user: What is the c source code of the assembly code below:

```asm
<FFT>:
  endbr64
  push   %r13
  push   %r12
  push   %rbp
  lea    (%rsi,%rsi,1),%rbp
  push   %rbx
  sub    $0x18,%rsp
  cmp    $0x1,%rbp
  jbe    L105
  mov    %rsi,%rax
  mov    %edx,%r9d
  btr    $0x3f,%rsi
  mov    %rdi,%r12
  movabs $0x7ffffffffffffffe,%rdx
  mov    $0x1,%ecx
  test   %rdx,%rax
  mov    $0x1,%edx
  setne  %r8b
  nopl   (%rax)
L145:
  mov    %rsi,%rax
  cmp    %rsi,%rdx
  jbe    L111
  test   %r8b,%r8b
  jne    L80
  jmp    L111
  nopw   0x0(%rax,%rax,1)
L32:
  cmp    %rax,%rdx
  jbe    L111
L80:
  sub    %rax,%rdx
  shr    %rax
  cmp    $0x1,%rax
  ja     L32
L111:
  add    $0x2,%rcx
  add    %rax,%rdx
  cmp    %rcx,%rbp
  jbe    L156
  cmp    %rcx,%rdx
  jbe    L145
  lea    0x0(,%rdx,4),%rax
  movss  -0x4(%r12,%rcx,4),%xmm1
  lea    -0x4(%r12,%rax,1),%rdi
  add    %r12,%rax
  movss  (%rdi),%xmm0
  movss  %xmm1,(%rdi)
  movss  (%r12,%rcx,4),%xmm1
  movss  %xmm0,-0x4(%r12,%rcx,4)
  movss  (%rax),%xmm0
  movss  %xmm1,(%rax)
  movss  %xmm0,(%r12,%rcx,4)
  jmp    L145
  xchg   %ax,%ax
L89:
  cmp    %rbx,%rbp
  ja     L18
L105:
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
L156:
  cmp    $0x2,%rbp
  jbe    L105
  pxor   %xmm6,%xmm6
  mov    $0x2,%ebx
  cvtsi2sd %r9d,%xmm6
  movsd  %xmm6,0x8(%rsp)
  nopw   0x0(%rax,%rax,1)
L18:
  mov    %rbx,%r13
  add    %rbx,%rbx
  test   %r13,%r13
  js     L49
  pxor   %xmm0,%xmm0
  cvtsi2sd %r13,%xmm0
L130:
  movsd  D6(%rip),%xmm1
  divsd  %xmm0,%xmm1
  movss  D18(%rip),%xmm0
  mulsd  0x8(%rsp),%xmm1
  cvtsd2ss %xmm1,%xmm1
  mulss  %xmm1,%xmm0
  movss  %xmm1,0x4(%rsp)
  call   <sin@plt>
  movsd  D22(%rip),%xmm5
  movss  0x4(%rsp),%xmm1
  cvtss2sd %xmm0,%xmm0
  mulsd  %xmm0,%xmm5
  mulsd  %xmm0,%xmm5
  movaps %xmm1,%xmm0
  cvtsd2ss %xmm5,%xmm5
  movss  %xmm5,(%rsp)
  call   <sin@plt>
  cmp    $0x1,%r13
  movss  (%rsp),%xmm5
  movaps %xmm0,%xmm6
  jbe    L89
  lea    -0x1(%r13),%r9
  mov    %r12,%r8
  pxor   %xmm4,%xmm4
  mov    $0x1,%edi
  cmp    %rbp,%r9
  movss  D39(%rip),%xmm3
  lea    0x0(,%rbx,4),%rsi
  lea    0x4(,%r13,4),%r10
  cmova  %rbp,%r9
  nopl   0x0(%rax)
L158:
  lea    (%r10,%r8,1),%rdx
  mov    %r8,%rax
  mov    %rdi,%rcx
  nopw   0x0(%rax,%rax,1)
L61:
  movss  -0x4(%rdx),%xmm2
  movss  (%rdx),%xmm0
  add    %rbx,%rcx
  movaps %xmm2,%xmm1
  movaps %xmm0,%xmm7
  mulss  %xmm3,%xmm1
  mulss  %xmm4,%xmm7
  mulss  %xmm4,%xmm2
  mulss  %xmm3,%xmm0
  subss  %xmm7,%xmm1
  addss  %xmm2,%xmm0
  movss  (%rax),%xmm2
  subss  %xmm1,%xmm2
  movss  %xmm2,-0x4(%rdx)
  movss  0x4(%rax),%xmm2
  subss  %xmm0,%xmm2
  movss  %xmm2,(%rdx)
  addss  (%rax),%xmm1
  addss  0x4(%rax),%xmm0
  add    %rsi,%rdx
  movss  %xmm1,(%rax)
  movss  %xmm0,0x4(%rax)
  add    %rsi,%rax
  cmp    %rcx,%rbp
  jae    L61
  movaps %xmm5,%xmm0
  movaps %xmm6,%xmm1
  add    $0x2,%rdi
  add    $0x8,%r8
  mulss  %xmm4,%xmm1
  mulss  %xmm3,%xmm0
  subss  %xmm1,%xmm0
  movaps %xmm5,%xmm1
  mulss  %xmm4,%xmm1
  addss  %xmm3,%xmm0
  mulss  %xmm6,%xmm3
  addss  %xmm1,%xmm3
  addss  %xmm3,%xmm4
  cmp    %r9,%rdi
  ja     L89
  movaps %xmm0,%xmm3
  jmp    L158
L49:
  mov    %r13,%rax
  pxor   %xmm0,%xmm0
  shr    %rax
  cvtsi2sd %rax,%xmm0
  addsd  %xmm0,%xmm0
  jmp    L130
```

tool_calls: name: extract_symbolic_data
arguments: data_label: D6
data_type: byte[8]
name: extract_symbolic_data
arguments: data_label: D18
data_type: f32
name: extract_symbolic_data
arguments: data_label: D22
data_type: f32[2]
name: extract_symbolic_data
arguments: data_label: D39
data_type: f32

tool: {"D6": [0xfc,0x95,0xec,0x52,0xfb,0x21,0x19,0xc0]}

tool: D18: 0.5

tool: {"D22": [0.0,-2.0]}

tool: D39: 1

assistant: ```c
void FFT(float *data, unsigned long nn, int isign) {
  unsigned long n, mmax, m, j, istep, i;
  float wtemp, wr, wpr, wpi, wi, theta;
  float tempr, tempi;
  n = nn << 1;
  j = 1;
  for (i = 1; i < n; i += 2) {
    if (j > i) {
      tempr = (data[j - 1]);
      (data[j - 1]) = (data[i - 1]);
      (data[i - 1]) = tempr;
      tempr = (data[j]);
      (data[j]) = (data[i]);
      (data[i]) = tempr;
    }
    m = n >> 1;
    while ((m >= 2) && (j > m)) {
      j -= m;
      m >>= 1;
    }
    j += m;
  }
  mmax = 2;
  while (n > mmax) {
    istep = mmax << 1;
    theta = isign * (-2 * 3.14159264359 / mmax);
    wtemp = sin(0.5 * theta);
    wpr = -2.0 * wtemp * wtemp;
    wpi = sin(theta);
    wr = 1.0;
    wi = 0.0;
    for (m = 1; m < mmax; m += 2) {
      for (i = m; i <= n; i += istep) {
        j = i + mmax;
        tempr = wr * data[j - 1] - wi * data[j];
        tempi = wr * data[j] + wi * data[j - 1];
        data[j - 1] = data[i - 1] - tempr;
        data[j] = data[i] - tempi;
        data[i - 1] += tempr;
        data[i] += tempi;
      }
      wr = (wtemp = wr) * wpr - wi * wpi + wr;
      wi = wi * wpr + wtemp * wpi + wi;
    }
    mmax = istep;
  }
}
```