user: What would the C source look like for the assembly code provided here?

```asm
<rftbsub>:
  endbr64
  push   %r15
  pxor   %xmm0,%xmm0
  mov    %rsi,%r15
  push   %r14
  push   %r13
  lea    0x40(%r15),%r13
  push   %r12
  push   %rbp
  push   %rbx
  movslq %edi,%rbx
  cvtsi2sd %ebx,%xmm0
  sub    $0x38,%rsp
  movsd  D49(%rip),%xmm1
  lea    0x28(%rsp),%rbp
  lea    0x20(%rsp),%r12
  divsd  %xmm0,%xmm1
  mov    %r12,%rsi
  mov    %rbp,%rdi
  movapd %xmm1,%xmm0
  movsd  %xmm1,0x8(%rsp)
  call   <sincos@plt>
  movsd  0x28(%rsp),%xmm4
  mov    %ebx,%esi
  movsd  0x20(%rsp),%xmm2
  sar    %esi
  movsd  D2(%rip),%xmm1
  pxor   %xmm3,%xmm3
  movsd  D1(%rip),%xmm6
  mulsd  %xmm4,%xmm2
  lea    0x1(%rsi),%eax
  movapd %xmm3,%xmm7
  mulsd  %xmm4,%xmm4
  cltq
  lea    (%r15,%rax,8),%rax
  movapd %xmm2,%xmm5
  movapd %xmm4,%xmm0
  addsd  %xmm2,%xmm5
  addsd  %xmm4,%xmm0
  movsd  %xmm5,0x18(%rsp)
  addsd  %xmm5,%xmm5
  subsd  %xmm0,%xmm1
  movsd  (%rax),%xmm0
  xorpd  D12(%rip),%xmm0
  movsd  %xmm0,(%rax)
  movsd  %xmm1,0x10(%rsp)
  nopl   0x0(%rax)
L36:
  lea    -0x100(%rsi),%r14d
  mov    $0x4,%eax
  lea    -0x4(%rsi),%ecx
  cmp    %eax,%r14d
  cmovl  %eax,%r14d
  cmp    %ecx,%r14d
  jg     L3
  movslq %ecx,%rax
  mov    %rbx,%rdi
  sub    %r14,%rcx
  movslq %esi,%r8
  sub    %rax,%rdi
  lea    (%r15,%rax,8),%rdx
  and    $0xfffffffc,%ecx
  lea    (%r15,%rdi,8),%rax
  mov    %rbx,%rdi
  sub    %r8,%rdi
  add    %rdi,%rcx
  lea    0x0(%r13,%rcx,8),%rcx
  nopw   0x0(%rax,%rax,1)
L34:
  movsd  0x18(%rdx),%xmm10
  movsd  0x10(%rdx),%xmm8
  add    $0x20,%rax
  sub    $0x20,%rdx
  movsd  -0x28(%rax),%xmm0
  movapd %xmm8,%xmm9
  subsd  -0x30(%rax),%xmm9
  addsd  %xmm10,%xmm0
  movapd %xmm9,%xmm1
  mulsd  %xmm4,%xmm1
  movapd %xmm0,%xmm11
  mulsd  %xmm2,%xmm11
  mulsd  %xmm2,%xmm9
  mulsd  %xmm4,%xmm0
  addsd  %xmm11,%xmm1
  subsd  %xmm9,%xmm0
  subsd  %xmm1,%xmm8
  movsd  %xmm8,0x30(%rdx)
  movapd %xmm0,%xmm8
  subsd  %xmm10,%xmm8
  movsd  %xmm8,0x38(%rdx)
  subsd  -0x28(%rax),%xmm0
  addsd  -0x30(%rax),%xmm1
  movsd  %xmm0,-0x28(%rax)
  movapd %xmm5,%xmm0
  mulsd  %xmm2,%xmm0
  movsd  %xmm1,-0x30(%rax)
  movsd  0x20(%rdx),%xmm8
  movsd  0x28(%rdx),%xmm10
  movapd %xmm8,%xmm9
  subsd  -0x20(%rax),%xmm9
  addsd  %xmm0,%xmm7
  movapd %xmm6,%xmm0
  subsd  %xmm4,%xmm0
  movapd %xmm7,%xmm1
  mulsd  %xmm5,%xmm0
  mulsd  %xmm9,%xmm1
  addsd  %xmm0,%xmm3
  movsd  -0x18(%rax),%xmm0
  addsd  %xmm10,%xmm0
  mulsd  %xmm3,%xmm9
  movapd %xmm3,%xmm11
  mulsd  %xmm0,%xmm11
  mulsd  %xmm7,%xmm0
  addsd  %xmm11,%xmm1
  subsd  %xmm9,%xmm0
  subsd  %xmm1,%xmm8
  movsd  %xmm8,0x20(%rdx)
  movapd %xmm0,%xmm8
  subsd  %xmm10,%xmm8
  movsd  %xmm8,0x28(%rdx)
  subsd  -0x18(%rax),%xmm0
  addsd  -0x20(%rax),%xmm1
  movsd  %xmm0,-0x18(%rax)
  movapd %xmm5,%xmm0
  mulsd  %xmm3,%xmm0
  movsd  %xmm1,-0x20(%rax)
  addsd  %xmm0,%xmm4
  movapd %xmm6,%xmm0
  subsd  %xmm7,%xmm0
  mulsd  %xmm5,%xmm0
  addsd  %xmm0,%xmm2
  cmp    %rax,%rcx
  jne    L34
L3:
  movsd  %xmm5,(%rsp)
  cmp    $0x104,%esi
  jle    L16
  pxor   %xmm0,%xmm0
  mov    %r12,%rsi
  mov    %rbp,%rdi
  cvtsi2sd %r14d,%xmm0
  mulsd  0x8(%rsp),%xmm0
  call   <sincos@plt>
  mov    D1(%rip),%rax
  mov    %r14d,%esi
  movsd  0x28(%rsp),%xmm0
  movsd  0x20(%rsp),%xmm3
  movsd  0x10(%rsp),%xmm7
  movq   %rax,%xmm6
  movsd  0x18(%rsp),%xmm5
  movq   %rax,%xmm4
  mulsd  %xmm6,%xmm0
  movapd %xmm7,%xmm1
  mulsd  %xmm6,%xmm3
  movapd %xmm5,%xmm2
  mulsd  %xmm0,%xmm1
  mulsd  %xmm3,%xmm2
  mulsd  %xmm0,%xmm5
  mulsd  %xmm3,%xmm7
  subsd  %xmm2,%xmm1
  movapd %xmm5,%xmm2
  movsd  (%rsp),%xmm5
  addsd  %xmm7,%xmm2
  movq   %rax,%xmm7
  subsd  %xmm1,%xmm4
  subsd  %xmm0,%xmm7
  jmp    L36
  nop
L16:
  shl    $0x3,%rbx
  movsd  0x10(%r15),%xmm3
  movsd  0x18(%r15),%xmm6
  lea    -0x8(%r15,%rbx,1),%rax
  lea    -0x10(%r15,%rbx,1),%rdx
  movsd  (%rax),%xmm0
  movapd %xmm3,%xmm5
  subsd  (%rdx),%xmm5
  addsd  %xmm6,%xmm0
  movapd %xmm5,%xmm1
  mulsd  %xmm2,%xmm5
  mulsd  %xmm4,%xmm1
  movapd %xmm0,%xmm7
  mulsd  %xmm4,%xmm0
  mulsd  %xmm2,%xmm7
  subsd  %xmm5,%xmm0
  addsd  %xmm7,%xmm1
  movapd %xmm0,%xmm2
  subsd  %xmm1,%xmm3
  subsd  %xmm6,%xmm2
  movsd  %xmm3,0x10(%r15)
  movsd  %xmm2,0x18(%r15)
  addsd  (%rdx),%xmm1
  movsd  %xmm1,(%rdx)
  subsd  (%rax),%xmm0
  movsd  %xmm0,(%rax)
  movsd  0x8(%r15),%xmm0
  xorpd  D12(%rip),%xmm0
  movsd  %xmm0,0x8(%r15)
  add    $0x38,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

tool_calls: name: parse_data
arguments: label: D49
datatype: byte[8]
name: parse_data
arguments: label: D2
datatype: byte[8]
name: parse_data
arguments: label: D1
datatype: f64
name: parse_data
arguments: label: D12
datatype: byte[16]

tool: {"D49": [0x18,0x2d,0x44,0x54,0xfb,0x21,0x09,0x40]}

tool: {"D2": [0x00,0x00,0x00,0x00,0x00,0x00,0xf0,0x3f]}

tool: D1: 0.5

tool: {"D12": [0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00]}

assistant: ```c
void rftbsub(int n, double *a) {
  int i, i0, j, k;
  double ec, w1r, w1i, wkr, wki, wdr, wdi, ss, xr, xi, yr, yi;
  ec = 2 * 1.570796326794896619231321691639751442098584699687 / n;
  wkr = 0;
  wki = 0;
  wdi = cos(ec);
  wdr = sin(ec);
  wdi *= wdr;
  wdr *= wdr;
  w1r = 1 - 2 * wdr;
  w1i = 2 * wdi;
  ss = 2 * w1i;
  i = n >> 1;
  a[i + 1] = -a[i + 1];
  for (;;) {
    i0 = i - 4 * 64;
    if (i0 < 4) {
      i0 = 4;
    }
    for (j = i - 4; j >= i0; j -= 4) {
      k = n - j;
      xr = a[j + 2] - a[k - 2];
      xi = a[j + 3] + a[k - 1];
      yr = wdr * xr + wdi * xi;
      yi = wdr * xi - wdi * xr;
      a[j + 2] -= yr;
      a[j + 3] = yi - a[j + 3];
      a[k - 2] += yr;
      a[k - 1] = yi - a[k - 1];
      wkr += ss * wdi;
      wki += ss * (0.5 - wdr);
      xr = a[j] - a[k];
      xi = a[j + 1] + a[k + 1];
      yr = wkr * xr + wki * xi;
      yi = wkr * xi - wki * xr;
      a[j] -= yr;
      a[j + 1] = yi - a[j + 1];
      a[k] += yr;
      a[k + 1] = yi - a[k + 1];
      wdr += ss * wki;
      wdi += ss * (0.5 - wkr);
    }
    if (i0 == 4) {
      break;
    }
    wkr = 0.5 * sin(ec * i0);
    wki = 0.5 * cos(ec * i0);
    wdr = 0.5 - (wkr * w1r - wki * w1i);
    wdi = wkr * w1i + wki * w1r;
    wkr = 0.5 - wkr;
    i = i0;
  }
  xr = a[2] - a[n - 2];
  xi = a[3] + a[n - 1];
  yr = wdr * xr + wdi * xi;
  yi = wdr * xi - wdi * xr;
  a[2] -= yr;
  a[3] = yi - a[3];
  a[n - 2] += yr;
  a[n - 1] = yi - a[n - 1];
  a[1] = -a[1];
}
```