user: 请将以下的汇编代码转换成C语言代码：

```asm
<cftbsub>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  mov    %rdi,%r12
  push   %rbp
  push   %rbx
  mov    %rsi,%rbx
  sub    $0x8,%rsp
  cmp    $0x8,%rdi
  ja     L136
  mov    $0x2,%ebp
  je     L142
L60:
  lea    (%rbx,%rbp,4),%rdx
L193:
  xor    %eax,%eax
  movss  D50(%rip),%xmm3
  nopl   0x0(%rax,%rax,1)
L20:
  movss  (%rdx),%xmm5
  movss  (%rbx,%rax,4),%xmm1
  add    $0x8,%rdx
  movss  0x4(%rbx,%rax,4),%xmm0
  movss  -0x4(%rdx),%xmm4
  movaps %xmm1,%xmm2
  addss  %xmm5,%xmm1
  subss  %xmm0,%xmm4
  subss  %xmm5,%xmm2
  xorps  %xmm3,%xmm0
  movss  %xmm1,(%rbx,%rax,4)
  subss  -0x4(%rdx),%xmm0
  unpcklps %xmm4,%xmm2
  movss  %xmm0,0x4(%rbx,%rax,4)
  add    $0x2,%rax
  movlps %xmm2,-0x8(%rdx)
  cmp    %rbp,%rax
  jb     L20
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   0x0(%rax)
L136:
  mov    %rdx,%r13
  call   <cft1st@plt>
  cmp    $0x20,%r12
  jbe    L143
  mov    $0x8,%esi
  mov    $0x20,%ebp
  jmp    L116
  xchg   %ax,%ax
L117:
  mov    %rax,%rbp
L116:
  mov    %r13,%rcx
  mov    %rbx,%rdx
  mov    %r12,%rdi
  call   <cftmdl@plt>
  lea    0x0(,%rbp,4),%rax
  mov    %rbp,%rsi
  cmp    %r12,%rax
  jb     L117
  je     L58
  test   %rbp,%rbp
  je     L112
  lea    0x20(%rbx),%rax
  lea    (%rbx,%rbp,4),%rdx
  cmp    %rax,%rdx
  lea    0x20(,%rbp,4),%rcx
  setae  %al
  test   %rcx,%rcx
  setle  %sil
  or     %sil,%al
  je     L193
  cmp    $0x8,%rbp
  jbe    L193
  lea    -0x1(%rbp),%rsi
  movaps D47(%rip),%xmm4
  mov    %rbx,%rax
  lea    -0x1c(%rbx,%rcx,1),%rcx
  mov    %rsi,%rdi
  shr    $0x3,%rsi
  shl    $0x5,%rsi
  shr    %rdi
  add    %rbx,%rsi
  nopl   0x0(%rax)
L102:
  movups (%rax),%xmm0
  movups 0x10(%rax),%xmm7
  add    $0x20,%rax
  add    $0x20,%rdx
  movups -0x20(%rdx),%xmm1
  movups -0x10(%rax),%xmm6
  add    $0x20,%rcx
  movaps %xmm0,%xmm2
  shufps $0x88,%xmm7,%xmm2
  movups -0x10(%rdx),%xmm7
  movaps %xmm1,%xmm5
  shufps $0xdd,%xmm6,%xmm0
  movaps %xmm2,%xmm3
  movups -0x10(%rcx),%xmm6
  shufps $0x88,%xmm7,%xmm5
  shufps $0xdd,%xmm7,%xmm1
  movups -0xc(%rax),%xmm7
  subps  %xmm0,%xmm1
  movups -0x1c(%rax),%xmm0
  subps  %xmm5,%xmm3
  addps  %xmm5,%xmm2
  movups -0x20(%rcx),%xmm5
  shufps $0x88,%xmm7,%xmm0
  xorps  %xmm4,%xmm0
  shufps $0x88,%xmm6,%xmm5
  subps  %xmm5,%xmm0
  movaps %xmm2,%xmm5
  unpcklps %xmm0,%xmm5
  unpckhps %xmm0,%xmm2
  movaps %xmm3,%xmm0
  unpcklps %xmm1,%xmm0
  unpckhps %xmm1,%xmm3
  movups %xmm5,-0x20(%rax)
  movups %xmm2,-0x10(%rax)
  movups %xmm0,-0x20(%rdx)
  movups %xmm3,-0x10(%rdx)
  cmp    %rsi,%rax
  jne    L102
  mov    %rdi,%rax
  and    $0xfffffffffffffffc,%rax
  lea    (%rax,%rax,1),%rdx
  shl    $0x3,%rax
  lea    0x0(%rbp,%rdx,1),%rcx
  lea    (%rbx,%rax,1),%r8
  shl    $0x2,%rcx
  movss  (%r8),%xmm0
  lea    (%rbx,%rcx,1),%rsi
  lea    0x4(%rbx,%rcx,1),%rdi
  movss  (%rsi),%xmm3
  lea    0x4(%rbx,%rdx,4),%rcx
  movaps %xmm0,%xmm2
  movss  (%rdi),%xmm1
  subss  (%rcx),%xmm1
  addss  %xmm3,%xmm0
  subss  %xmm3,%xmm2
  movss  %xmm0,(%r8)
  movss  (%rcx),%xmm0
  unpcklps %xmm1,%xmm2
  movss  D50(%rip),%xmm1
  xorps  %xmm1,%xmm0
  subss  (%rdi),%xmm0
  movss  %xmm0,(%rcx)
  lea    0x2(%rdx),%rcx
  movlps %xmm2,(%rsi)
  cmp    %rcx,%rbp
  jbe    L112
  add    %rbp,%rcx
  lea    0x8(%rbx,%rax,1),%r8
  shl    $0x2,%rcx
  movss  (%r8),%xmm0
  lea    (%rbx,%rcx,1),%rsi
  lea    0x4(%rbx,%rcx,1),%rdi
  movss  (%rsi),%xmm4
  movaps %xmm0,%xmm2
  lea    0xc(%rbx,%rdx,4),%rcx
  movss  (%rdi),%xmm3
  subss  (%rcx),%xmm3
  addss  %xmm4,%xmm0
  subss  %xmm4,%xmm2
  movss  %xmm0,(%r8)
  movss  (%rcx),%xmm0
  unpcklps %xmm3,%xmm2
  xorps  %xmm1,%xmm0
  subss  (%rdi),%xmm0
  movss  %xmm0,(%rcx)
  lea    0x4(%rdx),%rcx
  movlps %xmm2,(%rsi)
  cmp    %rcx,%rbp
  jbe    L112
  add    %rbp,%rcx
  lea    0x10(%rbx,%rax,1),%r8
  shl    $0x2,%rcx
  movss  (%r8),%xmm0
  lea    (%rbx,%rcx,1),%rsi
  lea    0x4(%rbx,%rcx,1),%rdi
  movss  (%rsi),%xmm4
  movaps %xmm0,%xmm2
  lea    0x14(%rbx,%rdx,4),%rcx
  movss  (%rdi),%xmm3
  subss  (%rcx),%xmm3
  addss  %xmm4,%xmm0
  subss  %xmm4,%xmm2
  movss  %xmm0,(%r8)
  movss  (%rcx),%xmm0
  unpcklps %xmm3,%xmm2
  xorps  %xmm1,%xmm0
  subss  (%rdi),%xmm0
  movss  %xmm0,(%rcx)
  lea    0x6(%rdx),%rcx
  movlps %xmm2,(%rsi)
  cmp    %rcx,%rbp
  jbe    L112
  add    %rbp,%rcx
  lea    0x18(%rbx,%rax,1),%rdi
  lea    0x1c(%rbx,%rdx,4),%rax
  shl    $0x2,%rcx
  movss  (%rdi),%xmm0
  lea    (%rbx,%rcx,1),%rsi
  lea    0x4(%rbx,%rcx,1),%rcx
  movss  (%rsi),%xmm4
  movaps %xmm0,%xmm2
  movss  (%rcx),%xmm3
  subss  (%rax),%xmm3
  addss  %xmm4,%xmm0
  subss  %xmm4,%xmm2
  movss  %xmm0,(%rdi)
  movss  (%rax),%xmm0
  unpcklps %xmm3,%xmm2
  xorps  %xmm1,%xmm0
  subss  (%rcx),%xmm0
  movss  %xmm0,(%rax)
  movlps %xmm2,(%rsi)
L112:
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopw   0x0(%rax,%rax,1)
L142:
  lea    0x18(%rsi),%rsi
  mov    $0x10,%r8d
  mov    $0x2,%ebp
L174:
  sub    %r8,%rsi
  xor    %eax,%eax
  movss  D50(%rip),%xmm3
  lea    (%rsi,%r12,1),%rdx
  add    %rdx,%r12
  nopl   0x0(%rax,%rax,1)
L70:
  movss  0x4(%rbx,%rax,4),%xmm2
  movss  0x4(%rsi),%xmm0
  add    $0x8,%rdx
  add    $0x8,%rsi
  movss  -0x8(%rsi),%xmm6
  movq   (%r12),%xmm8
  add    $0x8,%r12
  movaps %xmm2,%xmm5
  movss  (%rbx,%rax,4),%xmm1
  xorps  %xmm3,%xmm5
  movaps %xmm6,%xmm9
  subss  %xmm0,%xmm5
  subss  %xmm2,%xmm0
  movq   -0x8(%rdx),%xmm2
  addss  %xmm1,%xmm9
  subss  %xmm6,%xmm1
  movaps %xmm2,%xmm7
  addps  %xmm8,%xmm2
  subps  %xmm8,%xmm7
  movaps %xmm0,%xmm6
  movaps %xmm9,%xmm4
  unpcklps %xmm1,%xmm6
  movaps %xmm2,%xmm14
  unpcklps %xmm5,%xmm4
  movaps %xmm2,%xmm8
  shufps $0xe5,%xmm14,%xmm14
  subss  %xmm14,%xmm5
  addps  %xmm7,%xmm6
  addss  %xmm9,%xmm8
  subss  %xmm7,%xmm0
  movss  %xmm5,0x4(%rbx,%rax,4)
  movaps %xmm4,%xmm5
  shufps $0xe1,%xmm6,%xmm6
  subps  %xmm2,%xmm5
  addps  %xmm4,%xmm2
  movaps %xmm7,%xmm4
  movss  %xmm8,(%rbx,%rax,4)
  shufps $0xe5,%xmm4,%xmm4
  subss  %xmm4,%xmm1
  add    $0x2,%rax
  movss  %xmm5,%xmm2
  movlps %xmm2,-0x8(%rdx)
  movss  %xmm1,-0x8(%rsi)
  movss  %xmm0,-0x4(%rsi)
  movlps %xmm6,-0x8(%r12)
  cmp    %rax,%rbp
  ja     L70
  jmp    L112
  nopl   0x0(%rax,%rax,1)
L58:
  test   %rbp,%rbp
  je     L112
L71:
  lea    0x0(%rbp,%rbp,2),%rdi
  lea    0x0(,%rbp,4),%r12
  shl    $0x2,%rdi
  lea    0x20(,%rbp,4),%r14
  lea    0x0(,%rbp,8),%r8
  lea    0x20(%rdi),%r9
  lea    0x20(%r8),%r11
  cmp    %r12,%r9
  lea    0x20(%rbx),%r10
  lea    (%rbx,%r12,1),%rcx
  setle  %al
  cmp    %r14,%rdi
  lea    (%rcx,%r12,1),%rdx
  setge  %r13b
  lea    (%rdx,%r12,1),%rsi
  or     %r13d,%eax
  cmp    %r11,%r12
  setge  %r13b
  cmp    %r14,%r8
  setge  %r15b
  or     %r15d,%r13d
  and    %r13d,%eax
  cmp    $0x6,%rbp
  seta   %r13b
  and    %r13d,%eax
  cmp    %r10,%rcx
  setae  %r13b
  test   %r14,%r14
  setle  %r14b
  or     %r14d,%r13d
  and    %r13d,%eax
  cmp    %r8,%r9
  setle  %r13b
  cmp    %r11,%rdi
  setge  %dil
  or     %r13d,%edi
  and    %edi,%eax
  cmp    %r10,%rdx
  setae  %dil
  test   %r11,%r11
  setle  %r11b
  or     %r11d,%edi
  test   %dil,%al
  je     L174
  cmp    %r10,%rsi
  setae  %al
  test   %r9,%r9
  setle  %dil
  or     %dil,%al
  je     L174
  lea    -0x1(%rbp),%rdi
  mov    $0x1,%eax
  movaps D47(%rip),%xmm4
  shr    %rdi
  add    $0x1,%rdi
  test   %rbp,%rbp
  cmove  %rax,%rdi
  xor    %eax,%eax
  mov    %rdi,%r8
  shr    $0x2,%r8
  shl    $0x5,%r8
  nopl   0x0(%rax,%rax,1)
L81:
  movups (%rbx,%rax,1),%xmm5
  movups 0x10(%rbx,%rax,1),%xmm7
  movups (%rcx,%rax,1),%xmm2
  movups 0x10(%rsi,%rax,1),%xmm12
  movaps %xmm5,%xmm0
  shufps $0xdd,%xmm7,%xmm5
  movaps %xmm5,%xmm3
  shufps $0x88,%xmm7,%xmm0
  movups 0x10(%rcx,%rax,1),%xmm7
  movaps %xmm2,%xmm6
  movaps %xmm0,%xmm1
  xorps  %xmm4,%xmm3
  shufps $0x88,%xmm7,%xmm6
  shufps $0xdd,%xmm7,%xmm2
  movaps %xmm0,%xmm7
  movups (%rdx,%rax,1),%xmm0
  subps  %xmm2,%xmm3
  subps  %xmm5,%xmm2
  movups 0x10(%rdx,%rax,1),%xmm5
  addps  %xmm6,%xmm1
  subps  %xmm6,%xmm7
  movaps %xmm0,%xmm6
  shufps $0x88,%xmm5,%xmm6
  shufps $0xdd,%xmm5,%xmm0
  movups (%rsi,%rax,1),%xmm5
  movaps %xmm5,%xmm10
  shufps $0xdd,%xmm12,%xmm5
  movaps %xmm5,%xmm8
  shufps $0x88,%xmm12,%xmm10
  movaps %xmm10,%xmm9
  addps  %xmm0,%xmm8
  subps  %xmm5,%xmm0
  addps  %xmm6,%xmm9
  subps  %xmm10,%xmm6
  movaps %xmm3,%xmm10
  subps  %xmm8,%xmm10
  addps  %xmm8,%xmm3
  movaps %xmm9,%xmm5
  addps  %xmm1,%xmm5
  subps  %xmm9,%xmm1
  movaps %xmm5,%xmm11
  unpckhps %xmm10,%xmm5
  movups %xmm5,0x10(%rbx,%rax,1)
  unpcklps %xmm10,%xmm11
  movaps %xmm1,%xmm5
  unpckhps %xmm3,%xmm1
  movups %xmm11,(%rbx,%rax,1)
  unpcklps %xmm3,%xmm5
  movaps %xmm2,%xmm3
  addps  %xmm6,%xmm2
  movups %xmm1,0x10(%rdx,%rax,1)
  movaps %xmm7,%xmm1
  subps  %xmm6,%xmm3
  subps  %xmm0,%xmm1
  addps  %xmm7,%xmm0
  movups %xmm5,(%rdx,%rax,1)
  movaps %xmm1,%xmm5
  unpckhps %xmm3,%xmm1
  movups %xmm1,0x10(%rcx,%rax,1)
  movaps %xmm2,%xmm1
  movaps %xmm0,%xmm2
  unpcklps %xmm3,%xmm5
  unpcklps %xmm1,%xmm2
  unpckhps %xmm1,%xmm0
  movups %xmm5,(%rcx,%rax,1)
  movups %xmm2,(%rsi,%rax,1)
  movups %xmm0,0x10(%rsi,%rax,1)
  add    $0x20,%rax
  cmp    %rax,%r8
  jne    L81
  mov    %rdi,%rdx
  and    $0xfffffffffffffffc,%rdx
  lea    (%rdx,%rdx,1),%rcx
  cmp    %rdi,%rdx
  je     L112
  lea    (%rcx,%rbp,1),%rax
  shl    $0x3,%rdx
  lea    0x4(%rbx,%rcx,4),%r9
  lea    (%rax,%rbp,1),%r11
  lea    (%rbx,%rdx,1),%r10
  shl    $0x2,%rax
  movss  (%r9),%xmm4
  movss  (%r10),%xmm2
  lea    (%rbx,%rax,1),%rdi
  lea    (%rbx,%r11,4),%r8
  movss  D50(%rip),%xmm3
  lea    0x4(%rbx,%rax,1),%rsi
  movss  (%rdi),%xmm5
  movaps %xmm4,%xmm1
  lea    (%r11,%rbp,1),%rax
  movss  (%rsi),%xmm0
  movaps %xmm2,%xmm8
  lea    (%rbx,%rax,4),%rax
  xorps  %xmm3,%xmm1
  addss  %xmm5,%xmm8
  subss  %xmm5,%xmm2
  movaps %xmm0,%xmm5
  subss  %xmm0,%xmm1
  movq   (%rax),%xmm0
  subss  %xmm4,%xmm5
  movq   (%r8),%xmm4
  movaps %xmm8,%xmm9
  movaps %xmm4,%xmm7
  unpcklps %xmm1,%xmm9
  subps  %xmm0,%xmm7
  addps  %xmm4,%xmm0
  movaps %xmm5,%xmm6
  unpcklps %xmm2,%xmm6
  movaps %xmm0,%xmm4
  addps  %xmm7,%xmm6
  subss  %xmm7,%xmm5
  addss  %xmm8,%xmm4
  shufps $0xe1,%xmm6,%xmm6
  movss  %xmm4,(%r10)
  movaps %xmm0,%xmm4
  shufps $0xe5,%xmm4,%xmm4
  subss  %xmm4,%xmm1
  movaps %xmm7,%xmm4
  shufps $0xe5,%xmm4,%xmm4
  subss  %xmm4,%xmm2
  movss  %xmm1,(%r9)
  movaps %xmm9,%xmm1
  subps  %xmm0,%xmm1
  addps  %xmm9,%xmm0
  movss  %xmm1,%xmm0
  movlps %xmm0,(%r8)
  movss  %xmm2,(%rdi)
  movss  %xmm5,(%rsi)
  movlps %xmm6,(%rax)
  lea    0x2(%rcx),%rax
  cmp    %rbp,%rax
  jae    L112
  add    %rbp,%rax
  lea    0xc(%rbx,%rcx,4),%r9
  lea    0x8(%rbx,%rdx,1),%r10
  movss  (%r9),%xmm0
  lea    (%rax,%rbp,1),%r11
  shl    $0x2,%rax
  movss  (%r10),%xmm6
  lea    0x4(%rbx,%rax,1),%rsi
  lea    (%rbx,%rax,1),%rdi
  movss  (%rsi),%xmm4
  movaps %xmm0,%xmm2
  movss  (%rdi),%xmm5
  lea    (%rbx,%r11,4),%r8
  xorps  %xmm3,%xmm2
  lea    (%r11,%rbp,1),%rax
  subss  %xmm4,%xmm2
  subss  %xmm0,%xmm4
  movaps %xmm5,%xmm9
  addss  %xmm6,%xmm9
  lea    (%rbx,%rax,4),%rax
  subss  %xmm5,%xmm6
  movq   (%rax),%xmm1
  movaps %xmm4,%xmm5
  movq   (%r8),%xmm4
  movaps %xmm9,%xmm7
  movaps %xmm5,%xmm10
  movaps %xmm4,%xmm8
  unpcklps %xmm2,%xmm7
  unpcklps %xmm6,%xmm10
  subps  %xmm1,%xmm8
  addps  %xmm4,%xmm1
  movaps %xmm7,%xmm0
  movaps %xmm1,%xmm4
  subps  %xmm1,%xmm0
  addps  %xmm8,%xmm10
  addss  %xmm9,%xmm4
  subss  %xmm8,%xmm5
  shufps $0xe1,%xmm10,%xmm10
  movss  %xmm4,(%r10)
  movaps %xmm1,%xmm4
  addps  %xmm7,%xmm1
  shufps $0xe5,%xmm4,%xmm4
  subss  %xmm4,%xmm2
  movaps %xmm8,%xmm4
  shufps $0xe5,%xmm4,%xmm4
  subss  %xmm4,%xmm6
  movss  %xmm0,%xmm1
  movss  %xmm2,(%r9)
  movlps %xmm1,(%r8)
  movss  %xmm6,(%rdi)
  movss  %xmm5,(%rsi)
  movlps %xmm10,(%rax)
  lea    0x4(%rcx),%rax
  cmp    %rax,%rbp
  jbe    L112
  lea    0x14(%rbx,%rcx,4),%r8
  add    %rbp,%rax
  lea    0x10(%rbx,%rdx,1),%rdi
  movss  (%r8),%xmm4
  lea    0x0(%rbp,%rax,1),%r9
  shl    $0x2,%rax
  movss  (%rdi),%xmm6
  lea    0x4(%rbx,%rax,1),%rcx
  lea    (%rbx,%rax,1),%rdx
  movss  (%rcx),%xmm1
  xorps  %xmm4,%xmm3
  movss  (%rdx),%xmm5
  lea    0x0(%rbp,%r9,1),%rax
  movaps %xmm3,%xmm0
  lea    (%rbx,%r9,4),%rsi
  lea    (%rbx,%rax,4),%rax
  subss  %xmm1,%xmm0
  subss  %xmm4,%xmm1
  movaps %xmm5,%xmm7
  movq   (%rax),%xmm4
  addss  %xmm6,%xmm7
  subss  %xmm5,%xmm6
  movaps %xmm1,%xmm5
  movq   (%rsi),%xmm1
  movaps %xmm7,%xmm2
  movaps %xmm5,%xmm3
  movaps %xmm1,%xmm8
  addps  %xmm4,%xmm1
  unpcklps %xmm0,%xmm2
  subps  %xmm4,%xmm8
  unpcklps %xmm6,%xmm3
  movaps %xmm1,%xmm4
  addss  %xmm7,%xmm4
  addps  %xmm8,%xmm3
  subss  %xmm8,%xmm5
  movss  %xmm4,(%rdi)
  movaps %xmm1,%xmm4
  shufps $0xe1,%xmm3,%xmm3
  shufps $0xe5,%xmm4,%xmm4
  subss  %xmm4,%xmm0
  movaps %xmm8,%xmm4
  shufps $0xe5,%xmm4,%xmm4
  subss  %xmm4,%xmm6
  movss  %xmm0,(%r8)
  movaps %xmm2,%xmm0
  addps  %xmm1,%xmm2
  subps  %xmm1,%xmm0
  movss  %xmm0,%xmm2
  movlps %xmm2,(%rsi)
  movss  %xmm6,(%rdx)
  movss  %xmm5,(%rcx)
  movlps %xmm3,(%rax)
  add    $0x8,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L143:
  mov    $0x8,%ebp
  jne    L60
  jmp    L71
```

tool_calls: name: read_data
arguments: label: D50
type: byte[4]
name: read_data
arguments: label: D47
type: byte[16]

tool: {"D50": [0x00,0x00,0x00,0x80]}

tool: {"D47": [0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x80]}

assistant: ```c
void cftbsub(size_t n, float *a, float *w) {
  size_t j, j1, j2, j3, l;
  float x0r, x0i, x1r, x1i, x2r, x2i, x3r, x3i;
  l = 2;
  if (n > 8) {
    cft1st(n, a, w);
    l = 8;
    while ((l << 2) < n) {
      cftmdl(n, l, a, w);
      l <<= 2;
    }
  }
  if ((l << 2) == 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 {
    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[j + 1] - a[j1 + 1];
      a[j1] = x0r;
      a[j1 + 1] = x0i;
    }
  }
}
```