user: 请将以下的汇编代码转换成C语言代码：

```asm
<iffts1>:
  endbr64
  push   %r15
  push   %r14
  push   %r13
  push   %r12
  push   %rbp
  push   %rbx
  sub    $0x28,%rsp
  mov    %rdi,%rbx
  mov    %esi,%ebp
  mov    %edx,%r12d
  mov    %rcx,0x8(%rsp)
  mov    %r8,0x10(%rsp)
  mov    $0x1,%eax
  mov    %esi,%ecx
  shl    %cl,%rax
  test   %rax,%rax
  js     L115
  pxor   %xmm1,%xmm1
  cvtsi2sd %rax,%xmm1
L51:
  movsd  D4(%rip),%xmm0
  divsd  %xmm1,%xmm0
  pxor   %xmm2,%xmm2
  cvtsd2ss %xmm0,%xmm2
  movss  %xmm2,0x4(%rsp)
  cmp    $0x2,%ebp
  je     L206
  jg     L94
  test   %ebp,%ebp
  je     L74
  cmp    $0x1,%ebp
  jne    L69
  mov    %r12d,%ebp
  shl    $0x4,%rbp
  add    %rbx,%rbp
  test   %r12d,%r12d
  jle    L74
L112:
  movss  0x4(%rsp),%xmm0
  mov    %rbx,%rdi
  call   <ifft2pt@plt>
  add    $0x10,%rbx
  cmp    %rbx,%rbp
  jne    L112
L74:
  add    $0x28,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
L115:
  mov    %rax,%rdx
  shr    %rdx
  and    $0x1,%eax
  or     %rax,%rdx
  pxor   %xmm1,%xmm1
  cvtsi2sd %rdx,%xmm1
  addsd  %xmm1,%xmm1
  jmp    L51
L94:
  cmp    $0x3,%ebp
  jne    L69
  mov    %r12d,%ebp
  shl    $0x6,%rbp
  add    %rbx,%rbp
  test   %r12d,%r12d
  jle    L74
L135:
  movss  0x4(%rsp),%xmm0
  mov    %rbx,%rdi
  call   <ifft8pt@plt>
  add    $0x40,%rbx
  cmp    %rbx,%rbp
  jne    L135
  jmp    L74
L206:
  mov    %r12d,%ebp
  shl    $0x5,%rbp
  add    %rbx,%rbp
  test   %r12d,%r12d
  jle    L74
L171:
  movss  0x4(%rsp),%xmm0
  mov    %rbx,%rdi
  call   <ifft4pt@plt>
  add    $0x20,%rbx
  cmp    %rbp,%rbx
  jne    L171
  jmp    L74
L69:
  test   %r12d,%r12d
  jle    L74
  lea    -0x1(%rbp),%eax
  movslq %eax,%r14
  imul   $0x55555556,%r14,%r14
  shr    $0x20,%r14
  cltd
  sub    %edx,%r14d
  lea    0x0(,%r14,4),%edx
  mov    %r14d,%r13d
  sub    %edx,%r13d
  add    %eax,%r13d
  mov    $0x8,%eax
  mov    %ebp,%ecx
  shl    %cl,%rax
  mov    %rax,0x18(%rsp)
  mov    $0x2,%r15d
  jmp    L79
L188:
  mov    %r15d,%edx
  mov    %ebp,%esi
  mov    %rbx,%rdi
  call   <ibfR2@plt>
  mov    $0x4,%r8d
  jmp    L211
L72:
  mov    %r15d,%edx
  mov    %ebp,%esi
  mov    %rbx,%rdi
  call   <ibfR4@plt>
  mov    $0x8,%r8d
  jmp    L211
L170:
  mov    %r14d,%r9d
  mov    $0x1,%ecx
  mov    0x8(%rsp),%rdx
  mov    %ebp,%esi
  mov    %rbx,%rdi
  call   <ifftrecurs@plt>
L34:
  add    0x18(%rsp),%rbx
  sub    $0x1,%r12d
  je     L74
L79:
  movss  0x4(%rsp),%xmm0
  mov    0x10(%rsp),%rdx
  mov    %ebp,%esi
  mov    %rbx,%rdi
  call   <scbitrevR2@plt>
  cmp    $0x1,%r13d
  je     L188
  mov    %r15d,%r8d
  cmp    $0x2,%r13d
  je     L72
L211:
  cmp    $0xb,%ebp
  ja     L170
  mov    %r14d,%r9d
  mov    $0x1,%ecx
  mov    0x8(%rsp),%rdx
  mov    %ebp,%esi
  mov    %rbx,%rdi
  call   <ibfstages@plt>
  jmp    L34
```

tool_calls: name: retrieve_data
arguments: tag: D4
type_guessed: f64

tool: D4: 1

assistant: ```c
void iffts1(float *ioptr, int M, int Rows, float *Utbl, short *BRLow) {
  int StageCnt;
  int NDiffU;
  const float scale = 1.0 / ((unsigned long)1 << (M));
  switch (M) {
  case 0:
    break;
  case 1:
    for (; Rows > 0; Rows--) {
      ifft2pt(ioptr, scale);
      ioptr += 2 * ((unsigned long)1 << (M));
    }
    break;
  case 2:
    for (; Rows > 0; Rows--) {
      ifft4pt(ioptr, scale);
      ioptr += 2 * ((unsigned long)1 << (M));
    }
    break;
  case 3:
    for (; Rows > 0; Rows--) {
      ifft8pt(ioptr, scale);
      ioptr += 2 * ((unsigned long)1 << (M));
    }
    break;
  default:
    for (; Rows > 0; Rows--) {
      scbitrevR2(ioptr, M, BRLow, scale);
      StageCnt = (M - 1) / 3;
      NDiffU = 2;
      if ((M - 1 - (StageCnt * 3)) == 1) {
        ibfR2(ioptr, M, NDiffU);
        NDiffU *= 2;
      }
      if ((M - 1 - (StageCnt * 3)) == 2) {
        ibfR4(ioptr, M, NDiffU);
        NDiffU *= 4;
      }
      if (M <= (11 - (sizeof(float) / 8)))
        ibfstages(ioptr, M, Utbl, 1, NDiffU, StageCnt);
      else {
        ifftrecurs(ioptr, M, Utbl, 1, NDiffU, StageCnt);
      }
      ioptr += 2 * ((unsigned long)1 << (M));
    }
  }
}
```