init commit

viterbi27_mmx.c

@@ -0,0 +1,96 @@
+/* K=7 r=1/2 Viterbi decoder for MMX
+ * Copyright Feb 2004, Phil Karn, KA9Q
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <memory.h>
+#include <mmintrin.h>
+#include "fec.h"
+
+typedef union { char c[64]; __m64 v[8];} decision_t;
+typedef union { unsigned char c[64]; __m64 v[8];} metric_t;
+
+unsigned char Mettab27_1[256][32] __attribute__ ((aligned(16)));
+unsigned char Mettab27_2[256][32] __attribute__ ((aligned(16)));
+static int Init = 0;
+
+/* State info for instance of Viterbi decoder
+ * Don't change this without also changing references in mmxbfly27.s!
+ */
+struct v27 {
+  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_viterbi27_mmx(void *p,int starting_state){
+  struct v27 *vp = (struct v27 *)p;
+  int i;
+
+  for(i=0;i<64;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 & 63] = 0; /* Bias known start state */
+  return 0;
+}
+
+/* Create a new instance of a Viterbi decoder */
+void *create_viterbi27_mmx(int len){
+  int state;
+  struct v27 *vp;
+
+  if(Init == 0){
+    /* Initialize branch tables */
+    for(state=0;state < 32;state++){
+      int symbol,bit1,bit2;
+      bit1 = parity((2*state) & V27POLYA);
+      bit2 = parity((2*state) & V27POLYB);
+      for(symbol = 0;symbol < 256;symbol++){
+	Mettab27_1[symbol][state] = (bit1 ? (255-symbol):symbol) / 16;
+	Mettab27_2[symbol][state] = (bit2 ? (255-symbol):symbol) / 16;
+      }
+    }
+    Init++;
+  }
+  vp = (struct v27 *)malloc(sizeof(struct v27));
+  vp->decisions = (decision_t *)malloc((len+6)*sizeof(decision_t));
+  init_viterbi27_mmx(vp,0);
+  return vp;
+}
+
+/* Viterbi chainback */
+int chainback_viterbi27_mmx(
+      void *p,
+      unsigned char *data, /* Decoded output data */
+      unsigned int nbits, /* Number of data bits */
+      unsigned int endstate){ /* Terminal encoder state */
+
+  struct v27 *vp = (struct v27 *)p;
+  decision_t *d = (decision_t *)vp->decisions;
+
+  endstate &= 63;
+  d += 6; /* Look past tail */
+  while(nbits-- != 0){
+    int k;
+
+    k = d[nbits].c[endstate>>2] & 1;
+    data[nbits>>3] = endstate = (endstate >> 1) | (k << 7);
+  }
+  return 0;
+}
+
+/* Delete instance of a Viterbi decoder */
+void delete_viterbi27_mmx(void *p){
+  struct v27 *vp = p;
+
+  if(vp != NULL){
+    free(vp->decisions);
+    free(vp);
+  }
+}