user: Please show me the C implementation that matches the assembly code listed below:

```asm
<ifrstage>:
  endbr64
  mov    $0x1,%eax
  mov    %rdi,%r9
  lea    -0x1(%rsi),%ecx
  mov    %rdx,%r10
  mov    %eax,%edi
  mov    %esi,%r11d
  push   %r12
  shl    %cl,%edi
  lea    -0x3(%rsi),%ecx
  push   %rbp
  mov    %edi,%edx
  mov    %edi,%esi
  push   %rbx
  mov    %eax,%ebx
  shr    %edx
  shl    $0x2,%rsi
  add    $0x1,%edi
  movq   (%r9),%xmm5
  lea    (%r9,%rdx,4),%rdx
  shl    %cl,%ebx
  shl    $0x2,%rdi
  lea    (%r9,%rsi,1),%r12
  lea    (%rdx,%rsi,1),%r8
  movss  (%rdx),%xmm0
  movslq %ebx,%rcx
  movss  0x4(%rdx),%xmm2
  movss  (%r8),%xmm10
  movss  (%r10,%rcx,4),%xmm6
  lea    (%rdx,%rdi,1),%rcx
  movaps %xmm5,%xmm3
  movaps %xmm0,%xmm1
  movss  (%rcx),%xmm9
  movaps %xmm2,%xmm4
  shufps $0xe5,%xmm5,%xmm5
  subss  %xmm10,%xmm0
  addss  %xmm10,%xmm1
  shufps $0xe0,%xmm3,%xmm3
  movss  (%r12),%xmm8
  addss  %xmm9,%xmm2
  subss  %xmm9,%xmm4
  lea    (%r9,%rdi,1),%rbp
  addss  %xmm8,%xmm8
  mulss  %xmm6,%xmm0
  movss  0x0(%rbp),%xmm7
  mulss  %xmm6,%xmm2
  movaps %xmm1,%xmm6
  addss  %xmm1,%xmm1
  subss  %xmm0,%xmm6
  addss  %xmm4,%xmm0
  addss  %xmm4,%xmm4
  subss  %xmm2,%xmm6
  subss  %xmm2,%xmm0
  movaps %xmm5,%xmm2
  addps  %xmm3,%xmm2
  subps  %xmm5,%xmm3
  subss  %xmm6,%xmm1
  movss  %xmm2,%xmm3
  movaps %xmm7,%xmm2
  xorps  D8(%rip),%xmm2
  movlps %xmm3,(%r9)
  subss  %xmm7,%xmm2
  movss  %xmm8,(%r12)
  movss  %xmm2,0x0(%rbp)
  movss  %xmm0,0x4(%rdx)
  subss  %xmm4,%xmm0
  movss  %xmm6,(%rdx)
  movss  %xmm1,(%r8)
  movss  %xmm0,(%rcx)
  lea    -0x2(%r11),%ecx
  movss  0x4(%r10),%xmm4
  shl    %cl,%eax
  mov    %eax,%edx
  cltq
  lea    -0x2(%rdx,%rdx,1),%edx
  lea    -0x4(%r10,%rax,4),%rcx
  movslq %edx,%rdx
  movss  (%rcx),%xmm3
  lea    (%r9,%rdx,4),%rdx
  cmp    $0x3,%r11d
  je     L1
  lea    0x8(%r9),%rax
  lea    -0x2(%rbx),%r9d
  lea    0x4(%r10),%r8
  lea    0x8(%r10,%r9,4),%r9
  nopl   (%rax)
L4:
  movss  (%rdx,%rsi,1),%xmm14
  movss  (%rax),%xmm2
  add    $0x4,%r8
  sub    $0x4,%rcx
  movss  (%rdx,%rdi,1),%xmm8
  movss  0x4(%rax),%xmm0
  sub    $0x8,%rdx
  add    $0x8,%rax
  movaps %xmm2,%xmm6
  subss  %xmm14,%xmm2
  movq   0x8(%rdx),%xmm11
  movss  -0x8(%rax,%rsi,1),%xmm12
  addss  %xmm14,%xmm6
  movaps %xmm0,%xmm7
  addss  %xmm8,%xmm0
  movss  -0x8(%rax,%rdi,1),%xmm10
  subss  %xmm8,%xmm7
  movaps %xmm12,%xmm5
  movaps %xmm11,%xmm9
  movaps %xmm2,%xmm1
  unpcklps %xmm10,%xmm5
  mulss  %xmm3,%xmm1
  movaps %xmm6,%xmm8
  subps  %xmm5,%xmm9
  mulss  %xmm4,%xmm2
  addps  %xmm11,%xmm5
  addss  %xmm6,%xmm6
  movaps %xmm9,%xmm13
  shufps $0xe5,%xmm9,%xmm9
  movss  %xmm5,%xmm13
  subss  %xmm1,%xmm8
  movaps %xmm0,%xmm1
  mulss  %xmm4,%xmm1
  addss  %xmm7,%xmm2
  addss  %xmm7,%xmm7
  mulss  %xmm3,%xmm0
  subss  %xmm1,%xmm8
  movaps %xmm11,%xmm1
  shufps $0xe5,%xmm11,%xmm11
  subss  %xmm12,%xmm1
  subss  %xmm0,%xmm2
  movaps %xmm4,%xmm0
  unpcklps %xmm3,%xmm0
  unpcklps %xmm4,%xmm3
  subss  %xmm8,%xmm6
  movss  %xmm8,-0x8(%rax)
  shufps $0xe0,%xmm1,%xmm1
  mulps  %xmm1,%xmm0
  movaps %xmm11,%xmm1
  movss  %xmm2,-0x4(%rax)
  addss  %xmm10,%xmm1
  movaps %xmm13,%xmm10
  subss  %xmm7,%xmm2
  movss  %xmm6,0x8(%rdx,%rsi,1)
  shufps $0xe0,%xmm1,%xmm1
  mulps  %xmm1,%xmm3
  movaps %xmm5,%xmm1
  movss  %xmm2,0x8(%rdx,%rdi,1)
  subps  %xmm0,%xmm10
  addps  %xmm13,%xmm0
  movss  (%r8),%xmm4
  addss  %xmm5,%xmm1
  movss  %xmm10,%xmm0
  subps  %xmm3,%xmm0
  movss  (%rcx),%xmm3
  subss  %xmm0,%xmm1
  movlps %xmm0,0x8(%rdx)
  shufps $0xe5,%xmm0,%xmm0
  movss  %xmm1,-0x8(%rax,%rsi,1)
  movaps %xmm9,%xmm1
  addss  %xmm9,%xmm1
  subss  %xmm1,%xmm0
  movss  %xmm0,-0x8(%rax,%rdi,1)
  cmp    %r9,%r8
  jne    L4
L1:
  pop    %rbx
  pop    %rbp
  pop    %r12
  ret
```

tool_calls: name: read_data
arguments: data_tag: D8
type: byte[16]

tool: {"D8": [0x00,0x00,0x00,0x80,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00]}

assistant: ```c
void ifrstage(float *ioptr, int M, float *Utbl) {
  unsigned int pos;
  unsigned int posi;
  unsigned int diffUcnt;
  float *p0r, *p1r;
  float *u0r, *u0i;
  float w0r, w0i;
  float f0r, f0i, f1r, f1i, f4r, f4i, f5r, f5i;
  float t0r, t0i, t1r, t1i;
  const float Two = 2.0;
  pos = ((uint32_t)1 << (M - 1));
  posi = pos + 1;
  p0r = ioptr;
  p1r = ioptr + pos / 2;
  u0r = Utbl + ((uint32_t)1 << (M - 3));
  w0r = *u0r;
  f0r = *(p0r);
  f0i = *(p0r + 1);
  f4r = *(p0r + pos);
  f4i = *(p0r + posi);
  f1r = *(p1r);
  f1i = *(p1r + 1);
  f5r = *(p1r + pos);
  f5i = *(p1r + posi);
  t0r = f0r + f0i;
  t0i = f0r - f0i;
  t1r = f4r + f4r;
  t1i = -f4i - f4i;
  f0r = f1r + f5r;
  f0i = f1i - f5i;
  f4r = f1r - f5r;
  f4i = f1i + f5i;
  f1r = f0r - w0r * f4r - w0r * f4i;
  f1i = f0i + w0r * f4r - w0r * f4i;
  f5r = Two * f0r - f1r;
  f5i = f1i - Two * f0i;
  *(p0r) = t0r;
  *(p0r + 1) = t0i;
  *(p0r + pos) = t1r;
  *(p0r + posi) = t1i;
  *(p1r) = f1r;
  *(p1r + 1) = f1i;
  *(p1r + pos) = f5r;
  *(p1r + posi) = f5i;
  u0r = Utbl + 1;
  u0i = Utbl + (((uint32_t)1 << (M - 2)) - 1);
  w0r = *u0r;
  w0i = *u0i;
  p0r = (ioptr + 2);
  p1r = (ioptr + (((uint32_t)1 << (M - 2)) - 1) * 2);
  for (diffUcnt = ((uint32_t)1 << (M - 3)) - 1; diffUcnt > 0; diffUcnt--) {
    f0r = *(p0r);
    f0i = *(p0r + 1);
    f5r = *(p1r + pos);
    f5i = *(p1r + posi);
    f1r = *(p1r);
    f1i = *(p1r + 1);
    f4r = *(p0r + pos);
    f4i = *(p0r + posi);
    t0r = f0r + f5r;
    t0i = f0i - f5i;
    t1r = f0r - f5r;
    t1i = f0i + f5i;
    f0r = t0r - w0i * t1r - w0r * t1i;
    f0i = t0i + w0r * t1r - w0i * t1i;
    f5r = Two * t0r - f0r;
    f5i = f0i - Two * t0i;
    t0r = f1r + f4r;
    t0i = f1i - f4i;
    t1r = f1r - f4r;
    t1i = f1i + f4i;
    f1r = t0r - w0r * t1r - w0i * t1i;
    f1i = t0i + w0i * t1r - w0r * t1i;
    f4r = Two * t0r - f1r;
    f4i = f1i - Two * t0i;
    *(p0r) = f0r;
    *(p0r + 1) = f0i;
    *(p1r + pos) = f5r;
    *(p1r + posi) = f5i;
    w0r = *++u0r;
    w0i = *--u0i;
    *(p1r) = f1r;
    *(p1r + 1) = f1i;
    *(p0r + pos) = f4r;
    *(p0r + posi) = f4i;
    p0r += 2;
    p1r -= 2;
  }
}
```