  lea    0x8(%rbp,%rbx,1),%ebp
  mov    %r15d,%r12d
  jmp    L85
L16:
  mov    %r15d,%r12d
  jmp    L85
L108:
  mov    %r15d,%r12d
  jmp    L85
L107:
  mov    $0x0,%ebp
L65:
  movslq %ebp,%rbp
  movb   $0x0,0x0(%r13,%rbp,1)
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void entab(char *line, int len) {
  int i, m = 0, j, k, stop, nt = 0, nb = 0;
  i = 0;
  j = 0;
  char *copy = (char *)malloc(len + 1);
  strcpy(copy, line);
  while (copy[i] != '\0') {
    if (copy[i] == ' ') {
      k = i;
      while (copy[k++] == ' ')
        ;
      nt = 0;
      nb = 0;
      stop = getStop(i);
      if (k < stop) {
        nb = (k - i) % 8;
        for (m = 0; m < nb - 1; m++) {
          line[j++] = ' ';
        }
      } else {
        while (stop <= k) {
          nt++;
          stop += 8;
        }
        for (m = 0; m < nt; m++) {
          line[j++] = '\t';
        }
        for (m = 0; m < k - stop + 8; m++) {
          line[j++] = ' ';
        }
      }
      i = --k;
    } else {
      line[j++] = copy[i++];
    }
  }
  line[j] = '\0';
}
```