user: 请从给定的汇编指令推导出C源代码：

```asm
<iffts1>:
  endbr64
  push   %r15
  mov    $0x1,%eax
  mov    %esi,%r15d
  push   %r14
  push   %r13
  mov    %rdi,%r13
  push   %r12
  mov    %r8,%r12
  push   %rbp
  mov    %rcx,%rbp
  mov    %esi,%ecx
  push   %rbx
  shl    %cl,%rax
  mov    %edx,%ebx
  sub    $0x18,%rsp
  test   %rax,%rax
  js     L175
  pxor   %xmm1,%xmm1
  cvtsi2sd %rax,%xmm1
L124:
  movsd  D6(%rip),%xmm0
  pxor   %xmm2,%xmm2
  divsd  %xmm1,%xmm0
  cvtsd2ss %xmm0,%xmm2
  movss  %xmm2,(%rsp)
  cmp    $0x2,%r15d
  je     L88
  jg     L125
  test   %r15d,%r15d
  je     L17
  cmp    $0x1,%r15d
  jne    L205
  movslq %ebx,%rbp
  shl    $0x4,%rbp
  add    %r13,%rbp
  test   %ebx,%ebx
  jle    L17
  xchg   %ax,%ax
L239:
  movss  (%rsp),%xmm0
  mov    %r13,%rdi
  add    $0x10,%r13
  call   <ifft2pt@plt>
  cmp    %r13,%rbp
  jne    L239
L17:
  add    $0x18,%rsp
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
  nopl   (%rax)
L125:
  cmp    $0x3,%r15d
  jne    L205
  movslq %ebx,%rbp
  shl    $0x6,%rbp
  add    %r13,%rbp
  test   %ebx,%ebx
  jle    L17
  nopl   0x0(%rax)
L154:
  movss  (%rsp),%xmm0
  mov    %r13,%rdi
  add    $0x40,%r13
  call   <ifft8pt@plt>
  cmp    %rbp,%r13
  jne    L154
  jmp    L17
  nopl   0x0(%rax,%rax,1)
L175:
  mov    %rax,%rdx
  and    $0x1,%eax
  pxor   %xmm1,%xmm1
  shr    %rdx
  or     %rax,%rdx
  cvtsi2sd %rdx,%xmm1
  addsd  %xmm1,%xmm1
  jmp    L124
  xchg   %ax,%ax
L205:
  test   %ebx,%ebx
  jle    L17
  lea    -0x1(%r15),%eax
  movslq %eax,%r14
  cltd
  imul   $0x55555556,%r14,%r14
  shr    $0x20,%r14
  sub    %edx,%r14d
  lea    0x0(,%r14,4),%edx
  mov    %r14d,%ecx
  sub    %edx,%ecx
  add    %ecx,%eax
  mov    %r15d,%ecx
  mov    %eax,0x4(%rsp)
  mov    $0x8,%eax
  shl    %cl,%rax
  mov    %rax,0x8(%rsp)
  jmp    L146
  nop
L131:
  call   <ibfstages@plt>
L190:
  add    0x8(%rsp),%r13
  sub    $0x1,%ebx
  je     L17
L146:
  movss  (%rsp),%xmm0
  mov    %r12,%rdx
  mov    %r15d,%esi
  mov    %r13,%rdi
  call   <scbitrevR2@plt>
  cmpl   $0x1,0x4(%rsp)
  je     L169
  cmpl   $0x2,0x4(%rsp)
  mov    $0x2,%r8d
  je     L50
L93:
  mov    %r14d,%r9d
  mov    $0x1,%ecx
  mov    %rbp,%rdx
  mov    %r15d,%esi
  mov    %r13,%rdi
  cmp    $0xb,%r15d
  jbe    L131
  call   <ifftrecurs@plt>
  jmp    L190
  nopl   0x0(%rax)
L88:
  movslq %ebx,%rbp
  shl    $0x5,%rbp
  add    %r13,%rbp
  test   %ebx,%ebx
  jle    L17
  nopw   0x0(%rax,%rax,1)
L227:
  movss  (%rsp),%xmm0
  mov    %r13,%rdi
  add    $0x20,%r13
  call   <ifft4pt@plt>
  cmp    %r13,%rbp
  jne    L227
  jmp    L17
  nopl   0x0(%rax,%rax,1)
L50:
  mov    $0x2,%edx
  mov    %r15d,%esi
  mov    %r13,%rdi
  call   <ibfR4@plt>
  mov    $0x8,%r8d
  jmp    L93
L169:
  mov    $0x2,%edx
  mov    %r15d,%esi
  mov    %r13,%rdi
  call   <ibfR2@plt>
  mov    $0x4,%r8d
  jmp    L93
```

tool_calls: name: extract_symbolic_data
arguments: tag: D6
datatype: f64

tool: D6: 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));
    }
  }
}
```