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openairinterface5g/openair1/PHY/NR_UE_TRANSPORT/nr_pbch.c
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/*
* Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The OpenAirInterface Software Alliance licenses this file to You under
* the OAI Public License, Version 1.0 (the "License"); you may not use this file
* except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.openairinterface.org/?page_id=698
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*-------------------------------------------------------------------------------
* For more information about the OpenAirInterface (OAI) Software Alliance:
* contact@openairinterface.org
*/
/*! \file PHY/LTE_TRANSPORT/pbch.c
* \brief Top-level routines for generating and decoding the PBCH/BCH physical/transport channel V8.6 2009-03
* \author R. Knopp, F. Kaltenberger
* \date 2011
* \version 0.1
* \company Eurecom
* \email: knopp@eurecom.fr,florian.kaltenberger.fr
* \note
* \warning
*/
#include "PHY/defs_nr_UE.h"
#include "PHY/CODING/coding_extern.h"
#include "PHY/phy_extern_nr_ue.h"
#include "PHY/sse_intrin.h"
//#define DEBUG_PBCH 1
//#define DEBUG_PBCH_ENCODING
#ifdef OPENAIR2
//#include "PHY_INTERFACE/defs.h"
#endif
#define PBCH_A 24
uint16_t nr_pbch_extract(int **rxdataF,
int **dl_ch_estimates,
int **rxdataF_ext,
int **dl_ch_estimates_ext,
uint32_t symbol,
uint32_t high_speed_flag,
NR_DL_FRAME_PARMS *frame_parms)
{
uint16_t rb;
uint8_t i,j,aarx,aatx;
int32_t *dl_ch0,*dl_ch0_ext,*rxF,*rxF_ext;
int rx_offset = frame_parms->ofdm_symbol_size-10*12;
int nushiftmod4 = frame_parms->nushift;
for (aarx=0; aarx<frame_parms->nb_antennas_rx; aarx++) {
rxF = &rxdataF[aarx][(rx_offset + (symbol*(frame_parms->ofdm_symbol_size)))];
rxF_ext = &rxdataF_ext[aarx][symbol*(20*12)];
#ifdef DEBUG_PBCH
printf("extract_rbs (nushift %d): rx_offset=%d, symbol %d\n",frame_parms->nushift,
(rx_offset + (symbol*(frame_parms->ofdm_symbol_size))),symbol);
int16_t *p = (int16_t *)rxF;
for (int i =0; i<8;i++){
printf("rxF [%d]= %d\n",i,rxF[i]);
printf("pbch extract rxF %d %d addr %p\n", p[2*i], p[2*i+1], &p[2*i]);
printf("rxF ext addr %p\n", &rxF_ext[i]);
}
#endif
for (rb=0; rb<20; rb++) {
if (rb==10) {
rxF = &rxdataF[aarx][((symbol*(frame_parms->ofdm_symbol_size)))];
}
j=0;
if ((symbol==1) || (symbol==3)) {
for (i=0; i<12; i++) {
if ((i!=nushiftmod4) &&
(i!=(nushiftmod4+4)) &&
(i!=(nushiftmod4+8))) {
rxF_ext[j]=rxF[i];
//printf("rxF ext[%d] = %d rxF [%d]= %d\n",j,rxF_ext[j],i,rxF[i]);
j++;
}
}
rxF+=12;
rxF_ext+=9;
} else { //symbol 2
if ((rb < 4) || (rb >15)){
for (i=0; i<12; i++) {
if ((i!=nushiftmod4) &&
(i!=(nushiftmod4+4)) &&
(i!=(nushiftmod4+8))) {
rxF_ext[j]=rxF[i];
//printf("symbol2 rxF ext[%d] = %d at %p\n",j,rxF_ext[j],&rxF[i]);
j++;
}
}
}
rxF+=12;
rxF_ext+=9;
}
}
for (aatx=0; aatx<frame_parms->nb_antenna_ports_eNB;aatx++) {
if (high_speed_flag == 1)
dl_ch0 = &dl_ch_estimates[(aatx<<1)+aarx][(symbol*(frame_parms->ofdm_symbol_size))];
else
dl_ch0 = &dl_ch_estimates[(aatx<<1)+aarx][0];
//printf("dl_ch0 addr %p\n",dl_ch0);
dl_ch0_ext = &dl_ch_estimates_ext[(aatx<<1)+aarx][symbol*(20*12)];
for (rb=0; rb<20; rb++) {
j=0;
if ((symbol==1) || (symbol==3)) {
for (i=0; i<12; i++) {
if ((i!=nushiftmod4) &&
(i!=(nushiftmod4+4)) &&
(i!=(nushiftmod4+8))) {
dl_ch0_ext[j]=dl_ch0[i];
//if ((rb==0) && (i<2))
//printf("dl ch0 ext[%d] = %d dl_ch0 [%d]= %d\n",j,dl_ch0_ext[j],i,dl_ch0[i]);
j++;
}
}
dl_ch0+=12;
dl_ch0_ext+=9;
}
else { //symbol 2
if ((rb < 4) || (rb >15)){
for (i=0; i<12; i++) {
if ((i!=nushiftmod4) &&
(i!=(nushiftmod4+4)) &&
(i!=(nushiftmod4+8))) {
dl_ch0_ext[j]=dl_ch0[i];
//printf("symbol2 dl ch0 ext[%d] = %d dl_ch0 [%d]= %d\n",j,dl_ch0_ext[j],i,dl_ch0[i]);
j++;
}
}
}
dl_ch0+=12;
dl_ch0_ext+=9;
}
}
} //tx antenna loop
}
return(0);
}
//__m128i avg128;
//compute average channel_level on each (TX,RX) antenna pair
int nr_pbch_channel_level(int **dl_ch_estimates_ext,
NR_DL_FRAME_PARMS *frame_parms,
uint32_t symbol)
{
int16_t rb, nb_rb=20;
uint8_t aatx,aarx;
#if defined(__x86_64__) || defined(__i386__)
__m128i avg128;
__m128i *dl_ch128;
#elif defined(__arm__)
int32x4_t avg128;
int16x8_t *dl_ch128;
#endif
int avg1=0,avg2=0;
for (aatx=0; aatx<frame_parms->nb_antenna_ports_eNB;aatx++)
for (aarx=0; aarx<frame_parms->nb_antennas_rx; aarx++) {
//clear average level
#if defined(__x86_64__) || defined(__i386__)
avg128 = _mm_setzero_si128();
dl_ch128=(__m128i *)&dl_ch_estimates_ext[(aatx<<1)+aarx][symbol*20*12];
#elif defined(__arm__)
avg128 = vdupq_n_s32(0);
dl_ch128=(int16x8_t *)&dl_ch_estimates_ext[(aatx<<1)+aarx][symbol*20*12];
#endif
for (rb=0; rb<nb_rb; rb++) {
#if defined(__x86_64__) || defined(__i386__)
avg128 = _mm_add_epi32(avg128,_mm_madd_epi16(dl_ch128[0],dl_ch128[0]));
avg128 = _mm_add_epi32(avg128,_mm_madd_epi16(dl_ch128[1],dl_ch128[1]));
avg128 = _mm_add_epi32(avg128,_mm_madd_epi16(dl_ch128[2],dl_ch128[2]));
#elif defined(__arm__)
// to be filled in
#endif
dl_ch128+=3;
/*
if (rb==0) {
print_shorts("dl_ch128",&dl_ch128[0]);
print_shorts("dl_ch128",&dl_ch128[1]);
print_shorts("dl_ch128",&dl_ch128[2]);
}
*/
}
avg1 = (((int*)&avg128)[0] +
((int*)&avg128)[1] +
((int*)&avg128)[2] +
((int*)&avg128)[3])/(nb_rb*12);
if (avg1>avg2)
avg2 = avg1;
//msg("Channel level : %d, %d\n",avg1, avg2);
}
#if defined(__x86_64__) || defined(__i386__)
_mm_empty();
_m_empty();
#endif
return(avg2);
}
#if defined(__x86_64__) || defined(__i386__)
__m128i mmtmpP0,mmtmpP1,mmtmpP2,mmtmpP3;
#elif defined(__arm__)
int16x8_t mmtmpP0,mmtmpP1,mmtmpP2,mmtmpP3;
#endif
void nr_pbch_channel_compensation(int **rxdataF_ext,
int **dl_ch_estimates_ext,
int **rxdataF_comp,
NR_DL_FRAME_PARMS *frame_parms,
uint8_t symbol,
uint8_t output_shift)
{
uint16_t rb,nb_rb=15;
uint8_t aatx,aarx;
#if defined(__x86_64__) || defined(__i386__)
__m128i *dl_ch128,*rxdataF128,*rxdataF_comp128;
#elif defined(__arm__)
#endif
for (aatx=0; aatx<frame_parms->nb_antenna_ports_eNB;aatx++)
for (aarx=0; aarx<frame_parms->nb_antennas_rx; aarx++) {
#if defined(__x86_64__) || defined(__i386__)
dl_ch128 = (__m128i *)&dl_ch_estimates_ext[(aatx<<1)+aarx][symbol*20*12];
rxdataF128 = (__m128i *)&rxdataF_ext[aarx][symbol*20*12];
rxdataF_comp128 = (__m128i *)&rxdataF_comp[(aatx<<1)+aarx][symbol*20*12];
//printf("ch compensation dl_ch ext addr %p \n", &dl_ch_estimates_ext[(aatx<<1)+aarx][symbol*20*12]);
//printf("rxdataf ext addr %p symbol %d\n", &rxdataF_ext[aarx][symbol*20*12], symbol);
//printf("rxdataf_comp addr %p\n",&rxdataF_comp[(aatx<<1)+aarx][symbol*20*12]);
#elif defined(__arm__)
// to be filled in
#endif
for (rb=0; rb<nb_rb; rb++) {
//printf("rb %d\n",rb);
#if defined(__x86_64__) || defined(__i386__)
// multiply by conjugated channel
mmtmpP0 = _mm_madd_epi16(dl_ch128[0],rxdataF128[0]);
// print_ints("re",&mmtmpP0);
// mmtmpP0 contains real part of 4 consecutive outputs (32-bit)
mmtmpP1 = _mm_shufflelo_epi16(dl_ch128[0],_MM_SHUFFLE(2,3,0,1));
mmtmpP1 = _mm_shufflehi_epi16(mmtmpP1,_MM_SHUFFLE(2,3,0,1));
mmtmpP1 = _mm_sign_epi16(mmtmpP1,*(__m128i*)&conjugate[0]);
// print_ints("im",&mmtmpP1);
mmtmpP1 = _mm_madd_epi16(mmtmpP1,rxdataF128[0]);
// mmtmpP1 contains imag part of 4 consecutive outputs (32-bit)
mmtmpP0 = _mm_srai_epi32(mmtmpP0,output_shift);
// print_ints("re(shift)",&mmtmpP0);
mmtmpP1 = _mm_srai_epi32(mmtmpP1,output_shift);
// print_ints("im(shift)",&mmtmpP1);
mmtmpP2 = _mm_unpacklo_epi32(mmtmpP0,mmtmpP1);
mmtmpP3 = _mm_unpackhi_epi32(mmtmpP0,mmtmpP1);
// print_ints("c0",&mmtmpP2);
// print_ints("c1",&mmtmpP3);
rxdataF_comp128[0] = _mm_packs_epi32(mmtmpP2,mmtmpP3);
// print_shorts("rx:",rxdataF128);
// print_shorts("ch:",dl_ch128);
// print_shorts("pack:",rxdataF_comp128);
// multiply by conjugated channel
mmtmpP0 = _mm_madd_epi16(dl_ch128[1],rxdataF128[1]);
// mmtmpP0 contains real part of 4 consecutive outputs (32-bit)
mmtmpP1 = _mm_shufflelo_epi16(dl_ch128[1],_MM_SHUFFLE(2,3,0,1));
mmtmpP1 = _mm_shufflehi_epi16(mmtmpP1,_MM_SHUFFLE(2,3,0,1));
mmtmpP1 = _mm_sign_epi16(mmtmpP1,*(__m128i*)&conjugate[0]);
mmtmpP1 = _mm_madd_epi16(mmtmpP1,rxdataF128[1]);
// mmtmpP1 contains imag part of 4 consecutive outputs (32-bit)
mmtmpP0 = _mm_srai_epi32(mmtmpP0,output_shift);
mmtmpP1 = _mm_srai_epi32(mmtmpP1,output_shift);
mmtmpP2 = _mm_unpacklo_epi32(mmtmpP0,mmtmpP1);
mmtmpP3 = _mm_unpackhi_epi32(mmtmpP0,mmtmpP1);
rxdataF_comp128[1] = _mm_packs_epi32(mmtmpP2,mmtmpP3);
// print_shorts("rx:",rxdataF128+1);
// print_shorts("ch:",dl_ch128+1);
// print_shorts("pack:",rxdataF_comp128+1);
// multiply by conjugated channel
mmtmpP0 = _mm_madd_epi16(dl_ch128[2],rxdataF128[2]);
// mmtmpP0 contains real part of 4 consecutive outputs (32-bit)
mmtmpP1 = _mm_shufflelo_epi16(dl_ch128[2],_MM_SHUFFLE(2,3,0,1));
mmtmpP1 = _mm_shufflehi_epi16(mmtmpP1,_MM_SHUFFLE(2,3,0,1));
mmtmpP1 = _mm_sign_epi16(mmtmpP1,*(__m128i*)&conjugate[0]);
mmtmpP1 = _mm_madd_epi16(mmtmpP1,rxdataF128[2]);
// mmtmpP1 contains imag part of 4 consecutive outputs (32-bit)
mmtmpP0 = _mm_srai_epi32(mmtmpP0,output_shift);
mmtmpP1 = _mm_srai_epi32(mmtmpP1,output_shift);
mmtmpP2 = _mm_unpacklo_epi32(mmtmpP0,mmtmpP1);
mmtmpP3 = _mm_unpackhi_epi32(mmtmpP0,mmtmpP1);
rxdataF_comp128[2] = _mm_packs_epi32(mmtmpP2,mmtmpP3);
// print_shorts("rx:",rxdataF128+2);
// print_shorts("ch:",dl_ch128+2);
// print_shorts("pack:",rxdataF_comp128+2);
dl_ch128+=3;
rxdataF128+=3;
rxdataF_comp128+=3;
#elif defined(__arm__)
// to be filled in
#endif
}
}
#if defined(__x86_64__) || defined(__i386__)
_mm_empty();
_m_empty();
#endif
}
void nr_pbch_detection_mrc(NR_DL_FRAME_PARMS *frame_parms,
int **rxdataF_comp,
uint8_t symbol)
{
uint8_t aatx, symbol_mod;
int i, nb_rb=6;
#if defined(__x86_64__) || defined(__i386__)
__m128i *rxdataF_comp128_0,*rxdataF_comp128_1;
#elif defined(__arm__)
int16x8_t *rxdataF_comp128_0,*rxdataF_comp128_1;
#endif
symbol_mod = (symbol>=(7-frame_parms->Ncp)) ? symbol-(7-frame_parms->Ncp) : symbol;
if (frame_parms->nb_antennas_rx>1) {
for (aatx=0; aatx<4; aatx++) { //frame_parms->nb_antenna_ports_eNB;aatx++) {
#if defined(__x86_64__) || defined(__i386__)
rxdataF_comp128_0 = (__m128i *)&rxdataF_comp[(aatx<<1)][symbol_mod*6*12];
rxdataF_comp128_1 = (__m128i *)&rxdataF_comp[(aatx<<1)+1][symbol_mod*6*12];
#elif defined(__arm__)
rxdataF_comp128_0 = (int16x8_t *)&rxdataF_comp[(aatx<<1)][symbol_mod*6*12];
rxdataF_comp128_1 = (int16x8_t *)&rxdataF_comp[(aatx<<1)+1][symbol_mod*6*12];
#endif
// MRC on each re of rb, both on MF output and magnitude (for 16QAM/64QAM llr computation)
for (i=0; i<nb_rb*3; i++) {
#if defined(__x86_64__) || defined(__i386__)
rxdataF_comp128_0[i] = _mm_adds_epi16(_mm_srai_epi16(rxdataF_comp128_0[i],1),_mm_srai_epi16(rxdataF_comp128_1[i],1));
#elif defined(__arm__)
rxdataF_comp128_0[i] = vhaddq_s16(rxdataF_comp128_0[i],rxdataF_comp128_1[i]);
#endif
}
}
}
#if defined(__x86_64__) || defined(__i386__)
_mm_empty();
_m_empty();
#endif
}
void nr_pbch_unscrambling(NR_DL_FRAME_PARMS *frame_parms,
int8_t* llr,
uint32_t length)
{
int i;
uint8_t reset;
uint32_t x1, x2, s=0;
reset = 1;
// x1 is set in first call to lte_gold_generic
x2 = frame_parms->Nid_cell; //this is c_init in 36.211 Sec 6.6.1
// msg("pbch_unscrambling: Nid_cell = %d\n",x2);
for (i=0; i<length; i++) {
if (i%32==0) {
s = lte_gold_generic(&x1, &x2, reset);
// printf("lte_gold[%d]=%x\n",i,s);
reset = 0;
}
if (((s>>(i%32))&1)==0)
llr[i] = -llr[i];
}
}
void nr_pbch_alamouti(NR_DL_FRAME_PARMS *frame_parms,
int **rxdataF_comp,
uint8_t symbol)
{
int16_t *rxF0,*rxF1;
// __m128i *ch_mag0,*ch_mag1,*ch_mag0b,*ch_mag1b;
uint8_t rb,re,symbol_mod;
int jj;
// printf("Doing alamouti\n");
symbol_mod = (symbol>=(7-frame_parms->Ncp)) ? symbol-(7-frame_parms->Ncp) : symbol;
jj = (symbol_mod*6*12);
rxF0 = (int16_t*)&rxdataF_comp[0][jj]; //tx antenna 0 h0*y
rxF1 = (int16_t*)&rxdataF_comp[2][jj]; //tx antenna 1 h1*y
for (rb=0; rb<6; rb++) {
for (re=0; re<12; re+=2) {
// Alamouti RX combining
rxF0[0] = rxF0[0] + rxF1[2];
rxF0[1] = rxF0[1] - rxF1[3];
rxF0[2] = rxF0[2] - rxF1[0];
rxF0[3] = rxF0[3] + rxF1[1];
rxF0+=4;
rxF1+=4;
}
}
}
void nr_pbch_quantize(int16_t *pbch_llr16,
int16_t *pbch_llr,
uint16_t len)
{
uint16_t i;
for (i=0; i<len; i++) {
/*if (pbch_llr[i]>7)
pbch_llr8[i]=7;
else if (pbch_llr[i]<-8)
pbch_llr8[i]=-8;
else*/
pbch_llr16[i] = (char)(pbch_llr[i]);
}
}
uint16_t nr_rx_pbch( PHY_VARS_NR_UE *ue,
UE_nr_rxtx_proc_t *proc,
NR_UE_PBCH *nr_ue_pbch_vars,
NR_DL_FRAME_PARMS *frame_parms,
uint8_t eNB_id,
MIMO_mode_t mimo_mode,
uint32_t high_speed_flag,
uint8_t frame_mod4)
{
NR_UE_COMMON *nr_ue_common_vars = &ue->common_vars;
uint8_t log2_maxh;
int max_h=0;
int symbol,i;
uint8_t pbch_a[8];
int16_t *pbch_e_rx;
uint8_t *decoded_output = nr_ue_pbch_vars->decoded_output;
uint16_t crc;
int8_t decoderState=0;
uint8_t decoderListSize = 8, pathMetricAppr = 0;
double aPrioriArray[frame_parms->pbch_polar_params.payloadBits]; // assume no a priori knowledge available about the payload.
int subframe_rx = proc->subframe_rx;
pbch_e_rx = &nr_ue_pbch_vars->llr[0];
// clear LLR buffer
memset(nr_ue_pbch_vars->llr,0,NR_POLAR_PBCH_PAYLOAD_BITS);
for (symbol=1; symbol<4; symbol++) {
//printf("address dataf %p",nr_ue_common_vars->common_vars_rx_data_per_thread[ue->current_thread_id[subframe_rx]].rxdataF);
//write_output("rxdataF0_pbch.m","rxF0pbch",nr_ue_common_vars->common_vars_rx_data_per_thread[ue->current_thread_id[subframe_rx]].rxdataF,frame_parms->ofdm_symbol_size*4,2,1);
nr_pbch_extract(nr_ue_common_vars->common_vars_rx_data_per_thread[ue->current_thread_id[subframe_rx]].rxdataF,
nr_ue_common_vars->common_vars_rx_data_per_thread[ue->current_thread_id[subframe_rx]].dl_ch_estimates[eNB_id],
nr_ue_pbch_vars->rxdataF_ext,
nr_ue_pbch_vars->dl_ch_estimates_ext,
symbol,
high_speed_flag,
frame_parms);
#ifdef DEBUG_PBCH
msg("[PHY] PBCH Symbol %d ofdm size %d\n",symbol, frame_parms->ofdm_symbol_size );
msg("[PHY] PBCH starting channel_level\n");
#endif
max_h = nr_pbch_channel_level(nr_ue_pbch_vars->dl_ch_estimates_ext,
frame_parms,
symbol);
log2_maxh = 3+(log2_approx(max_h)/2);
#ifdef DEBUG_PBCH
msg("[PHY] PBCH log2_maxh = %d (%d)\n",log2_maxh,max_h);
#endif
nr_pbch_channel_compensation(nr_ue_pbch_vars->rxdataF_ext,
nr_ue_pbch_vars->dl_ch_estimates_ext,
nr_ue_pbch_vars->rxdataF_comp,
frame_parms,
symbol,
log2_maxh); // log2_maxh+I0_shift
//write_output("rxdataF_comp.m","rxFcomp",nr_ue_pbch_vars->rxdataF_comp,180,2,1);
/*if (frame_parms->nb_antennas_rx > 1)
pbch_detection_mrc(frame_parms,
nr_ue_pbch_vars->rxdataF_comp,
symbol);*/
if (mimo_mode == ALAMOUTI) {
nr_pbch_alamouti(frame_parms,nr_ue_pbch_vars->rxdataF_comp,symbol);
} else if (mimo_mode != SISO) {
msg("[PBCH][RX] Unsupported MIMO mode\n");
return(-1);
}
if (symbol==2) {
nr_pbch_quantize(pbch_e_rx,
(short*)&(nr_ue_pbch_vars->rxdataF_comp[0][symbol*240]),
108);
pbch_e_rx+=108;
} else {
nr_pbch_quantize(pbch_e_rx,
(short*)&(nr_ue_pbch_vars->rxdataF_comp[0][symbol*240]),
360);
pbch_e_rx+=360;
}
}
pbch_e_rx = nr_ue_pbch_vars->llr;
//#ifdef DEBUG_PBCH
//pbch_e_rx = &nr_ue_pbch_vars->llr[0];
short *p = (short *)&(nr_ue_pbch_vars->rxdataF_comp[0][1*20*12]);
for (int cnt = 0; cnt < 8 ; cnt++)
printf("pbch rx llr %d rxdata_comp %d addr %p\n",*(pbch_e_rx+cnt), p[cnt], &p[0]);
//#endif
//polar decoding de-rate matching
decoderState = polar_decoder(pbch_e_rx, pbch_a, &frame_parms->pbch_polar_params, decoderListSize, aPrioriArray, pathMetricAppr);
memset(pbch_a,0,((16+NR_POLAR_PBCH_PAYLOAD_BITS)>>3));
//un-scrambling
nr_pbch_unscrambling(frame_parms,
pbch_a,
NR_POLAR_PBCH_PAYLOAD_BITS);
// Fix byte endian
for (i=0; i<(NR_POLAR_PBCH_PAYLOAD_BITS>>3); i++)
decoded_output[(NR_POLAR_PBCH_PAYLOAD_BITS>>3)-i-1] = pbch_a[i];
#ifdef DEBUG_PBCH
for (i=0; i<(NR_POLAR_PBCH_PAYLOAD_BITS>>3); i++)
msg("[PBCH] pbch_a[%d] = %x\n",i,decoded_output[i]);
#endif
#ifdef DEBUG_PBCH
msg("PBCH CRC %x : %x\n",
crc16(pbch_a,PBCH_A),
((uint16_t)pbch_a[PBCH_A>>3]<<8)+pbch_a[(PBCH_A>>3)+1]);
#endif
crc = (crc16(pbch_a,PBCH_A)>>16) ^
(((uint16_t)pbch_a[PBCH_A>>3]<<8)+pbch_a[(PBCH_A>>3)+1]);
if (crc == 0x0000)
return(1);
else if (crc == 0xffff)
return(2);
else if (crc == 0x5555)
return(4);
else
return(-1);
}