139 lines
3.2 KiB
C
139 lines
3.2 KiB
C
|
/* 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);
|
||
|
}
|
||
|
}
|