mirror of https://github.com/pvnis/srsRAN_4G.git
adding avx viterbi and avx vectors
yagoda
8 years ago
parent
8e6213e9cd
commit
e75a9865de
@ -0,0 +1,339 @@
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/* Adapted Phil Karn's r=1/3 k=9 viterbi decoder to r=1/3 k=7
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*
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* K=15 r=1/6 Viterbi decoder for x86 SSE2
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* Copyright Mar 2004, Phil Karn, KA9Q
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* May be used under the terms of the GNU Lesser General Public License (LGPL)
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <memory.h>
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#include <limits.h>
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#include "parity.h"
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//#define DEBUG
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#ifdef LV_HAVE_SSE
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#include <emmintrin.h>
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#include <tmmintrin.h>
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#include <immintrin.h>
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#include <emmintrin.h>
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#define _mm256_set_m128i(v0, v1) _mm256_insertf128_si256(_mm256_castsi128_si256(v1), (v0), 1)
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#define _mm256_setr_m128i(v0, v1) _mm256_set_m128i((v1), (v0))
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typedef union {
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unsigned char c[64];
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__m128i v[4];
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} metric_t;
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typedef union {
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unsigned int w[2];
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unsigned char c[8];
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unsigned short s[4];
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__m64 v;
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} decision_t;
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union branchtab27 {
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unsigned char c[32];
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__m256i v;
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} Branchtab37_sse2[3];
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int firstGo;
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/* State info for instance of Viterbi decoder */
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struct v37 {
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metric_t metrics1; /* path metric buffer 1 */
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metric_t metrics2; /* path metric buffer 2 */
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decision_t *dp; /* Pointer to current decision */
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metric_t *old_metrics,*new_metrics; /* Pointers to path metrics, swapped on every bit */
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decision_t *decisions; /* Beginning of decisions for block */
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uint32_t len;
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};
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void set_viterbi37_polynomial_avx2(int polys[3]) {
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int state;
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for(state=0;state < 32;state++){
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Branchtab37_sse2[0].c[state] = (polys[0] < 0) ^ parity((2*state) & polys[0]) ? 255:0;
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Branchtab37_sse2[1].c[state] = (polys[1] < 0) ^ parity((2*state) & polys[1]) ? 255:0;
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Branchtab37_sse2[2].c[state] = (polys[2] < 0) ^ parity((2*state) & polys[2]) ? 255:0;
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}
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}
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void clear_v37_avx2(struct v37 *vp) {
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bzero(vp->decisions, sizeof(decision_t)*vp->len);
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vp->dp = NULL;
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bzero(&vp->metrics1, sizeof(metric_t));
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bzero(&vp->metrics2, sizeof(metric_t));
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vp->old_metrics = NULL;
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vp->new_metrics = NULL;
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}
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/* Initialize Viterbi decoder for start of new frame */
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int init_viterbi37_avx2(void *p, int starting_state) {
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struct v37 *vp = p;
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uint32_t i;
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firstGo = 1;
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for(i=0;i<64;i++)
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vp->metrics1.c[i] = 63;
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clear_v37_avx2(vp);
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vp->old_metrics = &vp->metrics1;
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vp->new_metrics = &vp->metrics2;
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vp->dp = vp->decisions;
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if (starting_state != -1) {
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vp->old_metrics->c[starting_state & 63] = 0; /* Bias known start state */
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}
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return 0;
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}
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/* Create a new instance of a Viterbi decoder */
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void *create_viterbi37_avx2(int polys[3], uint32_t len) {
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void *p;
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struct v37 *vp;
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set_viterbi37_polynomial_avx2(polys);
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/* Ordinary malloc() only returns 8-byte alignment, we need 16 */
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if(posix_memalign(&p, sizeof(__m128i),sizeof(struct v37)))
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return NULL;
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vp = (struct v37 *)p;
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if(posix_memalign(&p, sizeof(__m128i),(len+6)*sizeof(decision_t))) {
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free(vp);
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return NULL;
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}
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vp->decisions = (decision_t *)p;
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vp->len = len+6;
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return vp;
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}
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/* Viterbi chainback */
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int chainback_viterbi37_avx2(
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void *p,
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uint8_t *data, /* Decoded output data */
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uint32_t nbits, /* Number of data bits */
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uint32_t endstate) { /* Terminal encoder state */
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struct v37 *vp = p;
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if (p == NULL)
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return -1;
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decision_t *d = (decision_t *)vp->decisions;
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/* Make room beyond the end of the encoder register so we can
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* accumulate a full byte of decoded data
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*/
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endstate %= 64;
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endstate <<= 2;
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/* The store into data[] only needs to be done every 8 bits.
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* But this avoids a conditional branch, and the writes will
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* combine in the cache anyway
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*/
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d += 6; /* Look past tail */
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while(nbits--) {
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int k;
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k = (d[nbits].c[(endstate>>2)/8] >> ((endstate>>2)%8)) & 1;
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endstate = (endstate >> 1) | (k << 7);
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data[nbits] = k;
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//printf("nbits=%d, endstate=%3d, k=%d, w[0]=%d, w[1]=%d, c=%d\n", nbits, endstate, k, d[nbits].s[1]&1, d[nbits].s[2]&1, d[nbits].c[(endstate>>2)/8]&1);
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}
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return 0;
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}
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/* Delete instance of a Viterbi decoder */
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void delete_viterbi37_avx2(void *p){
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struct v37 *vp = p;
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if(vp != NULL){
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free(vp->decisions);
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free(vp);
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}
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}
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void printer_256i(char *s, __m256i val) {
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printf("%s: ", s);
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uint8_t *x = (uint8_t*) &val;
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for (int i=0;i<32;i++) {
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printf("%3d, ", x[i]);
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}
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printf("\n");
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}
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void printer_128i(char *s, __m128i val) {
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printf("%s: ", s);
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uint8_t *x = (uint8_t*) &val;
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for (int i=0;i<16;i++) {
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printf("%3d, ", x[i]);
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}
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printf("\n");
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}
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void printer_m64(char *s, __m64 val) {
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printf("%s: ", s);
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uint8_t *x = (uint8_t*) &val;
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for (int i=0;i<8;i++) {
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printf("%3d, ", x[i]);
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}
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printf("\n");
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}
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void update_viterbi37_blk_avx2(void *p,unsigned char *syms,int nbits, uint32_t *best_state) {
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struct v37 *vp = p;
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decision_t *d;
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if(p == NULL)
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return;
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#ifdef DEBUG
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printf("[");
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#endif
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d = (decision_t *) vp->dp;
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for (int s=0;s<nbits;s++) {
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memset(d+s,0,sizeof(decision_t));
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}
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while(nbits--) {
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__m256i sym0v,sym1v,sym2v;
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void *tmp;
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sym0v = _mm256_set1_epi8(syms[0]);
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sym1v = _mm256_set1_epi8(syms[1]);
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sym2v = _mm256_set1_epi8(syms[2]);
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syms += 3;
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__m256i decision0,decision1,survivor0,survivor1,metric,m_metric,m0,m1,m2,m3;
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/* Form branch metrics */
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m0 = _mm256_avg_epu8(_mm256_xor_si256(Branchtab37_sse2[0].v,sym0v),_mm256_xor_si256(Branchtab37_sse2[1].v,sym1v));
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metric = _mm256_avg_epu8(_mm256_xor_si256(Branchtab37_sse2[2].v,sym2v),m0);
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#ifdef DEBUG
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print_128i("metric_initial", metric);
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#endif
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/* There's no packed bytes right shift in SSE2, so we use the word version and mask
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*/
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metric = _mm256_srli_epi16(metric,3);
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metric = _mm256_and_si256(metric,_mm256_set1_epi8(31));
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m_metric = _mm256_sub_epi8(_mm256_set1_epi8(31),metric);
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#ifdef DEBUG
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print_128i("metric ", metric);
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print_128i("m_metric ", m_metric);
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#endif
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__m256i temp = _mm256_set_m128i( vp->old_metrics->v[1], vp->old_metrics->v[0]);
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m0 = _mm256_add_epi8(temp,metric);
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m2 = _mm256_add_epi8(temp,m_metric);
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temp = _mm256_set_m128i( vp->old_metrics->v[3], vp->old_metrics->v[2]);
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m3 = _mm256_add_epi8(temp,metric);
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m1 = _mm256_add_epi8(temp,m_metric);
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/* Compare and select, using modulo arithmetic */
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decision0 = _mm256_cmpgt_epi8(_mm256_sub_epi8(m0,m1),_mm256_setzero_si256());
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decision1 =_mm256_cmpgt_epi8(_mm256_sub_epi8(m2,m3),_mm256_setzero_si256());
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survivor0 = _mm256_or_si256(_mm256_and_si256(decision0,m1),_mm256_andnot_si256(decision0,m0));
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survivor1 = _mm256_or_si256(_mm256_and_si256(decision1,m3),_mm256_andnot_si256(decision1,m2));
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unsigned int x = _mm256_movemask_epi8(_mm256_unpackhi_epi8(decision0,decision1));
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unsigned int y = _mm256_movemask_epi8(_mm256_unpacklo_epi8(decision0,decision1));
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d->s[0] = (short) y;
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d->s[1] = (short) x;
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d->s[2] = (short) (y >>16);
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d->s[3] = (short)(x>> 16);
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__m256i unpack;
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unpack = _mm256_unpacklo_epi8(survivor0,survivor1);
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vp->new_metrics->v[0] =_mm256_castsi256_si128(unpack);
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vp->new_metrics->v[1] = _mm256_extractf128_si256(unpack,1);
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unpack = _mm256_unpackhi_epi8(survivor0,survivor1);
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vp->new_metrics->v[2] =_mm256_castsi256_si128(unpack);
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vp->new_metrics->v[3] = _mm256_extractf128_si256(unpack,1);
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__m128i temp1 = vp->new_metrics->v[1];
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vp->new_metrics->v[1] = vp->new_metrics->v[2];
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vp->new_metrics->v[2] = temp1;
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// See if we need to normalize
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if (vp->new_metrics->c[0] > 100) {
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int i;
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uint8_t adjust;
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__m128i adjustv;
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union { __m128i v; signed short w[8]; } t;
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adjustv = vp->new_metrics->v[0];
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for(i=1;i<4;i++) {
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adjustv = _mm_min_epu8(adjustv,vp->new_metrics->v[i]);
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}
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adjustv = _mm_min_epu8(adjustv,_mm_srli_si128(adjustv,8));
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adjustv = _mm_min_epu8(adjustv,_mm_srli_si128(adjustv,4));
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adjustv = _mm_min_epu8(adjustv,_mm_srli_si128(adjustv,2));
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t.v = adjustv;
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adjust = t.w[0];
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adjustv = _mm_set1_epi8(adjust);
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/* We cannot use a saturated subtract, because we often have to adjust by more than SHRT_MAX
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* This is okay since it can't overflow anyway
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*/
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for(i=0;i<4;i++)
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vp->new_metrics->v[i] = _mm_sub_epi8(vp->new_metrics->v[i],adjustv);
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}
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firstGo = 0;
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d++;
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/* Swap pointers to old and new metrics */
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tmp = vp->old_metrics;
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vp->old_metrics = vp->new_metrics;
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vp->new_metrics = tmp;
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}
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if (best_state) {
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uint32_t i, bst=0;
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uint8_t minmetric=UINT8_MAX;
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for (i=0;i<64;i++) {
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if (vp->old_metrics->c[i] <= minmetric) {
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bst = i;
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minmetric = vp->old_metrics->c[i];
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}
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}
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*best_state = bst;
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}
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#ifdef DEBUG
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printf("];\n===========================================\n");
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#endif
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vp->dp = d;
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}
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#endif
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