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

```asm
<filter_fft>:
  endbr64
  push   %r15
  mov    %rcx,%r15
  mov    %esi,%ecx
  push   %r14
  mov    %rdx,%r14
  push   %r13
  mov    $0x1,%r13d
  push   %r12
  shl    %cl,%r13d
  mov    %edi,%r12d
  push   %rbp
  mov    %esi,%ebp
  push   %rbx
  sub    $0x28,%rsp
  mov    %r13d,0x1c(%rsp)
  movslq %r13d,%r13
  mov    %r13,%rdi
  sar    %rdi
  cmp    $0x1,%r13
  jle    L46
  lea    -0x1(%r13),%r9
  xor    %edx,%edx
  xor    %ecx,%ecx
  nopl   0x0(%rax)
L218:
  mov    %rdi,%rax
  cmp    %rdi,%rdx
  jl     L48
L37:
  sub    %rax,%rdx
  sar    %rax
  cmp    %rax,%rdx
  jge    L37
L48:
  add    $0x1,%rcx
  add    %rax,%rdx
  cmp    %r9,%rcx
  je     L46
  cmp    %rcx,%rdx
  jle    L218
  lea    0x0(,%rdx,4),%rax
  movss  (%r14,%rcx,4),%xmm1
  movss  (%r15,%rcx,4),%xmm0
  lea    (%r14,%rax,1),%r8
  add    %r15,%rax
  movss  (%r8),%xmm2
  movss  %xmm2,(%r14,%rcx,4)
  movss  (%rax),%xmm2
  movss  %xmm2,(%r15,%rcx,4)
  movss  %xmm1,(%r8)
  movss  %xmm0,(%rax)
  jmp    L218
L46:
  movslq %ebp,%rax
  mov    %rax,0x10(%rsp)
  test   %rax,%rax
  jle    L156
  movss  D66(%rip),%xmm6
  pxor   %xmm5,%xmm5
  mov    $0x1,%ebp
  xor    %ebx,%ebx
  nopl   0x0(%rax,%rax,1)
L227:
  mov    %rbp,%rax
  add    %rbp,%rbp
  test   %rax,%rax
  jle    L159
  test   %r13,%r13
  jle    L159
  cmp    %rax,%r13
  mov    %rax,%r9
  movss  D27(%rip),%xmm4
  pxor   %xmm3,%xmm3
  cmovle %r13,%r9
  shl    $0x2,%rax
  xor    %r8d,%r8d
  lea    (%r14,%rax,1),%rcx
  lea    (%r15,%rax,1),%rdx
  nopl   (%rax)
L124:
  mov    %r8,%rax
  nopl   0x0(%rax,%rax,1)
L64:
  movss  (%rcx,%rax,4),%xmm2
  movss  (%rdx,%rax,4),%xmm0
  movaps %xmm2,%xmm1
  movaps %xmm0,%xmm7
  mulss  %xmm4,%xmm1
  mulss  %xmm3,%xmm7
  mulss  %xmm3,%xmm2
  mulss  %xmm4,%xmm0
  subss  %xmm7,%xmm1
  addss  %xmm2,%xmm0
  movss  (%r14,%rax,4),%xmm2
  subss  %xmm1,%xmm2
  movss  %xmm2,(%rcx,%rax,4)
  movss  (%r15,%rax,4),%xmm2
  subss  %xmm0,%xmm2
  movss  %xmm2,(%rdx,%rax,4)
  addss  (%r14,%rax,4),%xmm1
  movss  %xmm1,(%r14,%rax,4)
  addss  (%r15,%rax,4),%xmm0
  movss  %xmm0,(%r15,%rax,4)
  add    %rbp,%rax
  cmp    %rax,%r13
  jg     L64
  movaps %xmm6,%xmm0
  movaps %xmm5,%xmm1
  add    $0x1,%r8
  mulss  %xmm4,%xmm0
  mulss  %xmm3,%xmm1
  mulss  %xmm5,%xmm4
  mulss  %xmm6,%xmm3
  subss  %xmm1,%xmm0
  addss  %xmm4,%xmm3
  cmp    %r9,%r8
  jge    L159
  movaps %xmm0,%xmm4
  jmp    L124
  nopl   (%rax)
L159:
  movsd  D49(%rip),%xmm0
  cvtss2sd %xmm6,%xmm6
  movsd  %xmm6,0x8(%rsp)
  subsd  %xmm6,%xmm0
  mulsd  D1(%rip),%xmm0
  call   <sqrt@plt>
  test   %r12d,%r12d
  movsd  0x8(%rsp),%xmm6
  movaps %xmm0,%xmm5
  je     L160
  xorps  D28(%rip),%xmm5
L160:
  addsd  D49(%rip),%xmm6
  movsd  D1(%rip),%xmm0
  movss  %xmm5,0x8(%rsp)
  add    $0x1,%rbx
  mulsd  %xmm6,%xmm0
  call   <sqrt@plt>
  cmp    0x10(%rsp),%rbx
  movss  0x8(%rsp),%xmm5
  movaps %xmm0,%xmm6
  jne    L227
L156:
  test   %r12d,%r12d
  je     L143
  test   %r13,%r13
  jle    L143
  lea    0xf(%r14),%rax
  pxor   %xmm1,%xmm1
  sub    %r15,%rax
  cvtsi2ssl 0x1c(%rsp),%xmm1
  cmp    $0x1e,%rax
  jbe    L24
  lea    -0x1(%r13),%rax
  cmp    $0x2,%rax
  jbe    L24
  mov    %r13,%rdx
  movaps %xmm1,%xmm2
  xor    %eax,%eax
  shr    $0x2,%rdx
  shufps $0x0,%xmm2,%xmm2
  shl    $0x4,%rdx
L233:
  movups (%r14,%rax,1),%xmm0
  divps  %xmm2,%xmm0
  movups %xmm0,(%r14,%rax,1)
  movups (%r15,%rax,1),%xmm0
  divps  %xmm2,%xmm0
  movups %xmm0,(%r15,%rax,1)
  add    $0x10,%rax
  cmp    %rax,%rdx
  jne    L233
  mov    %r13,%rdx
  and    $0xfffffffffffffffc,%rdx
  test   $0x3,%r13b
  je     L143
  lea    0x0(,%rdx,4),%rax
  lea    (%r14,%rax,1),%rcx
  add    %r15,%rax
  movss  (%rcx),%xmm0
  divss  %xmm1,%xmm0
  movss  %xmm0,(%rcx)
  movss  (%rax),%xmm0
  divss  %xmm1,%xmm0
  movss  %xmm0,(%rax)
  lea    0x1(%rdx),%rax
  cmp    %rax,%r13
  jle    L143
  shl    $0x2,%rax
  add    $0x2,%rdx
  lea    (%r14,%rax,1),%rcx
  movss  (%rcx),%xmm0
  divss  %xmm1,%xmm0
  movss  %xmm0,(%rcx)
  lea    (%r15,%rax,1),%rcx
  movss  (%rcx),%xmm0
  divss  %xmm1,%xmm0
  movss  %xmm0,(%rcx)
  cmp    %r13,%rdx
  jge    L143
  add    $0x4,%rax
  add    %rax,%r14
  add    %r15,%rax
  movss  (%r14),%xmm0
  divss  %xmm1,%xmm0
  movss  %xmm0,(%r14)
  movss  (%rax),%xmm0
  divss  %xmm1,%xmm0
  movss  %xmm0,(%rax)
L143:
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L24:
  xor    %eax,%eax
L42:
  movss  (%r14,%rax,4),%xmm0
  divss  %xmm1,%xmm0
  movss  %xmm0,(%r14,%rax,4)
  movss  (%r15,%rax,4),%xmm0
  divss  %xmm1,%xmm0
  movss  %xmm0,(%r15,%rax,4)
  add    $0x1,%rax
  cmp    %rax,%r13
  jne    L42
  jmp    L143
```

tool_calls: name: parse_data
arguments: data_tag: D66
type_guessed: byte[4]
name: parse_data
arguments: data_tag: D27
type_guessed: f32
name: parse_data
arguments: data_tag: D49
type_guessed: f32[2]
name: parse_data
arguments: data_tag: D1
type_guessed: f32[2]
name: parse_data
arguments: data_tag: D28
type_guessed: byte[16]

tool: {"D66": [0x00,0x00,0x80,0xbf]}

tool: D27: 1

tool: {"D49": [0.0,1.875]}

tool: {"D1": [0.0,1.75]}

tool: {"D28": [0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00]}

assistant: ```c
void filter_fft(int dir, int m, float *real, float *imag) {
  long n, i, i1, j, k, i2, l, l1, l2;
  float c1, c2, tx, ty, t1, t2, u1, u2, z;
  n = 1 << m;
  i2 = n >> 1;
  j = 0;
  for (i = 0; i < n - 1; i++) {
    if (i < j) {
      tx = real[i];
      ty = imag[i];
      real[i] = real[j];
      imag[i] = imag[j];
      real[j] = tx;
      imag[j] = ty;
    }
    k = i2;
    while (k <= j) {
      j -= k;
      k >>= 1;
    }
    j += k;
  }
  c1 = -1.0;
  c2 = 0.0;
  l2 = 1;
  for (l = 0; l < m; l++) {
    l1 = l2;
    l2 <<= 1;
    u1 = 1.0;
    u2 = 0.0;
    for (j = 0; j < l1; j++) {
      for (i = j; i < n; i += l2) {
        i1 = i + l1;
        t1 = u1 * real[i1] - u2 * imag[i1];
        t2 = u1 * imag[i1] + u2 * real[i1];
        real[i1] = real[i] - t1;
        imag[i1] = imag[i] - t2;
        real[i] += t1;
        imag[i] += t2;
      }
      z = u1 * c1 - u2 * c2;
      u2 = u1 * c2 + u2 * c1;
      u1 = z;
    }
    c2 = sqrt((1.0 - c1) / 2.0);
    if (dir) {
      c2 = -c2;
    }
    c1 = sqrt((1.0 + c1) / 2.0);
  }
  if (dir) {
    for (i = 0; i < n; i++) {
      real[i] /= n;
      imag[i] /= n;
    }
  }
}
```