1 files changed, 61 insertions, 0 deletions
diff --git a/encode_rs_av.c b/encode_rs_av.c
new file mode 100644
index 0000000..32e528f
--- /dev/null
+++ b/encode_rs_av.c
@@ -0,0 +1,61 @@
+/* Fast Reed-Solomon encoder for (255,223) CCSDS code on PowerPC G4/G5 using Altivec instructions
+ * Copyright 2004, Phil Karn KA9Q
+ * May be used under the terms of the GNU Lesser General Public License (LGPL)
+ */
+#include <stdio.h>
+#include <string.h>
+#include "fixed.h"
+
+/* Lookup table for feedback multiplications
+ * These are the low half of the coefficients. Since the generator polynomial is
+ * palindromic, we form it by reversing these on the fly
+ */
+static union { vector unsigned char v; unsigned char c[16]; } table[256];
+
+static vector unsigned char reverse = (vector unsigned char)(0,15,14,13,12,11,10,9,8,7,6,5,4,3,2,1);
+static vector unsigned char shift_right = (vector unsigned char)(15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30);
+
+extern data_t CCSDS_alpha_to[];
+extern data_t CCSDS_index_of[];
+extern data_t CCSDS_poly[];
+
+void rs_init_av(){
+  int i,j;
+
+  /* The PowerPC is big-endian, so the low-order byte of each vector contains the highest order term in the polynomial */
+  for(j=0;j<16;j++){
+    table[0].c[j] = 0;
+    for(i=1;i<256;i++){
+      table[i].c[16-j-1] = CCSDS_alpha_to[MODNN(CCSDS_poly[j+1] + CCSDS_index_of[i])];
+    }
+  }
+#if 0
+  for(i=0;i<256;i++){
+    printf("table[%3d] = %3vu\n",i,table[i].v);
+  }
+#endif
+}
+
+void encode_rs_av(unsigned char *data,unsigned char *parity,int pad){
+  union { vector unsigned char v[2]; unsigned char c[32]; } shift_register;
+  int i;
+
+  shift_register.v[0] = (vector unsigned char)(0);
+  shift_register.v[1] = (vector unsigned char)(0);
+  
+  for(i=0;i<NN-NROOTS-pad;i++){
+    vector unsigned char feedback0,feedback1;
+    unsigned char f;
+
+    f = data[i] ^ shift_register.c[31];
+    feedback1 = table[f].v;
+    feedback0 = vec_perm(feedback1,feedback1,reverse);
+
+    /* Shift right one byte */
+    shift_register.v[1] = vec_perm(shift_register.v[0],shift_register.v[1],shift_right) ^ feedback1;
+    shift_register.v[0] = vec_sro(shift_register.v[0],(vector unsigned char)(8)) ^ feedback0;
+    shift_register.c[0] = f;
+  }
+  for(i=0;i<NROOTS;i++)
+    parity[NROOTS-i-1] = shift_register.c[i];
+}