user: 这段汇编代码用C语言表示是什么样的?

```asm
<passf2>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  mov    %edi,%ebx
  mov    %esi,%r12d
  mov    %rdx,%r11
  mov    %rcx,%r10
  cmp    $0x2,%edi
  jle    L62
  test   %esi,%esi
  jle    L40
  imul   %esi,%edi
  lea    (%rbx,%rbx,1),%eax
  cltq
  mov    %rax,-0x10(%rsp)
  movslq %ebx,%r14
  shl    $0x3,%r14
  lea    (%rdx,%r14,1),%rax
  mov    %rax,-0x8(%rsp)
  sub    $0x2,%ebx
  shr    %ebx
  mov    %ebx,%ebx
  add    %rbx,%rbx
  mov    $0x0,%ebp
  mov    $0x0,%r13d
  lea    0x10(%rdx),%r15
  pxor   %xmm3,%xmm3
  cvtsi2sd %r9d,%xmm3
  movslq %edi,%rdi
L32:
  lea    0x0(,%rbp,8),%rdx
  lea    (%r11,%rdx,1),%rax
  add    -0x8(%rsp),%rdx
  lea    0x8(%r8),%rsi
  lea    (%rbx,%rbp,1),%rcx
  lea    (%r15,%rcx,8),%r9
  mov    %r10,%rcx
L29:
  movsd  (%rax),%xmm0
  addsd  (%rdx),%xmm0
  movsd  %xmm0,(%rcx)
  movsd  (%rax),%xmm0
  subsd  (%rdx),%xmm0
  movsd  0x8(%rax),%xmm1
  addsd  0x8(%rdx),%xmm1
  movsd  %xmm1,0x8(%rcx)
  movsd  0x8(%rax),%xmm2
  subsd  0x8(%rdx),%xmm2
  movapd %xmm3,%xmm1
  mulsd  (%rsi),%xmm1
  mulsd  %xmm0,%xmm1
  movapd %xmm2,%xmm4
  mulsd  -0x8(%rsi),%xmm4
  addsd  %xmm4,%xmm1
  movsd  %xmm1,0x8(%rcx,%rdi,8)
  mulsd  -0x8(%rsi),%xmm0
  movapd %xmm3,%xmm1
  mulsd  (%rsi),%xmm1
  mulsd  %xmm2,%xmm1
  subsd  %xmm1,%xmm0
  movsd  %xmm0,(%rcx,%rdi,8)
  add    $0x10,%rax
  add    $0x10,%rdx
  add    $0x10,%rcx
  add    $0x10,%rsi
  cmp    %r9,%rax
  jne    L29
  add    $0x1,%r13d
  add    -0x10(%rsp),%rbp
  add    %r14,%r10
  cmp    %r13d,%r12d
  jne    L32
  jmp    L40
L62:
  test   %esi,%esi
  jle    L40
  imul   %esi,%edi
  lea    (%rbx,%rbx,1),%esi
  movslq %esi,%rsi
  shl    $0x3,%rsi
  mov    %rdx,%rax
  movslq %ebx,%rcx
  shl    $0x3,%rcx
  add    %rcx,%r11
  mov    $0x0,%edx
  movslq %edi,%rdi
L19:
  movsd  (%rax),%xmm0
  addsd  (%r11),%xmm0
  movsd  %xmm0,(%r10)
  movsd  (%rax),%xmm0
  subsd  (%r11),%xmm0
  movsd  %xmm0,(%r10,%rdi,8)
  movsd  0x8(%rax),%xmm0
  addsd  0x8(%r11),%xmm0
  movsd  %xmm0,0x8(%r10)
  movsd  0x8(%rax),%xmm0
  subsd  0x8(%r11),%xmm0
  movsd  %xmm0,0x8(%r10,%rdi,8)
  add    $0x1,%edx
  add    %rsi,%rax
  add    %rsi,%r11
  add    %rcx,%r10
  cmp    %edx,%r12d
  jne    L19
L40:
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void passf2(int ido, int l1, const double cc[], double ch[], const double wa1[], int isign) {
  int i, k, ah, ac;
  double ti2, tr2;
  if (ido <= 2) {
    for (k = 0; k < l1; k++) {
      ah = k * ido;
      ac = 2 * k * ido;
      ch[ah] = cc[ac] + cc[ac + ido];
      ch[ah + ido * l1] = cc[ac] - cc[ac + ido];
      ch[ah + 1] = cc[ac + 1] + cc[ac + ido + 1];
      ch[ah + ido * l1 + 1] = cc[ac + 1] - cc[ac + ido + 1];
    }
  } else {
    for (k = 0; k < l1; k++) {
      for (i = 0; i < ido - 1; i += 2) {
        ah = i + k * ido;
        ac = i + 2 * k * ido;
        ch[ah] = cc[ac] + cc[ac + ido];
        tr2 = cc[ac] - cc[ac + ido];
        ch[ah + 1] = cc[ac + 1] + cc[ac + 1 + ido];
        ti2 = cc[ac + 1] - cc[ac + 1 + ido];
        ch[ah + l1 * ido + 1] = wa1[i] * ti2 + isign * wa1[i + 1] * tr2;
        ch[ah + l1 * ido] = wa1[i] * tr2 - isign * wa1[i + 1] * ti2;
      }
    }
  }
}
```