Added missing file lte_gold_generic.c

openair1/PHY/LTE_TRANSPORT/lte_gold_generic.c

@@ -0,0 +1,75 @@
+/*
+ * Licensed to the OpenAirInterface (OAI) Software Alliance under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The OpenAirInterface Software Alliance licenses this file to You under
+ * the OAI Public License, Version 1.1  (the "License"); you may not use this file
+ * except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.openairinterface.org/?page_id=698
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *-------------------------------------------------------------------------------
+ * For more information about the OpenAirInterface (OAI) Software Alliance:
+ *      contact@openairinterface.org
+ */
+
+#include "PHY/types.h"
+
+/**
+   \brief Gold Sequence Generation defined in 3x.211
+   \param x1 x1 shift register
+   \param x2 x2 shift register / cinit if reset is set
+   \param reset Reset flag / reinitialize the generator
+   \return c 32 bits of gold output
+*/
+extern inline  uint32_t lte_gold_generic(uint32_t *x1, uint32_t *x2, uint8_t reset)
+{
+  int32_t n;
+
+  // 3GPP 3x.211
+  // Nc = 1600
+  // c(n)     = [x1(n+Nc) + x2(n+Nc)]mod2
+  // x1(n+31) = [x1(n+3)                     + x1(n)]mod2
+  // x2(n+31) = [x2(n+3) + x2(n+2) + x2(n+1) + x2(n)]mod2
+  if (reset)
+  {
+      // Init value for x1: x1(0) = 1, x1(n) = 0, n=1,2,...,30
+      // x1(31) = [x1(3) + x1(0)]mod2 = 1
+      *x1 = 1 + (1<<31);
+      // Init value for x2: cinit = sum_{i=0}^30 x2*2^i
+      // x2(31) = [x2(3)    + x2(2)    + x2(1)    + x2(0)]mod2
+      //        =  (*x2>>3) ^ (*x2>>2) + (*x2>>1) + *x2
+      *x2 = *x2 ^ ((*x2 ^ (*x2>>1) ^ (*x2>>2) ^ (*x2>>3))<<31);
+
+      // x1 and x2 contain bits n = 0,1,...,31
+
+      // Nc = 1600 bits are skipped at the beginning
+      // i.e., 1600 / 32 = 50 32bit words
+
+      for (n = 1; n < 50; n++)
+      {
+          // Compute x1(0),...,x1(27)
+          *x1 = (*x1>>1) ^ (*x1>>4);
+          // Compute x1(28),..,x1(31) and xor
+          *x1 = *x1 ^ (*x1<<31) ^ (*x1<<28);
+          // Compute x2(0),...,x2(27)
+          *x2 = (*x2>>1) ^ (*x2>>2) ^ (*x2>>3) ^ (*x2>>4);
+          // Compute x2(28),..,x2(31) and xor
+          *x2 = *x2 ^ (*x2<<31) ^ (*x2<<30) ^ (*x2<<29) ^ (*x2<<28);
+      }
+  }
+
+  *x1 = (*x1>>1) ^ (*x1>>4);
+  *x1 = *x1 ^ (*x1<<31) ^ (*x1<<28);
+  *x2 = (*x2>>1) ^ (*x2>>2) ^ (*x2>>3) ^ (*x2>>4);
+  *x2 = *x2 ^ (*x2<<31) ^ (*x2<<30) ^ (*x2<<29) ^ (*x2<<28);
+
+  // c(n) = [x1(n+Nc) + x2(n+Nc)]mod2
+  return(*x1^*x2);
+}