Diff: FibonacciLFSR.cpp

Revision:

0:2038ff2b7de5

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FibonacciLFSR.cpp	Sat Jun 25 03:19:45 2016 +0000
@@ -0,0 +1,31 @@
+#include "FibonacciLFSR.h"
+#include "mbed.h"
+
+FibonacciLFSR::FibonacciLFSR(LFSR_SIZE_t size){
+    this->size = size;
+    this->lfsr_period = (1 << size) - 1;    // Number of random numbers
+    this->lfsr = 0x0001;
+}
+
+uint16_t FibonacciLFSR::getRandom(){
+    switch (size){
+        case LFSR_2:
+            feedback_bit = ((lfsr >> 1) ^ (lfsr >> 0)) & 0x01;
+            break;
+        case LFSR_4:
+            feedback_bit = ((lfsr >> 3) ^ (lfsr >> 2)) & 0x01;
+            break;
+        case LFSR_8:
+            feedback_bit = ((lfsr >> 7) ^ (lfsr >> 5) ^ (lfsr >> 4) ^ (lfsr >> 3)) & 0x01;
+            break;
+        case LFSR_16:
+            feedback_bit = ((lfsr >> 15) ^ (lfsr >> 14) ^ (lfsr >> 12) ^ (lfsr >> 3)) & 0x01;
+            break;
+        default: 
+            break;
+    }
+    
+    // Shift, add feedback, AND zero extra MSb's leaving only "size" number of bits representing lfsr
+    lfsr = ((lfsr << 1) | feedback_bit) & ((1 << size) - 1); 
+    return lfsr;
+}
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