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

```asm
<bitrevR2>:
  endbr64
  push   %r15
  mov    %esi,%eax
  mov    $0x1,%r10d
  push   %r14
  mov    %eax,%r11d
  mov    %r10d,%r8d
  push   %r13
  mov    %rdx,%r13
  lea    0x3(%rsi),%edx
  shr    $0x1f,%r11d
  mov    %edx,%ecx
  add    %eax,%r11d
  mov    %r10d,%esi
  push   %r12
  shr    $0x1f,%ecx
  sar    %r11d
  push   %rbp
  add    %edx,%ecx
  mov    %r10d,%edx
  push   %rbx
  sar    %ecx
  shl    %cl,%r8d
  mov    %eax,%ecx
  add    $0x1,%eax
  shl    %cl,%esi
  lea    -0x1(%r11),%ecx
  mov    %rdi,-0x58(%rsp)
  shl    %cl,%edx
  mov    %eax,%ecx
  mov    %esi,%ebp
  shr    $0x1f,%ecx
  lea    -0x1(%rdx),%r15d
  sub    %r8d,%ebp
  add    %ecx,%eax
  mov    %r15d,-0x10(%rsp)
  sar    %eax
  add    $0x1,%eax
  mov    %eax,-0x34(%rsp)
  lea    0x0(,%r8,4),%rax
  lea    (%rdi,%rax,1),%r14
  mov    %r14,-0x18(%rsp)
  cmp    %r14,%rdi
  jae    L38
  lea    0x2(%rsi),%ecx
  lea    0x1(%rsi),%edi
  movslq %r15d,%rbx
  lea    0x0(,%rcx,4),%r8
  lea    0x1(%r11),%ecx
  mov    %rbx,-0x50(%rsp)
  shl    $0x2,%rdi
  shl    %cl,%r10d
  lea    0x3(%rsi),%r9d
  lea    0x0(%r13,%rbx,4),%rbx
  shl    $0x2,%rsi
  movslq %r10d,%rcx
  shl    $0x2,%r9
  shl    $0x2,%rcx
  mov    %rcx,-0x20(%rsp)
  test   %r15d,%r15d
  js     L38
  mov    (%rbx),%ecx
  mov    %rax,%r14
  neg    %r14
  shl    $0x2,%ecx
  movslq %ecx,%rcx
  shl    $0x2,%rcx
  mov    %rcx,-0x40(%rsp)
  mov    %ebp,%ecx
  mov    %rcx,-0x48(%rsp)
  lea    -0x2(%rdx),%ecx
  mov    %ecx,-0xc(%rsp)
  mov    %rsi,%rcx
  sub    %rax,%rcx
  mov    %rcx,-0x30(%rsp)
  mov    %rdi,%rcx
  sub    %rax,%rcx
  mov    %rcx,-0x28(%rsp)
  nopw   0x0(%rax,%rax,1)
L18:
  mov    -0x50(%rsp),%rdx
  mov    -0x10(%rsp),%ecx
  mov    -0x58(%rsp),%r10
  mov    -0x48(%rsp),%r11
  nopl   0x0(%rax,%rax,1)
L49:
  mov    0x0(%r13,%rdx,4),%eax
  shl    $0x2,%eax
  cltq
  add    %r11,%rax
  lea    (%r10,%rax,4),%rax
  lea    (%rax,%rdi,1),%r12
  movss  (%rax,%rsi,1),%xmm1
  movups (%rax),%xmm0
  lea    (%rax,%r8,1),%rbp
  movss  (%r12),%xmm2
  movss  0x8(%rax),%xmm3
  lea    (%rax,%r9,1),%rbx
  movlhps %xmm0,%xmm0
  movss  0x0(%rbp),%xmm6
  movss  (%rbx),%xmm5
  unpcklps %xmm2,%xmm1
  movss  0xc(%rax),%xmm2
  movlhps %xmm1,%xmm1
  movaps %xmm1,%xmm4
  addps  %xmm0,%xmm4
  subps  %xmm1,%xmm0
  shufps $0xe4,%xmm0,%xmm4
  movaps %xmm3,%xmm0
  movups %xmm4,(%rax)
  subss  %xmm6,%xmm3
  addss  %xmm6,%xmm0
  movss  %xmm0,(%rax,%rsi,1)
  movaps %xmm2,%xmm0
  subss  %xmm5,%xmm2
  lea    -0x1(%rdx),%eax
  addss  %xmm5,%xmm0
  sub    $0x1,%rdx
  movss  %xmm0,(%r12)
  movss  %xmm3,0x0(%rbp)
  movss  %xmm2,(%rbx)
  cmp    %edx,%ecx
  jle    L49
  mov    -0xc(%rsp),%ecx
  movslq %eax,%rbp
  sub    %eax,%ecx
  mov    %ecx,-0x38(%rsp)
  cmp    $0xffffffff,%eax
  je     L26
  xchg   %ax,%ax
L48:
  mov    0x0(%r13,%rbp,4),%eax
  mov    -0x58(%rsp),%rbx
  movzbl -0x34(%rsp),%ecx
  shl    $0x2,%eax
  cltq
  add    -0x48(%rsp),%rax
  lea    (%rbx,%rax,4),%r12
  mov    %ebp,%eax
  shl    %cl,%eax
  movss  0x4(%r12),%xmm1
  mov    -0x50(%rsp),%rcx
  cltq
  movss  (%r12),%xmm0
  movss  (%r12,%rdi,1),%xmm4
  lea    (%rbx,%rax,4),%r15
  mov    -0x40(%rsp),%rax
  unpcklps %xmm1,%xmm0
  movss  (%r12,%rsi,1),%xmm1
  lea    (%r15,%rax,1),%rdx
  movlhps %xmm0,%xmm0
  mov    %r12,%rax
  nopw   0x0(%rax,%rax,1)
L41:
  lea    (%rdx,%rdi,1),%rbx
  movss  (%rdx,%rsi,1),%xmm10
  unpcklps %xmm4,%xmm1
  movups (%rdx),%xmm2
  movss  (%rbx),%xmm5
  movlhps %xmm1,%xmm1
  movss  0x8(%rax),%xmm4
  lea    (%rdx,%r8,1),%r11
  movss  (%rax,%r8,1),%xmm12
  movss  0xc(%rax),%xmm3
  lea    (%rdx,%r9,1),%r10
  movlhps %xmm2,%xmm2
  unpcklps %xmm5,%xmm10
  movaps %xmm1,%xmm5
  movss  (%rax,%r9,1),%xmm11
  movss  0x8(%rdx),%xmm9
  addps  %xmm0,%xmm5
  subps  %xmm1,%xmm0
  movss  0xc(%rdx),%xmm6
  movss  (%r11),%xmm8
  movss  (%r10),%xmm7
  movlhps %xmm10,%xmm10
  shufps $0xe4,%xmm0,%xmm5
  movaps %xmm12,%xmm0
  movups %xmm5,(%rdx)
  addss  %xmm4,%xmm0
  subss  %xmm12,%xmm4
  movss  %xmm0,(%rdx,%rsi,1)
  movaps %xmm11,%xmm0
  addss  %xmm3,%xmm0
  subss  %xmm11,%xmm3
  movss  %xmm0,(%rbx)
  movaps %xmm8,%xmm0
  mov    -0x4(%r13,%rcx,4),%ebx
  sub    $0x1,%rcx
  movss  %xmm4,(%r11)
  addss  %xmm9,%xmm0
  subss  %xmm8,%xmm9
  movss  %xmm3,(%r10)
  movaps %xmm10,%xmm3
  lea    0x0(,%rbx,4),%edx
  addps  %xmm2,%xmm3
  subps  %xmm10,%xmm2
  movslq %edx,%rdx
  lea    (%r15,%rdx,4),%rdx
  shufps $0xe4,%xmm2,%xmm3
  movups %xmm3,(%rax)
  movss  %xmm0,(%rax,%rsi,1)
  movaps %xmm7,%xmm0
  addss  %xmm6,%xmm0
  subss  %xmm7,%xmm6
  movss  %xmm0,(%rax,%rdi,1)
  movss  %xmm9,(%rax,%r8,1)
  movss  %xmm6,(%rax,%r9,1)
  add    %r14,%rax
  movss  (%rax),%xmm2
  movss  0x4(%rax),%xmm3
  movss  (%rax,%rsi,1),%xmm1
  movss  (%rax,%rdi,1),%xmm4
  movaps %xmm2,%xmm0
  unpcklps %xmm3,%xmm0
  movlhps %xmm0,%xmm0
  cmp    %ebp,%ecx
  jg     L41
  mov    -0x38(%rsp),%eax
  mov    %r14,%r10
  movaps %xmm1,%xmm0
  movaps %xmm4,%xmm9
  addss  %xmm2,%xmm0
  addss  %xmm3,%xmm9
  sub    $0x1,%rbp
  imul   %rax,%r10
  mov    %rax,%rbx
  subss  %xmm1,%xmm2
  add    $0x1,%rax
  imul   %r14,%rax
  subss  %xmm4,%xmm3
  add    $0x1,%ebx
  unpcklps %xmm9,%xmm0
  mov    %ebx,-0x38(%rsp)
  add    %r12,%rax
  unpcklps %xmm3,%xmm2
  add    %r10,%r12
  movss  0x8(%rax),%xmm6
  lea    (%rax,%r8,1),%rcx
  lea    (%rax,%r9,1),%rdx
  movlhps %xmm2,%xmm0
  movss  (%rcx),%xmm8
  movss  0xc(%rax),%xmm5
  movss  (%rdx),%xmm7
  movups %xmm0,(%rax)
  movaps %xmm6,%xmm0
  mov    -0x30(%rsp),%rax
  addss  %xmm8,%xmm0
  subss  %xmm8,%xmm6
  movss  %xmm0,(%r12,%rax,1)
  movaps %xmm5,%xmm0
  subss  %xmm7,%xmm5
  mov    -0x28(%rsp),%rax
  addss  %xmm7,%xmm0
  movss  %xmm0,(%r12,%rax,1)
  movss  %xmm6,(%rcx)
  movss  %xmm5,(%rdx)
  test   %ebp,%ebp
  jns    L48
L26:
  mov    -0x20(%rsp),%rcx
  add    %rcx,-0x58(%rsp)
  mov    -0x58(%rsp),%rax
  cmp    %rax,-0x18(%rsp)
  ja     L18
L38:
  pop    %rbx
  pop    %rbp
  pop    %r12
  pop    %r13
  pop    %r14
  pop    %r15
  ret
```

assistant: ```c
void bitrevR2(float *ioptr, int M, int16_t *BRLow) {
  float f0r;
  float f0i;
  float f1r;
  float f1i;
  float f2r;
  float f2i;
  float f3r;
  float f3i;
  float f4r;
  float f4i;
  float f5r;
  float f5i;
  float f6r;
  float f6i;
  float f7r;
  float f7i;
  float t0r;
  float t0i;
  float t1r;
  float t1i;
  float *p0r;
  float *p1r;
  float *IOP;
  float *iolimit;
  int Colstart;
  int iCol;
  unsigned int posA;
  unsigned int posAi;
  unsigned int posB;
  unsigned int posBi;
  const unsigned int Nrems2 = ((uint32_t)1 << ((M + 3) / 2));
  const unsigned int Nroot_1_ColInc = ((uint32_t)1 << (M)) - Nrems2;
  const unsigned int Nroot_1 = ((uint32_t)1 << (M / 2 - 1)) - 1;
  const unsigned int ColstartShift = (M + 1) / 2 + 1;
  posA = ((uint32_t)1 << (M));
  posAi = posA + 1;
  posB = posA + 2;
  posBi = posB + 1;
  iolimit = ioptr + Nrems2;
  for (; ioptr < iolimit; ioptr += ((uint32_t)1 << (M / 2 + 1))) {
    for (Colstart = Nroot_1; Colstart >= 0; Colstart--) {
      iCol = Nroot_1;
      p0r = ioptr + Nroot_1_ColInc + BRLow[Colstart] * 4;
      IOP = ioptr + (Colstart << ColstartShift);
      p1r = IOP + BRLow[iCol] * 4;
      f0r = *(p0r);
      f0i = *(p0r + 1);
      f1r = *(p0r + posA);
      f1i = *(p0r + posAi);
      for (; iCol > Colstart;) {
        f2r = *(p0r + 2);
        f2i = *(p0r + (2 + 1));
        f3r = *(p0r + posB);
        f3i = *(p0r + posBi);
        f4r = *(p1r);
        f4i = *(p1r + 1);
        f5r = *(p1r + posA);
        f5i = *(p1r + posAi);
        f6r = *(p1r + 2);
        f6i = *(p1r + (2 + 1));
        f7r = *(p1r + posB);
        f7i = *(p1r + posBi);
        t0r = f0r + f1r;
        t0i = f0i + f1i;
        f1r = f0r - f1r;
        f1i = f0i - f1i;
        t1r = f2r + f3r;
        t1i = f2i + f3i;
        f3r = f2r - f3r;
        f3i = f2i - f3i;
        f0r = f4r + f5r;
        f0i = f4i + f5i;
        f5r = f4r - f5r;
        f5i = f4i - f5i;
        f2r = f6r + f7r;
        f2i = f6i + f7i;
        f7r = f6r - f7r;
        f7i = f6i - f7i;
        *(p1r) = t0r;
        *(p1r + 1) = t0i;
        *(p1r + 2) = f1r;
        *(p1r + (2 + 1)) = f1i;
        *(p1r + posA) = t1r;
        *(p1r + posAi) = t1i;
        *(p1r + posB) = f3r;
        *(p1r + posBi) = f3i;
        *(p0r) = f0r;
        *(p0r + 1) = f0i;
        *(p0r + 2) = f5r;
        *(p0r + (2 + 1)) = f5i;
        *(p0r + posA) = f2r;
        *(p0r + posAi) = f2i;
        *(p0r + posB) = f7r;
        *(p0r + posBi) = f7i;
        p0r -= Nrems2;
        f0r = *(p0r);
        f0i = *(p0r + 1);
        f1r = *(p0r + posA);
        f1i = *(p0r + posAi);
        iCol -= 1;
        p1r = IOP + BRLow[iCol] * 4;
      }
      f2r = *(p0r + 2);
      f2i = *(p0r + (2 + 1));
      f3r = *(p0r + posB);
      f3i = *(p0r + posBi);
      t0r = f0r + f1r;
      t0i = f0i + f1i;
      f1r = f0r - f1r;
      f1i = f0i - f1i;
      t1r = f2r + f3r;
      t1i = f2i + f3i;
      f3r = f2r - f3r;
      f3i = f2i - f3i;
      *(p0r) = t0r;
      *(p0r + 1) = t0i;
      *(p0r + 2) = f1r;
      *(p0r + (2 + 1)) = f1i;
      *(p0r + posA) = t1r;
      *(p0r + posAi) = t1i;
      *(p0r + posB) = f3r;
      *(p0r + posBi) = f3i;
    }
  }
}
```