You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
120 lines
3.1 KiB
120 lines
3.1 KiB
/* K=9 r=1/2 Viterbi decoder for SSE2
|
|
* Copyright Feb 2004, Phil Karn, KA9Q
|
|
* May be used under the terms of the GNU Lesser General Public License (LGPL)
|
|
*/
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <memory.h>
|
|
#include <emmintrin.h>
|
|
#include "fec.h"
|
|
|
|
typedef union { unsigned char c[256]; __m128i v[16];} metric_t;
|
|
typedef union { unsigned long w[8]; unsigned char c[32];} decision_t;
|
|
|
|
union branchtab29 { unsigned char c[128]; } Branchtab29_sse2[2];
|
|
static int Init = 0;
|
|
|
|
/* State info for instance of Viterbi decoder
|
|
* Don't change this without also changing references in sse2bfly29.s!
|
|
*/
|
|
struct v29 {
|
|
metric_t metrics1; /* path metric buffer 1 */
|
|
metric_t metrics2; /* path metric buffer 2 */
|
|
decision_t *dp; /* Pointer to current decision */
|
|
metric_t *old_metrics,*new_metrics; /* Pointers to path metrics, swapped on every bit */
|
|
decision_t *decisions; /* Beginning of decisions for block */
|
|
};
|
|
|
|
/* Initialize Viterbi decoder for start of new frame */
|
|
int init_viterbi29_sse2(void *p,int starting_state){
|
|
struct v29 *vp = p;
|
|
int i;
|
|
|
|
for(i=0;i<256;i++)
|
|
vp->metrics1.c[i] = 63;
|
|
|
|
vp->old_metrics = &vp->metrics1;
|
|
vp->new_metrics = &vp->metrics2;
|
|
vp->dp = vp->decisions;
|
|
vp->old_metrics->c[starting_state & 255] = 0; /* Bias known start state */
|
|
return 0;
|
|
}
|
|
|
|
void set_viterbi29_polynomial_sse2(int polys[2]){
|
|
int state;
|
|
|
|
for(state=0;state < 128;state++){
|
|
Branchtab29_sse2[0].c[state] = (polys[0] < 0) ^ parity((2*state) & abs(polys[0])) ? 255 : 0;
|
|
Branchtab29_sse2[1].c[state] = (polys[1] < 0) ^ parity((2*state) & abs(polys[1])) ? 255 : 0;
|
|
}
|
|
Init++;
|
|
}
|
|
|
|
|
|
/* Create a new instance of a Viterbi decoder */
|
|
void *create_viterbi29_sse2(int len){
|
|
void *p;
|
|
struct v29 *vp;
|
|
|
|
if(!Init){
|
|
int polys[2] = {V29POLYA,V29POLYB};
|
|
|
|
set_viterbi29_polynomial(polys);
|
|
}
|
|
/* Ordinary malloc() only returns 8-byte alignment, we need 16 */
|
|
if(posix_memalign(&p, sizeof(__m128i),sizeof(struct v29)))
|
|
return NULL;
|
|
vp = (struct v29 *)p;
|
|
if((p = malloc((len+8)*sizeof(decision_t))) == NULL){
|
|
free(vp);
|
|
return NULL;
|
|
}
|
|
vp->decisions = (decision_t *)p;
|
|
init_viterbi29_sse2(vp,0);
|
|
return vp;
|
|
}
|
|
|
|
|
|
/* Viterbi chainback */
|
|
int chainback_viterbi29_sse2(
|
|
void *p,
|
|
unsigned char *data, /* Decoded output data */
|
|
unsigned int nbits, /* Number of data bits */
|
|
unsigned int endstate){ /* Terminal encoder state */
|
|
struct v29 *vp = p;
|
|
decision_t *d;
|
|
|
|
if(p == NULL)
|
|
return -1;
|
|
d = vp->decisions;
|
|
|
|
/* Make room beyond the end of the encoder register so we can
|
|
* accumulate a full byte of decoded data
|
|
*/
|
|
endstate %= 256;
|
|
|
|
/* The store into data[] only needs to be done every 8 bits.
|
|
* But this avoids a conditional branch, and the writes will
|
|
* combine in the cache anyway
|
|
*/
|
|
d += 8; /* Look past tail */
|
|
while(nbits-- != 0){
|
|
int k;
|
|
|
|
k = (d[nbits].c[endstate/8] >> (endstate%8)) & 1;
|
|
data[nbits>>3] = endstate = (endstate >> 1) | (k << 7);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
|
|
/* Delete instance of a Viterbi decoder */
|
|
void delete_viterbi29_sse2(void *p){
|
|
struct v29 *vp = p;
|
|
|
|
if(vp != NULL){
|
|
free(vp->decisions);
|
|
free(vp);
|
|
}
|
|
}
|