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

```asm
<dctsub>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x38,%rsp
  mov    %edi,%r13d
  mov    %rsi,%rbp
  pxor   %xmm0,%xmm0
  cvtsi2sd %edi,%xmm0
  movsd  D15(%rip),%xmm1
  divsd  %xmm0,%xmm1
  movsd  %xmm1,0x18(%rsp)
  lea    0x28(%rsp),%rdi
  lea    0x20(%rsp),%rsi
  movapd %xmm1,%xmm0
  call   <sincos@plt>
  movsd  0x20(%rsp),%xmm5
  movsd  %xmm5,0x8(%rsp)
  movsd  0x28(%rsp),%xmm2
  movsd  %xmm2,0x10(%rsp)
  movapd %xmm5,%xmm4
  subsd  %xmm2,%xmm4
  movsd  D32(%rip),%xmm3
  mulsd  %xmm3,%xmm4
  addsd  %xmm2,%xmm5
  mulsd  %xmm3,%xmm5
  movapd %xmm2,%xmm1
  addsd  %xmm2,%xmm1
  movsd  %xmm1,(%rsp)
  mov    %r13d,%r15d
  sar    %r15d
  movapd %xmm3,%xmm2
  mov    $0x0,%ecx
  lea    -0x1(%r15),%r14d
  lea    -0x2(%r15),%r12d
  movslq %r13d,%r13
L30:
  lea    0x80(%rcx),%ebx
  cmp    %ebx,%r14d
  cmovle %r12d,%ebx
  lea    0x2(%rcx),%eax
  cmp    %eax,%ebx
  jl     L11
  cltq
  mov    %r13,%rdx
  sub    %rax,%rdx
  lea    0x0(%rbp,%rdx,8),%rdx
  lea    -0x8(%rbp,%rax,8),%rax
  mov    %ebx,%esi
  sub    %ecx,%esi
  lea    -0x2(%rsi),%esi
  shr    %esi
  mov    %esi,%esi
  movslq %ecx,%rcx
  lea    (%rcx,%rsi,2),%rcx
  lea    0x18(%rbp,%rcx,8),%rcx
L28:
  movsd  (%rax),%xmm0
  movsd  0x8(%rdx),%xmm1
  movapd %xmm0,%xmm7
  mulsd  %xmm5,%xmm7
  movapd %xmm1,%xmm6
  mulsd  %xmm4,%xmm6
  subsd  %xmm6,%xmm7
  mulsd  %xmm4,%xmm0
  mulsd  %xmm5,%xmm1
  addsd  %xmm0,%xmm1
  movsd  (%rsp),%xmm9
  movapd %xmm9,%xmm0
  mulsd  %xmm5,%xmm0
  subsd  %xmm0,%xmm3
  movapd %xmm9,%xmm0
  mulsd  %xmm4,%xmm0
  addsd  %xmm0,%xmm2
  movsd  0x8(%rax),%xmm0
  movsd  (%rdx),%xmm6
  movapd %xmm9,%xmm8
  mulsd  %xmm2,%xmm8
  subsd  %xmm8,%xmm4
  mulsd  %xmm3,%xmm9
  addsd  %xmm9,%xmm5
  movsd  %xmm7,0x8(%rdx)
  movapd %xmm0,%xmm7
  mulsd  %xmm2,%xmm7
  movapd %xmm6,%xmm8
  mulsd  %xmm3,%xmm8
  subsd  %xmm8,%xmm7
  movsd  %xmm7,(%rdx)
  movsd  %xmm1,(%rax)
  mulsd  %xmm3,%xmm0
  mulsd  %xmm2,%xmm6
  addsd  %xmm6,%xmm0
  movsd  %xmm0,0x8(%rax)
  sub    $0x10,%rdx
  add    $0x10,%rax
  cmp    %rcx,%rax
  jne    L28
L11:
  cmp    %ebx,%r12d
  je     L25
  lea    0x28(%rsp),%rdi
  lea    0x20(%rsp),%rsi
  pxor   %xmm0,%xmm0
  cvtsi2sd %ebx,%xmm0
  mulsd  0x18(%rsp),%xmm0
  call   <sincos@plt>
  movsd  0x20(%rsp),%xmm2
  movsd  0x28(%rsp),%xmm0
  movapd %xmm2,%xmm3
  subsd  %xmm0,%xmm3
  mulsd  D32(%rip),%xmm3
  addsd  %xmm0,%xmm2
  mulsd  D32(%rip),%xmm2
  movsd  0x8(%rsp),%xmm1
  movapd %xmm1,%xmm4
  mulsd  %xmm3,%xmm4
  movsd  0x10(%rsp),%xmm5
  movapd %xmm5,%xmm0
  mulsd  %xmm2,%xmm0
  subsd  %xmm0,%xmm4
  mulsd  %xmm3,%xmm5
  mulsd  %xmm2,%xmm1
  addsd  %xmm1,%xmm5
  mov    %ebx,%ecx
  jmp    L30
L25:
  movslq %r15d,%rax
  shl    $0x3,%rax
  lea    -0x8(%rbp,%rax,1),%rcx
  movsd  (%rcx),%xmm0
  lea    0x8(%rbp,%rax,1),%rdx
  movsd  (%rdx),%xmm1
  movapd %xmm0,%xmm2
  mulsd  %xmm4,%xmm2
  movapd %xmm1,%xmm3
  mulsd  %xmm5,%xmm3
  addsd  %xmm3,%xmm2
  movsd  %xmm2,(%rcx)
  mulsd  %xmm5,%xmm0
  mulsd  %xmm4,%xmm1
  subsd  %xmm1,%xmm0
  movsd  %xmm0,(%rdx)
  add    %rax,%rbp
  movsd  D6(%rip),%xmm0
  mulsd  0x0(%rbp),%xmm0
  movsd  %xmm0,0x0(%rbp)
  add    $0x38,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

tool_calls: name: read_data
arguments: label: D15
datatype: f64
name: read_data
arguments: label: D32
datatype: f64
name: read_data
arguments: label: D6
datatype: f64

tool: D15: 1.5707963267948966

tool: D32: 0.5

tool: D6: 0.7071067811865476

assistant: ```c
void dctsub(int n, double *a) {
  int i, i0, j, k, m;
  double ec, w1r, w1i, wkr, wki, wdr, wdi, ss, xr, xi, yr, yi;
  ec = 1.570796326794896619231321691639751442098584699687 / n;
  wkr = 0.5;
  wki = 0.5;
  w1r = cos(ec);
  w1i = sin(ec);
  wdr = 0.5 * (w1r - w1i);
  wdi = 0.5 * (w1r + w1i);
  ss = 2 * w1i;
  m = n >> 1;
  i = 0;
  for (;;) {
    i0 = i + 2 * 64;
    if (i0 > m - 2) {
      i0 = m - 2;
    }
    for (j = i + 2; j <= i0; j += 2) {
      k = n - j;
      xr = wdi * a[j - 1] - wdr * a[k + 1];
      xi = wdr * a[j - 1] + wdi * a[k + 1];
      wkr -= ss * wdi;
      wki += ss * wdr;
      yr = wki * a[j] - wkr * a[k];
      yi = wkr * a[j] + wki * a[k];
      wdr -= ss * wki;
      wdi += ss * wkr;
      a[k + 1] = xr;
      a[k] = yr;
      a[j - 1] = xi;
      a[j] = yi;
    }
    if (i0 == m - 2) {
      break;
    }
    wdr = cos(ec * i0);
    wdi = sin(ec * i0);
    wkr = 0.5 * (wdr - wdi);
    wki = 0.5 * (wdr + wdi);
    wdr = wkr * w1r - wki * w1i;
    wdi = wkr * w1i + wki * w1r;
    i = i0;
  }
  xr = wdi * a[m - 1] - wdr * a[m + 1];
  a[m - 1] = wdr * a[m - 1] + wdi * a[m + 1];
  a[m + 1] = xr;
  a[m] *= 0.707106781186547524400844362104849039284835937688;
}
```