From 4f9797af3b4432a7e26279e039709b7cee5ca06e Mon Sep 17 00:00:00 2001
From: Steffen Gaisser <gaisser@irs.uni-stuttgart.de>
Date: Mon, 28 Mar 2022 21:24:33 +0200
Subject: [PATCH] Updated CCSDS CuC Functions

---
 src/fsfw/timemanager/CCSDSTime.cpp            | 12 ++++-----
 src/fsfw/timemanager/CCSDSTime.h              | 27 ++++++++++++++++---
 .../unit/timemanager/TestCCSDSTime.cpp        | 21 +++++++++++++++
 3 files changed, 50 insertions(+), 10 deletions(-)

diff --git a/src/fsfw/timemanager/CCSDSTime.cpp b/src/fsfw/timemanager/CCSDSTime.cpp
index 9ebd1d79..ff20142f 100644
--- a/src/fsfw/timemanager/CCSDSTime.cpp
+++ b/src/fsfw/timemanager/CCSDSTime.cpp
@@ -428,7 +428,7 @@ ReturnValue_t CCSDSTime::convertFromCUC(timeval* to, const uint8_t* from, size_t
   from++;
   ReturnValue_t result = convertFromCUC(to, pField, from, foundLength, maxLength - 1);
   if (result == HasReturnvaluesIF::RETURN_OK) {
-    if (foundLength != NULL) {
+    if (foundLength != nullptr) {
       *foundLength += 1;
     }
   }
@@ -588,18 +588,18 @@ ReturnValue_t CCSDSTime::convertFromCUC(timeval* to, uint8_t pField, const uint8
   uint8_t nCoarse = ((pField & 0b1100) >> 2) + 1;
   uint8_t nFine = (pField & 0b11);
   size_t totalLength = nCoarse + nFine;
-  if (foundLength != NULL) {
+  if (foundLength != nullptr) {
     *foundLength = totalLength;
   }
   if (totalLength > maxLength) {
     return LENGTH_MISMATCH;
   }
-  for (int count = 0; count < nCoarse; count++) {
-    secs += *from << ((nCoarse * 8 - 8) * (1 + count));
+  for (int count = nCoarse; count > 0; count--) {
+    secs += *from << (count * 8 - 8);
     from++;
   }
-  for (int count = 0; count < nFine; count++) {
-    subSeconds += *from << ((nFine * 8 - 8) * (1 + count));
+  for (int count = nFine; count > 0; count--) {
+    subSeconds += *from << (count * 8 - 8);
     from++;
   }
   // Move to POSIX epoch.
diff --git a/src/fsfw/timemanager/CCSDSTime.h b/src/fsfw/timemanager/CCSDSTime.h
index 19c980d0..59e16a1c 100644
--- a/src/fsfw/timemanager/CCSDSTime.h
+++ b/src/fsfw/timemanager/CCSDSTime.h
@@ -161,18 +161,37 @@ class CCSDSTime : public HasReturnvaluesIF {
    */
   static ReturnValue_t convertFromCcsds(timeval *to, uint8_t const *from, size_t *foundLength,
                                         size_t maxLength);
-
+  /**
+   * @brief Currently unsupported conversion due to leapseconds
+   *
+   * @param to Time Of Day (UTC)
+   * @param from Buffer to take the CUC from
+   * @param length Length of buffer
+   * @return ReturnValue_t UNSUPPORTED_TIME_FORMAT in any case ATM
+   */
   static ReturnValue_t convertFromCUC(Clock::TimeOfDay_t *to, uint8_t const *from, uint8_t length);
-
+  /**
+   * @brief Converts from CCSDS CUC to timeval
+   *
+   * If input is CCSDS Epoch this is TAI! -> No leapsecond support.
+   *
+   * Currently, it only supports seconds + 2 Byte Subseconds (1/65536 seconds)
+   *
+   *
+   * @param to Timeval to write the result to
+   * @param from Buffer to read from
+   * @param foundLength Length found by this function (can be nullptr if unused)
+   * @param maxLength Max length of the buffer to be read
+   * @return ReturnValue_t - RETURN_OK if successful
+   *                       - LENGTH_MISMATCH if expected length is larger than maxLength
+   */
   static ReturnValue_t convertFromCUC(timeval *to, uint8_t const *from, size_t *foundLength,
                                       size_t maxLength);
-
   static ReturnValue_t convertFromCUC(timeval *to, uint8_t pField, uint8_t const *from,
                                       size_t *foundLength, size_t maxLength);
 
   static ReturnValue_t convertFromCCS(timeval *to, uint8_t const *from, size_t *foundLength,
                                       size_t maxLength);
-
   static ReturnValue_t convertFromCCS(timeval *to, uint8_t pField, uint8_t const *from,
                                       size_t *foundLength, size_t maxLength);
 
diff --git a/tests/src/fsfw_tests/unit/timemanager/TestCCSDSTime.cpp b/tests/src/fsfw_tests/unit/timemanager/TestCCSDSTime.cpp
index a43ff8ab..e96ddfc9 100644
--- a/tests/src/fsfw_tests/unit/timemanager/TestCCSDSTime.cpp
+++ b/tests/src/fsfw_tests/unit/timemanager/TestCCSDSTime.cpp
@@ -179,6 +179,27 @@ TEST_CASE("CCSDSTime Tests", "[TestCCSDSTime]") {
     CHECK(todFromCCSDS.second == time.second);
     CHECK(todFromCCSDS.usecond == 123000);
   }
+  SECTION("CUC") {
+    timeval to;
+    // seconds = 0x771E960F, microseconds = 0x237
+    // microseconds = 567000
+    // This gives 37158.912 1/65536 seconds -> rounded to 37159 -> 0x9127
+    // This results in -> 567001 us
+    std::array<uint8_t, 7> cucBuffer = {
+        CCSDSTime::P_FIELD_CUC_6B_CCSDS, 0x77, 0x1E, 0x96, 0x0F, 0x91, 0x27};
+    size_t foundLength = 0;
+    auto result = CCSDSTime::convertFromCUC(&to, cucBuffer.data(), &foundLength, cucBuffer.size());
+    REQUIRE(result == HasReturnvaluesIF::RETURN_OK);
+    REQUIRE(foundLength == 7);
+    REQUIRE(to.tv_sec == 1619801999);  // TAI (no leap seconds)
+    REQUIRE(to.tv_usec == 567001);
+
+    Clock::TimeOfDay_t tod;
+    result = CCSDSTime::convertFromCUC(&tod, cucBuffer.data(), cucBuffer.size());
+    // This test must be changed if this is ever going to be implemented
+    REQUIRE(result == CCSDSTime::UNSUPPORTED_TIME_FORMAT);
+  }
+
   SECTION("CCSDS Failures") {
     Clock::TimeOfDay_t time;
     time.year = 2020;