viterbi_lte.c 13.8 KB
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/*******************************************************************************

  Eurecom OpenAirInterface
  Copyright(c) 1999 - 2014 Eurecom

  This program is free software; you can redistribute it and/or modify it under 
  the terms of the GNU General Public License as published by the Free Software 
  Foundation; either version 2 of the License, or (at your option) any later version

  This program is distributed in the hope it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  more details.

  You should have received a copy of the GNU General Public License along with
  this program; if not, write to the Free Software Foundation, Inc.,
  51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.

  The full GNU General Public License is included in this distribution in
  the file called "COPYING".

  Contact Information
  Openair Admin: openair_admin@eurecom.fr
  Openair Tech : openair_tech@eurecom.fr
  Forums       : http://forums.eurecom.fsr/openairinterface
  Address      : Eurecom, 2229, route des crtes, 06560 Valbonne Sophia Antipolis, France

*******************************************************************************/

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/* file: viterbit_lte.c
   purpose: SIMD optimized LTE Viterbi Decoder for rate 1/3 Tail-biting convolutional code.  Performs two iterations
            of code.  First pass does Viterbi with all initial partial metrics set to zero.  Second pass does Viterbi
            with initial partial metrics set to values from final state values after first pass. Max is selected at
	    end to do trace-back.
   author: raymond.knopp@eurecom.fr
   date: 21.10.2009 
*/

#ifdef USER_MODE
#include <stdio.h>
#endif

#ifndef TEST_DEBUG
#include "PHY/defs.h"
#include "PHY/extern.h"
#else
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define msg printf
#endif

#ifndef EXPRESSMIMO_TARGET
#include "emmintrin.h"
#endif //EXPRESSMIMO_TARGET

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extern uint8_t ccodelte_table[128],ccodelte_table_rev[128];
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#ifdef __KERNEL__
#define printf rt_printk
#endif

#ifndef EXPRESSMIMO_TARGET

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static int8_t m0_table[64*16*16*16] __attribute__ ((aligned(16)));
static int8_t m1_table[64*16*16*16] __attribute__ ((aligned(16)));
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// Set up Viterbi tables for SSE2 implementation
void phy_generate_viterbi_tables_lte() {

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  int8_t w[8],in0,in1,in2;
  uint8_t state,index0,index1;
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  for (in0 = -8; in0 <8 ; in0++) {   // use 4-bit quantization
    for (in1 = -8; in1 <8 ;in1++) {
      for (in2 = -8; in2 <8 ;in2++) {

	
	w[0] = 24 - in0 - in1 - in2;           // -1,-1,-1
	w[1] = 24 + in0 - in1 - in2;           // -1, 1,-1
	w[2] = 24 - in0 + in1 - in2;           //  1,-1,-1
	w[3] = 24 + in0 + in1 - in2;           //  1, 1,-1
	w[4] = 24 - in0 - in1 + in2;           // -1,-1, 1
	w[5] = 24 + in0 - in1 + in2;           // -1, 1, 1
	w[6] = 24 - in0 + in1 + in2;           //  1,-1, 1
	w[7] = 24 + in0 + in1 + in2;           //  1, 1, 1
	
	//    printf("w: %d %d %d %d\n",w[0],w[1],w[2],w[3]);
	for (state=0; state<64 ; state++) {
	  
	  // input 0
	  index0 = (state<<1);

	  m0_table[(in0+8 + (16*(in1+8)) + (256*(in2+8)))*64 +state] = w[ccodelte_table_rev[index0]];
	  
	  
	  //	  if (position < 8)
	  //	  printf("%d,%d : prev_state0 = %d,m0 = %d,w=%d (%d)\n",position,state,prev_state0%64,m0,w[ccodelte_table[prev_state0]],partial_metrics[prev_state0%64]);
	  
	  // input 1
	  index1 = (1+ (state<<1));
	  m1_table[(in0+8 + (16*(in1+8)) + (256*(in2+8)))*64 +state] = w[ccodelte_table_rev[index1]]; 
	  
	}
      }
    }
  }
}


#define INIT0 0x00000080
#define RESCALE 0x00000040

//#define DEBUG_VITERBI

#ifdef DEBUG_VITERBI
void print_bytes(char *s,__m128i *x) {

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  uint8_t *tempb = (uint8_t *)x;
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  printf("%s  : %d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d,%d\n",s,
	 tempb[0],tempb[1],tempb[2],tempb[3],tempb[4],tempb[5],tempb[6],tempb[7],
	 tempb[8],tempb[9],tempb[10],tempb[11],tempb[12],tempb[13],tempb[14],tempb[15]);

}

/*
void print_shorts(__m128i x,char *s) {

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  int16_t *tempb = (int16_t *)&x;
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  printf("%s  : %d,%d,%d,%d,%d,%d,%d,%d\n",s,
	 tempb[0],tempb[1],tempb[2],tempb[3],tempb[4],tempb[5],tempb[6],tempb[7]
	 );

}
*/
#endif // USER_MODE


static __m128i  TB[4*8192];

static __m128i metrics0_15,metrics16_31,metrics32_47,metrics48_63,even0_30a,even0_30b,even32_62a,even32_62b,odd1_31a,odd1_31b,odd33_63a,odd33_63b,TBeven0_30,TBeven32_62,TBodd1_31,TBodd33_63;// __attribute__((aligned(16)));

static __m128i min_state,min_state2;// __attribute__((aligned(16)));

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void phy_viterbi_lte_sse2(int8_t *y,uint8_t *decoded_bytes,uint16_t n) {
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  static __m128i *m0_ptr,*m1_ptr,*TB_ptr = &TB[0];


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  int8_t *in = y;
  uint8_t prev_state0,maxm,s;
  static uint8_t *TB_ptr2;
  uint32_t table_offset;
  uint8_t iter;
  int16_t position;
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  // set initial metrics
  //debug_msg("Doing viterbi\n");

  metrics0_15 = _mm_xor_si128(metrics0_15,metrics0_15);
  metrics16_31 = _mm_xor_si128(metrics16_31,metrics16_31);
  metrics32_47 = _mm_xor_si128(metrics32_47,metrics32_47);
  metrics48_63 = _mm_xor_si128(metrics32_47,metrics32_47);
#ifndef USER_MODE
  //debug_msg("Doing viterbi 2\n");
#endif
  /*
  print_bytes(metrics0_15,"metrics0_15");
  print_bytes(metrics16_31,"metrics16_31");
  print_bytes(metrics32_47,"metrics32_47");
  print_bytes(metrics48_63,"metrics48_63");
  */

  for (iter=0;iter<2;iter++) {
    in = y;
    TB_ptr=&TB[0];

    //    printf("Iteration %d\n",iter);
    for (position=0;position<n;position++) {
      
      
      //      printf("%d/%d : (%d,%d,%d)\n",position,n-1,in[0],in[1],in[2]);
      

      // get branch metric offsets for the 64 states
      table_offset = (in[0]+8 + ((in[1]+8)<<4) + ((in[2]+8)<<8))<<6;
      /*       
      printf("Table_offset = %u (in[0]=%d,in[1]=%d,in[2]=%d)\n",table_offset,in[0],in[1],in[2]);
      print_bytes("m0",&m0_table[table_offset]);
      print_bytes("m1",&m1_table[table_offset]);
      */
      m0_ptr = (__m128i *)&m0_table[table_offset];
      m1_ptr = (__m128i *)&m1_table[table_offset];
      
      //    printf("\n");
      
      // even states
      even0_30a  = _mm_adds_epu8(metrics0_15,m0_ptr[0]);
      //    print_bytes(even0_30a,"even0_30a");
      
      even32_62a = _mm_adds_epu8(metrics16_31,m0_ptr[1]);
      //    print_bytes(even32_62a,"even32_62a");
      
      even0_30b  = _mm_adds_epu8(metrics32_47,m0_ptr[2]);
      //    print_bytes(even0_30b,"even0_30b");
      
      even32_62b = _mm_adds_epu8(metrics48_63,m0_ptr[3]);
      //    print_bytes(even32_62b,"even32_62b");
      
      //    printf("\n");
      
      // odd states
      odd1_31a   = _mm_adds_epu8(metrics0_15,m1_ptr[0]);
      
      //    print_bytes(odd1_31a,"odd1_31a");
      
      odd33_63a  = _mm_adds_epu8(metrics16_31,m1_ptr[1]);
      
      //    print_bytes(odd33_63a,"odd33_63a");
      
      odd1_31b   = _mm_adds_epu8(metrics32_47,m1_ptr[2]);
      
      //    print_bytes(odd1_31b,"odd1_31b");
      
      odd33_63b  = _mm_adds_epu8(metrics48_63,m1_ptr[3]);
      
      //    print_bytes(odd33_63b,"odd33_63b");
      
      

      
      // select maxima
      //    printf("\n");
      
      even0_30a  = _mm_max_epu8(even0_30a,even0_30b);
      
      //    print_bytes(even0_30a,"even0_30a");
      
      even32_62a = _mm_max_epu8(even32_62a,even32_62b);
      
      //    print_bytes(even32_62a,"even32_62a");
      
      odd1_31a   = _mm_max_epu8(odd1_31a,odd1_31b);
      
      //    print_bytes(odd1_31a,"odd1_31a");
      
      odd33_63a  = _mm_max_epu8(odd33_63a,odd33_63b);
      
      //    print_bytes(odd33_63a,"odd33_63a");
      
      //    printf("\n");    
      // Traceback information
      
      TBeven0_30  = _mm_cmpeq_epi8(even0_30a,even0_30b);
      
      
      TBeven32_62 = _mm_cmpeq_epi8(even32_62a,even32_62b);
      
      
      TBodd1_31   = _mm_cmpeq_epi8(odd1_31a,odd1_31b);
      
      
      TBodd33_63  = _mm_cmpeq_epi8(odd33_63a,odd33_63b);
      
      
      metrics0_15        = _mm_unpacklo_epi8(even0_30a ,odd1_31a);
      metrics16_31       = _mm_unpackhi_epi8(even0_30a ,odd1_31a);
      metrics32_47       = _mm_unpacklo_epi8(even32_62a,odd33_63a);
      metrics48_63       = _mm_unpackhi_epi8(even32_62a,odd33_63a);
      
      /*      
      print_bytes(metrics0_15,"metrics0_15");
      print_bytes(metrics16_31,"metrics16_31");
      print_bytes(metrics32_47,"metrics32_47");
      print_bytes(metrics48_63,"metrics48_63");
      */
      
      
      TB_ptr[0]  = _mm_unpacklo_epi8(TBeven0_30,TBodd1_31);
      
      //    print_bytes(TB_ptr[0],"TB0_15");
      
      TB_ptr[1] = _mm_unpackhi_epi8(TBeven0_30,TBodd1_31);
      
      //    print_bytes(TB_ptr[1],"TB16_31");
      
      TB_ptr[2] = _mm_unpacklo_epi8(TBeven32_62,TBodd33_63);
      
      //    print_bytes(TB_ptr[2],"TB32_47");
      
      TB_ptr[3] = _mm_unpackhi_epi8(TBeven32_62,TBodd33_63);
      
      //    print_bytes(TB_ptr[3],"TB48_63");
      
      in+=3;
      TB_ptr += 4;
      
      // rescale by subtracting minimum
      /****************************************************
    USE SSSE instruction phminpos!!!!!!!
      ****************************************************/
      min_state =_mm_min_epu8(metrics0_15,metrics16_31);
      min_state =_mm_min_epu8(min_state,metrics32_47);
      min_state =_mm_min_epu8(min_state,metrics48_63);
      
      //    print_bytes(min_state,"min_state");
      
      min_state2 = min_state;
      min_state  = _mm_unpacklo_epi8(min_state,min_state);
      min_state2 = _mm_unpackhi_epi8(min_state2,min_state2);
      min_state  = _mm_min_epu8(min_state,min_state2);
      
      //    print_bytes(min_state,"min_state");
      
      min_state2 = min_state;
      min_state  = _mm_unpacklo_epi8(min_state,min_state);
      min_state2 = _mm_unpackhi_epi8(min_state2,min_state2);
      min_state  = _mm_min_epu8(min_state,min_state2);
      
      //    print_bytes(min_state,"min_state");
      
      min_state2 = min_state;
      min_state  = _mm_unpacklo_epi8(min_state,min_state);
      min_state2 = _mm_unpackhi_epi8(min_state2,min_state2);
      min_state  = _mm_min_epu8(min_state,min_state2);
      
      //    print_bytes(min_state,"min_state");
      
      min_state2 = min_state;
      min_state  = _mm_unpacklo_epi8(min_state,min_state);
      min_state2 = _mm_unpackhi_epi8(min_state2,min_state2);
      min_state  = _mm_min_epu8(min_state,min_state2);
      
      //    print_bytes(min_state,"min_state");
      
      metrics0_15  = _mm_subs_epu8(metrics0_15,min_state);
      metrics16_31 = _mm_subs_epu8(metrics16_31,min_state);
      metrics32_47 = _mm_subs_epu8(metrics32_47,min_state);
      metrics48_63 = _mm_subs_epu8(metrics48_63,min_state);
      
      /*            
	print_bytes("metrics0_15",&metrics0_15);
	print_bytes("metrics16_31",&metrics16_31);
	print_bytes("metrics32_47",&metrics32_47);
	print_bytes("metrics48_63",&metrics48_63);
      
      printf("\n");
      */
      
    }

  } // iteration

  // Traceback
  prev_state0 = 0;
  maxm = 0;

  for (s=0;s<16;s++)
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    if (((uint8_t *)&metrics0_15)[s] > maxm) {
      maxm = ((uint8_t *)&metrics0_15)[s];
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      prev_state0 = s;
    }

  for (s=0;s<16;s++)
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    if (((uint8_t *)&metrics16_31)[s] > maxm) {
      maxm = ((uint8_t *)&metrics16_31)[s];
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      prev_state0 = s+16;
    }

  for (s=0;s<16;s++)
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    if (((uint8_t *)&metrics32_47)[s] > maxm) {
      maxm = ((uint8_t *)&metrics32_47)[s];
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      prev_state0 = s+32;
    }

  for (s=0;s<16;s++)
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    if (((uint8_t *)&metrics48_63)[s] > maxm) {
      maxm = ((uint8_t *)&metrics48_63)[s];
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      prev_state0 = s+48;
    }

  //  printf("Max state %d\n",prev_state0);
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  TB_ptr2 = (uint8_t *)&TB[(n-1)*4];
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  for (position = n-1 ; position>-1; position--) {

//    if ((position%8) == 0)
//	printf("%d: %x\n",1+(position>>3),decoded_bytes[1+(position>>3)]);
		     	
    decoded_bytes[(position)>>3] += (prev_state0 & 0x1)<<(7-(position & 0x7));
    
    //    printf("pos %d : ps = %d -> %d\n",position,prev_state0,TB_ptr2[prev_state0]);
    
    if (TB_ptr2[prev_state0] == 0) 
      prev_state0 = (prev_state0 >> 1);
    else
      prev_state0 = 32 + (prev_state0>>1);

    TB_ptr2-=64;
  }
  //  printf("Max state %d\n",prev_state0);
  _mm_empty();
  _m_empty();

}

#else //EXPRESSMIMO_TARGET

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void phy_viterbi_lte(int8_t *y,uint8_t *decoded_bytes,uint16_t n) {
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}

#endif //EXPRESSMIMO_TARGET

/*
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void print_bytes(__m128i x,int8_t *s) {
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  uint8_t *tempb = (uint8_t *)&x;
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  printf("%s  : %u,%u,%u,%u,%u,%u,%u,%u,%u,%u,%u,%u,%u,%u,%u,%u\n",s,
	 tempb[0],tempb[1],tempb[2],tempb[3],tempb[4],tempb[5],tempb[6],tempb[7],
	 tempb[8],tempb[9],tempb[10],tempb[11],tempb[12],tempb[13],tempb[14],tempb[15]);

}
*/

#ifdef TEST_DEBUG
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int test_viterbi(uint8_t dabflag)
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{
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  uint8_t test[8];
  //_declspec(align(16))  int8_t channel_output[512];
  //_declspec(align(16))  uint8_t output[512],decoded_output[16], *inPtr, *outPtr;
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  int8_t channel_output[512];
  uint8_t output[512],decoded_output[16], *inPtr, *outPtr;
  uint32_t i;
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  test[0] = 7;
  test[1] = 0xa5;
  test[2] = 0;
  test[3] = 0xfe;
  test[4] = 0x1a;
  test[5] = 0x33;
  test[6] = 0x99;
  test[7] = 0x14;
  
  if (dabflag==0) {
    ccodelte_init();
    ccodelte_init_inv();
  }
  else {
    ccodedab_init();
    ccodedab_init_inv();
    printf("Running with DAB polynomials\n");
  }
  inPtr = test;
  outPtr = output;
  phy_generate_viterbi_tables_lte();
  ccodelte_encode(64,     //input length in bits 
		  0,      // add 16-bit crc with rnti scrambling
		  inPtr,  // input pointer
		  outPtr, // output pointer
		  0);     // rnti (optional)

  for (i = 0; i < 64*3; i++){
    channel_output[i] = 7*(2*output[i] - 1);
  }

  memset(decoded_output,0,16);
  phy_viterbi_lte_sse2(channel_output,decoded_output,64);
  printf("Optimized Viterbi :");
  for (i =0 ; i<8 ; i++)
    printf("input %d : %x => %x\n",i,inPtr[i],decoded_output[i]);
}




int main(int argc, char **argv) {

  char c;
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  uint8_t dabflag=0;
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  while ((c = getopt (argc, argv, "d")) != -1) {
    if (c=='d')
      dabflag=1;
  }

  test_viterbi(dabflag);
  return(0);
}

#endif // TEST_DEBUG