From 57f3103e52d19c26fca380a44832cf40564aa9cd Mon Sep 17 00:00:00 2001
From: Irini Kosmidou <st155836@stud.uni-stuttgart.de>
Date: Fri, 29 Apr 2022 13:31:14 +0200
Subject: [PATCH] update

---
 linux/boardtest/UartTestClass.cpp | 28 +++++++++++++++++-----------
 linux/boardtest/UartTestClass.h   |  2 +-
 2 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/linux/boardtest/UartTestClass.cpp b/linux/boardtest/UartTestClass.cpp
index 1fa6a10c..b958579a 100644
--- a/linux/boardtest/UartTestClass.cpp
+++ b/linux/boardtest/UartTestClass.cpp
@@ -9,6 +9,9 @@
 #include <linux/devices/ScexUartReader.h>
 #include <unistd.h>  // write(), read(), close()
 
+#include <random>
+#include <string>
+
 #include "OBSWConfig.h"
 #include "fsfw/globalfunctions/CRC.h"
 #include "fsfw/globalfunctions/DleEncoder.h"
@@ -216,7 +219,7 @@ void UartTestClass::scexPeriodic() {
         // helper.getTotalPacketCounter()) { nach 2min  reader->finish();
         if (helper.getCmd() == FRAM) {
           if (not fileNameSet) {
-            fileId = gen_random(12);
+            fileId = random_string(12);
             fileName = "/tmp/scex-fram_" + fileId + ".bin";
             fileNameSet = true;
           }
@@ -382,18 +385,21 @@ void UartTestClass::handleFoundDlePacket(uint8_t* packet, size_t len) {
   sif::info << "Detected DLE encoded packet with decoded size " << len << std::endl;
 }
 
-std::string UartTestClass::gen_random(const int len) {
-  static const char alphanum[] =
+std::string UartTestClass::random_string(std::string::size_type length) {
+  static auto& chrs =
       "0123456789"
-      "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
-      "abcdefghijklmnopqrstuvwxyz";
+      "abcdefghijklmnopqrstuvwxyz"
+      "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
 
-  std::string tmp_s;
-  tmp_s.reserve(len);
+  thread_local static std::mt19937 rg{std::random_device{}()};
+  thread_local static std::uniform_int_distribution<std::string::size_type> pick(0,
+                                                                                 sizeof(chrs) - 2);
 
-  for (int i = 0; i < len; ++i) {
-    tmp_s += alphanum[rand() % (sizeof(alphanum) - 1)];
-  }
+  std::string s;
 
-  return tmp_s;
+  s.reserve(length);
+
+  while (length--) s += chrs[pick(rg)];
+
+  return s;
 }
diff --git a/linux/boardtest/UartTestClass.h b/linux/boardtest/UartTestClass.h
index 8c6bc22f..ca42a688 100644
--- a/linux/boardtest/UartTestClass.h
+++ b/linux/boardtest/UartTestClass.h
@@ -46,7 +46,7 @@ class UartTestClass : public TestTask {
 
   static void foundDlePacketHandler(const DleParser::Context& ctx);
   void handleFoundDlePacket(uint8_t* packet, size_t len);
-  std::string gen_random(const int len);
+  std::string random_string(std::string::size_type length);
 
   std::string fileId = "";
   std::string fileName = "";