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

```asm
<realft>:
  endbr64
  push   %r13
  pxor   %xmm0,%xmm0
  mov    %rsi,%r13
  push   %r12
  mov    %rsi,%r12
  push   %rbp
  shr    %r12
  mov    %rdi,%rbp
  push   %rbx
  cvtsi2sd %r12,%xmm0
  mov    %edx,%ebx
  sub    $0x38,%rsp
  movsd  D55(%rip),%xmm1
  divsd  %xmm0,%xmm1
  cmp    $0x1,%edx
  je     L35
  movsd  D75(%rip),%xmm6
  xorpd  D58(%rip),%xmm1
  movsd  D84(%rip),%xmm8
  movapd %xmm6,%xmm7
L49:
  movapd %xmm1,%xmm0
  movsd  %xmm8,0x28(%rsp)
  mulsd  %xmm6,%xmm0
  movsd  %xmm7,0x20(%rsp)
  movsd  %xmm6,0x10(%rsp)
  movsd  %xmm1,0x18(%rsp)
  call   <sin@plt>
  movsd  D52(%rip),%xmm5
  movsd  0x18(%rsp),%xmm1
  mulsd  %xmm0,%xmm5
  mulsd  %xmm0,%xmm5
  movapd %xmm1,%xmm0
  movsd  %xmm5,0x8(%rsp)
  call   <sin@plt>
  movsd  0x8(%rsp),%xmm5
  mov    %r13,%rcx
  movsd  D56(%rip),%xmm3
  shr    $0x2,%rcx
  cmp    $0x7,%r13
  movsd  0x10(%rsp),%xmm6
  movsd  0x20(%rsp),%xmm7
  addsd  %xmm5,%xmm3
  movsd  0x28(%rsp),%xmm8
  movapd %xmm0,%xmm9
  jbe    L7
  shl    $0x4,%rcx
  lea    0x18(%rbp),%rax
  lea    0x0(%rbp,%r13,8),%rdx
  lea    0x8(%rbp,%rcx,1),%rcx
  movapd %xmm0,%xmm4
  nopl   0x0(%rax,%rax,1)
L1:
  movsd  (%rdx),%xmm12
  movsd  (%rax),%xmm0
  add    $0x10,%rax
  sub    $0x10,%rdx
  movsd  -0x8(%rax),%xmm1
  movsd  0x8(%rdx),%xmm11
  movapd %xmm0,%xmm2
  movapd %xmm1,%xmm10
  addsd  %xmm12,%xmm1
  subsd  %xmm11,%xmm0
  addsd  %xmm11,%xmm2
  subsd  %xmm12,%xmm10
  mulsd  %xmm8,%xmm1
  mulsd  %xmm7,%xmm0
  mulsd  %xmm6,%xmm2
  mulsd  %xmm6,%xmm10
  movapd %xmm1,%xmm12
  mulsd  %xmm3,%xmm12
  movapd %xmm0,%xmm11
  mulsd  %xmm4,%xmm11
  mulsd  %xmm3,%xmm0
  mulsd  %xmm4,%xmm1
  movapd %xmm12,%xmm13
  addsd  %xmm2,%xmm13
  subsd  %xmm12,%xmm2
  subsd  %xmm11,%xmm13
  addsd  %xmm11,%xmm2
  movsd  %xmm13,-0x10(%rax)
  movapd %xmm0,%xmm13
  subsd  %xmm10,%xmm0
  addsd  %xmm10,%xmm13
  addsd  %xmm1,%xmm0
  addsd  %xmm1,%xmm13
  movapd %xmm9,%xmm1
  mulsd  %xmm4,%xmm1
  movsd  %xmm13,-0x8(%rax)
  movsd  %xmm0,0x10(%rdx)
  movapd %xmm5,%xmm0
  mulsd  %xmm3,%xmm0
  movsd  %xmm2,0x8(%rdx)
  subsd  %xmm1,%xmm0
  movapd %xmm3,%xmm1
  mulsd  %xmm9,%xmm1
  addsd  %xmm0,%xmm3
  movapd %xmm5,%xmm0
  mulsd  %xmm4,%xmm0
  addsd  %xmm1,%xmm0
  addsd  %xmm0,%xmm4
  cmp    %rcx,%rax
  jne    L1
L7:
  movupd 0x8(%rbp),%xmm1
  movapd %xmm1,%xmm0
  shufpd $0x1,%xmm1,%xmm0
  movapd %xmm0,%xmm2
  subpd  %xmm1,%xmm0
  addpd  %xmm1,%xmm2
  movsd  %xmm2,%xmm0
  cmp    $0x1,%ebx
  jne    L45
  movups %xmm0,0x8(%rbp)
  add    $0x38,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  ret
  nopl   0x0(%rax,%rax,1)
L45:
  mulpd  D75(%rip),%xmm0
  mov    %r12,%rsi
  mov    %rbp,%rdi
  mov    $0xffffffff,%edx
  movups %xmm0,0x8(%rbp)
  add    $0x38,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  jmp    1060 <four1@plt>
  xchg   %ax,%ax
L35:
  mov    $0x1,%edx
  mov    %r12,%rsi
  movsd  %xmm1,0x8(%rsp)
  call   <four1@plt>
  movsd  D75(%rip),%xmm6
  movsd  D84(%rip),%xmm7
  movsd  0x8(%rsp),%xmm1
  movapd %xmm6,%xmm8
  jmp    L49
```

tool_calls: name: unpack_data
arguments: tag: D55
data_type: f64
name: unpack_data
arguments: tag: D75
data_type: f64[2]
name: unpack_data
arguments: tag: D58
data_type: byte[16]
name: unpack_data
arguments: tag: D84
data_type: byte[8]
name: unpack_data
arguments: tag: D52
data_type: byte[8]
name: unpack_data
arguments: tag: D56
data_type: f64

tool: D55: 3.141592653589793

tool: {"D75": [0.5,0.5]}

tool: {"D58": [0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00]}

tool: {"D84": [0x00,0x00,0x00,0x00,0x00,0x00,0xe0,0xbf]}

tool: {"D52": [0x00,0x00,0x00,0x00,0x00,0x00,0x00,0xc0]}

tool: D56: 1

assistant: ```c
void realft(double *data, unsigned long n, int isign) {
  unsigned long i, i1, i2, i3, i4, np3;
  double c1 = 0.5, c2, h1r, h1i, h2r, h2i;
  double wr, wi, wpr, wpi, wtemp, theta;
  theta = 3.141592653589793 / (double)(n >> 1);
  if (isign == 1) {
    c2 = -0.5;
    four1(data, n >> 1, 1);
  } else {
    c2 = 0.5;
    theta = -theta;
  }
  wtemp = sin(0.5 * theta);
  wpr = -2.0 * wtemp * wtemp;
  wpi = sin(theta);
  wr = 1.0 + wpr;
  wi = wpi;
  np3 = n + 3;
  for (i = 2; i <= (n >> 2); i++) {
    i4 = 1 + (i3 = np3 - (i2 = 1 + (i1 = i + i - 1)));
    h1r = c1 * (data[i1] + data[i3]);
    h1i = c1 * (data[i2] - data[i4]);
    h2r = -c2 * (data[i2] + data[i4]);
    h2i = c2 * (data[i1] - data[i3]);
    data[i1] = h1r + wr * h2r - wi * h2i;
    data[i2] = h1i + wr * h2i + wi * h2r;
    data[i3] = h1r - wr * h2r + wi * h2i;
    data[i4] = -h1i + wr * h2i + wi * h2r;
    wr = (wtemp = wr) * wpr - wi * wpi + wr;
    wi = wi * wpr + wtemp * wpi + wi;
  }
  if (isign == 1) {
    data[1] = (h1r = data[1]) + data[2];
    data[2] = h1r - data[2];
  } else {
    data[1] = c1 * ((h1r = data[1]) + data[2]);
    data[2] = c1 * (h1r - data[2]);
    four1(data, n >> 1, -1);
  }
}
```