user: Translate the below assembly code into C programming language:

```asm
<dfct>:
  endbr64
  push   %r15
  mov    %rsi,%r15
  push   %r14
  push   %r13
  push   %r12
  mov    %rdx,%r12
  push   %rbp
  push   %rbx
  sub    $0x68,%rsp
  mov    (%rcx),%ebp
  mov    %edi,0x1c(%rsp)
  lea    0x0(,%rbp,8),%eax
  mov    %rcx,0x48(%rsp)
  mov    %r8,0x40(%rsp)
  cmp    %edi,%eax
  jl     L7
L351:
  mov    0x48(%rsp),%rax
  mov    0x1c(%rsp),%ebx
  mov    0x4(%rax),%eax
  mov    %ebx,%r14d
  sar    %r14d
  mov    %eax,0x28(%rsp)
  add    %eax,%eax
  cmp    %ebx,%eax
  jl     L280
L136:
  movslq 0x1c(%rsp),%rbx
  movss  (%r15),%xmm1
  movslq %r14d,%rdx
  movss  (%r15,%rdx,4),%xmm0
  lea    0x0(,%rdx,4),%rax
  mov    %rbx,%rdi
  shl    $0x2,%rbx
  movaps %xmm1,%xmm2
  lea    (%r15,%rbx,1),%rcx
  movss  (%rcx),%xmm3
  mov    %rcx,0x50(%rsp)
  addss  %xmm3,%xmm2
  subss  %xmm3,%xmm1
  movss  %xmm1,(%r15)
  movaps %xmm2,%xmm1
  subss  %xmm0,%xmm1
  addss  %xmm2,%xmm0
  movss  %xmm1,(%r12)
  movss  %xmm0,(%r12,%rdx,4)
  cmp    $0x2,%edi
  jle    L227
  mov    %edi,%r13d
  sar    $0x2,%r13d
  cmp    $0x7,%edi
  jle    L201
  movslq %r13d,%rsi
  mov    %rbx,%rcx
  lea    -0x4(,%rdx,4),%rdx
  mov    %rsi,0x8(%rsp)
  sub    %rax,%rcx
  mov    $0x1,%eax
  add    %r15,%rcx
  nopl   0x0(%rax)
L138:
  movss  (%r15,%rax,4),%xmm2
  movss  (%rcx,%rdx,1),%xmm5
  movss  (%r15,%rdx,1),%xmm1
  movss  (%rcx,%rax,4),%xmm4
  movaps %xmm2,%xmm0
  subss  %xmm5,%xmm2
  addss  %xmm5,%xmm0
  movaps %xmm1,%xmm3
  subss  %xmm4,%xmm1
  addss  %xmm4,%xmm3
  movss  %xmm2,(%r15,%rax,4)
  movss  %xmm1,(%r15,%rdx,1)
  movaps %xmm0,%xmm1
  subss  %xmm3,%xmm1
  addss  %xmm3,%xmm0
  movss  %xmm1,(%r12,%rax,4)
  add    $0x1,%rax
  movss  %xmm0,(%r12,%rdx,1)
  sub    $0x4,%rdx
  cmp    %rax,%rsi
  jne    L138
L76:
  mov    0x1c(%rsp),%edx
  mov    0x8(%rsp),%rdi
  movslq %ebp,%rbp
  mov    %r15,%rsi
  sub    %r13d,%edx
  lea    (%r15,%rdi,4),%rax
  movslq %edx,%rdx
  movss  (%rax),%xmm0
  lea    (%r15,%rdx,4),%rdx
  addss  (%rdx),%xmm0
  movss  %xmm0,(%r12,%rdi,4)
  movss  (%rax),%xmm0
  subss  (%rdx),%xmm0
  mov    %r14d,%edi
  mov    0x28(%rsp),%edx
  movss  %xmm0,(%rax)
  mov    0x40(%rsp),%rax
  lea    (%rax,%rbp,4),%rax
  lea    -0x4(%r15,%rbx,1),%rbp
  mov    %rax,%rcx
  mov    %rax,0x30(%rsp)
  lea    -0x2(%r14),%ebx
  call   <dctsub@plt>
  cmp    $0x4,%r14d
  jg     L101
  je     L34
  movss  (%r15),%xmm0
  subss  0x4(%r15),%xmm0
  movss  %xmm0,0x0(%rbp)
  movss  0x4(%r15),%xmm0
  addss  (%r15),%xmm0
  movss  %xmm0,0x4(%r15)
  cmp    $0x1,%ebx
  jle    L209
L321:
  movslq %ebx,%rbx
  nopw   0x0(%rax,%rax,1)
L184:
  movss  (%r15,%rbx,4),%xmm0
  addss  0x4(%r15,%rbx,4),%xmm0
  movss  %xmm0,0x4(%r15,%rbx,8)
  movss  (%r15,%rbx,4),%xmm0
  subss  0x4(%r15,%rbx,4),%xmm0
  movss  %xmm0,-0x4(%r15,%rbx,8)
  sub    $0x2,%rbx
  cmp    $0x1,%ebx
  jg     L184
L209:
  lea    0x10(%r12),%rax
  movl   $0x2,0x18(%rsp)
  mov    %rax,0x38(%rsp)
  lea    0x4(%r12),%rax
  mov    %rax,0x58(%rsp)
  mov    $0x8,%eax
  cmp    $0x1,%r13d
  jle    L2
  nopl   0x0(%rax)
L127:
  mov    0x30(%rsp),%rcx
  mov    0x28(%rsp),%edx
  mov    %r12,%rsi
  mov    %r13d,%edi
  call   <dctsub@plt>
  mov    0x18(%rsp),%ebx
  mov    0x1c(%rsp),%eax
  sub    %ebx,%eax
  cltq
  lea    (%r15,%rax,4),%rbp
  movslq %ebx,%rax
  mov    %rax,0x10(%rsp)
  lea    (%r15,%rax,4),%rbx
  cmp    $0x4,%r13d
  jg     L130
  je     L172
  movss  (%r12),%xmm0
  subss  0x4(%r12),%xmm0
  movss  %xmm0,0x0(%rbp)
  movss  (%r12),%xmm0
  addss  0x4(%r12),%xmm0
  movss  %xmm0,(%rbx)
  cmp    $0x3,%r13d
  jne    L11
L303:
  mov    0x18(%rsp),%eax
  xor    %r14d,%r14d
  lea    -0x3(%r13),%r11d
  lea    0x8(%r12),%rdx
  lea    0x0(,%rax,4),%ebx
  mov    0x10(%rsp),%rax
  movslq %ebx,%r8
  lea    (%rax,%r8,1),%rcx
  mov    %r8,%r9
  lea    0x0(,%r8,8),%rbp
  shl    $0x2,%rcx
  sub    %rax,%r9
  test   %ebx,%ebx
  cmovs  %rbp,%r14
  shr    %r11d
  cmp    $0x2,%r13d
  lea    0x0(,%r8,4),%rsi
  lea    0x1(%r11),%eax
  lea    -0x1(%rax),%rdi
  lea    0x4(,%rax,8),%r10
  mov    %eax,0x2c(%rsp)
  mov    $0xc,%eax
  cmovle %rax,%r10
  xor    %eax,%eax
  add    %r12,%r10
  cmp    $0x2,%r13d
  cmovle %rax,%rdi
  xor    %r11d,%r11d
  imul   %rsi,%rdi
  test   %ebx,%ebx
  cmovs  %rdi,%r11
  cmovs  %rax,%rdi
  lea    0x0(,%r9,4),%rax
  add    %r8,%r9
  shl    $0x2,%r9
  mov    %r9,0x20(%rsp)
  mov    %rcx,%r9
  sub    0x20(%rsp),%r9
  sub    %r14,%r9
  add    %r14,%r14
  sub    %r14,%rbp
  lea    (%rcx,%rdi,1),%r14
  cmp    %rbp,%r9
  seta   %bpl
  cmp    $0xc,%r13d
  setg   %r9b
  and    %r9d,%ebp
  lea    (%rcx,%r11,1),%r9
  add    %r15,%r9
  cmp    %r9,%r10
  setb   %r9b
  add    %r15,%r14
  cmp    %r14,%rdx
  seta   %r14b
  or     %r14d,%r9d
  test   %r9b,%bpl
  je     L45
  add    %rax,%rdi
  lea    (%r11,%rax,1),%r9
  add    %r15,%rdi
  cmp    %rdi,%rdx
  seta   %dil
  add    %r15,%r9
  cmp    %r9,%r10
  setb   %r9b
  or     %dil,%r9b
  je     L45
  cmp    $0x2,%r13d
  mov    $0x1,%r9d
  cmovg  0x2c(%rsp),%r9d
  mov    %r8,%rdi
  lea    (%r8,%r8,2),%r8
  shl    $0x4,%rdi
  add    %r15,%rax
  mov    %r9d,%r10d
  add    %r15,%rcx
  shl    $0x2,%r8
  shr    $0x2,%r10d
  sub    $0x1,%r10d
  shl    $0x5,%r10
  lea    0x28(%r12,%r10,1),%r10
  xchg   %ax,%ax
L316:
  movups (%rdx),%xmm1
  movups 0x10(%rdx),%xmm3
  add    $0x20,%rdx
  movaps %xmm1,%xmm0
  shufps $0xdd,%xmm3,%xmm1
  shufps $0x88,%xmm3,%xmm0
  subps  %xmm1,%xmm0
  movaps %xmm0,%xmm1
  movss  %xmm0,(%rax)
  shufps $0x55,%xmm0,%xmm1
  movss  %xmm1,(%rax,%rsi,1)
  movaps %xmm0,%xmm1
  unpckhps %xmm0,%xmm1
  shufps $0xff,%xmm0,%xmm0
  movss  %xmm1,(%rax,%rsi,2)
  movss  %xmm0,(%rax,%r8,1)
  movups -0x20(%rdx),%xmm1
  movups -0x10(%rdx),%xmm6
  add    %rdi,%rax
  movaps %xmm1,%xmm0
  shufps $0xdd,%xmm6,%xmm1
  shufps $0x88,%xmm6,%xmm0
  addps  %xmm1,%xmm0
  movaps %xmm0,%xmm1
  movss  %xmm0,(%rcx)
  shufps $0x55,%xmm0,%xmm1
  movss  %xmm1,(%rcx,%rsi,1)
  movaps %xmm0,%xmm1
  unpckhps %xmm0,%xmm1
  shufps $0xff,%xmm0,%xmm0
  movss  %xmm1,(%rcx,%rsi,2)
  movss  %xmm0,(%rcx,%r8,1)
  add    %rdi,%rcx
  cmp    %rdx,%r10
  jne    L316
  mov    %r9d,%ecx
  mov    %ebx,%eax
  and    $0xfffffffc,%ecx
  imul   %ecx,%eax
  lea    0x2(%rcx,%rcx,1),%edx
  cmp    %ecx,%r9d
  je     L11
  movslq %edx,%rcx
  mov    0x18(%rsp),%r14d
  add    %ebx,%eax
  lea    0x0(,%rcx,4),%rsi
  lea    0x4(%r12,%rcx,4),%rdi
  mov    %eax,%ecx
  lea    (%r12,%rsi,1),%r8
  sub    %r14d,%ecx
  movss  (%r8),%xmm0
  subss  (%rdi),%xmm0
  movslq %ecx,%rcx
  movss  %xmm0,(%r15,%rcx,4)
  movss  (%r8),%xmm0
  addss  (%rdi),%xmm0
  lea    (%rax,%r14,1),%ecx
  movslq %ecx,%rcx
  movss  %xmm0,(%r15,%rcx,4)
  lea    0x2(%rdx),%ecx
  cmp    %ecx,%r13d
  jle    L11
  lea    0x3(%rdx),%ecx
  add    %ebx,%eax
  lea    0x8(%r12,%rsi,1),%r8
  movslq %ecx,%rcx
  movss  (%r8),%xmm0
  lea    (%r12,%rcx,4),%rdi
  mov    %eax,%ecx
  subss  (%rdi),%xmm0
  sub    %r14d,%ecx
  movslq %ecx,%rcx
  movss  %xmm0,(%r15,%rcx,4)
  movss  (%r8),%xmm0
  addss  (%rdi),%xmm0
  lea    (%rax,%r14,1),%ecx
  movslq %ecx,%rcx
  movss  %xmm0,(%r15,%rcx,4)
  lea    0x4(%rdx),%ecx
  cmp    %ecx,%r13d
  jle    L11
  add    $0x5,%edx
  lea    0x10(%r12,%rsi,1),%rcx
  add    %ebx,%eax
  movslq %edx,%rdx
  movss  (%rcx),%xmm0
  mov    %eax,%esi
  add    %r14d,%eax
  lea    (%r12,%rdx,4),%rdx
  sub    %r14d,%esi
  cltq
  subss  (%rdx),%xmm0
  movslq %esi,%rsi
  movss  %xmm0,(%r15,%rsi,4)
  movss  (%rcx),%xmm0
  addss  (%rdx),%xmm0
  movss  %xmm0,(%r15,%rax,4)
L11:
  mov    0x8(%rsp),%rsi
  mov    %r13d,%r9d
  mov    %r12,%rax
  shll   0x18(%rsp)
  sar    %r9d
  mov    %rsi,%r8
  lea    0x4(,%rsi,4),%r11
  movslq %r9d,%rbx
  mov    %r9d,%r10d
  neg    %r8
  lea    0x0(,%rsi,8),%rcx
  lea    0x0(,%rbx,4),%rdi
  shl    $0x2,%r8
  lea    0xc(%r8),%rdx
  sub    %r8,%rax
  cmp    $0x8,%rdx
  seta   %sil
  cmp    $0x1,%r9d
  setne  %dl
  and    %esi,%edx
  cmp    0x38(%rsp),%rax
  setae  %sil
  and    %esi,%edx
  mov    $0x4,%esi
  sub    %r8,%rsi
  sub    %rdi,%rsi
  cmp    %rdi,%rsi
  setge  %sil
  test   %sil,%dl
  je     L266
  lea    0x4(%rcx),%rdx
  sub    %rdi,%rdx
  cmp    %rdi,%rdx
  jl     L266
  lea    -0x1(%r9),%edx
  cmp    $0x2,%edx
  jbe    L125
  mov    %r12,%rsi
  mov    %r9d,%r11d
  lea    -0xc(%r12,%rcx,1),%rdx
  mov    %r12,%rdi
  sub    %r8,%rsi
  shr    $0x2,%r11d
  lea    -0x1(%r11),%ebp
  lea    -0xc(%rsi),%r10
  sub    $0x1c,%rsi
  shl    $0x4,%rbp
  mov    %rsi,%r11
  sub    %rbp,%r11
  jmp    L137
  cs nopw 0x0(%rax,%rax,1)
L0:
  sub    $0x10,%rsi
L137:
  movups (%rdx),%xmm0
  movups (%rax),%xmm7
  sub    $0x10,%rdx
  add    $0x10,%rax
  add    $0x10,%rdi
  shufps $0x1b,%xmm0,%xmm0
  subps  %xmm7,%xmm0
  movups %xmm0,-0x10(%rdi)
  movups 0x10(%rdx),%xmm0
  movups -0x10(%rax),%xmm5
  shufps $0x1b,%xmm0,%xmm0
  addps  %xmm5,%xmm0
  shufps $0x1b,%xmm0,%xmm0
  movups %xmm0,(%r10)
  mov    %rsi,%r10
  cmp    %r11,%rsi
  jne    L0
  mov    %r9d,%edx
  and    $0xfffffffc,%edx
  mov    %edx,%eax
  cmp    %r9d,%edx
  je     L361
  mov    %r9d,%r10d
  sub    %edx,%r10d
  cmp    $0x1,%r10d
  je     L251
L358:
  mov    %rdx,%rsi
  mov    0x8(%rsp),%rdi
  not    %rsi
  shl    $0x2,%rsi
  add    %rdx,%rdi
  add    %rsi,%rcx
  lea    (%r12,%rdi,4),%rdi
  sub    %r8,%rsi
  add    %r12,%rcx
  movq   (%rdi),%xmm1
  movq   (%rcx),%xmm0
  shufps $0xe1,%xmm0,%xmm0
  subps  %xmm1,%xmm0
  movlps %xmm0,(%r12,%rdx,4)
  movq   (%rcx),%xmm0
  movq   (%rdi),%xmm1
  mov    %r10d,%edx
  and    $0xfffffffe,%edx
  shufps $0xe1,%xmm0,%xmm0
  add    %edx,%eax
  addps  %xmm1,%xmm0
  shufps $0xe1,%xmm0,%xmm0
  movlps %xmm0,(%r12,%rsi,1)
  cmp    %r10d,%edx
  je     L361
L251:
  mov    %r13d,%edx
  lea    0x0(%r13,%rax,1),%esi
  sub    %eax,%edx
  movslq %esi,%rsi
  cltq
  lea    0x0(%r13,%rdx,1),%ecx
  lea    (%r12,%rsi,4),%rsi
  movslq %edx,%rdx
  movslq %ecx,%rcx
  lea    (%r12,%rcx,4),%rcx
  movss  (%rcx),%xmm0
  subss  (%rsi),%xmm0
  movss  %xmm0,(%r12,%rax,4)
  movss  (%rsi),%xmm0
  addss  (%rcx),%xmm0
  movss  %xmm0,(%r12,%rdx,4)
L361:
  add    %r9d,%r13d
  movslq %r13d,%r13
  movss  (%r12,%r13,4),%xmm0
  movss  %xmm0,(%r12,%rbx,4)
L106:
  movslq %r9d,%rax
  mov    %rax,0x8(%rsp)
  mov    %rax,%r13
  jmp    L127
  nopl   (%rax)
L227:
  movss  (%r15),%xmm0
  movss  %xmm0,0x4(%r15)
  movss  (%r12),%xmm0
  movss  %xmm0,0x8(%r15)
  movss  0x4(%r12),%xmm0
L285:
  movss  %xmm0,(%r15)
  add    $0x68,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopw   0x0(%rax,%rax,1)
L130:
  mov    0x48(%rsp),%rax
  mov    %r12,%rdx
  mov    %r13d,%edi
  lea    0x8(%rax),%rsi
  call   <bitrv2@plt>
  mov    0x40(%rsp),%rdx
  mov    %r12,%rsi
  mov    %r13d,%edi
  call   <cftfsub@plt>
  mov    0x30(%rsp),%rcx
  mov    %r12,%rsi
  mov    %r13d,%edi
  mov    0x28(%rsp),%edx
  call   <rftfsub@plt>
L386:
  movss  (%r12),%xmm0
  subss  0x4(%r12),%xmm0
  movss  %xmm0,0x0(%rbp)
  movss  0x4(%r12),%xmm0
  addss  (%r12),%xmm0
  movss  %xmm0,(%rbx)
  jmp    L303
L266:
  mov    0x58(%rsp),%rdi
  lea    -0x1(%r9),%edx
  add    0x8(%rsp),%rdx
  add    %r12,%rcx
  lea    -0x4(%r12,%r11,1),%rax
  lea    (%rdi,%rdx,4),%rdx
  nopw   0x0(%rax,%rax,1)
L320:
  movss  (%rcx),%xmm0
  subss  (%rax),%xmm0
  add    $0x4,%rax
  sub    $0x4,%rcx
  movss  %xmm0,-0x4(%rax,%r8,1)
  movss  -0x4(%rax),%xmm0
  addss  0x4(%rcx),%xmm0
  movss  %xmm0,0x4(%rcx,%r8,1)
  cmp    %rdx,%rax
  jne    L320
  add    %r9d,%r13d
  movslq %r13d,%r13
  movss  (%r12,%r13,4),%xmm0
  movss  %xmm0,(%r12,%rbx,4)
  cmp    $0x1,%r9d
  jne    L106
  movslq 0x18(%rsp),%rax
  shl    $0x2,%rax
L2:
  movss  (%r12),%xmm0
  movss  %xmm0,(%r15,%rax,1)
  movss  0x8(%r12),%xmm0
  mov    0x50(%rsp),%rax
  subss  0x4(%r12),%xmm0
  movss  %xmm0,(%rax)
  movss  0x8(%r12),%xmm0
  addss  0x4(%r12),%xmm0
  jmp    L285
  nopl   0x0(%rax,%rax,1)
L45:
  mov    0x10(%rsp),%rcx
  add    %r15,%rax
  mov    $0x2,%edx
  nopl   (%rax)
L379:
  movss  (%r12,%rdx,4),%xmm0
  subss  0x4(%r12,%rdx,4),%xmm0
  movss  %xmm0,(%rax)
  movss  (%r12,%rdx,4),%xmm0
  addss  0x4(%r12,%rdx,4),%xmm0
  add    $0x2,%rdx
  movss  %xmm0,(%rax,%rcx,8)
  add    %rsi,%rax
  cmp    %edx,%r13d
  jg     L379
  jmp    L11
  nopl   0x0(%rax)
L172:
  mov    0x40(%rsp),%rdx
  mov    %r12,%rsi
  mov    $0x4,%edi
  call   <cftfsub@plt>
  jmp    L386
L280:
  mov    0x40(%rsp),%rbx
  movslq %ebp,%rax
  mov    0x48(%rsp),%rsi
  mov    %r14d,%edi
  lea    (%rbx,%rax,4),%rdx
  call   <makect@plt>
  mov    %r14d,0x28(%rsp)
  jmp    L136
L7:
  mov    %edi,%ebp
  mov    %r8,%rdx
  mov    %rcx,%rsi
  sar    $0x3,%ebp
  mov    %ebp,%edi
  call   <makewt@plt>
  jmp    L351
L125:
  xor    %eax,%eax
  xor    %edx,%edx
  jmp    L358
L201:
  movslq %r13d,%rax
  mov    %rax,0x8(%rsp)
  jmp    L76
L101:
  mov    0x48(%rsp),%rax
  mov    %r15,%rdx
  mov    %r14d,%edi
  lea    0x8(%rax),%rsi
  call   <bitrv2@plt>
  mov    0x40(%rsp),%rdx
  mov    %r15,%rsi
  mov    %r14d,%edi
  call   <cftfsub@plt>
  mov    0x30(%rsp),%rcx
  mov    %r15,%rsi
  mov    %r14d,%edi
  mov    0x28(%rsp),%edx
  call   <rftfsub@plt>
L70:
  movss  (%r15),%xmm0
  subss  0x4(%r15),%xmm0
  movss  %xmm0,0x0(%rbp)
  movss  0x4(%r15),%xmm0
  addss  (%r15),%xmm0
  movss  %xmm0,0x4(%r15)
  jmp    L321
L34:
  mov    0x40(%rsp),%rdx
  mov    %r15,%rsi
  mov    $0x4,%edi
  call   <cftfsub@plt>
  jmp    L70
```

assistant: ```c
void dfct(int n, float *a, float *t, int *ip, float *w) {
  int j, k, l, m, mh, nw, nc;
  float xr, xi, yr, yi;
  nw = ip[0];
  if (n > (nw << 3)) {
    nw = n >> 3;
    makewt(nw, ip, w);
  }
  nc = ip[1];
  if (n > (nc << 1)) {
    nc = n >> 1;
    makect(nc, ip, w + nw);
  }
  m = n >> 1;
  yi = a[m];
  xi = a[0] + a[n];
  a[0] -= a[n];
  t[0] = xi - yi;
  t[m] = xi + yi;
  if (n > 2) {
    mh = m >> 1;
    for (j = 1; j < mh; j++) {
      k = m - j;
      xr = a[j] - a[n - j];
      xi = a[j] + a[n - j];
      yr = a[k] - a[n - k];
      yi = a[k] + a[n - k];
      a[j] = xr;
      a[k] = yr;
      t[j] = xi - yi;
      t[k] = xi + yi;
    }
    t[mh] = a[mh] + a[n - mh];
    a[mh] -= a[n - mh];
    dctsub(m, a, nc, w + nw);
    if (m > 4) {
      bitrv2(m, ip + 2, a);
      cftfsub(m, a, w);
      rftfsub(m, a, nc, w + nw);
    } else if (m == 4) {
      cftfsub(m, a, w);
    }
    a[n - 1] = a[0] - a[1];
    a[1] = a[0] + a[1];
    for (j = m - 2; j >= 2; j -= 2) {
      a[2 * j + 1] = a[j] + a[j + 1];
      a[2 * j - 1] = a[j] - a[j + 1];
    }
    l = 2;
    m = mh;
    while (m >= 2) {
      dctsub(m, t, nc, w + nw);
      if (m > 4) {
        bitrv2(m, ip + 2, t);
        cftfsub(m, t, w);
        rftfsub(m, t, nc, w + nw);
      } else if (m == 4) {
        cftfsub(m, t, w);
      }
      a[n - l] = t[0] - t[1];
      a[l] = t[0] + t[1];
      k = 0;
      for (j = 2; j < m; j += 2) {
        k += l << 2;
        a[k - l] = t[j] - t[j + 1];
        a[k + l] = t[j] + t[j + 1];
      }
      l <<= 1;
      mh = m >> 1;
      for (j = 0; j < mh; j++) {
        k = m - j;
        t[j] = t[m + k] - t[m + j];
        t[k] = t[m + k] + t[m + j];
      }
      t[mh] = t[m + mh];
      m = mh;
    }
    a[l] = t[0];
    a[n] = t[2] - t[1];
    a[0] = t[2] + t[1];
  } else {
    a[1] = a[0];
    a[2] = t[0];
    a[0] = t[1];
  }
}
```