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

```asm
<FFT>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x28,%rsp
  mov    %edi,0x18(%rsp)
  mov    %esi,%r15d
  mov    %rdx,%rbx
  mov    %rcx,%rbp
  mov    $0x1,%eax
  mov    %esi,%ecx
  shl    %cl,%eax
  mov    %eax,0x1c(%rsp)
  movslq %eax,%r12
  mov    %r12,%rsi
  sar    %rsi
  cmp    $0x1,%r12
  jle    L161
  mov    %r12,%r8
  sub    $0x1,%r8
  mov    $0x0,%edx
  mov    $0x0,%ecx
L112:
  cmp    %rsi,%rdx
  jl     L206
  mov    %rsi,%rax
L251:
  sub    %rax,%rdx
  sar    %rax
  cmp    %rax,%rdx
  jge    L251
L244:
  add    %rax,%rdx
  add    $0x1,%rcx
  cmp    %r8,%rcx
  je     L161
  cmp    %rcx,%rdx
  jle    L112
  movsd  (%rbx,%rcx,8),%xmm1
  movsd  0x0(%rbp,%rcx,8),%xmm0
  lea    0x0(,%rdx,8),%rax
  lea    (%rbx,%rax,1),%rdi
  movsd  (%rdi),%xmm2
  movsd  %xmm2,(%rbx,%rcx,8)
  add    %rbp,%rax
  movsd  (%rax),%xmm2
  movsd  %xmm2,0x0(%rbp,%rcx,8)
  movsd  %xmm1,(%rdi)
  movsd  %xmm0,(%rax)
  jmp    L112
L206:
  mov    %rsi,%rax
  jmp    L244
L161:
  movslq %r15d,%r15
  test   %r15,%r15
  jle    L204
  pxor   %xmm7,%xmm7
  movsd  %xmm7,0x10(%rsp)
  movsd  D17(%rip),%xmm7
  movsd  %xmm7,0x8(%rsp)
  mov    $0x1,%r13d
  mov    $0x0,%r14d
  jmp    L49
L6:
  movsd  (%rcx,%rax,8),%xmm2
  movsd  (%rdx,%rax,8),%xmm0
  movapd %xmm2,%xmm1
  mulsd  %xmm4,%xmm1
  movapd %xmm0,%xmm5
  mulsd  %xmm3,%xmm5
  subsd  %xmm5,%xmm1
  mulsd  %xmm4,%xmm0
  mulsd  %xmm3,%xmm2
  addsd  %xmm2,%xmm0
  movsd  (%rbx,%rax,8),%xmm2
  subsd  %xmm1,%xmm2
  movsd  %xmm2,(%rcx,%rax,8)
  movsd  0x0(%rbp,%rax,8),%xmm2
  subsd  %xmm0,%xmm2
  movsd  %xmm2,(%rdx,%rax,8)
  addsd  (%rbx,%rax,8),%xmm1
  movsd  %xmm1,(%rbx,%rax,8)
  addsd  0x0(%rbp,%rax,8),%xmm0
  movsd  %xmm0,0x0(%rbp,%rax,8)
  add    %r13,%rax
  cmp    %rax,%r12
  jg     L6
L68:
  movsd  0x8(%rsp),%xmm6
  movapd %xmm6,%xmm0
  mulsd  %xmm4,%xmm0
  movsd  0x10(%rsp),%xmm7
  movapd %xmm7,%xmm1
  mulsd  %xmm3,%xmm1
  subsd  %xmm1,%xmm0
  mulsd  %xmm6,%xmm3
  mulsd  %xmm7,%xmm4
  addsd  %xmm4,%xmm3
  add    $0x1,%rsi
  cmp    %rdi,%rsi
  je     L200
  movapd %xmm0,%xmm4
L37:
  mov    %rsi,%rax
  cmp    %rsi,%r12
  jg     L6
  jmp    L68
L200:
  movsd  D41(%rip),%xmm0
  subsd  0x8(%rsp),%xmm0
  mulsd  D50(%rip),%xmm0
  pxor   %xmm1,%xmm1
  ucomisd %xmm0,%xmm1
  ja     L253
  sqrtsd %xmm0,%xmm0
  movsd  %xmm0,0x10(%rsp)
L151:
  cmpl   $0x1,0x18(%rsp)
  je     L19
L203:
  movsd  0x8(%rsp),%xmm0
  addsd  D41(%rip),%xmm0
  mulsd  D50(%rip),%xmm0
  pxor   %xmm1,%xmm1
  ucomisd %xmm0,%xmm1
  ja     L147
  sqrtsd %xmm0,%xmm0
  movsd  %xmm0,0x8(%rsp)
L193:
  add    $0x1,%r14
  cmp    %r15,%r14
  je     L204
L49:
  mov    %r13,%rdi
  add    %r13,%r13
  test   %rdi,%rdi
  jle    L200
  lea    0x0(,%rdi,8),%rdx
  lea    (%rbx,%rdx,1),%rcx
  add    %rbp,%rdx
  pxor   %xmm3,%xmm3
  movsd  D41(%rip),%xmm4
  mov    $0x0,%esi
  jmp    L37
L253:
  call   <sqrt@plt>
  movsd  %xmm0,0x10(%rsp)
  jmp    L151
L19:
  movsd  0x10(%rsp),%xmm7
  xorpd  D39(%rip),%xmm7
  movsd  %xmm7,0x10(%rsp)
  jmp    L203
L147:
  call   <sqrt@plt>
  movsd  %xmm0,0x8(%rsp)
  jmp    L193
L204:
  cmpl   $0x1,0x18(%rsp)
  je     L40
L67:
  mov    $0x1,%eax
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L40:
  test   %r12,%r12
  jle    L67
  mov    $0x0,%eax
  pxor   %xmm1,%xmm1
  cvtsi2sdl 0x1c(%rsp),%xmm1
L247:
  movsd  (%rbx,%rax,8),%xmm0
  divsd  %xmm1,%xmm0
  movsd  %xmm0,(%rbx,%rax,8)
  movsd  0x0(%rbp,%rax,8),%xmm0
  divsd  %xmm1,%xmm0
  movsd  %xmm0,0x0(%rbp,%rax,8)
  add    $0x1,%rax
  cmp    %rax,%r12
  jne    L247
  jmp    L67
```

tool_calls: name: disassemble_data
arguments: data_tag: D17
datatype: f32[2]
name: disassemble_data
arguments: data_tag: D41
datatype: f64
name: disassemble_data
arguments: data_tag: D50
datatype: f32[2]
name: disassemble_data
arguments: data_tag: D39
datatype: f32[4]

tool: {"D17": [0.0,-1.875]}

tool: D41: 1

tool: {"D50": [0.0,1.75]}

tool: {"D39": [0.0,-0.0,0.0,0.0]}

assistant: ```c
int FFT(int dir, int m, double *x, double *y) {
  long nn, i, i1, j, k, i2, l, l1, l2;
  double c1, c2, tx, ty, t1, t2, u1, u2, z;
  nn = 1 << m;
  i2 = nn >> 1;
  j = 0;
  for (i = 0; i < nn - 1; i++) {
    if (i < j) {
      tx = x[i];
      ty = y[i];
      x[i] = x[j];
      y[i] = y[j];
      x[j] = tx;
      y[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 < nn; i += l2) {
        i1 = i + l1;
        t1 = u1 * x[i1] - u2 * y[i1];
        t2 = u1 * y[i1] + u2 * x[i1];
        x[i1] = x[i] - t1;
        y[i1] = y[i] - t2;
        x[i] += t1;
        y[i] += t2;
      }
      z = u1 * c1 - u2 * c2;
      u2 = u1 * c2 + u2 * c1;
      u1 = z;
    }
    c2 = sqrt((1.0 - c1) / 2.0);
    if (dir == 1)
      c2 = -c2;
    c1 = sqrt((1.0 + c1) / 2.0);
  }
  if (dir == 1) {
    for (i = 0; i < nn; i++) {
      x[i] /= (double)nn;
      y[i] /= (double)nn;
    }
  }
  return (1);
}
```