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openairinterface5g/openair1/PHY/CODING/viterbi.c
T
Raymond Knopp b4635ac44f Clean-up and bug-fixes from S. Held (IMST) 
git-svn-id: http://svn.eurecom.fr/openair4G/trunk@6420 818b1a75-f10b-46b9-bf7c-635c3b92a50f
2015-01-22 07:24:06 +00:00

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/*******************************************************************************
OpenAirInterface
Copyright(c) 1999 - 2014 Eurecom
OpenAirInterface 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 3 of the License, or
(at your option) any later version.
OpenAirInterface is distributed in the hope that 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 OpenAirInterface.The full GNU General Public License is
included in this distribution in the file called "COPYING". If not,
see <http://www.gnu.org/licenses/>.
Contact Information
OpenAirInterface Admin: openair_admin@eurecom.fr
OpenAirInterface Tech : openair_tech@eurecom.fr
OpenAirInterface Dev : openair4g-devel@eurecom.fr
Address : Eurecom, Campus SophiaTech, 450 Route des Chappes, CS 50193 - 06904 Biot Sophia Antipolis cedex, FRANCE
*******************************************************************************/
/* file: viterbi.c
purpose: SIMD Optimized 802.11/802.16 Viterbi Decoder
author: raymond.knopp@eurecom.fr
date: 10.2004
*/
#ifndef EXPRESSMIMO_TARGET
#include "PHY/sse_intrin.h"
#endif //EXPRESSMIMO_TARGET
extern unsigned char ccodedot11_table[128],ccodedot11_table_rev[128];
static unsigned char inputs[64][2048];
static unsigned short survivors[64][2048];
static short partial_metrics[64],partial_metrics_new[64];
#ifdef __KERNEL__
#define printf rt_printk
#endif
#ifndef EXPRESSMIMO_TARGET
void phy_viterbi_dot11(char *y,unsigned char *decoded_bytes,unsigned short n) {
/* y is a pointer to the input
decoded_bytes is a pointer to the decoded output
n is the size in bits of the coded block, with the tail */
char *in = y;
short m0,m1,w[4],max_metric;
short position;
unsigned short prev_state0,prev_state1,state;
partial_metrics[0] = 0;
for (state=1; state<64; state++)
partial_metrics[state] = -127;
for (position=0;position<n;position++) {
// printf("Channel Output %d = (%d,%d)\n",position,*in,*(in+1));
// printf("%d %d\n",in[0],in[1]);
w[3] = in[0] + in[1]; // 1,1
w[0] = -w[3]; // -1,-1
w[1] = in[0] - in[1]; // -1, 1
w[2] = -w[1]; // 1 ,-1
max_metric = -127;
// printf("w: %d %d %d %d\n",w[0],w[1],w[2],w[3]);
for (state=0; state<64 ; state++) {
// input 0
prev_state0 = (state<<1);
m0 = partial_metrics[prev_state0%64] + w[ccodedot11_table[prev_state0]];
/*
if (position < 8)
printf("%d,%d : prev_state0 = %d,m0 = %d,w=%d (%d)\n",position,state,prev_state0%64,m0,w[ccodedot11_table[prev_state0]],partial_metrics[prev_state0%64]);
*/
// input 1
prev_state1 = (1+ (state<<1));
m1 = partial_metrics[prev_state1%64] + w[ccodedot11_table[prev_state1]];
/*
if (position <8)
printf("%d,%d : prev_state1 = %d,m1 = %d,w=%d (%d)\n",position,state,prev_state1%64,m1,w[ccodedot11_table[prev_state1]],partial_metrics[prev_state0%64]);
*/
if (m0>m1) {
partial_metrics_new[state] = m0;
survivors[state][position] = prev_state0%64;
inputs[state][position] = (state>31) ? 1 : 0;
if (m0>max_metric)
max_metric = m0;
}
else{
partial_metrics_new[state] = m1;
survivors[state][position] = prev_state1%64;
inputs[state][position] = (state>31) ? 1 : 0;
if (m1>max_metric)
max_metric = m1;
}
}
for (state=0 ; state<64; state++) {
partial_metrics[state] = partial_metrics_new[state]- max_metric;
// printf("%d partial_metrics[%d] = %d\n",position,state,partial_metrics[state]);
}
in+=2;
}
// Traceback
prev_state0 = 0;
for (position = n-1 ; position>-1; position--) {
decoded_bytes[(position)>>3] += (inputs[prev_state0][position]<<(position%8));
// if (position%8==0)
// printf("%d\n",decoded_bytes[(position)>>3]);
prev_state0 = survivors[prev_state0][position];
}
}
static char m0_table[64*256] __attribute__ ((aligned(16)));
static char m1_table[64*256] __attribute__ ((aligned(16)));
// Set up Viterbi tables for SSE2 implementation
void phy_generate_viterbi_tables(void) {
char w[4],in0,in1;
unsigned char state,index0,index1;
for (in0 = -8; in0 <8 ; in0++) { // use 4-bit quantization
for (in1 = -8; in1 <8 ;in1++) {
w[3] = 16+ in0 + in1; // 1,1
w[0] = 16 - in0 - in1; // -1,-1
w[1] = 16+ in0 - in1; // -1, 1
w[2] = 16 - in0 + in1; // 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)))*64 +state] = w[ccodedot11_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[ccodedot11_table[prev_state0]],partial_metrics[prev_state0%64]);
// input 1
index1 = (1+ (state<<1));
m1_table[(in0+8 + (16*(in1+8)))*64 +state] = w[ccodedot11_table_rev[index1]];
}
}
}
}
#define INIT0 0x00000080
#define RESCALE 0x00000040
static __m128i __attribute__((aligned(16))) TB[4*4095*8];
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 rescale,min_state,min_state2 __attribute__((aligned(16)));
void phy_viterbi_dot11_sse2(char *y,unsigned char *decoded_bytes,unsigned short n,int offset, int traceback ) {
__m128i *m0_ptr,*m1_ptr,*TB_ptr = &TB[offset<<2];
char *in = y;
unsigned char prev_state0;
unsigned char *TB_ptr2;
unsigned short table_offset;
short position;
// printf("offset %d, TB_ptr %p\n",offset,TB_ptr);
if (offset == 0) {
// set initial metrics
metrics0_15 = _mm_cvtsi32_si128(INIT0);
metrics16_31 = _mm_setzero_si128();
metrics32_47 = _mm_setzero_si128();
metrics48_63 = _mm_setzero_si128();
}
rescale = _mm_cvtsi32_si128(RESCALE);
/*
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 (position=offset;position<(offset+n);position++) {
//printf("%d : (%d,%d)\n",position,in[0],in[1]);
// get branch metric offsets for the 64 states
table_offset = (in[0]+8 + ((in[1]+8)<<4))<<6;
// printf("Table_offset = %u (in[0]=%d,in[1]=%d)\n",table_offset,in[0],in[1]);
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+=2;
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");
*/
}
// Traceback
if (traceback == 1) {
prev_state0 = 0;
TB_ptr2 = (unsigned char *)&TB[(offset+n-1)<<2];
for (position = offset+n-1 ; position>-1; position--) {
// printf("pos %d: decoded %x\n",position>>3,decoded_bytes[position>>3]);
decoded_bytes[(position)>>3] += (prev_state0 & 0x1)<<(position & 0x7);
/*
if ((position%8) == 0)
printf("%d: %x\n",(position>>3),decoded_bytes[(position>>3)]);
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;
}
}
_mm_empty();
}
#else //EXPRESSMIMO_TARGET
void phy_viterbi_dot11(char *y,unsigned char *decoded_bytes,unsigned short n) {
}
#endif //EXPRESSMIMO_TARGET
/*
void print_bytes(__m128i x,char *s) {
unsigned char *tempb = (unsigned char *)&x;
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
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int test_viterbi()
{
unsigned char test[8];
//_declspec(align(16)) char channel_output[512];
//_declspec(align(16)) unsigned char output[512],decoded_output[16], *inPtr, *outPtr;
char channel_output[512];
unsigned char output[512],decoded_output[16], *inPtr, *outPtr;
unsigned int i;
test[0] = 7;
test[1] = 0xa5;
test[2] = 0;
test[3] = 0xfe;
test[4] = 0x1a;
test[5] = 0x33;
test[6] = 0x99;
test[7] = 0;
ccodedot11_init();
ccodedot11_init_inv();
inPtr = test;
outPtr = output;
phy_generate_viterbi_tables();
ccodedot11_encode(8, inPtr, outPtr,0);
for (i = 0; i < 128; i++){
channel_output[i] = 7*(2*output[i] - 1);
}
memset(decoded_output,0,16);
phy_viterbi_dot11(channel_output,decoded_output,64);
printf("Input :");
for (i =0 ; i<8 ; i++)
printf("%x ",inPtr[i]);
printf("\n");
printf("Unoptimized Viterbi :");
for (i =0 ; i<8 ; i++)
printf("%x ",decoded_output[i]);
printf("\n");
memset(decoded_output,0,16);
phy_viterbi_dot11_sse2(channel_output,decoded_output,64);
printf("Optimized Viterbi :");
for (i =0 ; i<8 ; i++)
printf("%x ",decoded_output[i]);
printf("\n");
printf("\n");
}
int main() {
test_viterbi();
return(0);
}
#endif // TEST_DEBUG
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