user: 这段汇编代码用C语言表示是什么样的:

```asm
<cftfsub>:
  endbr64
  push   %r13
  push   %r12
  mov    %edi,%r12d
  push   %rbp
  push   %rbx
  mov    %rsi,%rbx
  sub    $0x8,%rsp
  cmp    $0xf,%edi
  jg     L187
  cmp    $0x4,%edi
  jle    L41
  mov    $0x2,%ebp
L197:
  movslq %ebp,%rdx
  lea    -0x1(%rbp),%edi
  mov    $0x1,%eax
  shl    $0x3,%rdx
  shr    %edi
  lea    (%rbx,%rdx,1),%rsi
  add    $0x1,%edi
  lea    (%rsi,%rdx,1),%rcx
  add    %rcx,%rdx
  test   %ebp,%ebp
  cmovle %rax,%rdi
  xor    %eax,%eax
  shl    $0x4,%rdi
  cs nopw 0x0(%rax,%rax,1)
L9:
  movupd (%rbx,%rax,1),%xmm5
  movupd (%rsi,%rax,1),%xmm2
  movupd (%rsi,%rax,1),%xmm6
  movupd (%rcx,%rax,1),%xmm0
  addpd  %xmm5,%xmm2
  movapd %xmm5,%xmm1
  movupd (%rdx,%rax,1),%xmm5
  subpd  %xmm6,%xmm1
  movupd (%rcx,%rax,1),%xmm6
  subpd  %xmm5,%xmm0
  movapd %xmm1,%xmm3
  shufpd $0x1,%xmm0,%xmm0
  subpd  %xmm0,%xmm3
  addpd  %xmm1,%xmm0
  movapd %xmm5,%xmm1
  addpd  %xmm6,%xmm1
  movapd %xmm0,%xmm7
  movapd %xmm1,%xmm4
  movsd  %xmm3,%xmm7
  movsd  %xmm0,%xmm3
  addpd  %xmm2,%xmm4
  subpd  %xmm1,%xmm2
  movups %xmm4,(%rbx,%rax,1)
  movups %xmm2,(%rcx,%rax,1)
  movups %xmm7,(%rsi,%rax,1)
  movups %xmm3,(%rdx,%rax,1)
  add    $0x10,%rax
  cmp    %rdi,%rax
  jne    L9
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
  nopl   0x0(%rax,%rax,1)
L41:
  je     L227
L66:
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
  nopl   0x0(%rax)
L187:
  mov    %rdx,%r13
  call   <cft1st@plt>
  cmp    $0x7f,%r12d
  jle    L51
  mov    $0x10,%esi
  mov    $0x80,%ebp
  jmp    L202
  xchg   %ax,%ax
L91:
  mov    %eax,%ebp
L202:
  mov    %r13,%rcx
  mov    %rbx,%rdx
  mov    %r12d,%edi
  call   <cftmdl@plt>
  lea    0x0(,%rbp,8),%eax
  mov    %ebp,%esi
  cmp    %r12d,%eax
  jle    L91
  lea    0x0(%rbp,%rbp,1),%eax
  cmp    %r12d,%eax
  jge    L79
  test   %ebp,%ebp
  jg     L197
  jmp    L66
  nopl   0x0(%rax)
L79:
  jne    L66
  test   %ebp,%ebp
  jle    L66
L200:
  movslq %ebp,%rax
  lea    0x20(%rbx),%rdx
  lea    0x20(,%rax,8),%rcx
  lea    (%rbx,%rax,8),%rax
  cmp    %rdx,%rax
  jb     L83
  cmp    $0x4,%ebp
  jle    L83
  lea    -0x1(%rbp),%edx
  xor    %r8d,%r8d
  lea    -0x18(%rbx,%rcx,1),%rsi
  shr    %edx
  test   %ebp,%ebp
  setg   %r8b
  imul   %edx,%r8d
  mov    %rbx,%rdx
  mov    %r8d,%ecx
  shr    %ecx
  lea    -0x1(%rcx),%edi
  lea    0x20(%rsi),%rcx
  shl    $0x5,%rdi
  add    %rcx,%rdi
  jmp    L46
  nopw   0x0(%rax,%rax,1)
L195:
  add    $0x20,%rcx
L46:
  movupd (%rdx),%xmm3
  movupd (%rax),%xmm6
  add    $0x20,%rdx
  add    $0x20,%rax
  movupd -0x10(%rdx),%xmm2
  movupd -0x10(%rax),%xmm5
  movapd %xmm3,%xmm1
  movapd %xmm6,%xmm0
  movupd (%rsi),%xmm4
  subpd  %xmm6,%xmm3
  unpcklpd %xmm2,%xmm1
  unpcklpd %xmm5,%xmm0
  subpd  %xmm5,%xmm2
  addpd  %xmm1,%xmm0
  movupd -0x18(%rdx),%xmm1
  movhpd 0x10(%rsi),%xmm4
  mov    %rcx,%rsi
  movhpd -0x8(%rdx),%xmm1
  addpd  %xmm4,%xmm1
  movapd %xmm0,%xmm4
  unpcklpd %xmm1,%xmm4
  unpckhpd %xmm1,%xmm0
  movups %xmm4,-0x20(%rdx)
  movups %xmm0,-0x10(%rdx)
  movups %xmm3,-0x20(%rax)
  movups %xmm2,-0x10(%rax)
  cmp    %rcx,%rdi
  jne    L195
  and    $0xfffffffe,%r8d
  lea    (%r8,%r8,1),%eax
  movslq %eax,%rsi
  lea    0x0(%rbp,%rax,1),%edx
  lea    0x0(,%rsi,8),%r8
  movslq %edx,%rdx
  lea    0x8(%rbx,%rsi,8),%rsi
  shl    $0x3,%rdx
  lea    (%rbx,%r8,1),%rdi
  movupd (%rdi),%xmm0
  lea    (%rbx,%rdx,1),%rcx
  movupd (%rcx),%xmm2
  movapd %xmm0,%xmm1
  addsd  %xmm2,%xmm1
  subpd  %xmm2,%xmm0
  movsd  %xmm1,(%rdi)
  movsd  (%rsi),%xmm1
  addsd  0x8(%rbx,%rdx,1),%xmm1
  lea    0x2(%rax),%edx
  movsd  %xmm1,(%rsi)
  movups %xmm0,(%rcx)
  cmp    %ebp,%edx
  jge    L66
  add    %ebp,%edx
  lea    0x10(%rbx,%r8,1),%rsi
  add    $0x3,%eax
  movslq %edx,%rdx
  movupd (%rsi),%xmm0
  cltq
  shl    $0x3,%rdx
  lea    (%rbx,%rax,8),%rax
  lea    (%rbx,%rdx,1),%rcx
  movapd %xmm0,%xmm1
  movupd (%rcx),%xmm2
  addsd  %xmm2,%xmm1
  subpd  %xmm2,%xmm0
  movsd  %xmm1,(%rsi)
  movsd  (%rax),%xmm1
  addsd  0x8(%rbx,%rdx,1),%xmm1
  movsd  %xmm1,(%rax)
  movups %xmm0,(%rcx)
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
L51:
  cmp    $0x20,%r12d
  jg     L101
  jne    L66
  mov    $0x10,%ebp
  jmp    L200
  nopl   0x0(%rax)
L227:
  lea    0x10(%rsi),%rax
  mov    $0x2,%ebp
L83:
  xor    %edx,%edx
  nopl   0x0(%rax,%rax,1)
L73:
  movupd (%rbx),%xmm0
  movupd (%rax),%xmm2
  add    $0x2,%edx
  add    $0x10,%rbx
  add    $0x10,%rax
  movapd %xmm0,%xmm1
  subpd  %xmm2,%xmm0
  addsd  %xmm2,%xmm1
  movsd  %xmm1,-0x10(%rbx)
  movsd  -0x8(%rax),%xmm1
  addsd  -0x8(%rbx),%xmm1
  movsd  %xmm1,-0x8(%rbx)
  movups %xmm0,-0x10(%rax)
  cmp    %edx,%ebp
  jg     L73
  jmp    L66
L101:
  mov    $0x10,%ebp
  jmp    L197
```

assistant: ```c
void cftfsub(int n, double *a, double *w) {
  int j, j1, j2, j3, l;
  double x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;
  l = 2;
  if (n >= 16) {
    cft1st(n, a, w);
    l = 16;
    while ((l << 3) <= n) {
      cftmdl(n, l, a, w);
      l <<= 3;
    }
  }
  if ((l << 1) < n) {
    for (j = 0; j < l; j += 2) {
      j1 = j + l;
      j2 = j1 + l;
      j3 = j2 + l;
      x0r = a[j] + a[j1];
      x0i = a[j + 1] + a[j1 + 1];
      x1r = a[j] - a[j1];
      x1i = a[j + 1] - a[j1 + 1];
      x2r = a[j2] + a[j3];
      x2i = a[j2 + 1] + a[j3 + 1];
      x3r = a[j2] - a[j3];
      x3i = a[j2 + 1] - a[j3 + 1];
      a[j] = x0r + x2r;
      a[j + 1] = x0i + x2i;
      a[j2] = x0r - x2r;
      a[j2 + 1] = x0i - x2i;
      a[j1] = x1r - x3i;
      a[j1 + 1] = x1i + x3r;
      a[j3] = x1r + x3i;
      a[j3 + 1] = x1i - x3r;
    }
  } else if ((l << 1) == n) {
    for (j = 0; j < l; j += 2) {
      j1 = j + l;
      x0r = a[j] - a[j1];
      x0i = a[j + 1] - a[j1 + 1];
      a[j] += a[j1];
      a[j + 1] += a[j1 + 1];
      a[j1] = x0r;
      a[j1 + 1] = x0i;
    }
  }
}
```