From a31630e0d5b9880c716d9004ef4154396ba41ebc Mon Sep 17 00:00:00 2001
From: "Matthias P. Braendli" <matthias.braendli@mpb.li>
Date: Thu, 2 Jan 2014 21:55:13 +0100
Subject: Extract fec-3.0.1

---
 encode_rs.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 encode_rs.c

(limited to 'encode_rs.c')

diff --git a/encode_rs.c b/encode_rs.c
new file mode 100644
index 0000000..0649094
--- /dev/null
+++ b/encode_rs.c
@@ -0,0 +1,52 @@
+/* Reed-Solomon encoder
+ * Copyright 2002, Phil Karn, KA9Q
+ * May be used under the terms of the GNU Lesser General Public License (LGPL)
+ */
+#include <string.h>
+
+#ifdef FIXED
+#include "fixed.h"
+#elif defined(BIGSYM)
+#include "int.h"
+#else
+#include "char.h"
+#endif
+
+void ENCODE_RS(
+#ifdef FIXED
+data_t *data, data_t *bb,int pad){
+#else
+void *p,data_t *data, data_t *bb){
+  struct rs *rs = (struct rs *)p;
+#endif
+  int i, j;
+  data_t feedback;
+
+#ifdef FIXED
+  /* Check pad parameter for validity */
+  if(pad < 0 || pad >= NN)
+    return;
+#endif
+
+  memset(bb,0,NROOTS*sizeof(data_t));
+
+  for(i=0;i<NN-NROOTS-PAD;i++){
+    feedback = INDEX_OF[data[i] ^ bb[0]];
+    if(feedback != A0){      /* feedback term is non-zero */
+#ifdef UNNORMALIZED
+      /* This line is unnecessary when GENPOLY[NROOTS] is unity, as it must
+       * always be for the polynomials constructed by init_rs()
+       */
+      feedback = MODNN(NN - GENPOLY[NROOTS] + feedback);
+#endif
+      for(j=1;j<NROOTS;j++)
+	bb[j] ^= ALPHA_TO[MODNN(feedback + GENPOLY[NROOTS-j])];
+    }
+    /* Shift */
+    memmove(&bb[0],&bb[1],sizeof(data_t)*(NROOTS-1));
+    if(feedback != A0)
+      bb[NROOTS-1] = ALPHA_TO[MODNN(feedback + GENPOLY[0])];
+    else
+      bb[NROOTS-1] = 0;
+  }
+}
-- 
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