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author | Matthias P. Braendli <matthias.braendli@mpb.li> | 2014-01-02 21:55:13 +0100 |
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committer | Matthias P. Braendli <matthias.braendli@mpb.li> | 2014-01-02 21:55:13 +0100 |
commit | a31630e0d5b9880c716d9004ef4154396ba41ebc (patch) | |
tree | aebbd3b132e5f2dd31bc34750ccded2378fc687a /viterbi29_mmx.c | |
parent | 9aaac5be9db5e1537badc65242412ef14c5096e3 (diff) | |
download | ka9q-fec-a31630e0d5b9880c716d9004ef4154396ba41ebc.tar.gz ka9q-fec-a31630e0d5b9880c716d9004ef4154396ba41ebc.tar.bz2 ka9q-fec-a31630e0d5b9880c716d9004ef4154396ba41ebc.zip |
Extract fec-3.0.1
Diffstat (limited to 'viterbi29_mmx.c')
-rw-r--r-- | viterbi29_mmx.c | 118 |
1 files changed, 118 insertions, 0 deletions
diff --git a/viterbi29_mmx.c b/viterbi29_mmx.c new file mode 100644 index 0000000..563f40a --- /dev/null +++ b/viterbi29_mmx.c @@ -0,0 +1,118 @@ +/* K=9 r=1/2 Viterbi decoder for MMX + * 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 <mmintrin.h> +#include "fec.h" + +typedef union { char c[256]; __m64 v[32];} decision_t; +typedef union { unsigned char c[256]; __m64 v[32];} metric_t; + +unsigned char Mettab29_1[256][128] __attribute__ ((aligned(8))); +unsigned char Mettab29_2[256][128] __attribute__ ((aligned(8))); +static int Init = 0; + +/* State info for instance of Viterbi decoder + * Don't change this without also changing references in mmxbfly29.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 */ +}; + +/* Create a new instance of a Viterbi decoder */ +void *create_viterbi29_mmx(int len){ + struct v29 *vp; + + if(Init == 0){ + int polys[2] = {V29POLYA,V29POLYB}; + + set_viterbi29_polynomial_mmx(polys); + } + if((vp = (struct v29 *)malloc(sizeof(struct v29))) == NULL) + return NULL; + + if((vp->decisions = (decision_t *)malloc((len+8)*sizeof(decision_t))) == NULL){ + free(vp); + return NULL; + } + init_viterbi29(vp,0); + return vp; +} + +void set_viterbi29_polynomial_mmx(int polys[2]){ + int state; + + for(state=0;state < 128;state++){ + int symbol; + + for(symbol = 0;symbol < 256;symbol++){ + int sym; + + sym = parity((2*state) & abs(polys[0])) ^ (polys[0] < 0); + Mettab29_1[symbol][state] = (sym ? (255-symbol):symbol) / 16; + + sym = parity((2*state) & abs(polys[1])) ^ (polys[1] < 0); + Mettab29_2[symbol][state] = (sym ? (255-symbol):symbol) / 16; + } + } + Init++; +} + +/* Initialize Viterbi decoder for start of new frame */ +int init_viterbi29_mmx(void *p,int starting_state){ + struct v29 *vp = p; + int i; + + if(p == NULL) + return -1; + 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; +} + +/* Viterbi chainback */ +int chainback_viterbi29_mmx( + void *p, + unsigned char *data, /* Decoded output data */ + unsigned int nbits, /* Number of data bits */ + unsigned int endstate){ /* Terminal encoder state */ + + struct v29 *vp = (struct v29 *)p; + decision_t *d; + + if(p == NULL) + return -1; + + d = (decision_t *)vp->decisions; + endstate &= 255; + d += 8; /* Look past tail */ + while(nbits-- != 0){ + int k; + + k = d[nbits].c[endstate] & 1; + data[nbits>>3] = endstate = (endstate >> 1) | (k << 7); + } + return 0; +} + +/* Delete instance of a Viterbi decoder */ +void delete_viterbi29_mmx(void *p){ + struct v29 *vp = p; + + if(vp != NULL){ + free(vp->decisions); + free(vp); + } +} |