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499 lines
14 KiB
C
499 lines
14 KiB
C
/**
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*
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* \section COPYRIGHT
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*
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* Copyright 2013-2015 Software Radio Systems Limited
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*
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* \section LICENSE
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*
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* This file is part of the srsLTE library.
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*
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* srsLTE is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version.
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*
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* srsLTE is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* A copy of the GNU Affero General Public License can be found in
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* the LICENSE file in the top-level directory of this distribution
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* and at http://www.gnu.org/licenses/.
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*
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <string.h>
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#include <strings.h>
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#include <math.h>
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#include "srslte/phy/fec/turbodecoder_simd.h"
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#include "srslte/phy/utils/vector.h"
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#include <inttypes.h>
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#ifdef LV_HAVE_SSE
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#include <smmintrin.h>
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#endif
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#define NUMSTATES 8
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#define NINPUTS 2
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#define TAIL 3
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#define TOTALTAIL 12
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#define INF 10000
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#define ZERO 0
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#ifdef LV_HAVE_SSE
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/*
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static void print_128i(__m128i x) {
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int16_t *s = (int16_t*) &x;
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printf("[%d", s[0]);
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for (int i=1;i<8;i++) {
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printf(",%d", s[i]);
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}
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printf("]\n");
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}
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*/
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//#define use_beta_transposed_max
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#ifndef use_beta_transposed_max
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/* Computes the horizontal MAX from 8 16-bit integers using the minpos_epu16 SSE4.1 instruction */
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static inline int16_t hMax(__m128i buffer)
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{
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__m128i tmp1 = _mm_sub_epi16(_mm_set1_epi16(0x7FFF), buffer);
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__m128i tmp3 = _mm_minpos_epu16(tmp1);
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return (int16_t)(_mm_cvtsi128_si32(tmp3));
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}
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/* Computes beta values */
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void map_sse_beta(map_gen_t * s, int16_t * output, uint32_t long_cb)
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{
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int k;
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uint32_t end = long_cb + 3;
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const __m128i *alphaPtr = (const __m128i*) s->alpha;
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__m128i beta_k = _mm_set_epi16(-INF, -INF, -INF, -INF, -INF, -INF, -INF, 0);
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__m128i g, bp, bn, alpha_k;
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/* Define the shuffle constant for the positive beta */
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__m128i shuf_bp = _mm_set_epi8(
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15, 14, // 7
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7, 6, // 3
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5, 4, // 2
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13, 12, // 6
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11, 10, // 5
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3, 2, // 1
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1, 0, // 0
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9, 8 // 4
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);
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/* Define the shuffle constant for the negative beta */
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__m128i shuf_bn = _mm_set_epi8(
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7, 6, // 3
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15, 14, // 7
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13, 12, // 6
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5, 4, // 2
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3, 2, // 1
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11, 10, // 5
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9, 8, // 4
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1, 0 // 0
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);
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alphaPtr += long_cb-1;
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/* Define shuffle for branch costs */
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__m128i shuf_g[4];
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shuf_g[3] = _mm_set_epi8(3,2,1,0,1,0,3,2,3,2,1,0,1,0,3,2);
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shuf_g[2] = _mm_set_epi8(7,6,5,4,5,4,7,6,7,6,5,4,5,4,7,6);
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shuf_g[1] = _mm_set_epi8(11,10,9,8,9,8,11,10,11,10,9,8,9,8,11,10);
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shuf_g[0] = _mm_set_epi8(15,14,13,12,13,12,15,14,15,14,13,12,13,12,15,14);
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__m128i gv;
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int16_t *b = &s->branch[2*long_cb-8];
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__m128i *gPtr = (__m128i*) b;
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/* Define shuffle for beta normalization */
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__m128i shuf_norm = _mm_set_epi8(1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0);
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/* This defines a beta computation step:
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* Adds and substracts the branch metrics to the previous beta step,
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* shuffles the states according to the trellis path and selects maximum state
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*/
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#define BETA_STEP(g) bp = _mm_add_epi16(beta_k, g);\
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bn = _mm_sub_epi16(beta_k, g);\
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bp = _mm_shuffle_epi8(bp, shuf_bp);\
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bn = _mm_shuffle_epi8(bn, shuf_bn);\
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beta_k = _mm_max_epi16(bp, bn);
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/* Loads the alpha metrics from memory and adds them to the temporal bn and bp
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* metrics. Then computes horizontal maximum of both metrics and computes difference
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*/
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#define BETA_STEP_CNT(c,d) g = _mm_shuffle_epi8(gv, shuf_g[c]);\
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BETA_STEP(g)\
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alpha_k = _mm_load_si128(alphaPtr);\
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alphaPtr--;\
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bp = _mm_add_epi16(bp, alpha_k);\
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bn = _mm_add_epi16(bn, alpha_k);\
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output[k-d] = hMax(bn)-hMax(bp);
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/* The tail does not require to load alpha or produce outputs. Only update
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* beta metrics accordingly */
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for (k=end-1; k>=long_cb; k--) {
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int16_t g0 = s->branch[2*k];
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int16_t g1 = s->branch[2*k+1];
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g = _mm_set_epi16(g1, g0, g0, g1, g1, g0, g0, g1);
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BETA_STEP(g);
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}
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/* We inline 2 trelis steps for each normalization */
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__m128i norm;
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for (; k >= 0; k-=8) {
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gv = _mm_load_si128(gPtr);
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gPtr--;
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BETA_STEP_CNT(0,0);
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BETA_STEP_CNT(1,1);
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BETA_STEP_CNT(2,2);
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BETA_STEP_CNT(3,3);
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norm = _mm_shuffle_epi8(beta_k, shuf_norm);
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beta_k = _mm_sub_epi16(beta_k, norm);
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gv = _mm_load_si128(gPtr);
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gPtr--;
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BETA_STEP_CNT(0,4);
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BETA_STEP_CNT(1,5);
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BETA_STEP_CNT(2,6);
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BETA_STEP_CNT(3,7);
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norm = _mm_shuffle_epi8(beta_k, shuf_norm);
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beta_k = _mm_sub_epi16(beta_k, norm);
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}
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}
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#endif
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/* Computes alpha metrics */
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void map_sse_alpha(map_gen_t * s, uint32_t long_cb)
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{
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uint32_t k;
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int16_t *alpha = s->alpha;
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uint32_t i;
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alpha[0] = 0;
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for (i = 1; i < 8; i++) {
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alpha[i] = -INF;
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}
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/* Define the shuffle constant for the positive alpha */
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__m128i shuf_ap = _mm_set_epi8(
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15, 14, // 7
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9, 8, // 4
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7, 6, // 3
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1, 0, // 0
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13, 12, // 6
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11, 10, // 5
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5, 4, // 2
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3, 2 // 1
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);
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/* Define the shuffle constant for the negative alpha */
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__m128i shuf_an = _mm_set_epi8(
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13, 12, // 6
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11, 10, // 5
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5, 4, // 2
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3, 2, // 1
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15, 14, // 7
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9, 8, // 4
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7, 6, // 3
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1, 0 // 0
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);
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/* Define shuffle for branch costs */
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__m128i shuf_g[4];
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shuf_g[0] = _mm_set_epi8(3,2,3,2,1,0,1,0,1,0,1,0,3,2,3,2);
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shuf_g[1] = _mm_set_epi8(7,6,7,6,5,4,5,4,5,4,5,4,7,6,7,6);
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shuf_g[2] = _mm_set_epi8(11,10,11,10,9,8,9,8,9,8,9,8,11,10,11,10);
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shuf_g[3] = _mm_set_epi8(15,14,15,14,13,12,13,12,13,12,13,12,15,14,15,14);
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__m128i shuf_norm = _mm_set_epi8(1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0);
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__m128i* alphaPtr = (__m128i*) alpha;
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alphaPtr++;
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__m128i gv;
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__m128i *gPtr = (__m128i*) s->branch;
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__m128i g, ap, an;
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__m128i alpha_k = _mm_set_epi16(-INF, -INF, -INF, -INF, -INF, -INF, -INF, 0);
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/* This defines a alpha computation step:
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* Adds and substracts the branch metrics to the previous alpha step,
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* shuffles the states according to the trellis path and selects maximum state
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*/
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#define ALPHA_STEP(c) g = _mm_shuffle_epi8(gv, shuf_g[c]); \
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ap = _mm_add_epi16(alpha_k, g);\
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an = _mm_sub_epi16(alpha_k, g);\
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ap = _mm_shuffle_epi8(ap, shuf_ap);\
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an = _mm_shuffle_epi8(an, shuf_an);\
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alpha_k = _mm_max_epi16(ap, an);\
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_mm_store_si128(alphaPtr, alpha_k);\
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alphaPtr++; \
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/* In this loop, we compute 8 steps and normalize twice for each branch metrics memory load */
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__m128i norm;
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for (k = 0; k < long_cb/8; k++) {
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gv = _mm_load_si128(gPtr);
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gPtr++;
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ALPHA_STEP(0);
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ALPHA_STEP(1);
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ALPHA_STEP(2);
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ALPHA_STEP(3);
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norm = _mm_shuffle_epi8(alpha_k, shuf_norm);
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alpha_k = _mm_sub_epi16(alpha_k, norm);
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gv = _mm_load_si128(gPtr);
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gPtr++;
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ALPHA_STEP(0);
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ALPHA_STEP(1);
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ALPHA_STEP(2);
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ALPHA_STEP(3);
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norm = _mm_shuffle_epi8(alpha_k, shuf_norm);
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alpha_k = _mm_sub_epi16(alpha_k, norm);
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}
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}
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/* Compute branch metrics (gamma) */
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void map_sse_gamma(map_gen_t * h, int16_t *input, int16_t *app, int16_t *parity, uint32_t long_cb)
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{
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__m128i res00, res10, res01, res11, res0, res1;
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__m128i in, ap, pa, g1, g0;
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__m128i *inPtr = (__m128i*) input;
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__m128i *appPtr = (__m128i*) app;
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__m128i *paPtr = (__m128i*) parity;
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__m128i *resPtr = (__m128i*) h->branch;
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__m128i res00_mask = _mm_set_epi8(0xff,0xff,7,6,0xff,0xff,5,4,0xff,0xff,3,2,0xff,0xff,1,0);
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__m128i res10_mask = _mm_set_epi8(0xff,0xff,15,14,0xff,0xff,13,12,0xff,0xff,11,10,0xff,0xff,9,8);
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__m128i res01_mask = _mm_set_epi8(7,6,0xff,0xff,5,4,0xff,0xff,3,2,0xff,0xff,1,0,0xff,0xff);
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__m128i res11_mask = _mm_set_epi8(15,14,0xff,0xff,13,12,0xff,0xff,11,10,0xff,0xff,9,8,0xff,0xff);
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for (int i=0;i<long_cb/8;i++) {
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in = _mm_load_si128(inPtr);
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inPtr++;
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pa = _mm_load_si128(paPtr);
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paPtr++;
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if (appPtr) {
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ap = _mm_load_si128(appPtr);
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appPtr++;
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in = _mm_add_epi16(ap, in);
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}
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g1 = _mm_add_epi16(in, pa);
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g0 = _mm_sub_epi16(in, pa);
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g1 = _mm_srai_epi16(g1, 1);
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g0 = _mm_srai_epi16(g0, 1);
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res00 = _mm_shuffle_epi8(g0, res00_mask);
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res10 = _mm_shuffle_epi8(g0, res10_mask);
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res01 = _mm_shuffle_epi8(g1, res01_mask);
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res11 = _mm_shuffle_epi8(g1, res11_mask);
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res0 = _mm_or_si128(res00, res01);
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res1 = _mm_or_si128(res10, res11);
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_mm_store_si128(resPtr, res0);
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resPtr++;
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_mm_store_si128(resPtr, res1);
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resPtr++;
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}
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for (int i=long_cb;i<long_cb+3;i++) {
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h->branch[2*i] = (input[i] - parity[i])/2;
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h->branch[2*i+1] = (input[i] + parity[i])/2;
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}
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}
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/***********************
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*
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* This is an attempt to parallelize the horizontal max
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* by doing a 8x8 tranpose of the vectors and computing max
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* in cascade. However since we need to store 16 registers
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* for the positive and negative values the performance is not very good
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*/
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#ifdef use_beta_transposed_max
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static inline __m128i transposed_max(__m128i a, __m128i b, __m128i c, __m128i d,
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__m128i e, __m128i f, __m128i g, __m128i h)
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{
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// Transpose 8 vectors
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__m128i t0 = _mm_unpacklo_epi16(a, b);
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__m128i t1 = _mm_unpacklo_epi16(c, d);
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__m128i t2 = _mm_unpacklo_epi16(e, f);
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__m128i t3 = _mm_unpacklo_epi16(g, h);
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__m128i t4 = _mm_unpackhi_epi16(a, b);
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__m128i t5 = _mm_unpackhi_epi16(c, d);
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__m128i t6 = _mm_unpackhi_epi16(e, f);
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__m128i t7 = _mm_unpackhi_epi16(g, h);
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__m128i s0 = _mm_unpacklo_epi32(t0, t1);
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__m128i s1 = _mm_unpackhi_epi32(t0, t1);
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__m128i s2 = _mm_unpacklo_epi32(t2, t3);
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__m128i s3 = _mm_unpackhi_epi32(t2, t3);
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__m128i s4 = _mm_unpacklo_epi32(t4, t5);
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__m128i s5 = _mm_unpackhi_epi32(t4, t5);
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__m128i s6 = _mm_unpacklo_epi32(t6, t7);
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__m128i s7 = _mm_unpackhi_epi32(t6, t7);
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__m128i x0 = _mm_unpacklo_epi64(s0, s2);
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__m128i x1 = _mm_unpackhi_epi64(s0, s2);
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__m128i x2 = _mm_unpacklo_epi64(s1, s3);
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__m128i x3 = _mm_unpackhi_epi64(s1, s3);
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__m128i x4 = _mm_unpacklo_epi64(s4, s6);
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__m128i x5 = _mm_unpackhi_epi64(s4, s6);
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__m128i x6 = _mm_unpacklo_epi64(s5, s7);
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__m128i x7 = _mm_unpackhi_epi64(s5, s7);
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// Cascade max on the transposed vector
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__m128i res = _mm_max_epi16(x0,
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_mm_max_epi16(x1,
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_mm_max_epi16(x2,
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_mm_max_epi16(x3,
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_mm_max_epi16(x4,
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_mm_max_epi16(x5,
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_mm_max_epi16(x6,
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x7)))))));
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return res;
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}
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void map_sse_beta(map_gen_t * s, int16_t * output, uint32_t long_cb)
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{
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int k;
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uint32_t end = long_cb + 3;
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const __m128i *alphaPtr = (const __m128i*) s->alpha;
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__m128i beta_k = _mm_set_epi16(-INF, -INF, -INF, -INF, -INF, -INF, -INF, 0);
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__m128i g, alpha_k;
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__m128i bn, bn_0, bn_1, bn_2, bn_3, bn_4, bn_5, bn_6, bn_7;
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__m128i bp, bp_0, bp_1, bp_2, bp_3, bp_4, bp_5, bp_6, bp_7;
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/* Define the shuffle constant for the positive beta */
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__m128i shuf_bp = _mm_set_epi8(
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15, 14, // 7
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7, 6, // 3
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5, 4, // 2
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13, 12, // 6
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11, 10, // 5
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3, 2, // 1
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1, 0, // 0
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9, 8 // 4
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);
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/* Define the shuffle constant for the negative beta */
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__m128i shuf_bn = _mm_set_epi8(
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7, 6, // 3
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15, 14, // 7
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13, 12, // 6
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5, 4, // 2
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3, 2, // 1
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11, 10, // 5
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9, 8, // 4
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1, 0 // 0
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);
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alphaPtr += long_cb-1;
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/* Define shuffle for branch costs */
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__m128i shuf_g[4];
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shuf_g[3] = _mm_set_epi8(3,2,1,0,1,0,3,2,3,2,1,0,1,0,3,2);
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shuf_g[2] = _mm_set_epi8(7,6,5,4,5,4,7,6,7,6,5,4,5,4,7,6);
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shuf_g[1] = _mm_set_epi8(11,10,9,8,9,8,11,10,11,10,9,8,9,8,11,10);
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shuf_g[0] = _mm_set_epi8(15,14,13,12,13,12,15,14,15,14,13,12,13,12,15,14);
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__m128i gv;
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int16_t *b = &s->branch[2*long_cb-8];
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__m128i *gPtr = (__m128i*) b;
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/* Define shuffle for beta normalization */
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__m128i shuf_norm = _mm_set_epi8(1,0,1,0,1,0,1,0,1,0,1,0,1,0,1,0);
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/* This defines a beta computation step:
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* Adds and substracts the branch metrics to the previous beta step,
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* shuffles the states according to the trellis path and selects maximum state
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*/
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#define BETA_STEP(g) bp = _mm_add_epi16(beta_k, g);\
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bn = _mm_sub_epi16(beta_k, g);\
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bp = _mm_shuffle_epi8(bp, shuf_bp);\
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bn = _mm_shuffle_epi8(bn, shuf_bn);\
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beta_k = _mm_max_epi16(bp, bn);
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/* Loads the alpha metrics from memory and adds them to the temporal bn and bp
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* metrics.
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*/
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#define BETA_STEP_CNT(c,d) g = _mm_shuffle_epi8(gv, shuf_g[c]);\
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BETA_STEP(g)\
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alpha_k = _mm_load_si128(alphaPtr);\
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alphaPtr--;\
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bp_##d = _mm_add_epi16(bp, alpha_k);\
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bn_##d = _mm_add_epi16(bn, alpha_k);\
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/* The tail does not require to load alpha or produce outputs. Only update
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* beta metrics accordingly */
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for (k=end-1; k>=long_cb; k--) {
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int16_t g0 = s->branch[2*k];
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int16_t g1 = s->branch[2*k+1];
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g = _mm_set_epi16(g1, g0, g0, g1, g1, g0, g0, g1);
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BETA_STEP(g);
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}
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/* We inline 2 trelis steps for each normalization */
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__m128i norm;
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__m128i *outPtr = (__m128i*) &output[long_cb-8];
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for (; k >= 0; k-=8) {
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gv = _mm_load_si128(gPtr);
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gPtr--;
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BETA_STEP_CNT(0,0);
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BETA_STEP_CNT(1,1);
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BETA_STEP_CNT(2,2);
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BETA_STEP_CNT(3,3);
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norm = _mm_shuffle_epi8(beta_k, shuf_norm);
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beta_k = _mm_sub_epi16(beta_k, norm);
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gv = _mm_load_si128(gPtr);
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gPtr--;
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BETA_STEP_CNT(0,4);
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BETA_STEP_CNT(1,5);
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BETA_STEP_CNT(2,6);
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BETA_STEP_CNT(3,7);
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norm = _mm_shuffle_epi8(beta_k, shuf_norm);
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beta_k = _mm_sub_epi16(beta_k, norm);
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__m128i bn_transp = transposed_max(bn_7, bn_6, bn_5, bn_4, bn_3, bn_2, bn_1, bn_0);
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__m128i bp_transp = transposed_max(bp_7, bp_6, bp_5, bp_4, bp_3, bp_2, bp_1, bp_0);
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__m128i outval = _mm_sub_epi16(bp_transp,bn_transp);
|
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_mm_store_si128(outPtr, outval);
|
|
outPtr--;
|
|
}
|
|
}
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#endif
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#endif
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